Endosulfan’s Effects: Saiyed’s Response

Omissions and Flawed Data The main objective of the Endosulfan Manufacturers and Formulators Welfare Association in India is disseminating scientific facts concerning the use of endosulfan. Because endosulfan is used in several countries, the association watches for global news and information relevant to endosulfan. Members of the Endosulfan Manufacturers and Formulators Welfare Association are of the strong opinion that Saiyed et al. (2003) omitted significant information in their published report “Effect of Endosulfan on Male Reproductive Development.” Consequently, to uninitiated readers the article presented an alarming picture of endosulfan, a pesticide registered for use in over 70 countries for more than 40 years. Saiyed et al. (2003) failed to mention the origin of their study. In fact, their study is an integral part of an epidemiologic study submitted to the government of India in 2003, “Report of the Investigation of Unusual Illnesses Allegedly Produced by Endosulfan Exposure in Padre Village of Kasargod District” [National Institute of Occupational Health (NIOH) 2003]. After studying this report and other related studies, an expert group appointed by the government of India categorically concluded in February 2003 that “there is no link established between use of endosulfan in PCK [Plantation Corporation of Kerala] plantations and health problems reported in Padre village” (Central Insecticides Board and Registration Committee 2003). The government of India has since accepted this conclusion. Epidemiology is a science of proving association and not causation. Therefore, we consider the conclusion of Saiyed et al. (2003) that their “study results suggest that endosulfan exposure may delay sexual maturity and interfere with hormone synthesis in male children” to be unscientific, uncalled for, and objectionable. Saiyed et al. (2003) failed to mention the fact that, besides endosulfan, a host of other pesticides were also used in both exposed and control study areas. The comment by EHP’s Science Editor, Jim Burkhart, in the press release dated 1 December 2003 (EHP 2003) that “decades of spraying this pesticide [endosulfan], and only this pesticide” is therefore erroneous. The authors failed to mention the actual quantity of endosulfan aerially applied in the cashew plantation block closest to Vaninagar school (exposed group), which was 105 g active ingredient (ai)/acre/year. This rate should be compared with the permissible seasonal application rates elsewhere, including the United States, where 1,000 g ai/acre/year is often exceeded. Saiyed et al. (2003) failed to take into consideration the fact that the interval between annual aerial applications was nearly 11 months and that the aerial applications were made 5–6 months ahead of monsoon rains. All this must be weighed against the known half-life of endosulfan in conditions in India (30–50 days). In the proceedings of the expert group, the experts on epidemiology and residue science raised serious objections to the study design, sample selection, and residue analysis adopted by the NIOH (2003). Endosulfan residue levels reported by Saiyed et al. (2003) in blood samples are 1,000 times greater than the residue levels reported in water samples by the authors in the original report submitted in India (NIOH 2003). The scientific properties of endosulfan do not support this phenomenon. Also, two studies by Kerala Agricultural University (State of Kerala 2001) that preceded the article by Saiyed et al. (2003) did not find endosulfan residues in water in Padre village. These are a few representative omissions and flaws in the article by Saiyed et al. (2003). Knowing the reputation and professional excellence of EHP, I appreciate the chance to address these problems here. The author declares a competing financial interest because he is retained as executive secretary to the Endosulfan Manufacturers and Formulators Welfare Association of India.