3Hayes, T., K. Haston, M. Tsui, A. Hoang, C. Haeffele, and A. Vonk. 2002. Atrazine Induced Hermaphroditism at 0.1 ppb in American Leopard Frogs ( Rana pipiens): Laboratory and Field Evidence. Environmental Health Perspectives.

4Hayes, T., A. Collins, M. Lee, M. Mendoza, N. Noriega, A. Stuart, A. Vonk. 2002b. Hermaphroditic, Demasculinized Frogs Following Exposure to the Herbicide Atrazine at Ecologically Relevant Low Doses. Proc. Natl. Acad. Sci U. S. A., 99 ( 8): 5476  5480.

5Carr, J. A., A. Gentles, E. E. Smith, W. L. Goleman, L. J. Urquidi, K. Thuett, R. J. Kendall, J. P. Giesy, T. S. Gross, K. R. Solomon, and G. Van Der Kraak. 2003. Response of Larval Xenopus laevis to atrazine: assessment of growth, metamorphosis, and gonadal and laryngeal morphology. Environmental Toxicology and Chemistry 22( 2): 396  405.

XI  18 Amphibians:

Studies ( Tavera Mendoza et al. 2002a1, Tavera Mendoza et al. 2002b2, Hayes et al. 2002a3, Hayes et al. 2002b4, Carr et al. 20035) have recently been conducted on the affects of atrazine on gonadal development in amphibians. These studies are in review and will be presented before a Scientific Advisory Panel in June 2003. Since the studies are currently in review, their results are not included in this discussion.

iv. Freshwater Invertebrates, Acute A freshwater aquatic invertebrate toxicity test using the TGAI is required to establish the toxicity of atrazine to aquatic invertebrates. The preferred test species is Daphnia magna. Results of this test and others are tabulated below.

Freshwater Invertebrate Acute Toxicity Surrogate Species/ Static or Flow through % ai 96 hour LC50/ EC50 FG/ L ( ppb) ( measured/ nominal) Probit Slope Toxicity Category MRID No. Author/ Year Study Classification Midge ( Chironomus tentans) Static test 94 720 ( nominal) highly toxic 00024377 Macek et al. 1976 Supplemental ( 48 hour LC50 & raw data are missing)

Midge ( Chironomus riparius) 85.5 1,000 ( unknown) highly toxic 45087413 Johnson 1986 Supplemental ( raw data are missing) Freshwater Invertebrate Acute Toxicity XI  19 Waterflea ( Daphnia magna) 85.5 3,500 ( unknown) moderately toxic 45087413 Johnson 1986 Supplemental ( raw data are missing)

Waterflea < 24 hours old ( Daphnia magna) 26 Hour static test ?? 3,600 ( unknown) at least moderately toxic 00002875 Frear & Boyd 1967 Supplemental ( unknown ai, 26 hour test & no raw data)

Waterflea ( Ceriodaphnia dubia) 48 Hour static test 97 > 4,900 ( measured) Slope  no mortality unknown 45208309 Jop 1991 Supplemental ( EC50 value not determined)

Scud ( Gammarus fasciatus) Static test 94 5,700 ( nominal) moderately toxic 00024377 Macek et al. 1976 Supplemental ( 48 hour LC50 & raw data are missing)

Stonefly ( nymph) ( Acroneuria sp.) Flow through test 67.4 mg/ L CaCO3 98.5 6,700 ( measured) moderately toxic Brooke 1990 Supplemental ( study not seen; OW in draft WQC)

Waterflea ( Daphnia magna) Static test 94 6,900 ( nominal) moderately toxic 00024377 Macek et al. 1976 Supplemental ( raw data are missing)

Scud juvenile ( Hyalella azteca) Flow through test 67.4 mg/ L Ca CO3 98.5 14,700 ( measured) slightly toxic Brooke 1990 Supplemental ( no study; cited by OW in draft WQC)

Scud juvenile ( Gammarus pulex) Static renewal  daily ?? 14,900 ( measured) 4.4 @ 10 days slightly toxic 45202917 Taylor, Maund & Pascoe 1991 Supplemental ( raw data are missing)

Leech ( Glossiphonia complanata) Static renewal weekly 99.2 > 16,000 ( measured) 6,300 Fg/ L @ 28 days slightly toxic 45202916 Streit & Peter 1978 Supplemental ( raw data are missing)

Leech ( Helobdella stagnalis) Static renewal weekly 99.2 > 16,000 ( measured) 9,900 Fg/ L @ 27 days slightly toxic 45202916 Streit & Peter 1978 Supplemental ( raw data are missing)

Snail ( Ancylus fluviatilis) Static renewal weekly 99.2 > 16,000 ( measured) > 16, 000 Fg/ L @ 40 days ( 35 % mortality) slightly toxic 45208305 Oris, Winner & Moore 1991 Supplemental ( raw data are missing)

Waterflea < 12 hr old ( Ceriodaphnia dubia) Static 48 hour test 57 mg/ L CaCO3 > 99 > 30,000 ( measured) Slope  no data slightly toxic 45202917 Taylor, Maund & Pascoe 1991 Supplemental ( raw data are missing)

Midge ( Chironomus riparius) Static renewal  daily 10 Day test ?? > 33,000 ( measured) 18,900 Fg/ L @ 10 days slightly toxic 00027204 Drake 1976 Supplemental ( raw data are missing) ( EC50 115 ppm exceeds water solubility ( 33 ppm)

Formulations % ai Product Waterflea ( Daphnia magna) Flow through test 79.6 80 WP 49,000 ( higher concs. than 31,000 Fg/ L were cloudy) ( measured) slope 2.433 slightly toxic 42041401 Putt 1991 Supplemental for formulation ( EC50 was not identified due to insolubility) Freshwater Invertebrate Acute Toxicity XI  20 Waterflea ( Daphnia pulex) Static test; 15EC 282 mg/ L hardness With & without sediment 40.8 4 L 36,500 ( nominal) 46,500 ( with sediment) slightly toxic 45227712 Hartman & Martin 1985 Supplemental for formulation ( EC50 exceeds water solublity and low temp.)

Since the lowest LC50/ EC50 is in the range of 0.1 to 1 ppm, atrazine is categorized as highly toxic to aquatic invertebrates on an acute basis. The guideline requirement ( 72 2) is not fulfilled.

Degradates: The major atrazine degradate, hydroxyatrazine, forms a large percentage of the recoverable pesticide in aquatic compartments of the environment. Therefore, acute aquatic invertebrate testing with Daphnia magna is required to address degradate concerns. The requirement for the special degradate test ( 72 2) has not been fulfilled.

v. Freshwater Invertebrate, Chronic A freshwater aquatic invertebrate life cycle test using the TGAI is required for atrazine since the end use product is expected to be transported to water from the intended use site and the following conditions are met: the pesticide is intended for use such that its presence in water is likely to be continuous; an aquatic acute LC50 is less than 1 mg/ L; and the pesticide is persistent in water ( i. e., half life greater than 4 days). The preferred test species is Daphnia magna. Results of these tests are tabulated below.

Freshwater Aquatic Invertebrate Life Cycle Toxicity Surrogate Species/ Study Duration/ Flow through or Static Renewal % ai NOEC/ LOEC Fg/ L ( ppb) ( measured or nominal) Statistically sign. ( p= 0.05) Endpoints Affected MRID No. Author/ Year Study Classification Scud ( Gammarus fasciatus) 30 days / flow through 94 NOAEC 60 LOAEC 140 ( measured) 25 % red. in development of F1 to seventh instar. 00024377 Macek et al. 1976 Core Midge ( Chironomus tentans) 38 days / flow through 94 NOAEC 110 LOAEC 230 ( measured) 25 % red. in F0 pupation 29 % red. in F0 adult emergence 18 % red. in F1 pupation 28 % red. in F1 adult emergence 00024377 Macek et al. 1976 Core Waterflea ( Daphnia magna) 21 days / flow through 94 NOAEC 140 LOAEC 250 ( measured) 54 % red. in F0 young/ female 00024377 Macek et al. 1976 Core Waterflea ( Daphnia pulex) 28 Day static renewal 70 Day static renewal test 99.2 NOAEC 1,000 LOAEC 2,000 ( nominal) 16 % sign. red. in young/ adult 31 % red. in young/ adult 45202915 Schober & Lampert 1977 Supplemental ( no raw data for statistical analyses) Freshwater Aquatic Invertebrate Life Cycle Toxicity XI  21 Waterflea  6 generations ( Daphnia magna) Static renewal test ?? Cups: NOAEC 200 LOAEC 2,000 ( unknown) 4 L aquarium: NOAEC ?? LOAEC ?? ( water from treated corrals) 66 % reduction in # of young in generations 4, 5, & 6.

72% reduction in # of young Kaushik, Solomon, Stephenson and Day 1985 Supplemental ( methods and raw data are not reported)

Leech ( Helobdella stagnalis) 40 Days Static Renewal weekly 99.2 NOAEC < 1,000 LOAEC 1,000 ( measured) 65% red. in percent hatch 45202916 Streit & Peter 1978 Supplemental ( no raw data for statistical analyses)

Waterflea < 12 hr. old ( Ceriodaphnia dubia) Two 7 Day static renewal tests; Renewed M, W, & F 57 CaCO3; Temp. 25EC > 99 NOAEC 2,500 LOAEC 5,000 NOAEC 2,500 LOAEC 5,000 ( measured) sign. red. in mean total number of young per living female ( 3 broods) 45208305 Oris, Winner and Moore 1991 Supplemental ( no raw data for analyses)

Green hydra ( normal) ( Chlorohydra viridissima) 21 Day Static test ?? NOAEC < 5,000 LOAEC 5,000 ( nominal) sign. red. in budding rates 45202901 Benson & Boush 1983 Supplemental ( no raw data for analyses)

Waterflea 3 day old adult ( Ceriodaphnia dubia) Two 4 Day static renewal tests; Renewed M & W 57 CaCO3; Temp. 25EC > 99 NOAEC 5,000 LOAEC 10,000 NOAEC 10,000 LOAEC 20,000 ( measured) sign. red. in mean total number of young per living female ( 3 broods) 45208305 Oris, Winner and Moore 1991 Supplemental ( no raw data for analyses)

Freshwater Snail ( Ancylus fluviatilis) 40 Days Static Renewal weekly 99.2 1,000 4,000 16,000 ( measured) 38 39% red. in egg capsules & eggs in April/ May 56 57% red. in eggs in April/ May 15 16% red. in eggs in July/ Aug. 68 73% red. in eggs in April/ May 65 71% red. in eggs in July/ Aug. 45202916 Streit & Peter 1978 Supplemental ( no raw data for statistical analyses)

Leech ( Glossiphonia complanata) 27 Days Static Renewal weekly 99.2 1,000 4,000 16,000 ( measured) no reduction in egg production 17 % higher mortality 33 % higher mortality 67 % higher mortality 45202916 Streit & Peter 1978 Supplemental ( no raw data for statistical analyses)

Growth stages and/ or number of young are reduced by atrazine exposures for insects and crustaceans. The guideline requirement ( 72 4) is fulfilled ( MRID 00024377).

Daphnia pulicaria was tested in a 12 day partial life cycle study to determine whether atrazine has an effect on the sex ratio ( Madsen, 2000). No male Daphnia young were found at measured test concentrations 0, 0.93, 4.1, 8.7, 44, and 87 Fg/ L ( MRID # 45299504).

Degradates: The major atrazine degradate is hydroxyatrazine which forms a large percent of the recoverable pesticide in aquatic compartments of the environment. Therefore, a special aquatic invertebrate life cycle test ( 72 4) is reserved to address degradate concerns, pending the results of acute test.

vi. Freshwater Field Studies XI  22 Walker ( 1964) treated Missouri ponds and plastic lined limnocorrals with atrazine for aquatic weed control at levels of 500 to 2,000 Fg/ L and quantitatively examined effects on bottom organisms. Among the most sensitive organisms were mayflies ( Ephemeroptera), caddis flies ( Tricoptera), leeches ( Hirudinea) and gastropods ( Musculium). The most significant reduction in bottom fauna was observed during the period immediately following the application. Six to eight weeks after treatment, nine out of fourteen taxonomic groups had not recovered. The total number of bottom organisms per square foot was 52 percent lower than in the controls. In addition, three categories ( water bugs, mosquitoes, and leeches) were no longer present. ( MRID # 45202919).

Streit and Peter ( 1978) reviewed Walker's findings and investigated long term atrazine effects on three benthic freshwater invertebrates: Ancylus fluviatilis ( Gastropoda  Basommatophora), Glossiphonia complanata and Helobdella stagnalis ( both: Annelida  Hirudinea) in the laboratory ( see Chronic Invertebrate toxicity table). Ingestion rates for G. complanata were determined over a 27 day period at atrazine concentrations of 1, 4 and 16 ppm. The total ingestion per individual was measured daily ( except between Day 23 and 27). Two significant results were: ( 1) Contaminated leeches ate significantly more limpets than the controls ( 300, 345 and 405% of control ingestion rates for 1,000, 4,000 and 16,000 Fg/ L atrazine exposures, respectively). ( 2) There was a constant feeding intensity from immediately after the beginning of the exposure period. The same phenomenon was seen for snails, A. fluviatilis, but the intensity of feeding was much less ( i. e., 120, 130 and 140% of control ingestion rates at 1,000, 4,000 and 16,000 Fg/ L, respectively). Other observations included: ( 1) Leeches found sometimes lying on their backs suggesting that they have difficulty staying firmly attached to the substrate. ( 2) With increasing atrazine concentrations, an increasing percentage of snails could be detected that were just sucked out but not wholly eaten. Similar effects were observed with the snails which suggest that leech and snail behavior might be affected in some way. Compared to controls, Ancylus egg production was significantly reduced after 40 days exposure to atrazine at 16,000 Fg/ L in March/ April, April/ May ( 68% fewer egg capsules and 73% fewer eggs) and July/ August ( 65% fewer egg capsules and 71% fewer eggs). Lower Ancylus reproduction was also found at 4 Fg/ L in April/ May ( 56 57 percent) and July/ August ( 15 16 percent). At 1,000 Fg/ L, fewer capsules and eggs were found only in April/ May ( 38 and 39 percent, respectively). The average number of eggs per brood in leech, Glossiphonia complanata was not affected by 27 days of atrazine exposure. The no significant effect was found on the number of live born young of Helobdella stagnalis. At 1,000 and 4,000 Fg/ L only a part of the egg masses developed. Only about 10 percent of the young in the 16,000 Fg/ L treatment hatched. Atrazine did not affect the time for normal development ( 5 6 days). ( MRID # 45202916).

Kettle et al. ( 1987) monitored effects of atrazine ( 40.8%) on diet and reproductive success of bluegill in experimental, Kansas ponds. The 0.045 hectare, 2.1 meter deep ponds were each stocked with adult fish ( 50 bluegills, 20 channel catfish and 7 gizzard shad). On July 24, atrazine was applied to two ponds at 20 Fg/ L, another two ponds at 500 Fg/ L and two controls. Atrazine concentrations were measured during the study and 70% of the original concentration was detected at the end of the 136 day study. Bluegills were the only species to spawn during the study. Atrazine had no significant effect on mortality of the original stocked fish, but the XI  23 number of young bluegills retrieved were significantly ( p < 0.01) reduced compared to control ponds ( i. e., 95.7 % fewer in 20 Fg/ L treated ponds and 96.1 % fewer in 500 Fg/ L treated ponds). Stomach analyses of adult bluegills indicate that the bluegill controls had significantly ( p < 0.001) higher numbers of food items per fish stomach and higher numbers of prey taxa per fish stomach. The number of food items per stomach were reduced 85 and 78 percent in 20 and 500 Fg/ L  treated ponds, respectively. Reductions in taxa per stomach were 57 and 52 percent in 20 and 500 Fg/ L treated ponds, respectively. Stomachs of bluegills from treated ponds had fewer numbers of Ephemeroptera ( p < 0.001), Odonata ( p < 0.001), Coleoptera ( p < 0.01) and Diptera ( not significant, p > 0.05) than the controls. The macrophyte community in treated ponds was noticeably reduced, relative to controls, throughout the summer. Visual estimates of the macrophyte communities in the ponds showed roughly a 60 percent decline in the 20 Fg/ L ponds and a 90 percent decline in the 500 Fg/ L ponds two months after atrazine addition. These estimates were verified by rake hauls which produced these same relative differences. The following May, 10 months after treatment, when macrophytes are normally well established in Kansas ponds, the ponds were drained. Relative to control ponds, 20 Fg/ L ponds had a 90 percent reduction in macrophyte coverage and the 500 Fg/ L ponds had a > 95 percent reduction in macrophyte coverage. Differences were noted in the macrophyte species present. Control ponds contained Potamogeton pusillus and P. nodosus, Najas quadalupensis, and small amounts of Chara globularis, whereas the treated ponds contained mostly C. globularis. ( MRID # 45202912).

c. Toxicity to Estuarine and Marine Animals i. Estuarine and Marine Fish, Acute Acute toxicity testing with estuarine/ marine fish using the TGAI is required for atrazine because the end use product is expected to reach this environment because of its use in coastal counties. The preferred test species is sheepshead minnow. Results of these tests are tabulated below.

