what is the {afflicts} for {arsenic} has {minimal lethal dose} as {300.0} ?
Arsenic has a minimal lethal dose of 300; what effects does it have at that level?
What effects does arsenic have at the minimal lethal dose of 300?
SELECT ?u WHERE { resource:Arsenic property:minimal_lethal_dose ?p . FILTER ( CONTAINS ( ?k , '300.0' ) ) . ?p property:minimal_lethal_dose ?k . ?p property:afflicts ?u }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q871> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P2300> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <300.0> .
?statement <http://www.wikidata.org/entity/P689> ?value. 
} 

SELECT ?value WHERE { wd:Q871 p:P2300 ?s . ?s ps:P2300 ?x filter(contains(?x , '300.0')) . ?s pq:P689 ?value}