This review examines the potential for γ-hexachlorocyclohexane (HCH) to be transformed into other isomers of HCH. HCH residues are among the most widely distributed and frequently detected organochlorine contaminants in the environment. The potential environmental and human health risks associated with these residues have prompted Canada, the United States, and Mexico to consider the development of a North American Regional Action Plan (NARAP) to assess and mitigate HCH pollution. More information on the propensity of γ-HCH to transform into other isomers is essential to the development of an effective regional management program. The high relative concentrations of α-HCH in the Arctic suggest that γ-HCH may be transformed into other isomers in the environment. Laboratory studies show that significant photoisomerization of γ-HCH to α-HCH is possible. However, field studies do not find evidence for significant isomerization of γ-HCH, and recent environmental samples suggest that α-HCH residues are declining as the use of technical HCH has ended in most parts of the world. Alternative explanations for the patterns of isomer contamination are discussed.

A nine-home pilot study was conducted to evaluate monitoring methods in the field that may be used to assess the potential exposures of children aged 6 months to 5 years to pesticides found in the home environment. Several methods, some of which were newly developed in this study, were tested for measuring pesticide residues in indoor air, carpet dust, outdoor soil, and on the children's hands. Information was also collected on household characteristics, pesticides used and stored at the residence, and children's activities. Pesticides were detected at all nine study homes. With the exception of one home, at least one pesticide was detected in all matrices sampled at each house. Of the 30 target pesticides, 23 were detected during the study. The most frequently detected pesticides were chlordane, chlorpyrifos, dieldrin, hepatachlor, and pentachlorophenol. The greatest number of pesticides and highest concentrations were found in carpet dust. The results of these investigations will be discussed in terms of performance of the methods and the distribution of pesticides across the various media sampled.

The Non-Occupational Pesticide Exposure Study, funded by the U.S. Environmental Protection Agency, was designed to assess total human exposures to 32 pesticides and pesticide degradation products in the non-occupational environment; however, the study focused primarily on inhalation exposures. Two sites--Jacksonville, Florida (USA) and Springfield/Chicopee, Massachusetts (USA)--were studied during three seasons: Summer 1986 (Jacksonville only), Spring 1987, and Winter 1988. Probability samples of 49 to 72 persons participated in individual site/seasons. The primary environmental monitoring consisted of 24-hr indoor, personal, and outdoor air samples analyzed by gas chromatography/mass spectrometry and gas chromatography/electron capture detection. Indoor and personal air concentrations tended to be higher in Jacksonville than in Springfield/Chicopee. Concentrations tended to be highest in summer, lower in spring, and lowest in winter. Indoor and personal air concentrations were generally comparable and were usually much higher than outdoor air concentrations. Inhalation exposure exceeded dietary exposure for cyclodiene termiticides and for pesticides used mainly in the home. Dietary exposures were greater for many of the other pesticides. Inhalation risks were uncertain for termiticides (depending on rates of degradation) but were negligible for other pesticides. The data were insufficient to support risk assessments for food, dermal contact, or house dust exposures.