EnvironmentAsia (Jul 2015)
Accumulation and Clearance of PAHs and CYP1A Levels in Farmed Green Mussels (Perna viridis L.) from a Coastal Industrial Area in Thailand
Abstract
Green mussels (Perna viridis L.) that inhabit along coastal areas with established petro-chemical industries are likely to be exposed to petroleum hydrocarbons. In year 2011, polycyclic aromatic hydrocarbons (PAHs) accumulated (i.e. total of 16 PAH congeners) in three different sizes of farmed mussels in the Maptaphut industrial estate which is an industrial park in the Gulf of Thailand. The levels of mean total PAHs (0.4303 ± 0.3067 µg/g dry weight) in large sized (consumable size) mussels were 16 and 8 times higher than medium and small sized mussels. Levels of total carcinogenic PAHs (0.0311± 0.0310 µg/g dry weight) in consumable size mussels were 15 and 11 times higher compared to medium and small sized mussels. Two carcinogenic PAHs (i.e. chrysene and benzo[a]anthracene) were detected in all sized mussels. The ratio of high molecular weight versus low molecular weight PAHs in all sized mussels indicated the presence of pyrogenic PAHs contamination over petrogenic PAHs in this coastal area. Further studies were carried out in year 2012 involved depuration in consumable sized mussels and effects on the cytochrome P450 1A (CYP1A) biomarker were analyzed over a 30 day depuration period. The half-life was five days for total PAH burden (0.4765 ± 0.0615 µg/g dry weight), which included four non-carcinogenic PAHs. After 10, 15 and 30 days depuration in clean water, the mean total PAHs levels decreased gradually but yet significantly (0.2501 ± 0.0186, 0.1350 ± 0.0122 and 0.1554 ± 0.0353 µg/g dry weight, respectively) compared to the PAH levels at day 0. Levels of CYP1A declined accordingly and at 30 days depuration CYP1A protein levels were significantly reduced by almost 3-fold compared the PAH levels in mussels from the Maptaphut industrial estate. The results show that farmed green mussels reared for human consumptions are exposed to PAHs including carcinogenic PAHs and that clearance of these PAHs is evident at 30 days depuration. This study demonstrates the importance of analysing PAHs in mussels and the usefulness of the CYP1A biomarker to assess exposures of PAHs in Thailand coastal waters. Therefore, a continuous monitoring and evaluation of PAHs contamination in marine species is a priority in this area and other petro-chemical estate areas of Thailand in order to reduce the risk of dietary exposures to carcinogenic PAHs from consumption of green mussels as well as to endorse reduced anthropogenic releases of PAHs into the marine ecosystem.