Estuarine/ Marine Fish Acute Toxicity Surrogate Species/ Static or Flow through/ Salinity & Temperature % ai 96 hour LC50 ( ppb) ( measured/ nominal) Probit Slope Toxicity Category MRID No. Author/ Year Study Classification Sheepshead Minnow larvae < 24 hours old ( Cyprinodon variegatus) Static test, T  20EC Salinity 25, 15, 5 g/ L; 97.1 Sal. 25 g/ L 2,000 Sal. 15 g/ L 2,300 Sal. 5 g/ L 16,200 ( measured) Slope  no data moderately toxic 45208303 & 45227711 Hall, Jr., Ziegenfuss, Anderson, Spittler & Leichtweis 1994 Supplemental ( no raw data on mortalities)

Spot ( Leiostomus xanthurus) Static test Salinity  12 g/ L; T  22+ 1EC 97.4 8,500 ( nominal) Slope  no data moderately toxic 45202920 Ward & Ballantine 1985 Supplemental ( no raw data)

Sheepshead minnow ( Cyprinodon variegatus) Flow through test Salinity  31 g/ L; T  22 23EC 97.1 13,400 ( measured) Slope 4.377 slightly toxic 43344901 Machado 1994 Core Estuarine/ Marine Fish Acute Toxicity Surrogate Species/ Static or Flow through/ Salinity & Temperature % ai 96 hour LC50 ( ppb) ( measured/ nominal) Probit Slope Toxicity Category MRID No. Author/ Year Study Classification XI  24 Spot ( juvenile) ( Leiostomus xanthurus) Flow through test Salinity  29 g/ L; T  28EC 99.7 > 1,000 ( nominal) Slope  none unknown 40228401 Mayer 1986 Supplement ( 48 hour test)

Sheepshead minnow ( Cyprinodon variegatus) Flow through test 97.4 > 16,000 ( 30 % mortlity) ( measured) Slope  none unknown 45202920 Ward & Ballantine 1985 Supplemental ( no raw data)

Since the LC50 are in the range of 1  10 ppm, Atrazine is categorized as moderately toxic to estuarine/ marine fish on an acute basis. Toxicity data on sheepshead minnow, Cyprinodon variegatus, indicates that atrazine toxicity increases with increasing salinity levels. The pattern of increasing toxicity is opposite to atrazine toxicity data on the copepod, Eurytemora affinis. The guideline requirement ( 72 3a) is fulfilled ( MRID 43344901).

Degradates: The major atrazine degradate, hydroxyatrazine, forms a large percentage of the recoverable pesticide in aquatic environmental compartments. Therefore, a special acute estuarine fish test ( 72 3) is required to address concerns for the toxicity of atrazine degradates to estuarine fish ( preferably sheepshead minnow). The requirement ( 72 3) has not been fulfilled.

ii. Estuarine and Marine Fish, Chronic An estuarine/ marine fish early life stage toxicity test using the TGAI is required for atrazine because the end use product may be applied directly to the estuarine/ marine environment or is expected to be transported to this environment from the intended use site, and the following conditions are met: the pesticide is intended for use such that its presence in water is likely to be continuous; an aquatic acute LC50 or EC50 is less than 1 mg/ L; and the pesticide is persistent in water ( i. e., half life greater than 4 days). The preferred test species is sheepshead minnow. Results of this test are tabulated below.

Estuarine/ Marine Fish Early Life Stage Toxicity Under Flow through Conditions Surrogate Species/ Study Duration/ Flow through or Static Salinity & Temperature % ai NOAEC/ LOAEC Fg/ L ( ppb) ( measured or nominal) Statistically sign. ( p= 0.05) Endpoints Affected MRID No. Author/ Year Study Classification Sheepshead Minnow ( Cyprinodon variegatus) Study duration  unknown Flow through test Salinity  13g/ L; T 30+ 1EC 97.4 NOAEC 1,900 LOAEC 3,400 ( measured) 89 % red. in juvenile survival 45202920 Ward & Ballantine 1985 Supplemental ( no raw data for statistical analyses)

Biagianti Risbourg and Bastide ( 1995) exposed juvenile gray mullets ( Liza ramada) to 170 Fg/ L atrazine for 9, 20, and 29 days in static tests and for 11 days followed by 18 days of XI  25 decontamination; and then measured the sublethal effects on the liver. At 170 Fg/ L, 10, 25 and 60 percent mortality occurred following 9, 20 and 29 day exposures, respectively; control mortality was a constant 10 percent throughout the test. Treated mullets showed normal behavior until Day 20 after which they stopped feeding and rapidly died; which is in contrast to the 90 percent survival of the treated fish that were transferred to clean water after 11 days of exposure. After 3 days exposure, a number of abnormalities were found in the liver ( i. e., hepatic parenchyma with a few cytologically detectable perturbations and hepatocytes had particularly large lipofuscin granules ( MRID # 45204902). The guideline requirement ( 72 4) is not fulfilled since the study was lacking raw data and could not be evaluated.

Degradates: The major atrazine degradate, hydroxyatrazine, forms a large percentage of the recoverable pesticide in aquatic environmental compartments. Therefore, a special estuarine fish early life stage test ( 72 4) is considered to address concerns for the toxicity of atrazine degradates to estuarine fish ( preferably sheepshead minnow). The requirement ( 72 4) has not been fulfilled and is reserved pending the results of the acute estuarine fish test.

An estuarine/ marine fish life cycle test using the TGAI is reserved pending the results of acute and early life stage tests on estuarine fish studies. The guideline requirements ( 72 5) is reserved.

iii. Estuarine and Marine Invertebrates, Acute Acute toxicity testing with estuarine/ marine invertebrates using the TGAI is required for atrazine because the end use product is expected to reach this environment because of its use in coastal counties. The preferred test species are mysid shrimp and eastern oyster. Results of these tests are tabulated below.

Estuarine/ Marine Invertebrate Acute Toxicity Surrogate Species/ Static or Flow through/ Salinity & Temperature % ai. 96 hour LC50/ EC50 Fg/ L ( ppb) ( measured/ nominal) Probit Slope Toxicity Category MRID No. Author/ Year Study Classification Copepod ( Acartia tonsa) Static renewal  daily Salinity  31 g/ L; T 22EC 70 Tech. 88 ( measured) Slope 0.947 very highly toxic 45202918 Thursby et al. 1990 memo Supplemental ( 12% control mortality)

Copepod ( Acartia tonsa) Static test Salinity  20 g/ L; T 20+ 1EC 97.4 94 ( nominal) Slope  none very highly toxic 45202920 Ward & Ballantine 1985 Supplemental ( no raw data)

Copepod ( Acartia tonsa) Static renewal  daily Salinity  31 32 g/ L; T 22EC 70 Tech. 139 ( measured) Slope 0.543 highly toxic 45202918 Thursby et al. 1990 memo Supplemental ( 20% control mortality)

Copepod nauplii < 24 hours old ( Eurytemora affinis) Static test; T  20EC Salinity  5, 15 & 25g/ L 97.1 Sal. 5 g/ L 500 Sal. 15 g/ L 2,600 Sal. 25 g/ L 13,300 ( measured) Slope  no data highly toxic to slightly toxic 45208303 & 45227711 Hall, Ziegenfuss, Anderson, Spittler & Leichtweis 1994 Supplemental ( no raw data on mortality) Estuarine/ Marine Invertebrate Acute Toxicity Surrogate Species/ Static or Flow through/ Salinity & Temperature % ai. 96 hour LC50/ EC50 Fg/ L ( ppb) ( measured/ nominal) Probit Slope Toxicity Category MRID No. Author/ Year Study Classification XI  26 Mysid Shrimp ( Americamysis bahia) Flow through test Salinity 26 g/ L; T 22+ 1EC 97.4 1,000 ( Measured) Slope  none highly toxic 45202920 Ward & Ballantine 1985 Supplemental ( no raw data)

Brown Shrimp ( juvenile) ( Penaeus aztecus) Flow through test Salinity  30 g/ L; T 27EC 99.7 1,000 ( nominal) Slope  none at least highly toxic 40228401 Mayer 1986 Supplemental ( 48 hr LC50 & no raw data)

Copepod  17 days old ( Acartia tonsa) Flow through test Salinity  31 33 / L, T  20EC 97.1 4,300 ( measured) Slope  2.467 moderately toxic 45208308 McNamara 1991 Supplemental ( cloudy with no 0.45 Fm filter of undissolved test material)

Mysid Shrimp ( Americamysis bahia) Flow through test Salinity  32 g/ L; T 25 26EC 97.1 5,400 ( measured) Slope 4.513 moderately toxic 43344902 Machado 1994 Core Pink Shrimp ( Penaeus duorarum) Static test Salinity 26 g/ L; T 22+ 1EC 97.4 6,900 ( nominal) Slope  none moderately toxic 45202920 Ward & Ballantine 1985 Supplemental ( no raw data)

Copepod ( Acartia clausii) Static renewal  daily Salinity  31 g/ L; T 6 6.2EC 70 Tech. 7,900 ( nominal) Slope 0.958 moderately toxic 45202918 Thursby et al. 1990 memo Core Grass Shrimp ( Palaemonetes pugio) Static test Salinity  26 g/ L; T 22+ 1EC 97.4 9,000 ( nominal) Slope  none Moderately toxic 45202920 Ward & Ballantine 1985 Supplemental ( no raw data)

Eastern oyster ( juvenile) ( Crassostrea virginica) ( Shell deposition) Flow through test Salinity  28 g/ L; T  28EC 99.7 > 1,000 no effect ( nominal) Slope  none unknown 40228401 Mayer 1986 Supplemental ( EC50 has not been identified & no raw data)

Mud Crab ( Neopanope texana) Static test Salinity & T  unknown Tech. > 1,000 ( nominal) Slope  none slightly toxic 00024719 Bentley & Macek 1973 Supplemental ( LC50 exceeds water solubility)

Since the lowest acute LC50/ EC50 value is in the range of > 1  10 ppm, atrazine is categorized as moderately toxic to estuarine/ marine invertebrates on an acute basis. Toxicity data on the copepod, Eurytemora affinis, indicates that atrazine toxicity decreases with increasing salinity levels. The pattern of decreasing toxicity is opposite to atrazine toxicity data on sheepshead minnows, Cyprinodon variegatus. The guideline requirement ( 72 3c) for shrimp is fulfilled ( MRID 43344902), but the guideline requirement ( 72 3b) for oysters is not fulfilled. XI  27 Estuarine/ Marine Invertebrate Acute Toxicity  Formulations Surrogate Species/ Static or Flow through % ai. Product 96 hour LC50/ EC50 Fg/ L ( ppb) ( measured/ nominal) Probit Slope Toxicity Category MRID No. Author/ Year Study Classification Eastern Oyster ( Crassostrea virginica) ( Shell deposition) Flow through test Salinity  11.8 mg/ L; T 21EC 79.6 80 WP > 800 no effect ( nominal) Slope  none unknown 00024720 Wright & Beliles 1966 Supplemental ( EC50 has not been identified)

Pacific Oyster ( Crassostrea gigas) 24 Hour Static Renewal ?? > 100 ( nominal) 0.1  50% dead at 22 days 0.2  50% dead at 18 days unknown 45227722 Moraga & Tanguy 2000 Supplemental ( no 96 hour LC50 value)

European Brown Shrimp ( Crangon crangon) Static test; 15EC ?? WP 10,000  33,000 ( nominal) no slope slightly toxic 45227728 Portmann 1972 Supplemental ( only 48 hours & no raw data)

European Cockle ( Cardium edule) Static test; 15EC ?? WP > 100,000 ( nominal) no slope practically non toxic 45227728 Portmann 1972 Supplemental ( only 48 hours; LC50 exceeds water solubility & no raw data)

Fiddler Crab ( Uca pugilator) Static test Salinity  30 g/ L; T 19EC 79.6 80 WP 198,000 ( nominal) Slope  none unknown 00024395 Union Carbide Corp. 1975 Supplemental ( LC50 exceeds water solubility)

Fiddler Crab ( Uca pugilator) Static test Salinity  30 g/ L; T 19EC Unknown 4 1 3 1 WDL 239,000 ( nominal) Slope  none unknown 00024395 Union Carbide Corp. 1975 Supplemental ( LC50 exceeds water solubility)

The toxicity of formulated atrazine products to marine/ estuarine invertebrates are uncertain, because the EC/ LC50 values are not definitive.

Degradates: The major atrazine degradate, hydroxyatrazine, forms a large percentage of the recoverable pesticide in aquatic environmental compartments. Therefore, estuarine invertebrate acute tests ( 72 3b and c) are required to address concerns for the toxicity of atrazine degradates to estuarine invertebrates ( preferably Americamysis bahia and Crassostrea virginica). The requirement ( 72 3b and c) have not been fulfilled for any atrazine degradate.

iv. Estuarine and Marine Invertebrate, Chronic An estuarine/ marine invertebrate life cycle toxicity test using the TGAI is required for atrazine because the end use product may be applied directly to the estuarine/ marine environment or is expected to be transported to this environment from the intended use site, and the following conditions are met: the pesticide is intended for use such that its presence in water is likely to be continuous and recurrent; an aquatic acute EC50 is less than 1 mg/ L; and the pesticide is persistent in water ( e. g., half life greater than 4 days). The preferred test species is mysid shrimp. Results of this test are tabulated below. XI  28 Estuarine/ Marine Invertebrate Life Cycle Toxicity Species/ Duration/ Flow through/ Static renewal % ai NOAEC/ LOAEC Fg/ L ( ppb) ( measured/ nominal) Statistically sign. ( P= 0.05) Endpoints Affected MRID No. Author/ Year Study Classification Mysid ( Americamysis bahia) Duration of test  unknown Flow though test Salinity 20 g/ L; 25+ 1EC 97.4 NOAEC 80 LOAEC 190 ( measured) 37 % red. in adult survival 45202920 Ward & Ballantine 1985 Supplemental ( no raw data for statistical analyses)

The guideline requirement ( 72 4b) for an estuarine invertebrate life cycle test is not fulfilled.

Degradates: The major atrazine degradate, hydroxyatrazine, forms a large percentage of the recoverable pesticide in aquatic environmental compartments. Therefore, a special estuarine invertebrate life cycle test ( 72 3) is required to address concerns for the toxicity of atrazine degradates to estuarine invertebrates ( preferably Americamysis bahia). The requirement ( 72 4b) has not been fulfilled for any atrazine degradate, but is reserved pending the results of the acute mysid test.

v. Estuarine and Marine Field Studies Field studies are not available with atrazine effects on estuarine and/ or marine animals. No estuarine field studies are required.

d. Toxicity to Plants I. Terrestrial Terrestrial plant testing ( seedling emergence and vegetative vigor) is required for herbicides that have terrestrial non residential outdoor use patterns and that may move off the application site through volatilization ( vapor pressure > 1.0 x 10 5mm Hg at 25oC) or drift ( aerial or irrigation) and/ or that may have endangered or threatened plant species associated with the application site.

For seedling emergence and vegetative vigor testing the following plant species and groups should be tested: ( 1) six species of at least four dicotyledonous families, one species of which is soybean ( Glycine max) and the second is a root crop, and ( 2) four species of at least two monocotyledonous families, one of which is corn ( Zea mays).

