Risk Assessment for Dermal Exposure of Organochlorine Pesticides for Local Fishermen in the Rangsit Agricultural Area, Central Thailand

ABSTRACT

Organochlorine pesticides (OCPs) used in agriculture and for public health purposes were banned in Thailand over the past decade; however, their persistent residues have been found in several agricultural areas of the country. This may result in adverse effects to human populations. This study investigated the concentration of organochlorine pesticides residues (OCPRs) in surface water and evaluated the potential cancer risk associated with dermal contact of the local fisherman fishing in the Khlong 7 canal, Rangsit agricultural area, central Thailand. Water samples were extracted using liquid-liquid extraction (LLE) and then analyzed by gas chromatography with microelectron capture detector (μ -ECD). The results show that low concentrations of OCPRs were detected in parts per billion (ppb or ng/ml) levels, that is, ∑ Endosulfan (α -, β -, and -sulfate) 0.082 ng/ml > DDT and derivatives 0.019 ng/ml > ∑ HCH (α -, γ -, β -, and δ -HCH) 0.014 ng/ml > aldrin and dieldrin 0.007 ng/ml > heptachlor and heptachlor epoxide 0.0068 ng/ml > endrin and endrin aldehyde 0.005 ng/ml > methoxychlor 0.001 ng/ml, respectively. Using the worst-case scenario defined as the reasonable maximum exposure (RME) to assess the potential cancer risk, five OCPs (dieldrin, 4,4′ -DDT, β -HCH, heptachlor, and heptachlor epoxide) may pose a risk of concern on a lifetime human carcinogenesis greater than one in a million.

Key Words:

• organochlorine pesticides
• human health risk assessment
• dermal exposure

ACKNOWLEDGMENTS

We thank both grant-supporting sources for each part of this study. Part I, the analysis of OCPs concentration, was supported by the National Center of Excellence for Environmental and Hazardous Waste Management, Chulalongkorn University. Part II, cancer risk assessment, was supported by the Thai Fogarty Project D43 TW007849-01 Fogarty International Center–National Institutes of Health–National Institute of Environmental Health Sciences, USA. Furthermore, we also thank Ms. J. Rohitrattana and Ms. P. Thongkongowm for their assistance with sample collections.

Notes

¹ This study protocol was exempted from Institution Review Board (IRB) review by the authors' Thai institution because there were no identifiers for the questionnaires and no personal or biological samples were taken from the interviewed participants; the primary sampling for this study was environmental sampling including environmental media and food samples.

^a Available from USEPA (1992);

^b CSF—Cancer Slope Factor available from Integrated Risk Information System (IRIS 2008);

^c LADD—Lifetime Average Daily Dose calculated by Eq. (1);

^d Weight-of-Evidence classified as B₂ class; probable human carcinogen (IRIS 2008);

^e Weight-of-Evidence classified as C class; possible human carcinogen (IRIS 2008).