Pesticide Residues, Heavy Metals, and DNA Damage in Sentinel Oysters Crassostrea gigas From Sinaloa and Sonora, Mexico

Abstract

Pesticides and heavy metals were analyzed in sentinel Crassostrea gigas oysters placed in six aquaculture sites close to a contaminated agricultural region. Each site was sampled twice. Tests revealed the presence of organochlorine (OC) pesticides in the oysters at concentrations varying from 31.8 to 72.5 μg/kg for gamma-hexachlorocyclohexane (γ-HCH); from 1.2 to 3.1 μg/kg for dichlorodiphenyldichloroethylene (4,4-DDE); from 1.6 to 2.3 μg/kg for endosulfan I; and from 1.4 to 41.2 μg/kg for endosulfan II, as well as heavy metals in concentrations that exceeded Mexican tolerance levels (405.5 to 987.8 μg/g for zinc; 4.2 to 7.3 μg/g for cadmium; and 7.2 to 9.9 μg/g for lead). Significant levels of DNA damage in oyster hemocytes were also detected. There was a significant, positive correlation between genotoxic damage and concentration of nickel or the presence of endosulfan II. Cellular viability evaluated by cytotoxic analyses was found to be high at 80%. Marked inhibition in activity of acetylcholinesterase (AChE ) and induction of glutathione S-transferase (GST) activity was noted. Data demonstrated a significant relation between AChE activity inhibition and presence of endosulfan II, γ-HCH, copper, lead, and 4,4-DDE, as well as between AChE and GST activity at different sites.

ACKNOWLEDGMENTS

The authors thank C. Escobedo and B. Acosta for their collaboration. The results presented here are part of the B.Sc. thesis by Emilie Bigaud under the direction of C. Vazquez Boucard.