Terrestrial Tier II studies are required for all herbicides and any pesticide showing a negative response equal to or greater than 25% in Tier I tests. Tier II tests measure the response of plants, relative to a control, and five or more test concentrations at a test level that is equal to the highest use rate ( expressed as lbs ai/ A). Results of Tier II toxicity testing on the technical material are tabulated below. XI  29 Nontarget Terrestrial Plant Seedling Germination Toxicity ( Tier II)

Surrogate Species % ai EC25/ EC05 ( lbs ai/ A) Probit Slope Endpoint Affected MRID No. Author/ Year Study Classification Monocot  Corn ( Zea mays) 97.7 < 4.0 / < 4.0 No effect 41223001 Chetram 1989 Core Monocot  Oat ( Avena sativa) 97.7 1.8 / 0.12 slope 0.834 % red.. in radicle length 41223001 Chetram 1989 Core Monocot  Onion ( Allium cepa) 97.7 < 4.0 /< 4.0 No effect 41223001 Chetram 1989 Core Monocot  Ryegrass ( Lolium perenne) 97.7 < 4.0 / < 4.0 slope 0.834 No effect 41223001 Chetram 1989 Core Dicot  Root Crop  Carrot ( Daucus carota) 97.7 < 4.0 / < 4.0 No effect 41223001 Chetram 1989 Core Dicot  Soybean ( Glycine max) 97.7 < 4.0 / < 4.0 No effect 41223001 Chetram 1989 Core Dicot  Lettuce ( Lactuca sativa) 97.7 < 4.0 / < 4.0 No effect 41223001 Chetram 1989 Core Dicot  Cabbage ( Brassica oleracea alba) 97.7 < 4.0 / < 4.0 No effect 41223001 Chetram 1989 Core Dicot  Tomato ( Lycopersicon esculentum) 97.7 < 4.0 / < 4.0 No effect 41223001 Chetram 1989 Core Dicot  Cucumber ( Cucumis sativus) 97.7 0.80 / 0.60 slope 0.864 % red. in radicle length 41223001 Chetram 1989 Core Results from the Tier II seedling germination tests indicate that cucumber is the most sensitive dicot and oats is the most sensitive monocot. These studies are acceptable ( MRID 41223001), but the guideline requirement for seed germination testing has now been included in the seedling emergence toxicity test.

Nontarget Terrestrial Plant Seedling Emergence Toxicity ( Tier II)

Surrogate Species % ai EC25 / NOAEC ( lbs ai/ A) Probit Slope Endpoint Affected MRID No. Author/ Year Study Classification Monocot  Corn ( Zea mays) 97.7 < 4.0 / < 4.0 No effect 42041403 Chetram 1989 Core Monocot  Oat ( Avena sativa) 97.7 0.004 / 0.0025 red. in dry weight 42041403 Chetram 1989 Core Monocot  Onion ( Allium cepa) 97.7 0.009 / 0.005 red. in dry weight 42041403 Chetram 1989 Core Monocot  Ryegrass ( Lolium perenne) 97.7 0.004 / 0.005 red. in dry weight 42041403 Chetram 1989 Core Dicot  Root Crop  Carrot ( Daucus carota) 97.7 0.003 / 0.0025 red. in dry weight 42041403 Chetram 1989 Core Dicot  Soybean ( Glycine max) 97.7 0.19 / 0.025 red. in dry weight 42041403 Chetram 1989 Core Dicot  Lettuce ( Lactuca sativa) 97.7 0.005 / 0.005 red. in dry weight 42041403 Chetram 1989 Core Nontarget Terrestrial Plant Seedling Emergence Toxicity ( Tier II)

Surrogate Species % ai EC25 / NOAEC ( lbs ai/ A) Probit Slope Endpoint Affected MRID No. Author/ Year Study Classification XI  30 Dicot  Cabbage ( Brassica oleracea alba) 97.7 0.014 / 0.01 red. in dry weight 42041403 Chetram 1989 Core Dicot  Tomato ( Lycopersicon esculentum) 97.7 0.034 / 0.01 red. in dry weight 42041403 Chetram 1989 Core Dicot  Cucumber ( Cucumis sativus) 97.7 0.013 / 0.005 red. in dry weight 42041403 Chetram 1989 Core For Tier II seedling emergence, the most sensitive dicot is the carrot and the most sensitive monocots are oat and ryegrass. The guideline requirement ( 123 1a) is fulfilled ( MRID 42041403).

Nontarget Terrestrial Plant Vegetative Vigor Toxicity ( Tier II)

Surrogate Species % ai EC25 / NOAEC ( lbs ai/ A) Endpoint Affected MRID No. Author/ Year Study Classification Monocot  Corn ( Zea mays) 97.7 < 4.0 / < 4.0 No effect 42041403 Chetram 1989 Core Monocot  Oat ( Avena sativa) 97.7 2.4 / 2.0 red. in dry weight 42041403 Chetram 1989 Core Monocot  Onion ( Allium cepa) 97.7 0.61 / 0.5 red. in dry weight 42041403 Chetram 1989 Core Monocot  Ryegrass ( Lolium perenne) 97.7 < 4.0 / < 4.0 No effect 42041403 Chetram 1989 Core Dicot  Root Crop  Carrot ( Daucus carota) 97.7 1.7 / 2.0 red. in plant height 42041403 Chetram 1989 Core Dicot  Soybean ( Glycine max) 97.7 0.026 / 0.02 red. in dry weight 42041403 Chetram 1989 Core Dicot  Lettuce ( Lactuca sativa) 97.7 0.33 / 0.25 red. in dry weight 42041403 Chetram 1989 Core Dicot  Cabbage ( Brassica oleracea alba) 97.7 0.014 / 0.005 red. in dry weight 42041403 Chetram 1989 Core Dicot  Tomato ( Lycopersicon esculentum) 97.7 0.72 / 0.5 red. in plant height 42041403 Chetram 1989 Core Dicot  Cucumber ( Cucumis sativus) 97.7 0.008 / 0.005 red. in dry weight 42041403 Chetram 1989 Core For Tier II vegetative vigor, the most sensitive dicot is cucumber and the most sensitive monocot is onion. The guideline requirement ( 123 1b) is fulfilled ( MRID 42041402).

ii. Aquatic Plants Aquatic plant testing is required for any herbicide that has outdoor non residential terrestrial uses that may move off site by runoff ( solubility > 10 ppm in water), by drift ( aerial or irrigation), or XI  31 that is applied directly to aquatic use sites ( except residential). Aquatic Tier II studies are required for all herbicides and any pesticide showing a negative response equal to or greater than 50% in Tier I tests. The following species should be tested at Tier II: Kirchneria subcapitata, Lemna gibba, Skeletonema costatum, Anabaena flos aquae, and a freshwater diatom. Aquatic plant testing is required for atrazine because atrazine is applied on crops outdoors and would appear to be mobile with a water solubility value of 33 ppm.

Results of Tier II toxicity testing on technical grade and typical end use products ( TEP) are tabulated below. The data are presented in four toxicity tables separating the freshwater data from the marine data and the short, 7 day or less tests from the longer tests.

Nontarget Freshwater Plant Toxicity ( Tier II)

Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification Vascular Plants:

Duckweed ( Lemna gibba) 5 Day test; Static Renewal 97 170 ( nominal) Slope 3.93 50% red. in growth 41065203d Hughes 1986 Supplemental ( 5 days, not 14 days)

Duckweed ( Lemna gibba) 7 Day test; Static Renewal 97 170 ( measured) Slope 2.2 50% red. in growth 42041404 Hoberg 1991 Supplemental ( 7 days, not 14 days)

Non Vascular Plants:

Cyanophyceae Oscillatoria lutea ( 1week; nominal) 76 80 W < 1 1,000 93% red. chlorophyll production 100% red. chlorophyll prod. Torres and O'Flaherty 1976 Supplemental ( raw data unavailable)

Chlorophyceae Stigeoclonium tenue ( 1 week; nominal) 76 80 W < 1 1,000 67% red. chlorophyll production 90% red. chlorophyll production Torres and O'Flaherty 1976 Supplemental ( raw data unavailable)

Green Algae  Chlorophyceae Chlorella vulgaris ( 1 week; nominal) 76 80 W 1 1,000 50% red. chlorophyll production 80 87% red. chlorophyll production Torres and O'Flaherty 1976 Supplemental ( raw data unavailable)

Xanthophyceae Tribonema sp. ( 1 week; nominal) 76 80 W 1 1,000 42% red. chlorophyll production 75% red. chlorophyll production Torres and O'Flaherty 1976 Supplemental ( raw data unavailable)

Xanthophyceae Vaucheria geminata ( 1 week; nominal) 76 80 W 1 1,000 41% red. chlorophyll production 100% red. chlorophyll production Torres and O'Flaherty 1976 Supplemental ( raw data unavailable)

Chlorophyceae Chlamydomonas reinhardi ( 24 hour; nominal) Unk. 19 44 48 50% red. carbon uptake; media: Taub & Dollar ( TD) 45020015 Larsen et al. 1986 Supplemental ( raw data unavailable) Nontarget Freshwater Plant Toxicity ( Tier II)

Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification XI  32 Chlorophyceae Kirchneria subcapitata = Selenastrum capricornutum ( 96 hours; nominal) Tech. 26 26 50% red. cell growth 50% red. floresence Caux, Menard, and Kent 1996 Supplemental ( NOAEC and raw data unavailable)

Chlorophyceae Kirchneria subcapitata = Selenastrum capricornutum ( 24 hours; nominal) Unk. 34 42 53 50% red. 14 carbon uptake; media: Taub & Dollar ( TD); algal assay & TD, respect. 45020015 Larsen et al. 1986 Supplemental ( raw data unavailable)

Cyanophyceae Anabaena cylindrica (?? hours; nominal) 97 37 50% red. in photosynthesis Stratton & Corke 1981 Supplemental ( no raw data)

Chlorophyceae Scenedesmus obliquus ( 24 hour; nominal) Unk. 38 49 57 50% red. 14 carbon uptake; media: Taub & Dollar ( TD) 45020015 Larsen et al. 1986 Supplemental ( raw data unavailable)

Chlorophyceae Kirchneria subcapitata = Selenastrum capricornutum ( 120 hours; measured) 97.1 49 NOAEC 16 Slope 4.002 50% red. cell growth 43074802 Hoberg 1993 Core Cyanophyceae Anabaena inaequalis (?? hours; nominal) 97 50 50% red. in photosynthesis Stratton & Corke 1981 Supplemental ( no raw data)

Chlorophyceae Kirchneria subcapitata = Selenastrum capricornutum ( 120 hours; nominal) 97.4 53 NOAEC < 32 LOAEC 32 Slope 4.127 50% red. growth 17% red. growth 41065204 Parrish 1978 Supplemental ( NOAEC, method & raw data unavailable)

Bacillariophyceae Navicula pelliculosa ( 120 hours; nominal) 97.1 60 NOAEC < 10 LOAEC 10 Slope 2.31 50% red. growth 41065203a Hughes 1986 Core ( EC50 extrapolated; and NOAEC was not determined)

Chlorophyceae Ankistrodesmus sp. ( 24 hours; nominal) Unk. 61 72 219 50% red. 14 carbon uptake; media: Taub & Dollar ( TD), TD & algal assay, respect. 45020015 Larsen et al. 1986 Supplemental ( raw data unavailable)

Ulothrix subconstricta Tentative species identification ( 24 hours; nominal) Unk. 88 50% red. 14 carbon uptake; medium: Taub & Dollar ( TD) 45020015 Larsen et al. 1986 Supplemental ( raw data unavailable)

Cyanophyceae Anabaena variabilis (?? hours; Nominal) 97 100 50% red. in photosnythesis Stratton & Corke 1981 Supplemental ( no raw data)

Stigeoclonium tenue Tentative species Identification ( 24 hours; nominal) Unk. 127 224 50% red. 14 carbon uptake; media: Taub & Dollar ( TD) 45020015 Larsen et al. 1986 Supplemental ( raw data unavailable) Nontarget Freshwater Plant Toxicity ( Tier II)

Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification XI  33 Chlorophyceae Kirchneria subcapitata = Selenastrum capricornutum ( 96 hours; measured) 97 130 NOAEC 76 Slope 6.628 50% red. cell growth 42060701 Hoberg 1991 Supplemental ( higher light intensity than recommended)

Cyanophyceae Anabaena cylindrica ( 24 hour; nominal) Unk. 178 182 253 50% red. 14 carbon uptake; media: Taub & Dollar ( TD), algal assay, & TD, respect. 45020015 Larsen et al. 1986 Supplemental ( raw data unavailable)

Cyanophyceae Anabaena flos aquae ( 120 hours; nominal) 97 230 NOAEC < 100 LOAEC 100 Slope 1.95 50% red. growth 22% red. growth 41065203a Hughes 1986 Core ( NOAEC was not determined)

Chlorophyceae Chlorella pyrenoidosa ( 120 hours; nominal) 97.4 282 NOAEC 130 Slope 4.216 50% red. growth 7% red. growth 41065204 Parrish 1978 Supplemental ( NOAEC, method & raw data unavailable)

Chlorophyceae Chlorella vulgaris ( 24 hours; nominal) Unk. 293 305 325 50% red. 14 carbon uptake; media: Algal assay, Taub & Dollar ( TD), & TD, respect. 45020015 Larsen et al. 1986 Supplemental ( raw data unavailable)

Longer Term, Nontarget Freshwater Plant Toxicity Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification Vascular Plants:

Broad Waterweed Elodea canadensis ( 20 days; measured) ???? NOAEC 2 LOAEC 10 200% incr. dark respiration 33% incr. net photosynthesis 45227714 Hofmann and Winkler 1990 Supplemental ( raw data unavailable)

Pondweed Potamogeton perfoliatus ( 4 weeks; initial conc. nominal, terminal conc. measured) ??? 30 Week 3: LOAEC 5 NOAEC < 5 4 Weeks: LOAEC 50 NOAEC 5 50% red. O2 product. sign. red. O2 product.

sign. red. O2 product. Kemp et al. 1985 Supplemental ( raw data unavailable)

Duckweed Lemna gibba ( 14 days; measured) 97.1 37 LOAEC 3.4 NOAEC < 3.4 Slope 1.716 50% red. growth 19% red. growth ( frond production) 43074804 Hoberg 1993 Supplemental ( NOAEC was not determined)

Duckweed  Lemna gibba ( 14 days; measured) 97.4 43 NOAEC 10 Slope 1.995 50% red. growth ( frond production) 43074803 Hoberg 1993 Core Broad Waterweed Elodea canadensis ( 3 weeks; nominal) ??? 80 50% red. shoot length 45087410 Forney and Davis 1981 Supplemental ( raw data unavailable) Longer Term, Nontarget Freshwater Plant Toxicity Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification XI  34 Eurasian Water Milfoil Myriophyllum spicatum ( 4 weeks; initial conc. nominal, terminal conc. measured) ???? 91 NOAEC 5 LOAEC 50 50% red, O2 product.

Sign. red. O2 product. Kemp et al. 1985 Supplemental ( raw data unavailable)

Non Vascular Plants:

36 freshwater algal strains ( 2 weeks; nominal) 99.0 10 1,000 growth < than control strong growth red. Butler et al. 1975 Supplemental ( raw data unavailable)

Chlorophyceae Chlorella vulgaris ( 11 days; nominal) 99.9 25 50% red. cell growth 45227703 Burrell et al. 1985 Supplemental ( raw data unavailable)

Cyanophyceae Anabaena inaequalis ( 12 14 days1; nominal) > 95 30 100 300 50% red. cell count 50% red. growth rate 50% red. photosynthesis 45087401 Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Chlorophyceae Ankistrodesmus braunii ( 11 days; nominal) 99.9 60 50% red. cell growth 45227703 Burrell et al. 1985 Supplemental ( raw data unavailable)

Chlorophyceae Scenedesmus quadricauda ( 12 14 days1; nominal) > 95 100 200 300 50% red. cell count 50% red. growth rate 50% red. photosynthesis 45087401 Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Chlorophyceae Chlorella pyrenoidosa ( 12 14 days1; nominal) > 95 300 1,000 500 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Cyanophyceae Anabaena cylindrica ( 12 14 days; nominal) > 95 1,200 3,600 500 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Cyanophyceae Anabaena variabilis ( 12 14 days; nominal) > 95 4,000 5,000 100 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Nontarget Marine/ Estuarine Plant Toxicity ( Tier II)

Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification Vascular Plants:

Fontinalis sp. ( 24 hours; measured) ???? NOAEC 2 LOAEC 10 red. net O2 production Supplemental ( raw data unavailable) Nontarget Marine/ Estuarine Plant Toxicity ( Tier II)

Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification XI  35 Pondweed ( Estuarine) Potamogeton perfoliatus ( 2 hours; nominal) ???? 77 50% red. O2 evolution 45227718 Jones and Winchell 1984 Supplemental ( Insufficient duration; raw data unavailable)

Pondweed Potamogeton perfoliatus ( 2 hours; nominal) ??? 80 650 50% red. O2 product.

