Heptachlor: Uptake, depuration, retention, and metabolism by spot, Leiostomus xanthurus

Abstract

The estuarine fish, spot (Leiostomus xanthurus), was exposed to 0.27, 0.52, 1.01, 1.99, and 3.87 μg/liter technical grade heptachlor (65% heptachlor, 22% trans‐chlordane, 2% cis‐chlordane, 2% nonochlor, and 9% unidentified compounds) for 24 days in a flowthrough bioassay, followed by 28 days in heptachlor‐free seawater. Concentrations of heptachlor, heptachlor epoxide, and trans‐ and cis‐chlordane in edible tissues were monitored at day 3 and weekly thereafter throughout the bioassay and at the end of the postexposure period. All four chemicals were accumulated by spot. Maximum concentrations of heptachlor were observed on day 3; maximum concentrations of the other three compounds were observed on day 17. The average bioconcentration factors for heptachlor and trans‐chlordane were 3,600 and 4,600, respectively. Only 10% or less of the maximum concentrations of heptachlor, heptachlor epoxide, and trans‐chlordane accumulated during the exposure period remained after 28 days in pesticide‐free seawater; an average of 35% of the cis‐chlordane remained. Relative total amounts of heptachlor and cis‐chlordane changed during the exposure and post‐exposure periods. Nearly all of the heptachlor was eliminated or metabolized to its epoxide. Cis‐chlordane, which averaged 4–7% of the total residues (chlordanes and heptachlors) in edible tissues during the exposure, increased to 18–23% of the total residues by the end of the postexposure period.