HCHs Only three of four HCH isomers and were

3.3.4. HCHs
Only three of four HCH isomers (α, β and γ) were detected in the present study; δ-HCH was systematically below the LOQ of 0.05 ng/g ww (Table SI-1). The proportion of α- and γ-HCHs decreased significantly with time, while β-HCH increased (Fig. 4D), perhaps because β-HCH LDN193189 more effectively bioaccumulated than γ-HCH (ATSDR, 2005). The decreasing proportion and concentrations of γ-HCH (Table 2) indicate minor recent inputs to LO, reflecting limitations on its use in North America to quasi-pure γ-HCH in pharmaceuticals (ATSDR, 2005).