87% red. O2 product.. 45227718 Jones et al. 1986 Supplemental ( Insufficient duration; raw data unavailable)

Zannichellia palustris ( 2 hours; nominal) ???? 91 50% red. O2 evolution 45227719 Jones and Winchell 1984 Supplemental ( Insufficient duration; raw data unavailable)

Pondweed ( Estuarine) Potamogeton perfoliatus ( 2 hours; nominal) Unk. 100 52 to 69% red. in photosynthesis 45087404 Jones & Estes 1984 Supplemental ( raw data unavailable)

Widgeon Grass ( Estuarine) Ruppia maritima ( 2 hours; nominal ????? 102 50% red. O2 evolution 45227719 Jones and Winchell 1984 Supplemental ( Insufficient duration; raw data unavailable)

Non Vascular Plants:

Blue green  Cyanophyceae Oscillatoria lutea ( 1week; nominal) 76 80 W 1 1,000 93% red. chlorophyll production 100% red. chlorophyll prod. 00023544 Torres and O'Flaherty 1976 Supplemental ( raw data unavailable)

Green Algae  Chlorophyceae Stigeoclonium tenue ( 1 week; nominal) 76 80 W 1 1,000 67% red. chlorophyll production 90% red. chlorophyll production 00023544 Torres and O'Flaherty 1976 Supplemental ( raw data unavailable)

Green Algae  Chlorophyceae Chlorella vulgaris ( 1 week; nominal) 76 80 W 1 1,000 50% red. chlorophyll production 80 87% red. chlorophyll prod. 00023544 Torres and O'Flaherty 1976 Supplemental ( raw data unavailable)

Xanthophyceae Tribonema sp. ( 1 week; nominal) 76 80 W 1 1,000 42% red. chlorophyll production 75% red. chlorophyll production 00023544 Torres and O'Flaherty 1976 Supplemental ( raw data unavailable)

Xanthophyceae Vaucheria geminata ( 1 week; nominal) 76 80 W 1 1,000 41% red. chlorophyll production 100% red. chlorophyll prod. 00023544 Torres and O'Flaherty 1976 Supplemental ( raw data unavailable)

Chrysophyceae Isochrysis galbana ( 120 hours; nominal) 97.4 22 NOAEC < 13 LOAEC 13 Slope 3.065 50% red. growth 30% red. growth 41065204 Parrish 1978 Supplemental ( NOAEC, method & raw data unavailable)

Marine Diatom Skeletonema costatum ( 120 hours; nominal) 97.4 24 NOAEC < 13 LOAEC 13 Slope 3.343 50% red. growth 14% red. growth 41065204 Parrish 1978 Supplemental ( NOAEC, method & raw data unavailable)

Marine Diatom Skeletonema costatum ( 120 hours; measured) 97.1 53 NOAEC 14 Slope 2.798 50% red. cell growth 43074801 Hoberg 1993 Core Nontarget Marine/ Estuarine Plant Toxicity ( Tier II)

Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification XI  36 Marine Green  Chlorophyceae Chlamydomonas sp. ( 72 hours; nominal); Salinity 30 g/ L 99.7 60 50% red. O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Yellow  Chrysophyceae Monochrysis lutheri ( 72 hours; nominal); Salinity 30 g/ L 99.7 77 50% red. O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Red  Rhodophyceae Porphyridium cruentum ( 72 hours; nominal); Salinity 30 g/ L 99.7 79 50% red. in O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Green  Chlorophyceae Neochloris sp. ( 72 hours; nominal); Salinity 30 g/ L 99.7 82 50% red. in O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Bacillariophyceae Cyclotella nana ( 72 hours; nominal); Salinity 30 g/ L 99.7 84 50% red. in O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Bacillariophyceae Achnanthes brevipes ( 72 hours; nominal); Salinity 30 g/ L 99.7 93 50% red. in O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Yellow  Chrysophyceae Isochrysis galbana ( 240 hours; nominal); Salinity 30 g/ L 99.7 100 50% red. cell growth 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Marine Green  Chlorophyceae Chlorococcum sp. ( 240 hours; nominal); Salinity 30 g/ L 99.7 100 50% red. cell growth 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Marine Green  Chlorophyceae Platymonas sp. ( 72 hours; nominal); Salinity 30 g/ L 99.7 100 50% red. O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Bacillariophyceae Thalassiosira fluviatilis ( 72 hours; nominal); Salinity 30 g/ L 99.7 110 50% red. O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Bacillariophyceae Stauroneis amphoroides ( 72 hours; nominal); Salinity 30 g/ L 99.7 110 50% red. O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint) Nontarget Marine/ Estuarine Plant Toxicity ( Tier II)

Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification XI  37 Marine Algae Microcystis aeruginosa ( 120 hours  nominal) 97.4 129 NOAEC 65 Slope 3.162 50% red. growth 7% red. growth 41065204 Parrish 1978 Supplemental ( NOAEC, method & raw data unavailable)

Marine Green  Chlorophyceae Chlorella sp. ( 72 hours; nominal); Salinity 30 g/ L 99.7 140 50% red. O2 production 40228401 Mayer 1986 Supplemental ( NOAEC unavailable Blue green  Cyanophyceae Anabaena cylindrica ( 24 hour; nominal) Unk. 178 182 253 50% red. 14 carbon uptake; media: Taub & Dollar ( TD), algal assay, & TD, respect. 45020015 Larsen et al. 1986 Supplemental ( raw data unavailable)

Marine green  Chlorophyceae Dunaliella tertiolecta ( 120 hours; nominal) 97 180 NOAEC < 100 LOAEC 100 Slope 1.95 50% red. growth 34% red. growth 41065203 Hughes 1986 Supplemental ( NOAEC unavailable)

Marine Yellow  Chrysophyceae Phaeodactylum tricornutum ( 240 hours; nominal); Salinity 30 g/ L 99.7 200 50% red. cell growth 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Marine Bacillariophyceae Nitzschia closterium ( 72 hours; nominal); Salinity 30 g/ L 99.7 290 50% red. O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Bacillariophyceae Amphora exigua ( 72 hours; nominal); Salinity 30 g/ L 99.7 300 50% red. O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Green  Chlorophyceae Dunaliella tertiolecta ( 240 hours; nominal); Salinity 30 g/ L 99.7 300 50% red. cell growth 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Marine Red  Rhodophyceae Porphyridium cruentum ( 120 hours) 97.4 308 NOAEC < 130 LOAEC 130 Slope 2.449 50% red. growth 16% red. growth 41065204 Parrish 1978 Supplemental ( NOAEC, method & raw data unavailable)

Marine Bacillariophyceae Nitzschia ( Ind. 684) ( 72 hours; nominal); Salinity 30 g/ L 99.7 430 50% red. O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Marine Green  Chlorophyceae Kirchneria subcapitata ( 120 hours; nominal) 97.4 431 NOAEC 200 Slope 4.217 5% red. in growth 4% red. in growth 41065204 Parrish 1978 Supplemental ( NOAEC, method & raw data unavailable) Nontarget Marine/ Estuarine Plant Toxicity ( Tier II)

Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification XI  38 Marine Bacillariophyceae Navicula inserta ( 72 hours; nominal); Salinity 30 g/ L 99.7 460 50% red. in O2 production 40228401 Mayer 1986 Supplemental ( 72 hrs & endpoint)

Formulation Nontarget Marine/ Estuarine Algal Toxicity ( Tier II)

Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit slope % Response MRID No. Author/ Year Study Classification Mar. Yellow  Chrysophyceae Isochrysis galbana ( nominal); Salinity 30 g/ L 76 80 WP 100 ( 240 hrs)

200 ( 2 hrs) 50% red. cell growth 50% red. O2 production 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Mar. Yellow Chlorophyceae Chlorococcum sp. ( nominal); Salinity 30 g/ L 76 80 WP 100 ( 240 hrs)

400 ( 2 hrs) 50% red. cell growth 50% red. O2 production 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Mar. Yellow  Chrysophyceae Phaeodactylum tricornutum ( nominal); Salinity 30 g/ L 76 80 WP 200 ( 240 hrs)

200 ( 2 hrs) 50% red. cell growth 50% red. O2 production 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Mar. Green  Chlorophyceae Dunaliella tertiolecta ( nominal); Salinity 30 g/ L 76 80 WP 400 ( 240 hrs)

600 ( 2 hrs) 50% red. cell growth 50% red. O2 production 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Longer term Nontarget Marine/ Estuarine Plant Toxicity Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification Vascular Plants:

Sago Pondweed ( Estuarine) Potamogeton pectinatus ( 28 days; measured/ nominal) ??? Salinity 12 ppt:

NOAEC 7.5 LOAEC 14.3 Salinity 1 & 6 ppt:

NOAEC 14.3 LOAEC 30 sign. red. dry weight sign. red. dry weight 45088231 Chesapeake Bay Program 1998 Supplemental ( raw data unavailable)

Estuarine rush Juncus roemerianus ( 5 weeks  1 year; measured 97.1 LOAEC 30 NOAEC 30 NOAEC < 30 250 ppb 3, 800 ppb sign. red. chlorophyll a in 5 weeks ( 1 year) partial recovery ( 1 yr) practically no survival 45087405 Lytle & Lytle 1998 Supplemental ( raw data unavailable) Longer term Nontarget Marine/ Estuarine Plant Toxicity Surrogate Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit Slope % Response MRID No. Author/ Year Study Classification XI  39 Pondweed Potamogeton perfoliatus ( 4 weeks; initial conc. nominal, terminal conc. measured) ??? 30 Week 3: LOAEC 5 NOAEC < 5 4 weeks: LOAEC 50 NOAEC 5 50% red. O2 product. sign. red. O2 product.

sign. red. O2 product. 45227720 Kemp et al. 1985 Supplemental ( raw data unavailable)

Pondweed ( Estuarine) Potamogeton perfoliatus ( 3 weeks; nominal) ??? 53 50% red. ???? 45087410 Forney and Davis 1981 Supplemental ( raw data unavailable)

Eelgrass ( Estuarine) Zostera marina ( 10 days; measured) Unk. est. 69 50 80 50% red. leaf growth 25% red. leaf growth 62% red. leaf growth 45227729 Schwarzschild et al. 1994 Supplemental ( raw data unavailable)

Estuarine Eelgrass Zostera marina ( 21 days; nominal) ??? 100 NOAEC 10 21 day LC50 red. production 45227705 Delistraty and Hershner 1984 Supplemental ( raw data unavailable)

Wild Celery ( Estuarine) Vallisneria americana ( 6 weeks; nominal) ??? 163 50% red. shoot length no difference at 0, 3, or 6 parts/ thousand 45087410 Forney and Davis 1981 Supplemental ( raw data unavailable)

Seagrass ( Estuarine) Halodule wrightii ( 22  23 days; measured) Atrazi ne 4L 30,000 46 58% red. total aboveground biomass 45205101 Mitchell 1987 Supplemental ( raw data unavailable)

Non Vascular Plants:

Marine Brown macroalgae Laminaria hyperborea ( 18 days; nominal) ??? NOAEC < 10 LOAEC 10 50 & 100 sign. red. growth rate delayed sporophyte formation ???? Hopkin & Kain 1978 Supplemental ( raw data unavailable)

Marine Yellow  Chrysophyceae Isochrysis galbana ( 240 hours; nominal); Salinity 30 g/ L 99.7 100 50% red. cell growth 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Marine Green  Chlorophyceae Chlorococcum sp. ( 240 hours; nominal); Salinity 30 g/ L 99.7 100 50% red. cell growth 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Marine Yellow  Chrysophyceae Phaeodactylum tricornutum ( 240 hours; nominal); Salinity 30 g/ L 99.7 200 50% red. cell growth 40228401 Mayer 1986 Supplemental ( NOAEC unavailable)

Marine Green  Chlorophyceae Dunaliella tertiolecta ( 240 hours; nominal); Salinity 30 g/ L 99.7 300 50% red. cell growth 40228401 Mayer 1986 Supplemental ( NOAEC unavailable) XI  40 The Tier II results indicate that the marine algae Isochrysis galbana is the most sensitive nonvascular aquatic plant ( EC50 22 ppb) and the most sensitive vascular aquatic plant is wild celery ( 4 ppb). Comparison of atrazine toxicity levels for three different endpoints suggest that the endpoints in decreasing order of sensitivity are cell count, growth rate and oxygen production ( Stratton 1984). Walsh ( 1983) exposed Skeletonema costatum to atrazine and concluded that atrazine is only slightly algicidal at relatively high concentrations ( i. e., 500 & 1,000 ppb). Caux et al. ( 1996) compared the cell count IC50 and fluorescence LC50 and concluded that atrazine is algicidal at concentrations which effect cell counts. Abou Waly et al. ( 1991) measured growth rates on days 3, 5, and 7 for two algal species. The pattern of atrazine effects on growth rates differ sharply between the two species. Atrazine had a strong early effect on Anabaena flosaquae followed by rapid recovery in clean water ( i. e., EC50 values for days 3, 5, and 7 are 58, 469, and 766 ppb, respectively). The EC50 values for Selenastrum capricornutum continued to decline from Day 3 through 7 ( i. e., 283, 218, and 214 ppb, respectively. Based on theses results, it appears that the timing of peak effects for atrazine may differ depending on the test species. The guideline requirement ( 123 2) is fulfilled for only three out of five species ( MRID 43074801, 43074802, 43074803). However, sufficient data exists on numerous other algal species to provide a broad range of toxicity effects. No additional algal studies are required.

Degradates: The major atrazine degradate is hydroxyatrazine which forms a large percent of the recoverable pesticide in aquatic compartments of the environment. Therefore, special tests are required for algal and vascular plant species ( 123 2) to address concerns for the toxicity of atrazine degradates to aquatic plants.

