Alterations in plasma and hepatic retinoid levels in flounder (Platichthys flesus) after chronic exposure to contaminated harbour sludge in a mesocosm study

Flounder (Platichthys flesus) were exposed to polluted harbour sludge or to sludge wash-off in mesocosms for 3 years. At the end of the study, flounder from all mesocosms were sacrificed, and plasma and liver were isolated for determination of retinoid levels. In addition, effects of harbour sludge on liver tumour development and skin infections, on spermatogenesis and testicular steroidogenesis, on plasma steroid levels and on induction of the CYP1A enzyme system were determined in flounder. Furthermore, levels of heavy metals and PHAHs were determined in both flounder and sediment. Here, we present the effects on retinoid levels in flounder. Data on other parameters are presented elsewhere. Retinol concentrations in flounder plasma and liver were significantly reduced in mesocosms containing polluted harbour sludge and sludge wash-off as compared to the control mesocosm. Retinoid stores in the liver, measured as the concentration of retinyl palmitate, were also reduced significantly in the mesocosm containing sludge wash-off as compared to the control mesocosm but not in the directly polluted mesocosm. A negative non-linear association was found between hepatic retinol concentrations and CYP1A protein levels (r(2) = 0.69; P < 0.05), suggesting the involvement of PHAH and PAH inducible enzymes. The present study clearly indicates that long-term exposure to environmental contaminants in complex matrices decreases retinoid levels in flounder. (C) 1998 Elsevier Science B.V. All rights reserved.