Furthermore, health effects were identified from chronic exposure to different contaminating substances that had previously not been identified as having a risk factor. Some were even considered beneficial, but with exposure effects over time it became evident that they were harmful to peoples' health.
Por otra parte, se identificaron efectos a la salud por exposición crónica a diversos contaminantes que antes no eran identificados como riesgosos, o inclusive, que eran considerados de uso benéfico, pero cuyos efectos de exposición a través de los años generaban daños a la salud.