Degradate Deethylatrazine Nontarget Aquatic Plant Toxicity ( Tier II)

Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit slope % Response MRID No. Author/ Year Study Classification Fresh. Blue Green  Cyanophyceae Anabaena inaequalis ( 12 14 days1; nominal) > 95 1,000 4,000 2,500 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Freshwater Green  Chlorophyceae Scenedesmus quadricauda ( 12 14 days; nominal) > 95 1,200 2,000 1,800 50% red. cell count 50% red. Growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Freshwater Green  Chlorophyceae Chlorella pyrenoidosa ( 12 14 days1; nominal) > 95 3,200 7,200 1,800 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Fresh. Blue Green  Cyanophyceae Anabaena variabilis ( 12 14 days; nominal) > 95 3,500 7,500 700 50% red. cell count 50% red. growth rate 50 % red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Fresh. Blue Green  Cyanophyceae Anabaena cylindrica ( 12 14 days; nominal) > 95 8,500 5.500 4,800 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable) XI  41 Degradate Deisopropylatrazine Nontarget Aquatic Plant Toxicity ( Tier II)

Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit slope % Response MRID No. Author/ Year Study Classification Fresh. Blue Green  Cyanophyceae Anabaena inaequalis ( 12 14 days1; nominal) > 95 2,500 7,000 9,000 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Freshwater Green  Chlorophyceae Scenedesmus quadricauda ( 12 14 days; nominal) > 95 6,900 6.500 4,000 50% red. cell count 50% red. Growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Freshwater Green  Chlorophyceae Chlorella pyrenoidosa ( 12 14 days1; nominal) > 95 > 10,000 > 10,000 3,600 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Fresh. Blue Green  Cyanophyceae Anabaena variabilis ( 12 14 days; nominal) > 95 5,500 9,200 4,700 50% red. cell count 50% red. growth rate 50 % red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Fresh. Blue Green  Cyanophyceae Anabaena cylindrica ( 12 14 days; nominal) > 95 > 10,000 > 10,000 9,300 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Degradate Diamino Atrazine Nontarget Aquatic Plant Toxicity ( Tier II)

Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit slope % Response MRID No. Author/ Year Study Classification Fresh. Blue Green  Cyanophyceae Anabaena inaequalis ( 12 14 days1; nominal) > 95 7,000 > 10,000 > 100,000 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Freshwater Green  Chlorophyceae Scenedesmus quadricauda ( 12 14 days; nominal) > 95 4,600 10,000 > 100,000 50% red. cell count 50% red. Growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Freshwater Green  Chlorophyceae Chlorella pyrenoidosa ( 12 14 days1; nominal) > 95 > 10,000 > 10,000 > 100,000 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Fresh. Blue Green  Cyanophyceae Anabaena variabilis ( 12 14 days; nominal) > 95 > 10,000 > 10,000 100,000 50% red. cell count 50% red. growth rate 50 % red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Fresh. Blue Green  Cyanophyceae Anabaena cylindrica ( 12 14 days; nominal) > 95 > 10,000 > 10,000 > 100,000 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Degradate Hydroxyatrazine Nontarget Aquatic Plant Toxicity ( Tier II)

Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit slope % Response MRID No. Author/ Year Study Classification Fresh. Blue Green  Cyanophyceae Anabaena inaequalis ( 12 14 days1; nominal) > 95 > 10,000 > 10,000 > 100,000 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Freshwater Green  Chlorophyceae Scenedesmus quadricauda ( 12 14 days; nominal) > 95 > 10,000 > 10,000 > 100,000 50% red. cell count 50% red. Growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable) Degradate Hydroxyatrazine Nontarget Aquatic Plant Toxicity ( Tier II)

Species/ Duration/ Measured/ nominal % ai Conc. ( ppb) Probit slope % Response MRID No. Author/ Year Study Classification XI  42 Freshwater Green  Chlorophyceae Chlorella pyrenoidosa ( 12 14 days1; nominal) > 95 > 10,000 > 10,000 > 100,000 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Fresh. Blue Green  Cyanophyceae Anabaena variabilis ( 12 14 days; nominal) > 95 > 10,000 > 10,000 > 100,000 50% red. cell count 50% red. growth rate 50 % red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

Fresh. Blue Green  Cyanophyceae Anabaena cylindrica ( 12 14 days; nominal) > 95 > 10,000 > 10,000 > 100,000 50% red. cell count 50% red. growth rate 50% red. photosynthesis Stratton 1984 Supplemental ( NOAEC and raw data unavailable)

The Tier II results for atrazine degradates indicate that deethylatrazine is more toxic than the other four degradates and the most sensitive algae of the five species usually is the blue green alga Anabaena inaequalis with EC50 values ranging from 100 to > 100,000 ppb. Atrazine is more toxic to these algal than any degradate. The order of descending toxicity for these algal species are atrazine > deethylatrazine > deisopropylatrazine > diamino atrazine > hydroxyatrazine The data are useful, but the test species are not the species specified for pesticide registration. The requirement ( 123 2) has not been fulfilled. XI  43 e. Multi species Tests ( Microcosms, Field Studies)

i. Simulated Aquatic Field Studies ( Microcosms)

a. Freshwater Microcosm Tests Application rate ( lb ai/ A)

Nominal/ Measured Conc. Concentration affecting endpoint ( time to effect)

o percent difference from controls Narrative of Study Trends MRID No.

Author/ Year Freshwater microcosm:

Measured close to nominal throughout the testing period:

concentrations of 0.5, 5, 50,

100, 500, and 5000 ppb 0.5 and 5 ppb o no reduction in net oxygen loss 50 ppb o 25 30% reduction in net oxygen loss 100 ppb o 40 50% reduction in net oxygen loss 500 ppb o 90% reduction in net oxygen loss 5,000 ppb o 100% reduction to negative net oxygen production Spirogyra, Oedogonium, Microcystis,

Apthanothece, and Scenedesmus sp. in mixed culture.

Microcosms inoculated with algae demonstrated effects at concentrations > 50 ppb. Physical appearance of the microcosms was altered at 5,000 ppb. Observations and reculture demonstrated that the effects were algistatic. 45087407 Brockway et al., 1984 Freshwater Microcosm:

( Duration 7 weeks exposure)

Mean measured concentrations of 5.08 + 0.03 Fg/ L;

range: 4.2  6.0 Fg/ L NOEC: 5 ppb o slight non sign. shifts in water parameters:

o DO decreased from means of 9.4  9.9 mg/ L ( controls) differing weekly by 0.2  0.6 mg/ L o pH decreased from means of 8.4  9.0 ( controls)

differing weekly by 0.0  0.4 units o conductivity increased from 159.3  189.3 FS/ cm ( controls) differing by 0.2  10.0 FS/ cm o alkalinity increased from means of 1.4  2.2 mg/ L ( controls) differing by 0.0  0.3 mg/ L o no significant adverse effects on phyto &

zooplankton, or 15 macro invertebrate species o Cyclopoida sign. increased in week 3 Laboratory microcosms ( 4 replicates) were tested with 0 and 5 Fg/ L atrazine for 7 weeks. The plankton and macroinvertebrates were introduced together with 2 cm layer of natural sediments into glass aquaria with a 50 cm water column with a 14 hour photoperiod. Water was circulated through the microcosms at a flow rate of 3.5 L/ min. during an acclimation period for biota of 3 months.

This test was part of a study of pesticide interaction between atrazine and chlorpyrifos to determine the adequacy of chronic safety factors. 45087417 van den Brink et al. 1995 Supplemntal ( raw data unavailable)

Freshwater Microcosm:

Mean measured concentrations of 3.2, 10, 32, 110, and 337 ppb NOEC: 10 ppb; LOEC: 32 ppb o dissolved oxygen, magnesium, and calcium;

NOEC: 110 ppb; LOEC: 337 ppb o potassium, chlorophyll a, protein, and species equilibrium number Laboratory microcosms were inoculated with foam blocks taken from a pond. The effect to protozoans from atrazine exposure was examined by measuring structure ( species number, biomass), and function ( colonization rate, oxygen production, chlorophyll concentration) of the community as well as ion concentrations of the biomass after 21 days. 45087416 Pratt et al. 1988 Supplemental ( raw data unavailable)

Freshwater Microcosm:

( 6 weeks)

Meas. peak 20 ppb on day 1,

mean measured concentration of approximately 10 ppb 10 ppb ( 6 weeks)

o sign. ( 0.05) reduced dissolved oxygen ( DO), but was recovering by test termination Laboratory microcosms were treated with a stock solution of atrazine and soil to which atrazine was bound. At the end of the study, no significant effects on plant biomass or daphnid/ midge survival were noted, but DO was affected. 45205102 Huckins et al. 1986 Supplemental ( raw data unavailable) Application rate ( lb ai/ A)

Nominal/ Measured Conc. Concentration affecting endpoint ( time to effect)

o percent difference from controls Narrative of Study Trends MRID No.

Author/ Year XI  44 Freshwater microcosm:

( 30 days): Macrophytes, algae,

zooplankton and benthic invertebrates;

Nominal conc. of 10, 100 and 1,000 ppb as a soil slurry 10 ppb ( Day 2)

o 23% red. in gross primary productivity ( GPP);

recovery by Day 7 and similar to controls at Day 30 100 ppb ( Day 2)

o 32% red. in GPP; recovery by Day 7 and similar to controls at Day 30 1,000 ppb ( Day 2)

o 91% red. in GPP; no recovery, 70% red.

throughout test 1,000 ppb ( Day 30)

o 48% red. ( sign. P< 0.05 level) macrophyte biomass o 36% red. ( sign., P< 0.05) Selenastrum dry weight 1,000 ppb ( 30 day aged microcosm water)

o 76% red. ( sign. P< 0.05) Selenastrum dry weight 1,000 ppb ( Day 30)

o reduced O2, community respiration, pH o 20% increase in conductivity o 120% increase in alkalinity o no effect on soil microbial activity 4 L microcosms were established in the laboratory and treated with a soil slurry of atrazine. The endpoints examined over the 30 day experiment included effects to zoo and phytoplankton as well as macrophytes ( i. e., Lemna sp., Ceratophyllum sp.,

and Elodea sp.). Static acute and chronic assays were conducted with Daphnia magna and Chironomus riparius using treated water that had come from the microcosm after 30 days or from a vessel that contained the treated water for 30 days ( i. e., aged treated water). The author concluded that microcosm itself ameliorated the phytotoxic effect at 1,000 ppb. No effect on invertebrates up to 1,000 ppb and effects to phytoplankton at 10 and 100 ppb were not observed by test termination ( 30 days). Conductivity, pH, and alkalinity were also affected at 1,000 ppb. 45087413 Johnson, 1986 Supplemental ( raw data unavailable)

Freshwater Microcosm:

Emergent vascular plants;

Nominal water conc. of 10, 50,

100, 500, and 1,500 ppb;

measured water conc. in the 50 and 500 ppb treatments of 1.3 and 1.6 ppb, respectively, after 16 weeks 500 ppb ( 6 weeks)

o sign. ( 0.05 level) red. shoot length of Scirpus acutus 1,500 ppb ( 6 weeks)

o sign. red. shoot length of Scirpus acutus and Typha latifolia Greenhouse microcosms were made by placing rhizome sections in tubs which were filled with treated water to 1 cm above the soil surface. The plants were allowed to grow for 16 weeks and shoot height of hardstem bulrush and broad leaved cattail was monitored bi weekly. Also non sign. effects of chlorosis and reduced growth noted at 50 and 100 ppb. A second test demonstrated resiliency of both plants at 500 ppb. 45087415 Langan and Hoagland,

1996 Supplemental ( raw data unavailable)

Freshwater Microcosm:

( 14 days) Measured atrazine concentrations approximately 75% of nominal ( 15 and 153 ppb) for first application and 150% of nominal ( 385 and 2,167 ppb) for the second application Sign. ( 0.1 level) reduction in turbidity and chlorophyll ( 7 days), and increase in phosphorous ( day 14) and nitrogen ( days 7 and 14) after the 1st application. Copepod and rotifer densities were also sign. reduced on days 7 and 14.

Sign. reductions in productivity, chlorophyll, green algal colonies, rotifers, and Bosmina sp. ( zooplankton) after 2nd application. Phosphorous, nitrogen, and pH were also sig.

affected. A 3x3 factorial design with three conc. of atrazine ( 0, 15, and 153 ppb) and three conc. of bifenthrin ( 0, 0.039, and 0.287 ppb) applied as soil slurry in May, then again one month later but with atrazine conc. of 0, 385, and 2,167 ppb and bifenthrin conc. of 0, 0.125, and 3.15 ppb. Atrazine alone caused doseresponsive reductions in chlorophyll, turbidity, primary production, increases in nitrogen and phosphorous, and reduced levels of chlorophytes, cladocerans, copepod nauplii,

and rotifers. General recovery after 14 days for atrazine alone in the first phase, but recovery not complete at sampling termination after second phase ( 14 days). No synergistic or antagonistic effects were noted. 45020014 Hoagland et al., 1993 Supplemental ( raw data unavailable) Application rate ( lb ai/ A)

Nominal/ Measured Conc. Concentration affecting endpoint ( time to effect)

o percent difference from controls Narrative of Study Trends MRID No.

Author/ Year XI  45 Freshwater microcosm:

( 2 months; measured)

Nominal concentrations of 0,

60, 100, 200, 500, 1,000 and 5,000 ppb. Measurements made three times during the two month study. 60 ppb ( nominal)

o 14 carbon uptake decreased immediately after treatment; recovery began after 10 days;

o stimulated production of chlorophyll a;

100 ppb ( nominal)

o 14 carbon uptake decreased immediately after treatment; recovery began after 10 days;

o stimulated production of chlorophyll a;

200 ppb ( nominal)

o 14 carbon uptake decreased immediately after treatment; slight recovery 2 months after treatment;

o stimulated production of chlorophyll a;

o inhibited increases in dissolved oxygen during light phase and decreases in DO during dark phase 500 ppb ( nominal)

o 14 carbon uptake decreased immediately after treatment; no recovery;

o minimal inhibition of chlorophyll a production;

1,000 and 5,000 ppb ( nominal)

o 14 carbon uptake decreased immediately after treatment; recovery began after 10 days.

EC50s for Days 0 10, 53 60, & Mean ( mean measured conc.)

Time period; 14C uptake; DO ( light); DO ( dark)

Days 0 10 : 103 ppb 126 ppb 106 ppb Days 53 60: 159 ppb 154 ppb 164 ppb Days 1 60: 131 ppb 165 ppb 142 ppb Results of single species assays, microcosm, and pond studies were compared. 14 Carbon fixation was used as the end point for all three study types. Laboratory results with eight algal species ranged from 37 to 308 ppb for carbon uptake inhibition EC50 values. Microcosm EC50 values ranged from 103 to 159 ppb. The mean pond EC50 was 100 ppb for carbon uptake and 82 ppb for chlorophyll a inhibition. The authors stated that multiple laboratory studies or a microcosm study represent( s)

entire ecosystem functional effects. 45020015 Larsen et al., 1986 and 45087419 Stay et al. 1985 Supplemental ( raw data unavailable)

Freshwater microcosm:

( 60 days; measured)

Nominal concentrations of 60,

100, 200, 500, 1,000, and 5,000 ppb. Concentrations measured on Days 7, 28, 53, 60. NOEC < 60 ppb;

60 ppb ( 1  20 days)

o sign. ( 0.05) red. 14 carbon uptake for first 20 days > 100 ppb ( 2 weeks)

o sign. ( 0.05 level) red. primary productivity;

o sign. red. in productivity/ dark respiration ratio;

o pH sign. less than control values > 500 ppb ( 6 weeks)

o all endpoints declined immediately after treatment and never recovered during the experiment. Taub microcosms were 3 L jars inoculated with 10 algal species on Day 0, Daphnia magna and 4 other animal species on Day 4. On Day 7, 27 microcosms were treated with atrazine; no other atrazine treatments um from four different aquatic systems. Community metabolism was measured for primary productivity and light and dark respiration. At the high treatment levels ( 500, 1000 and 5000 ug/ L), all process variables declined immediately after atrazine treatment and did not recover during the experiment. At the low treatment levels ( 60, 100 and 200 ug/ L), the magnitude of the responses to atrazine was not constant, but with 3 phases; an autotrophic phase, daphnid bloom and an equilibrium phase. 45087419 Stay et al., 1989 Supplemental ( raw data unavailable) Application rate ( lb ai/ A)

Nominal/ Measured Conc. Concentration affecting endpoint ( time to effect)

o percent difference from controls Narrative of Study Trends MRID No.

Author/ Year XI  46 Freshwater microcosm:

( 6 weeks; measured)

Single dose;

Nominal conc. 20, 100, 200,

500, 1,000 and 5,000 ppb.

Concentrations were measured on Days 0 and 42. On Day 42,

atrazine levels averaged 69 to 80% of the initial concentrations. NOEC = 20 ppb LOEC = 100 ppb in 3 out of 4 natural plankton communities and 200 ppb for the fourth community.

> 100 ppb ( 2 weeks)

o sign. ( 0.05 level) red. primary productivity o sign. red. in productivity/ dark respiration ratio o pH sign. less than control values Leffler microcosms were constructed with inoculum from four different aquatic systems from natural communities and contains organisms representing several trophic levels. The vessels were dosed after 6 weeks of seeding and monitoring for 6 more weeks. The LOEC for 3 of the systems was reported to be 100 ppb, while the LOEC for the fourth was 200 ppb. 45087418 Stay et al. 1989 Supplemental ( raw data unavailable) XI  47 b. Marine/ Estuarine Microcosm Tests Application rate ( lb ai/ A)

Nominal/ Measured Conc. Concentration affecting endpoint ( time to effect)

o percent difference from controls Narrative of Study Trends MRID No.

Author/ Year Estuarine microcosm:

( ; nominal)

Wild Celery Vallisneria americana 1 treatment Nominal concentrations of 4, 8, 16, 32, and 64 ppb NOEC < 4 ppb 4 ppb ( reproductive season)

o sign. 16% reduction in tuber formation o 55% reduction in biomass 8 ppb ( reproductive season)

o 21% reduction in tuber formation 16 ppb ( mid season and reproductive season)

o 60% reduction in tuber formation o 27% reduction in tuber weight o sign. reduction in leaf growth, biomass,

and female flowers 64 ppb ( reproductive season)

o 75% reduction in tubers o red. female flowers Laboratory microcosms were used to grow Vallisneria americana through entire seasons ( divided into three periods

early, mid, and reproductive). The aquaria were dosed one time at the nominal conc. after a 14 day acclimation period.

