Salmon mixup.

Posted by David Buchwalter, Ph.D. at Mar 05, 2009 02:49 PM |

A recent AP article accurately captures the science, rightfully points out the regulatory issues of testing chemical mixes and goofs by not raising important benefits of animal testing.

A March 3 story by AP science writer Jeff Barnard tells readers about a recent article in Environmental Health Perspectives finding that pesticide mixtures were more toxic to endangered Coho salmon than might be predicted by the pesticides’ individual potencies. 

The story did a good job of capturing the key scientific findings of the research article and augmented the presentation with quotes from both the lead investigator of the study and other pesticide experts not involved in the work. 
 
Mr. Barnard did a nice job of putting the science into a sociopolitical context in two ways. First, he highlighted that the testing of pesticides as mixtures was not required by law by the US Environmental Protection Agency (EPA). Second, he informed readers that the evaluation of pesticide safety currently being performed by NOAA Fisheries Service and EPA is the result of a lawsuit filed by the Northwest Coalition for Alternatives to Pesticides and others.
 
One subtle and important finding not mentioned in the news story relates to previous work done by some members of the research team that conducted the current Coho salmon study.
 
The earlier study with Chinook salmon did not find the synergistic effects of pesticide mixtures, as was observed with Coho salmon. A major difference between the two studies was the use of whole fish in the Coho study versus isolated tissue samples in the Chinook study. 
 
This difference is important because it calls to question whether chemical safety can be adequately addressed without using whole animals in research studies. Currently, some advocacy groups and regulatory agencies are proposing that researchers replace animals with tissues and cells during chemical safety tests and health effects experiments.