Data key to understanding relationship between pesticides, health

Editor’s note: The following document was sent to Kauai Council Members, Mayor Carvalho, and Scott Enright, chairman, Hawaii Department of Agriculture.

You recently received a communication from Peter Adler transmitting a May 19, 2015, analysis of the UH 2013 Kauai air study which had been omitted from the final JFF report. I was asked to serve as a JFF member (recommended by DOH) but took the role as a liaison, because I live only part time on Kauai.

My expertise concerns human exposure to pesticides and toxic chemicals and making recommendations to federal and state officials regarding appropriate environmental studies to assess human health risks. I served as the senior health and science advisor to U.S. EPA Region 5 Chicago for several decades and I am currently with the University of Illinois School of Public Health.

In my career, I have been involved in roughly a 100 environmental cases where the public and elected officials were concerned about potential environmental contamination from toxic chemicals.

Peter and JFF members requested that I evaluate the UH air study and the Waimea Canyon Middle School (WCMS) events. As you know the WCMS events were a key reason for the undertaking and funding the JFF Kauai Pesticides evaluation.

The UH air study (Review of Air Sampling and Analysis for Pesticide Residues and Odorous Chemicals in and around Waimea, Kauai, Qing X. Li, et al., UH, March 15, 2013) drew unsupportable conclusions that stinkweed and a chemical component called methyl isothiocyanate (MITC) likely caused the health issues at local schools. This was a $100,000 unpublished study that did not go through a scientific peer review process as is done with published studies.

You have certainly seen repeated statements in the press over the years stating that stinkweed and specifically MITC caused the adverse effects at WCMS. The scientific facts do not support this conclusion.

MITC was 230 times below a California Air Health Criteria at WCMS and 12 times below the criteria at an active stinkweed site on Maui. While excessive oral ingestion of stinkweed has known health effects, no literature or cases are known indicating that outdoor air levels of stinkweed organics are capable of causing the symptoms reported at WCMS. The authors should have included comparison to health criteria and conducted a complete literature review.

DOH has recently suggested that mass hysteria (psychogenic illness) as the probable cause of the WCMS events. While literature reports do exist of psychogenic illnesses at schools, these are rare events. In 30 years investigating health cases in conjunction with health departments from Michigan, Illinois, Ohio, and with Centers for Disease Control we never came across a mass psychogenic event. Sure it is a possibility, but the repeated events at WCMS, the severity of the symptoms, and no such determination of hysteria by attending health providers, make the psychogenic hypothesis unlikely.

Definitive conclusions could have been more readily drawn in the WCMS episodes and the recent 2016 Syngenta case, if blood and urine samples had been collected by health care providers and subsequently analyzed for pesticides and metabolites.

It is also possible that pesticide residues were missed in the WCMS analytical testing because broad scan (comprehensive) pesticide analyses appear not to have been conducted.

The most important recommendations in the May 19, 2015 memorandum are to have field test kits to assess pesticide exposure (cholinesterase depression) available at health care centers and to have a funding mechanism in place to test blood and urine in unusual, acute pesticide episodes. Samples can be shipped to mainland laboratories. For future pesticide events putting into practice these recommendations as soon as possible will help resolve these ongoing pesticide exposure debates and give greater reassurance to the public.

For the reasons discussed above, I believed it was important that you and your staff understand the May 19, 2015, analysis sooner rather than later within the context of the WCMS JFF report chapter and other information found in Appendix 2, Section 7.

Finally, the JFF report covers the majority of issues quite well and has valuable recommendations regarding environmental sampling (e.g., west side soils/dusts, air, and surface waters) that are worthy of funding and implementation. With data, definitive conclusions can be drawn about risks or lack of risks to public health and ecology. Without the data, debate and speculation will continue for years to come.


Milton Clark, Ph.D., University of Illinois School of Public Health, former senior health and science adviser, EPA, Chicago.


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