With respect to leaf growth, atrazine caused the plants to be shorter and more fragile. With respect to flowering and rhizome production, effects were generally first noted at the 16 to 32 ppb range. Tuber formation appeared to be the most sensitive endpoint, with production in terms of numbers significantly reduced at the 4 ppb level. 45020001 Cohn 1985 Supplemental ( raw data unavailable)

Estuarine lab. microcosm:

( 7 day exposure; nominal)

Nominal concentrations of 22,

220, and 2,200 ppb Estuarine field microcosm:

( 108 days; nominal)

Single exposure;

Nominal applications of 0.4,

1.4, 4.5, and 45 lb ai/ A " NOEC" = 10 ppb ( based on author's use of a 10 fold safety factor from the I1 level = 100 ppb)

220 ppb ( 1 week)

o sign. ( 0.05 level) red. in cell # of Thalassiosira fluviatilis o sign. red. in photosynthesis of T. fluviatilis and Nitzschia sigma 2,200 ppb ( 1 week)

o sign. red. in cell #, photosynthesis., and chlorophyll content for both algae 1.4 lb ai/ A ( effect up to 5 days)

o sign. red. in surface chlorophyll and primary prod.

( 85 89%)

1.4 lb ai/ A ( effect up to 8 & 17 days)

o sign. reduction in carbon fixation ( 52 73%)

0.4/ 4.5 lb ai/ A ( effect at 16 days, but not 26 days)

o sign. reduction in carbon fixation 45 lb ai/ A ( 42 days)

o sign. red. in carbon fixation Laboratory studies were conducted with the salt marsh edaphic diatoms Thalassiosira fluviatilis and Nitzschia sigma. The I50 for both species combined was reported to be 939 ppb. The I1 was reported to be 100 ppb, and by applying a 10 fold safety factor, the acceptable level ( NOEC) was reported to be 10 ppb.

Subsequently, studies were conducted in greenhouse microcosms ( 1.4 lb ai/ A) and in two field studies ( 1.4 lb ai/ A or 0.4, 4.5, and 45 lb ai/ A) on the beach wherein enclosures were sunk into the sand and exposed to tidal action. Atrazine treatment also appeared to cause a shift to a Navicula sp.

dominated system. Field results with higher rates of atrazine were as expected, with carbon fixation reduced for up to 16 days at the 2 lower rates and up to 42 days at the highest rate. 45087406 Plumley and Davis, 1980 Supplemental ( raw data unavailable) Application rate ( lb ai/ A)

Nominal/ Measured Conc. Concentration affecting endpoint ( time to effect)

o percent difference from controls Narrative of Study Trends MRID No.

Author/ Year XI  48 Estuarine microcosm:

( 5 Weeks; measured)

3 weekly applications followed by 2 weeks observation.

Mean measured concen. at approximately mid point of the Spartina test were 30, 280, and 3,100 ppb and in the Juncus test were 30, 250 and 3,800 ppb. 30, 280, and 3,100 ppb ( 5 weeks)

o sign. ( 0.05 level) increase in peroxidase activity in Spartina alterniflora 30, 250, and 3,800 ppb ( 5 weeks)

o sign. ( 0.05 level) red. in chlorophyll a ( Chl a) and Chl a/ Chl b ratio in Juncus roemerianus 250 and 3,800 ppb ( 5 weeks)

o sign. red. in Chl b in J. roemerianus 3,100 ppb ( 1 week)

o sign. red. in growth in S. alterniflora 3,800 ppb ( 5 weeks)

o sign. red. in growth in J. roemerianus o sign. increase in oxidized lipids in J. roemerianus 250 ppb ( 1 year)

o partial recovery in J. roemerianus 3,800 ppb ( 1 year)

o practically no survival of J. roemerianus. Two aquatic estuarine plants were exposed to atrazine in greenhouse microcosms. The plants were exposed to atrazine by placing treated sand on the surface of the pots three times ( once a week for the first 3 weeks of the study) followed by 2 more weeks for a total of 5 weeks. The water samples were taken after the third application. The pots were also tidallyexposed ( i. e., low tide during the day and high tide at night).

S. alterniflora plants demonstrated a dose response increase in peroxidase activity. In contrast, J. roemerianus plants demonstrated a dose responsive reduction in chlorophyll and an increase in the amount of oxidized lipids. The authors state that atrazine " should pose no significant adverse effects on S.

alterniflora. In contrast, if chronic levels of atrazine persist in the range of 250 ug/ L or greater, J. roemerianus most likely will exhibit die off or decline that may lead to loss of this species within the habitat." 45087405 Lytle and Lytle, 1998 Supplemental ( raw data unavailable)

Estuarine microcosm:

(???? days, nominal)

Nominal concentrations of 0,

50, and 100 ppb Both Nannochloris oculata and Phaeodactylum tricornutum were significantly ( mostly at the 0.01 level) affected by changes in light, temperature, and atrazine conc. A 3x3x3 factorial design examined the effect of temperature,

light, and atrazine conc. on two species of estuarine algae. N.

oculata was sig. affected by all variables, and the three twoway and one three way interactions were also significant. P.

tricornutum was affected by the main variables and the only sig. interaction was light by atrazine. Mayasich et al., 1986 Estuarine microcosm:

(????? day, nominal)

Nominal concentrations of 0,

15, 30, and 50 ppb The above mentioned algae were tested together and this variable also caused a sig. ( 0.01 level) effect on N. oculata growth rate An extension of the above described study. In addition to separate culture, the two estuarine algae were cultured together. The end result was that P. tricornutum dominated the cultures due to the stress of atrazine to N. oculata under optimum growth conditions Mayasich et al., 1987 Application rate ( lb ai/ A)

Nominal/ Measured Conc. Concentration affecting endpoint ( time to effect)

o percent difference from controls Narrative of Study Trends MRID No.

Author/ Year XI  49 Estuarine microcosm:

( 4 weeks; measured)

Mean measured concentrations in water were 130 ppb for the " low" treatment and 1,200 ppb for the " high" treatment over a four week period ( 4 weeks; measured) 130 ppb ( Week 1)

o no photosynthesis 130 ppb ( Week 2 4)

o sign. red. in plant total biomass; no change in biomass for 3 weeks 130 ppb ( Weeks 1 4)

o sign.; averaged 50% red. photosynthesis of Potamogeton perfoliatus during the test; steady recovery after first week, but not fully recovered 1,200 ppb ( Weeks 1 4)

o sign.; 100% red. photosynthesis throughout the test 1,200 ppb ( Weeks 2 4)

o sign.; plant total biomass steadily reduced 1,200 ppb ( Weeks 3 4)

o sign.; 80% red. shoot density Aquatic plants were planted and atrazine treated sediments were added to 700 L microcosms. On Day 1.5, 93.4% of the total atrazine was dissolved in water. In addition to photosynthesis, it was demonstrated that shoot growth was relatively unaffected at 130 ppb, but total biomass was sign.

reduced after 2 4 weeks. Plant biomass reductions followed a 1 week lag after photosynthesis reduction. At 1,200 ppb, plant biomass had been virtually eliminated by the end of the test.

Mean shoot length in the controls declined after week 1 and after week 3 for 1,200 ppb. 45087403 Cunningham et al., 1984 Supplemental ( raw data unavailable)

Estuarine microcosm:

( 22 23 days; measured)

Single dose:

Day 0: 30,000 ppb  nominal;

Measured only Day 22 or 23:

16,400 17,700 ppb 30,000 ppb ( Day 5 22)

o sign. ( p< 0.05) red. average ratio of no. of ramets ( branches): initial no. of ramets 30,000 ppb ( Day 22 or23)

o sign. ( p< 0.05) 46 58% red. in total above ground biomass o sign. ( p< 0.05) 18% red. in average dry weight per ramet Experiments were conducted with seagrass, Halodule wrightii,

examining the effect of atrazine and any interactions of salinity ( 15, 25, 35 ppt), light intensity ( 115, 140, 173 uEm 2s

1), and cropping ( either cut at 4 cm or 6 cm). None of these environmental factors affected the response of the grass to atrazine. 45205101 Mitchell, 1987 Supplemental ( raw data unavailable) XI  50 ii. Aquatic Field Studies ( including Mesocosms and Limnocorrals)

a. Freshwater Ponds, Lakes and Reservoirs Application rate ( lb ai/ A)

Nominal/ Measured Conc. Concentration affecting endpoint ( time to effect)

o Affected Species and Life Stage Narrative of Study Trends MRID No.

Author/ Year Freshwater Lake: Plankton ( Duration 18 days)

Measured = > 90% of nominal over the test period ( 18 days):

nominal concentrations of 0.1,

1, 10, and 100 ppb NOEC = < 0.1 ppb o transient effects on water chemistry 1 ppb ( 1 week)

o decreased primary production;

o increased bacterial numbers o decreased in zooplankton numbers ( cladocerans affected greater than copepods)

10 ppb ( 3 weeks)

o 65% sign. ( p < 0.01) red. in daphnid population growth ( combined effect of water & algae)

o 59% sign. ( p < 0.05) red. in daphnid growth ( algae)

100 ppb ( 3 weeks)

o 92% sign. ( p < 0.01) red. in daphnid growth ( combined)

o 69% sign. ( p < 0.01) red. daphnid growth ( algae) In situ enclosures in a German lake were treated and monitored over 18 days. Dose responsive reductions in chlorophyll a and oxygen and increases in particulate organic carbon were observed at 1, 10, and 100 ppb. Within 1 week at 1 ppb, primary production decreases and bacterial number increases were observed. Zooplankton numbers then decreased, with cladocerans affected more than copepods. Additional studies at 0.1 ppb also demonstrated transient effects on water chemistry and biological parameters. Most of the parameters were recovered or were recovering within 42 days of application. 45087414 Lampert et al., 1989 Supplemental ( raw data unavailable) Application rate ( lb ai/ A)

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Author/ Year XI  51 Freshwater Pond: Plankton Treated 3 times on 7/ 31, 8/ 28 ( 29 days later), and 9/ 21/ 1990 ( 24 days later) at 5, 10, 25, 75,

200, and 360 ppb. Weekly conc. relatively constant; mean measured conc. over two months are 5, 10, 22, 68, 182,

and 318 ppb ( 63 days; measured) NOEC: 5 ppb ( 63 days) compared to controls 10, 22 and 68 ppb o up to 40% red. dissolved oxygen ( Days 7 46)

o up to 10% incr. pH ( Days 18 63)

o up to 10% red. conductivity ( Days 7 53)

68 ppb o up to 78% red. copepod nauplii and no increase in nauplii at 182 & 318 ppb o diatoms appear to become the dominant phytoplankton 182 ppb o strong red. in dissolved oxygen and conductivity and strong increase in pH levels ( same for 318 ppb)

o up to 98% red. Cryptophyceae, Cryptomonas marsonii and S. erosa/ ovatata ( Days 21 to tests end)

o up to 10% red. conductivity ( Days 7 53)

o up to 98% red. seasonal blooms of Cryptomonas marsonii & S. erosa/ ovatata ( Days 21 to tests end)

o prevented Mallomonas sp. seasnal bloom ( 318 ppb too)

o prevented the seasonal bloom of Planktosphaeria sp.

( Chlorophyceae) after Day 30 ( same at 318 ppb)

o lower numbers & early seasonal decline of rotifers,

Synchaeta sp. ( same at 318 ppb)

318 ppb o up to 80% red. phytoplankton cell density ( throughout test, except on Day 35)

o up to 98% red. Cryptophyceae, Cryptomonas marsonii and S. erosa/ ovatata ( first appeared on Day 10  Days 21 to tests end)

o up to 9% incr. pH ( Days 18 63)

o up to 10% red. conductivity ( Days 7 53)

o strong red. in cell numbers of Planktosphaeria sp.

( Chlorophyceae) after Day 30 o delays in reaching and lower peak daphnid egg ratio,

and delayed peaks for numbers of young and adults Mesocosms ( 1,000 L cylinders ) in southern Bavaria were treated with atrazine 3 times ( 29 and 24 day intervals) over 63 summer days. Strongly dose response reductions in dissolved O2, pH, and conductivity were noted at concentrations greater than 5 ppb. Changes in oxygen concentrations at > 10 ppb and some zooplankton populations at 68, 182, and 318 ppb reflect indirect functional links as a result of altered primary production.

At 68 ppb, up to a 78% reduction in copepod nauplii was found and no increase in the number of nauplii was found at 182 and 318 ppb. At 182 ppb, threshold concentrations for direct effects by atrazine were exceeded in several phytoplankton species.

Diatoms appeared to become the dominant phytoplankton at 182 and 318 ppb. One rotifer species decreased at 182 ppb and another at 318 ppb and was virtually absent from Day 18 to the end of the study. Daphnid reproduction and populations decreased at 318 ppb. 45020022 Juttner et al. 1995 Supplemental ( raw data unavailable) Application rate ( lb ai/ A)

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Author/ Year XI  52 Artificial freshwater ponds in Kansas treated with atrazine to achieve concentrations of 20 and 500 Fg/ L Atrazine levels measured in the water column four times during the first two months of the study: 100% of nominal at time zero ( 163 days;

measured). Laboratory data shows results for atrazine sensitivity tests for treated field samples:

1 ppb o sign. ( 0.05) 4% increase in fluorescence 5 ppb o sign. ( 0.05) 9% increase in fluorescence o sign. ( 0.05) 8% decrease in C 14 uptake 20 ppb o sign. ( 0.05) 30% increase in fluorescence o sign. ( 0.05) 12% decrease in C 14 uptake 500 ppb o sign. ( 0.05) 136% increase in fluorescence o sign. ( 0.05) 88% decrease in C 14 uptake Field pond study results:

20 ppb o sign. ( 0.05) 51% red. C 14 uptake ( 4 hr.) ( Days 2 7)

o sign. 42% red. phytoplankton biomass ( Days 2 7)

o 3% red. growth & 28% red. daphnid reproduction Simocephalus serrulatus correlated with food levels 500 ppb o pH red. 0.3 units lower than controls for a few weeks o dissolved O2 generally red. 1 3 mg/ L ( a few weeks)

o sign. 94% red. C 14 uptake ( 4 hr.) ( Days 2 163)

o usually sign. red. phytoplankton biomass ( Days 2

136)

o rapid, nearly complete red. in abundant Peridinium inconspicuum, a small dinoflagellate and rapid red.

in 7+ other dominate phytoplankton sp. after 7 days o incr. in several flagellate species; mainly Mallomonas pseudocoronata, Cryptomonas marssonii & C. erosa o zooplankton dominance shifted to rotifers, mainly Keratella cochlearis after Day 31 o > 50% red. in the copepod, Tropocyclops prasinus mexicanus by Day 14 Single treatment of two 0.045 hectare ponds each with either 20 or 500 ppb atrazine produced dose responsive changes in pH,

DO and daily carbon uptake. Phytoplankton growth was reduced; population shifts were apparent at 20 and 500 ppb.

Effects on phytoplankton were immediate, within 2 days, for daily carbon 14 uptake and biomass declines at both treatment levels, which is consistent with other researchers in laboratory tests. Atrazine concentrations down to 1 ppb affected photosynthesis in lab tests with phytoplankton samples from the pond. While atrazine produced direct toxic effects on just certain members of the aquatic community, their responses also affected other members of the community. At 500 ppb, one species of herbivorous zooplankton declined by more than 75%

within 14 days of treatment.

Subsequent laboratory tests demonstrated some atrazine resistance in phytoplankton and showed zooplankton population effects were due to loss of food ( algae). Further evidence of resistance was indicated by a dominant phytoplankton species which showed less toxic responses than the same species in the control pond. 45020011 DeNoyelles et al. 1982 Supplemental ( raw data unavailable) Application rate ( lb ai/ A)

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Author/ Year XI  53 Artificial freshwater ponds in Kansas treated with atrazine to achieve concentrations of 20 and 500 Fg/ L NOAEC < 20 Fg/ L 20 Fg/ L  29% increase in turbidity.

 initial depressed phytoplankton, followed by an increase in standing crop and numerical dominance of resistant species.

 red. production of Naajas sp. and Potamogeton spp. in areas excluding carp.

 increase in Chara  82% reduction in total insect emergence.

 89% red. in non predator insect emergence.

 90% red. Labrundinia pilosella emergence.

