Dr. Don Weston

Dr Don Weston

Dr. Weston's research interests include invertebrate ecology and ecotoxicology. His work largely focuses on toxicity and bioaccumulation of sediment-associated pollutants.

Pyrethroid Pesticides

Since 2004, Dr. Weston has been studying the environmental effects of pyrethroid insecticides. Pyrethroids are the synthetic forms of a natural insecticide found in certain chrysanthemums. Pyrethroids are used in agriculture, by professional pest control firms, and in many insecticide products consumers use in homes and gardens.

Pyrethroids have been on the market for decades, but their use in non-agricultural urban and suburban settings has increased dramatically in the last several years. Over a million pounds of pyrethroids are now used annually in California.

Environmental Risks

Although pyrethroids are less toxic to humans and mammals than the organophosphates, a class of insecticides that is being increasingly restricted and whose use is declining, adequate testing to manage environmental risk to sediment-dwelling organisms was never done.

Recent studies led by Dr. Weston show that pyrethroids are found in the sediments of agriculture-affected streams and many urban creeks. Quite often they are in high enough concentration to be toxic to sensitive invertebrates. He continues to gather data to minimize the environmental impact of their use, such as developing new tools to determine when pyrethroids may be responsible for observed toxicity, quantifying the release of pyrethroids to streams from urban storm drains, and evaluating farming practices that minimize transport of pyrethroids off the fields and in to nearby creeks.

Dr. Westo​n: Q&A

Why did you decide to become a scientist?

As a kid I was always interested in biology, and I was constantly bringing home snakes, turtles, toads and the like.  I had always expected to go in to wildlife or marine biology. I went to graduate school to pursue work in marine biology, though my career path has taken a few twists and turns since then.

What led you to the questions you are now investigating in your research?

My current research focuses on the environmental risks of sediment-associated insecticides. When I started working on pesticides I was struck by the fact that all the emphasis in state and federal pesticide regulation had focused on the water column. We knew little about toxicity to bottom-dwelling organisms or persistence of the compounds in the sediments. Environmental monitoring was largely limited to water sampling, and I felt that by ignoring the sediments we were missing half the picture.

How does your research affect your classroom and/or lab?

I teach an environmental toxicology course, and I believe inclusion of my current pesticide research is one of several factors that give the course a “real-world” flavor. The topics I cover are very relevant to development of current environmental policies and regulations, and I think that students are interested in covering issues in class that could easily be on the front page when they pick up a newspaper.

What do you enjoy most about your research?

I like the fact that my research is contributing not only to our basic understanding of pesticide toxicology, but is being quickly incorporated into environmental decision making by state and federal agencies.  The state is now conducting a formal re-evaluation of pyrethroid pesticides because of the emerging evidence of aquatic toxicity. It is the largest pesticide re-evaluation California has ever done. I believe my work is making a meaningful contribution to that effort.

For more information, see:

Don Weston's Faculty Research Interests Page

November / December 2007