A new study on salmon has revealed that pesticides that overspill from the land and mix in rivers and streams combine to have a greater than expected toxic effect on the nervous system.
Scientist Nat Scholz, a fishery biologist with the National Oceanic and Atmospheric Administration, discovered that these pesticides are widely used in the United States and their occurrence as mixtures in the food supply for humans may also pose an unexpected risk for people.
"We have a pretty good handle on how to assess the health effects of single chemicals in conventional toxicity trials," said Scholz.
"But the real world is usually more complex, and exposures to mixtures of chemicals can be more of the rule than the exception. One of the major scientific challenges of our generation is to develop new approaches to anticipate and head off any ill effects of interacting chemicals," he added.
Scholz and his colleagues found that salmon died when exposed to combinations of pesticides that were not deadly when tested in individual trials.
He said that the findings for salmon could have important implications for the recovery of many threatened and endangered salmon populations throughout the western United States.
The research also points to the need for more study of how combinations of pesticides found on fruits and vegetables may be affecting humans, he added.
Scholz will present his research along with five other scientists from the U.S. government, the Canadian government and academia in the symposium entitled "From Kitchen Sinks to Ocean Basins: Emerging Chemical Contaminants and Human Health."