But the Town Hall discussion of the laboratory results earlier this month did not explore how the pesticide, which is applied as an oily solution to the heads and necks of deer as they feed at a 4-poster station, got into the neck meat and just what the results will mean for future testing as the three-year program progresses.
Susan Walker, the Cornell scientist studying the impacts of the 4-posters on deer, answered, via email, a few questions from the Reporter about the test data and its implications.
What are the ways that detectable permethrin could have gotten into the neck meat?
“Routes of entry can be transdermal (through the hide, from topical application from rollers and/or other sources such as landscape application), through wounds in the hide (also from topical application), from contamination of sample during collection and from contamination of sample in the analytical lab. Transdermal and contamination in the field seem most likely, followed by contamination in the lab. The sample protocol used takes precautions to avoid cross-contamination of the samples. However, working in field settings rather than controlled laboratory settings makes it difficult to be 100 percent certain cross-contamination does not occur. Thinking from a realistic mind-set, sampling done in the field more closely reflects the real setting in which a hunter field dresses his/her animal. Dan Gilrein and I suspect transdermal to be the main source in this case.”
Do you have pieces of the deer hide and can they be tested to see if permethrin passed through the skin to the muscle below?
“Yes, I still have the hide/skin samples from SI15. At this time I do not know what value this type of analysis would have because it would indicate presence of permethrin. The coat swabs already determined the presence of permethrin on the coat. Whether the analysts at the Animal Health Diagnostic Center can isolate specifically what is present in skin cells, I do not know. Nor do I know if an analyst sees any value in doing so. I am addressing various procedural and analytical questions that have arisen and I plan to discuss ideas such as this with the analyst.”
Who is considered the permethrin expert on this project? Is there someone from the DEC or Cornell that can speak authoritatively about the chemical and how it moves through or builds in animal tissues?
“We have several, depending on the question(s).
“Jim Leach (NYS Department of Health) addresses health issues and is one to whom I would address animal- and human-related questions. Vinny Palmer (DEC, Pesticide Control Specialist III) can address state registration and regulatory issues, and can also speak to some environmental issues. Dan Gilrein (Cornell Cooperative Extension of Suffolk County, entomologist) can answer questions related to use and pest management. Dan Gilrein indicated that for topics or questions that aren't covered by the above we can find someone who can speak to it, just as we have for groundwater questions, etc.”
Will testing protocols change in light of the October results? If so, how?
“We have discussed and reviewed field sampling protocol to address possible field contamination, and have talked about a couple of ideas (such as removing hair prior to skin removal and muscle exposure or removing the entire hide where acceptable, prior to collecting the sample). All decisions for the 2009/2010 sampling efforts will be discussed among Cornell, DEC, DOH and laboratory analysts. We also will ensure the analytical lab uses and analyzes material from center of sample and not outside in case of surface contamination. Also related to the topic, the lab's quality assurance documents are being reviewed by DEC and DOH. This is not field protocol-related, but does get at the question of handling in the lab as a source of contamination and test methods as a source of error.”