 50% red. in total insect species richness.

 57% red. in non predator insect species richness.

100 Fg/ L  62% increase in turbidity.

 absence of periphyton on walkway supports.

increase in Chara sp.

 83% reduction in total insect emergence.

 95% red. in non predator insect emergence.

 96% red. Labrundinia pilosella emergence.

 71% red. in total insect species richness.

 85% red. in non predator insect species richness.

 5% red. in insect species evenness.

500 Fg/ L  65% increase in turbidity.

 absence of periphyton on vascular plants.

 absence of Chara sp.

 70% reduction in total insect emergence.

 85% red. in non predator insect emergence.

 90% red. Labrundinia pilosella emergence.

 59% red. in total insect species richness.

 66% red. in non predator insect species richness.

 15% red. in insect species evenness. Two artificial Kansas ponds each ( 0.045 ha. and 2.1 m. deep)

were treated with technical atrazine at 20 Fg/ L and 100 Fg/ L and with a 41% ai CO OP liquid atrazine at 20 Fg/ L in 1981; two ponds served as controls. The ponds were treated again on 30 May 1982, but the 41% ai ponds were converted to 500 Fg/ L with technical atrazine. The macrophyte community in treated ponds was noticeably reduced, relative to controls, throughout the summer. For 16 sampling dates between 8 May and 28 September 1982 insect emergence was monitored in each pond with 4 emergence traps for 48 hour periods. No significant differences between ponds were found in water level,

temperature or oxygen levels. Mean turbidity varied significantly among treatments ( ANOVA), increasing with increasing atrazine levels up to 100 Fg/ L.

The phytoplankton community responses to atrazine during the present study corroborate results from the 1979 study by deNoyelles et al. ( 1979). Macrophyte response also paralleled the 1979 study. The presence of live plants of the primary emergent vegetation, Typha spp., gradually decreased, as in previous studies, with increasing atrazine concentration both within and outside carp exclusion areas ( Carney 1983,

deNoyelles and Kettle 1983). 45227706 Dewey 1986 Application rate ( lb ai/ A)

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Author/ Year XI  54 Artificial freshwater ponds in Kansas treated with atrazine to achieve concentrations of 20 and 500 Fg/ L NOAEC < 20 Fg/ L 20 Fg/ L  60% sign. ( p < 0.05) reduction in macrophtye vegetation at summer's end including elimination of Potamogeton pusillus,

P. nodosus, & Najas quadalupensis;

 95% sign. ( p < 0.05) red. macrophyte coverage in May, 10 months after treatment;

 96% sign. ( p < 0.01) reduction in the number of young bluegill;

 85% sign. ( p < 0.001) red. in the number of food items/ fish stomach;

 57% sign. ( p < 0.001) red. in the number of prey taxa/ fish stomach.

500 Fg/ L  90% sign. ( p < 0.05) reduction in macrophtye vegetation at summer's end including elimination of Potamogeton pusillus,

P. nodosus, & Najas quadalupensis;

 > 95% sign. ( p < 0.05) red. macrophyte coverage in May, 10 months after treatment;

 96% sign. ( p < 0.01) reduction in the number of young bluegill;

 78% sign. ( p < 0.001) red. in the number of food items/ fish stomach;

 52% sign. ( p < 0.001) red. in the number of prey taxa/ fish stomach. Two artificial Kansas ponds each ( 0.045 ha. and 2.1 m. deep)

were treated with 20 Fg/ L and 500 Fg/ L on 24 July and two ponds served as controls. The macrophyte community in treated ponds was noticeably reduced, relative to controls, throughout the summer. Visual estimates of the macrophyte communities in the ponds showed roughly a 60 percent decline in the 20 Fg/ L ponds and a 90 percent decline in the 500 Fg/ L ponds two months after atrazine addition. These estimates were verified by rake hauls which produced these same relative differences. The following May, 10 months after treatment, when macrophytes are normally well established in Kansas ponds, the ponds were drained. Relative to control ponds, 20 Fg/ L ponds had a 90 percent reduction in macrophyte coverage and the 500 Fg/ L ponds had a > 95 percent reduction in macrophyte coverage.

Differences were noted in the macrophyte species present.

Control ponds contained Potamogeton pusillus and P. nodosus,

Najas quadalupensis, and small amounts of Chara globularis,

whereas the treated ponds contained mostly C. globularis.

Significant indirect effects were found on bluegill diet and reproduction. 45202912 Kettle, de Noyelles, Jr.,

Heacock and Kadoum 1987 Supplemental ( raw data are not available for analyses) Application rate ( lb ai/ A)

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Author/ Year XI  55 Freshwater limnocorrals:

( 3 controls and 3 treated at nominal concentrations of 100 ppb on June 1 & July 6, 1983)

Measured conc. range: 80 140 ppb after the first application,

120 165 ppb after the second application ( 329 days; measured) Effects on periphyton and environmental parameters:

first application: 80  140 ppb o no sign. effects on DO, temperature, Secchi depth,

dissolved inorganic carbon ( DIS), NO3 NO2 N),

total nitrogen, and total phosphorus o periphyton dry wt. lower than controls after Day 14 at most depths; sign. ( 0.05) red. at a depth of 0.5 m on Day 34 and thereafter o sign. 94% red. C 14 uptake ( 4 hr.) ( Days 2 163)

o usually sign. red. phytoplankton biomass ( Days 2 136)

o rapid, nearly complete red. in the abundant Peridinium inconspicuum, a small dinoflagellate and rapid red.

in 7+ other dominate phytoplankton sp. after 7 days o incr. in several flagellate species; mainly Mallomonas pseudocoronata, Cryptomonas marssonii & C. erosa o zooplankton dominance shifted to rotifers, mainly Keratella cochlearis after Day 31 o > 50% red. in the copepod, Tropocyclops prasinus mexicanus by Day 14 second application 120  165 ppb o sign. ( 0.05) 20% red. dissolved oxygen ( Days 37 137)

o sign. ( 0.05) 33% increase in Secchi depth o sign. ( 0.05) 62% increase dissolved inorganic carbon o sign. ( 0.05) 103% increase in NO3 NO2 N o sign. ( 0.05) red. periphyton dry weight at depths of 0.5 and 1.5 m on most sampling days o sign. ( 0.05) red. decr. chlorophyll ( 19 days after second appl. ( Day 54 & on some days thereafter)

o zooplankton dominance shifted to rotifers, mainly Keratella cochlearis after Day 31 o > 50% red. in the copepod, Tropocyclops prasinus mexicanus by Day 14 Elaboration of the 80 ppb treatment from Hamilton et al., 1987.

After the first application ( pulse), blue green algae were eliminated and organic matter was significantly reduced. After the second pulse, organic matter, chlorophyll, biomass, and carbon assimilation were reduced by between 36 and 67%, along with certain species of green algae. Diatom numbers were greater in treatment limnocorrals than in the control limnocorrals for nine weeks after the second pulse. 45020012 Herman et al., 1986 Supplemental ( raw data unavailable) Application rate ( lb ai/ A)

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Author/ Year XI  56 Texas Lake Mesocosm:

Measured atrazine concentrations approximately 75% of nominal ( 15 and 153 ppb) for first application and 150% of nominal ( 385 and 2,167 ppb) for the second application Phyto and zooplankton A 3x3 factorial design with three conc. of atrazine ( 0, 15, and 153 ppb) and three conc. of bifenthrin ( 0, 0.039, and 0.287 ppb)

applied as soil slurry in May, then again one month later but with atrazine conc. of 0, 385, and 2,167 ppb and bifenthrin conc. of 0,

0.125, and 3.15 ppb. Atrazine alone caused dose responsive reductions in chlorophyll, turbidity, primary production,

increases in nitrogen and phosphorous, and reduced levels of chlorophytes, cladocerans, copepod nauplii, and rotifers.

General recovery after 14 days for atrazine alone in the first phase, but recovery not complete at sampling termination after second phase ( 14 days). No synergistic or antagonistic effects noted. 45020014 Hoagland et al., 1993 Supplemental ( raw data unavailable)

Duplicate check &

delete this Artificial ponds:

( measured)

Mean measured concentrations of 18.4, 91.5 or 114 ppb ( two years data), and 314 ppb Aquatic plants, phyto and zooplankton Nominal applications of either 20, 100, or 300 ppb atrazine were monitored for effect 8 weeks after June application and in the next summer. Conductivity and oxygen concentration were affected at the 100 and 300 ppb levels. Reductions in aquatic plant numbers were observed at > 100 ppb in the summer after application, but no effects on microflora or fauna were observed.

The year after treatment ( with 10 to 30% of atrazine still in the water column), Chara sp. replaced Myriophyllum spicatum and Potamogeton natans at levels > 100 ppb. Phytoplankton became dominated with cyanophytes and then cryptophytes as the concentration of atrazine increased. Zooplankton numbers at 100 and 300 ppb were also reduced the following year. 45020017 Neugebaur et al., 1990 Supplemental ( raw data unavailable) XI  57 b. Freshwater Natural and Artificial Streams Application rate ( lb ai/ A)

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Author/ Year Small Canadian first order stream adjacent to a tiled corn field. Atrazine of unspecified purity was applied at 4 liters per hectare on 6 June 1989.

The Canadian Water Quality Guidelines ( CCREM, 1987)

specify a guideline of 2.0 Fg/ L to protect freshwater life. Non statistical pair wise comparison of Total Phytoplankton counts vs sta 9, the control indicates reductions at all downstream stations with effects generally decreasing with time and distance.

Downstream station 11 ( 2.5 km from atrazine source  sta. 5):

0.047 Fg/ L ( range 0.004 0.2Fg/ L) atrazine conc.

o all samples with reduced total phytoplankton counts o mean reduction of 63 % ( range 6  97 %)

o highest red. ( 97 %) on June 9, first sampling day o reduced 70 % in final sample on 16 Nov.

Downstream station 10 ( 50 to 75 m from sta. 5)

0.366 Fg/ L ( range 0.1  1.7 Fg/ L) atrazine conc.

o 2 out of 11 samples exceed count at sta. 9 o mean reduction of 45 % ( range + 55  92 %)

o highest red. ( 92 %) on June 9 o reduced 47 % in final sample on 16 Nov.

Downstream stations 6 & 7 ( a few meters from sta. 5)

0.81 ( 0.17  1.89) and 0.05 ( 0.001 0.224) Fg/ L, resp.

o 1 out of 9 samples at sta. 6 exceeds count at sta. 9 o mean reduction sta. 6 of 53 % ( range + 68  99)

o mean reduction sta. 7 of 66 % ( range 3  95)

o highest red. ( 99 and 93 %, resp.) on July 21 o red. 45 & 27 %, resp. in final sample on 16 Nov.

Ditch ( station 5) receiving waters from the 4 tile outlets:

2.62 Fg/ L ( range 0.211  13.9 Fg/ L) atrazine conc.

o mean reduction of 79 % ( range 46  99 %)

o highest red. ( 92 %) on 3 dates, June 23  July 21 o reduced 51 % in final sample on 16 Nov. Atrazine concentrations up to 20.39 Fg/ L ( sta. 4) in field tile water, 13.9 Fg/ L ( sta. 5) in receiving ditch and 1.89 Fg/ L in a small stream ( sta. 6) were measured in New Brunswick,

Canada in a rural headwater basin of the Petitcodiac River.

The fist order stream flowed parallel to an 8 hectare subsurface tile drained field of silage corn. The field was divided into 4 plots and each drained separately into a small canal and into the stream.

Water, phytoplankton and zooplankton were sampled at 15 day intervals at 11 sampling sites during the growing season.

Total phytoplankton numbers in downstream samples were consistently much less than those from upstream ( control)

samples during the period of low flow and higher atrazine levels ( during the summer). Diatoms dominated the phytoplankton community. Occurrence of other algal species were erratic between stations and over time. Zooplankton numbers were too low to discern trends, but downstream samples were consistently lower in individuals than control samples. 45020008 Lakshinarayana, O'Neill,

Johnnavithula, Leger and Milburn 1992 Supplemental ( Replication of samples and statistical analyses were not made) Application rate ( lb ai/ A)

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Author/ Year XI  58 Artificial stream test:

( 14 day; measured)

Simulated pulsed exposures;

5 Fg/ l atrazine on Day 1 and gradually diluted until only about 1 Fg/ L on Day 7 5 Fg/ L to about 1 Fg/ L on Day 7 o atrazine concentrations:

Day Mean conc.

1 4.74 5 3.56 10 1.20 14 1.19 Possible atrazine effect:

o 58 to 126 fold increase sign. ( p< 0.05) in number of emergent insects on Days 3, 5 and 7;

treatment numbers were equal to or greater than controls in all samples No statistical effects found in atrazine treatments on:

o periphyton growth measured as chlorophyll a levels;

chlorophyll a levels decreased gradually in all samples ( treatments & controls) over time,

" may have masked an effect of atrazine"

o indirect effects on function or taxonomic composition of benthic community structure A community of benthic, stream invertebrates from the Patrick Brook in Hinesburg, Vermont, located in the LaPlatte River watershed. Microbial community growth was incubated for 2 weeks this substrate was placed in 10 x 10 x 7 cm polyethylene boxes and placed in the stream for invertebrate colonization for 3 weeks in July 1993. During the same 3 week period glass slides were placed in the stream for algal settling and growth.

Four benthic invertebrate boxes and 9 periphyton slides were randomly placed in each of six replicate tanks. The flow rate was calculated as 20.8 L/ min. throughout the test. After a 24

hour equilibration period, treatment at 5 Fg/ L atrazine was introduced to 3 replicates and 3 controls. On Day 3, about 15 percent of the water was replaced; on Days 6 and 7 water replacements were 50 percent each day; about 15 % was replaced on Day 11 during the 14 day test.

" Dewey ( 1986) also observed herbivorous insects emerging earlier from artificial ponds treated with 20 Fg/ L atrazine compared to controls. Dewey suggested that the changes she saw were the indirect effect of atrazine exposure, which had reduced the amount of food available to herbivorous insects." 45087411 Gruessner and Watzin 1996 Supplemental ( raw data unavailable for statistical analyses)

Artificial stream tests:

( 14 day; measured)

One dose and recirculation;

two atrazine levels ( 40.8% ai):

15.2 + 1.4 and 155.4 + 1.4 Fg/ l atrazine on Day 1;

17.5 + 1.2 and 135.0 + 4.5 Fg/ L on Day 28 Interaction test with alachlor discussed under the section on pesticide interactions. 15.2 Fg/ L ( initial atrazine concentration):

o 45% red. in benthic algal biovolume after 1 week sign. ( p < 0.05);

o 35% red. in benthic algal biovolume after 2 weeks non. sign. ( p < 0.05);

o 45% red. in benthic algal biovolume after 4 weeks sign. ( p < 0.05).

155.6 Fg/ L ( initial atrazine concentration):

o 45% red. in benthic algal biovolume after 1 week sign. ( p < 0.05)

o 50% red. in benthic algal biovolume after 2 weeks sign. ( p < 0.05);

o 57% red. in benthic algal biovolume after 4 weeks sign. ( p < 0.05).

Time dependent analyses showed sign. ( p = 0.0083)

reduction in algal biovolume treated with both 15.2 and 155.6 Fg/ L atrazine throughout the test, but no sign. ( p =

0.3629) difference between 15.2 and 155.6 Fg/ L levels. A benthic mud community of epipelic algae were collected from various locations of Wahoo Creek and acclimated for 6 weeks prior to atrazine treatments. Stream water came from Wahoo Creek on March 25, 1993. Wahoo Creek is a third order, sediment dominated Nebraska stream draining primarily agricultural land and subject to major runoff events.

Each model stream was constructed from a 114 L oval shaped plastic tub and lined with two layers of 4 mil clear plastic.

Stream velocities ranged from 0.05 to 0.1 m/ sec. in the sending segment and 0.01 to 0.05 m/ sec. in the returning segment.

Lighting was 12 hour/ 12 hour light/ dark cycle. To replace evaporated water, stream water from the transport tank was mixed for 24 hours prior addition to each stream. Epipelic algae were sampled immediately before herbicide atrazine addition, 24 hours after addition, and after 1, 2 and 4 weeks.

