Lead and Arsenic Accumulation and Its Effects on Plasma Cortisol Levels in Oreochromis sp.

The accumulation, elimination and effect of heavy metals on plasma cortisol levels in Oreochromis sp. were studied in the exposure and recovery phases. In the exposure phase, the mean rate of accumulation in the tissues was in the order gill > liver > muscle for Pb exposure and muscle > liver > gill for As exposure. In the recovery phase, the order of elimination in the tissues was gill > liver > muscle for Pb and liver > gill > muscle for As. The amount of cortisol secreted by the Oreochromis sp. after Pb or As treatment was lower compared to Oreochromis sp. in the control group during the exposure phase. In the recovery phase, plasma cortisol levels in Oreochromis sp. increased in all Pb treatment groups while it continuously decreased in all As treatment groups. A fish affected by As has obvious difficulty recovering from the stress response. It was concluded that exposure to the tested concentrations of Pb and As over 20 days could be a potent endocrine disruptor, which may lead to adverse impacts on the health of the Oreochromis sp.