Salmon and pesticides

Research conducted by NOAA’s Northwest Fisheries Science Center and Washington State University has discovered that common agricultural pesticides which attack the nervous systems of salmon can turn more deadly when they combine with other pesticides.  This development is likely to underscore requirements for no spray buffer zones along salmon waterways – a requirement which agricultural groups have been fighting ever since it was ordered by a federal judge. 

Anti-spray groups have long sought study of the “synergistic effects” that can occur when pesticides are used in combination and when they are mixed with so-called “inert ingredients” like oils. Combining pesticide in toxic cocktails and combining them with "inert ingredients” to help the pesticides better cover the target area are common practices. But studies of synergistic effects has been rare. 

What is not rare, however, is for the Northwest Fisheries Science Center to be on the cutting edge of salmon research.  For example, Robin Waples, one of the Centers most senior researchers, is credited with creating the concept of the Evolutionarily Significant Unit (ESU).  As applied to salmon, the ESU comes between the species and the stock; it has been used to separate salmon for risk assessment and endangered species listings. The ESU concept has made maintaining diversity within salmon species a workable proposition.   

The new science finding is likely to be used by the Northwest Coalition for Alternatives to Pesticides (NCAP) to further advance the organization's seven-year campaign to force the government to address risks to salmon from pesticides.  That effort has been covered by HCN  since NCAP first published a report on how pesticides impact salmon in 2002 - including the lawsuits the group led, first to force the EPA to address pesticide risks to salmon and subsequently to ban use of 38 pesticides near streams that host threatened and endangered runs of salmon and steelhead in Washington, Oregon and California.  

The implications of the pesticide cocktail study extend far beyond the salmon issue. Rebecca Clarren has reported in HCN on the risks posed to farm workers from pesticides. But farmworker risk assessments have only studied the impact of single pesticides. The new salmon studies suggest that farmworkers too may be even more at risk when pesticides are used in combination.