Algal samples were analyzed for cell density, cell biovolume and the relative abundance of 6 dominant taxa. 45020002 Carder & Hoagland 1998 Application rate ( lb ai/ A)

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Author/ Year XI  59 Natural Tasmanian stream:

( 2 weeks to 7 months:

measured concentrations)

Forests aerially sprayed once at either 3 or 6 liters ai per hectare of Gesaprim: peak of 22 ppb; median conc. of 2.5 ppb for the 2 weeks after application Atrazine levels in 24 Tasmanian streams averaged 2.85 Fg/ L ( range< 0.01 53 mg/ L). In forestry areas, the mean stream conc. was 2.00 (< 0.01 8.9) Fg/ L with 35% below the detection limit of 1.0 Fg/ L.

Spray drift into the stream appeared the same as in the treated forest as estimated by spray droplet deposits on wood.

22 Fg/ L:

o sign. increase ( p < 0.01) in daytime invertebrate drift at site 2, 12 hours after treatment o site 3 also showed an increase in daytime invertebrate drift on day of treatment, but not statistically sign. ( p > 0.05)

o sign. ( p< 0.001) increase in night drift in number of hydroptylid larvae on days 1, 2, 4, and 9 o sign. ( p< 0.001) increase in night drift in number of hydropsychid larvae on days 2, 4, and 9 The effects of invertebrate drift at site 2 were associated with increased spray drift, during the 12 hours immediately following application. Poor habitat and limited taxa at site 2 precluded drift analyses on specific taxa.

o no sign. affect on mean densities of benthic invertebrates, number of taxa or taxa proportions o 71% sign. ( p< 0.01) increase in trout population at site 2 sustained over four months o no sign. effect on fish mortality or physiology Tasmanian stream, Big Creek, with a catchment area of 36 km2 was studied for atrazine aerially sprayed on two forest areas of 20 and 66 hectares, at rates of 3 and 6 kg ai/ ha on 13 and 14 October 1987, respectively. Three sampling sites were picked:

Site 1 above the 2 plantations, sites 2 and 3 were just below each plantation. Each site consisted of an upstream riffle for invertebrate samples and an area 100 m downstream for sampling brown trout ( Salmo trutta).

Atrazine levels in 174 water samples from 44 sites from 24 streams averaged 2.85 Fg/ L ( range< 0.01 53 mg/ L). Only 9.6% of samples were below detection limit ( 0.1Fg/ L) and only 24 % were below 1.0 Fg/ L. In forestry areas, the mean stream conc. was 2.00 Fg/ L ( range < 0.01 8.9 Fg/ L) with 35%

below the detection limit of 1.0 Fg/ L.

The initial measured concentration in Big creek was 22 Fg/ L,

2 weeks later atrazine averaged 2.5 ( range 1.2 4.6) Fg/ L, and over the following 2 months ranged from 0.01 to 0.09 Fg/ L.

Atrazine levels in a small seepage draining the 2 plantations range 0.8 68 Fg/ L over the next 2 months.

Site 2 sediments ranged from 1.6 to 22 Fg/ kg wet weight two weeks after spraying.

No fish mortality or behavioral changes were recorded during applications. However, brown trout movement within the application area was significantly different ( increased) than the upstream control movement. No changes in trout physiology were observed. 45020003 Davies et al., 1994 ( Species are not native to North America;

Raw data unavailable for statistical analyses) Application rate ( lb ai/ A)

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Author/ Year XI  60 Artificial stream in laboratory Technical Atrazine: 98.2%

Experiment 1:

Constant 12 day exposures at 0, 24 & 134 Fg/ L atrazine Experiment 2 involved pulsed exposures of 4 herbicides mixed together at nominal concentrations of:

Atrazine at 135 Fg/ L;

Alachlor at 90 Fg/ L;

Metolachlor at 200 Fg/ L;

Metribuzin at 20 Fg/ L.

Full concentrations on Days 8 & 9, halved on Days 10 & 11,

and discontinued on Day 12. Constant 12 day exposure tests ( Days 8 17) 10 and 25EC:

o 24 Fg/ L:

 24% red. sign. ( p<. 001) in ash free dry wt. at 25EC  30% red. sign. ( p<. 01) in chlorophyll a at 25EC o 134 ug/ L:

 47% red. sign. ( p<. 001) in ash free dry wt. at 10EC  31% red. sign. ( p<. 001) in ash free dry wt. at 25EC  44% red. s ign. ( P<. 001) in chlorophyll a at 25EC  30% red. s ign. ( P<. 01) in chlorophyll a at 10EC Nutrient uptake was affected more by the 15EC difference,

than the atrazine concentrations. Raw data were absent and statistically analyses could not be assessed. As cited:

 35% red. N uptake at 134 Fg/ L at 10EC; not sign.

 25% red. N uptake at 134 Fg/ L at 25EC; not sign.

 31% red. silica uptake at 134 Fg/ L at 10EC; not sign.

 58% red. silica uptake at 134 Fg/ L at 25EC; not sign.

 14% red. P uptake at 134 Fg/ L at 10EC; not sign.

 8 % red. P uptake at 134 Fg/ L at 25EC; not sign. Six artificial streams consisting of a 7.5 cm OD x 123 cm long Pyrex glass tube were tested concurrently for pesticide effects on aufwuchs productivity and nutrient uptake ( NO2, NO3,

phosphorus PO4 and silica were tested after an 7 day colonization period with natural waters from a third order stream in the Sandusky Basin, Ohio. Two experimental designs ( continuous and pulsed exposures) were tested under constant lighting, flow rates of 7.8 mL/ min. natural creek water and 1.0 mL/ min. nutrient water for 20 day periods.

Experiment 1. Two " streams" were exposed to continuous nominal atrazine concentrations of 0, 50 and 200 Fg/ L at 25EC and then repeated at 10EC on Days 8 17.

Experiment 2. Three streams were treated to pulsed exposures of a mixture of four herbicides. These results are not relevant to the risk assessment for atrazine. 45020007 Krieger, Baker and Kramer 1988 Supplemental ( The solvent methanol 0.00057% v/ v was not added to controls;

raw data unavailable for statistical analyses)

Two artificial model streams in laboratory continuously exposed for 30 days with 60

day recovery period and repeated 4 times in one year.

Nominal concentration of 25 Fg/ L technical grade atrazine dissolved in DMSO; atrazine concentrations in streams were not measured. 25 Fg/ L Atrazine:

After one year of 4 treatment and recovery cycles, it was reported that the treatment did not have any significant or lasting effect on macroinvertebrate population structure,

periphyton standing biomass or rates of primary production and community respiration.

Two out of 200 statistical tests showed significant effects for atrazine treatment: equitability ( p < 0.029) during Winter ,

month 3, and taxa/ sample ( P < 0.001) during the Spring,

month 3. Macroinvertebrate drift in streams increased abruptly upon injection in both controls and treatments which was attributed to the solvent rather than to atrazine.

Initial drift samples were collected only in the autumn and summer. Drift in the summer samples were " substantially higher" in the atrazine treated streams than in the DMSOtreated control. Pulses in the number of drifting organisms following toxicant/ solvent injection were primarily due to Baetis mayflies. Continuous flow stream treatment for 30 days at 25 ppb,

followed by 60 days of no treatment, and repeated 4 times for one year in artificial, 3.96 m. long concrete lined streams inside a laboratory. Invertebrate populations were introduced by colonization from incoming drift with water flowing from a natural creek over a one year period before treatment. Atrazine was injected into the flowing water for periods as described above. Benthic invertebrate populations as follows: two samples ( 10.2 cm diameter cores) during pretreatment were collected at 45 day intervals for 1 year. Three post treatment samples were made every 30 days.

24 Hour invertebrate drift samples were collected were collected on days 1, 5, 10, 20, and 29 during treatment and on days 14, 42 and 60 during recovery periods.

Dry and ash weights of periphyton standing crop on four 25 x 75 mm glass slides were sampled at 4 day intervals for 28 days before and after each treatment.

24 Hour gross primary production and community respiration rates ( O2 levels) were measured during the autumn on days 2,

4, 8, 15, 24 and 29 after treatment and on days 20, 42, 54 and 60 during the recovery period. 45020009 Lynch et al., 1985 Supplemental DMSO is not an acceptable solvent,

because it accelerates the movement of chemicals across cell membranes. As such it represents a worst case exposure.

Raw data were not available for statistical analyses. Three or four samples are considered inadequate for field samples to show anything short of severe effects. Application rate ( lb ai/ A)

Nominal/ Measured Conc. Concentration affecting endpoint ( time to effect)

o Affected species and life stage Narrative of Study Trends MRID No.

Author/ Year XI  61 Artificial model streams in laboratory:

( 7 days; nominal)

Single applications to spring water; Brazos, Texas.

Nominal test concentrations: 0,

100, 1000 and 10,000 Fg/ L o statistically significant reductions (*) in net stream community productivity compared to controls:

Day 1 Day 3 Day 7 100 Fg/ L 736 %* 117 %* 34 %

1000 Fg/ L 1367 %* 227 %* 119 %*

10,000 Fg/ L 1716 %* 264 %* 135 o sign. ( p< 0.02) increase in Nitzschia cell numbers o no significant effect on other dominant algal groups o no significant effect on community respiration rates o no significant effect on conductivity or alkalinity Four replicate recirculating artificial streams per treatment.

Each stream ( 2.43 m long, 12.5 cm wide and 6 cm deep) was lined with polyethylene plastic and a single layer of gravel.

Water from Minter Spring is a nearly anoxic and has a constant temperature ( 21EC). The flow rate was about 5 cm/ sec. The principal algae genera were Anabaena, Nitzschia, Rhopalodia and Navicula. Five weeks for colonization of benthic algae on glass slides. Each stream received a single treatment which was recirculated. Nominal conc. were 0, 0.1, 1.0 and 10 Fg/ L.

Endpoints were net community productivity, respiration rate,

cell numbers of dominant species, conductivity and alkalinity. 45020010 Moorhead and Kosinski 1986 Supplemental ( raw data unavailable)

Not assayed, nominal conc. of 5, 25, and 125 ppb Snail ( Lymnaea palustris) Snails exposed to one time dosing in mesocosm of either 5, 25,

or 125 ppb and monitored for 12 weeks, no affect on growth,

fecundity, or saccharide metabolism. 45020013 Baturo et al., 1995 Mean concentrations over two months of 5, 10, 22, 68, 182,

and 318 ppb Phyto and zooplankton Mesocosms in Bavaria were treated with atrazine 3 times over 3 summer months. Dose responsive reductions in dissolved oxygen and pH were noted at concentrations greater than 5 ppb. Substantial biological effects were generally noted at concentrations > 182 ppb. Some effects on copepod nauplii were noted at 68 ppb. Diatoms appeared to become the dominant phytoplankton. 45020022 Jüttner et al., 1995 Supplemental ( raw data unavailable)

Nominal concentrations of 20,

100, 200, and 500 ppb.

Measurements bi weekly or monthly but results based on nominal concentration Phytoplankton Results of single species assays, microcosm, and pond studies were compared. Carbon fixation was used as the end point for all three study types. Laboratory results with eight algal species ranged from 37 to 308 ppb for carbon uptake inhibition EC50 values. Microcosm EC50 values ranged from 103 to 159 ppb. The mean pond EC50 was 100 ppb for carbon uptake and 82 ppb for chlorophyll a inhibition. Authors stated that multiple laboratory studies or a microcosm study represent( s)

entire ecosystem functional effects. 45020015 Larsen et al., 1986 Supplemental ( raw data unavailable)

Table 1  cont. Atrazine Field or Mesocosm Studies. XI  62 Application rate ( lb ai/ A)

and/ or Nominal/ Measured Concentration Affected Species and Life Stage Percentage Affected in Comparison to the Control and Type of Effect Author/

Year Measured = nominal ( 50 ppb)

at time zero, declined to 40%

of nominal after 8 weeks Aquatic plants and fish Atrazine and esfenvalerate were applied together in mesocosms to examine possible synergism ( reduction of macrophytes leading to extension of insecticide residues and increased fish mortality).

Combinations of 50 ppb atrazine and esfenvalerate at 0.25 to 1.71 ppb did not result in synergism.

However, Chara sp. totally replaced the co dominant Naja sp. six weeks after application. Fairchild et al., 1994 Day 1 measured concentrations of 80, 140, or 1,560 ppb Periphyton Applications were made to in situ limnocorrals in June ( 140 and 1,560 ppb) or June & July ( 80 ppb)

and colonized periphyton slides were submersed in August and monitored for either 56 days ( 140 and 1,560 ppb) or 210 days ( 80 ppb). Trends from both years included a shift from a chlorophyte to a diatom community, and a development of some atrazine " resistant" colonies. Community production was reduced by 21% and 82% at the 140 and 1,560 ppb levels, respectively, and certain algae were reduced up to 93%. All biotic measures indicated reduced growth, with cell densities lagging productivity. All parameters except species richness returned to control levels prior to 56 days after first or second applications. 45020020 Hamilton et al., 1987 Supplemental ( raw data unavailable)

Day 1 measured concentration of 80 ppb ( two applications of 100 ppb made 35 days apart) Phyto and zooplankton Elaboration of the 80 ppb treatment from Hamilton et al., 1987. Two weeks after first application,

significant declines in multiple species of green algae were observed, whereas crypto and dinoflagellates either increased or stayed the same. Low population densities persisted for 114 days after the second application. Average of .25% fewer species in atrazine limnocorrals. Control and treated values equilibrated within one year of treatment. Only two zooplankters were affected ( after the second application). A MATC was suggested to be between 100 and 200 ppb. Hamilton et al., 1988 Table 1  cont. Atrazine Field or Mesocosm Studies.

Application rate ( lb ai/ A)

and/ or Nominal/ Measured Concentration Affected Species and Life Stage Percentage Affected in Comparison to the Control and Type of Effect Author/

Year Measured after a single dose at 1,100 ppb

Day 1: 200 ppb, 55 days later:

60 ppb Phytoplankton Treatment related reductions in oxygen, and pH, and increases in conductivity were noted after atrazine treatment, with oxygen and pH returning to control values within 30 40 days. At 26 days after dosing, 78 algal cells/ mL were present in the control and no cells were present in the treated enclosures. Diversity was also reduced the month after application. 45020016 Lay et al., 1984 Supplemental ( raw data unavailable)

Not assayed, nominal concentrations of 50,000,

100,000, and 150,000 ppb Autotrophs Primary production and respiration was monitored in a freshwater ecosystem in India. Net productivity in water samples was reduced by 23% and 73%, respectively, at 50,000 and 100,000 ppb,

in comparison to control values, and was negative in the 150,000 ppb treatment group. Piska and Waghray,

1990 XI  63 c. Marine and Estuarine Waters Application rate ( lb ai/ A)

Nominal/ Measured Conc. Concentration affecting endpoint ( time to effect)

o Affected Species and Life Stage Narrative of Study Trends MRID No.

Author/ Year Marine Mesocosm:

Open Ocean: Phytoplankton:

( 15 days; measured conc.)

Measured = nominal at time zero, concentrations of 0.12,

0.56, and 5.8 ppb 0.12 ppb ( differences compared to controls)

o sign. lower pH levels ( Days 5 14); indicative of reduced photosynthesis o higher dissolved organic nitrogen ( DON) ( Days 6 11)

o up to 50% red. primary production ( Days 3 11)

o up to 60% red. particulate carbohydrates ( Days 5 15)

o up to 70% red. chlorophyll ( Days 4 15)

0.56 ppb o sign. lower pH levels ( Days 5 13)

o incr. total dis. organic phosphate ( DOP) ( Days 3 14)

o higher DON ( Days 5 15)

o up to 50 % red. primary production ( Day 3 13)

o up to 85% red. particulate carbohydrate ( Days 5 15)

o up to 80% red. chlorophyll ( Days 4 15)

5.8 ppb o sign. lower pH levels ( Days 5 11)

o up to 200% increase in total DOP ( Days 3 14)

o up to 200 % increase in total DON ( Days 2 15)

o up to 50% red. in primary productivity ( Days 3 7)

o up to 60% red. in partic. carbohydrates ( Days 5 15)

o up to 30% red. in chlorophyll conc. ( Days 4 15) Mesocosms ( 2 m2) inoculated with the diatoms Thalassiosira punctigera, T. rotula, Nitzschia pungens and Skeletonema costatum and a prymnesiophtye, Phaeocystis globosa.

evidenced a dose responsive elevation in dissolved nitrogen and phosphorous and reduction in primary production at 0.12, 0.56,