Organ Specific Distribution of PAHs in a Carnivorous Fish Species Following Chronic Exposure to Used Synthetic-Based Drilling Mud

The rapid growth of offshore oil and gas exploration on the Western Indian Continental shelf has generated the need for both general and region-specific scientific information on the environmental consequences of drilling activities. Much of the toxicity related to drilling mud discharges has been attributed to Polycyclic Aromatic Hydrocarbons (PAH) content. This study addressed concerns related to the potential for contamination and subsequent bioaccumulation of PAHs in Oreochromis Mossambicus from the disposal of used synthetic-based drilling mud (SBM). The LC₅₀, 96 h for solid phase and suspended particulate liquid phase, was 37,550 mg/L and 40,390 mg/L, respectively, which was within the acceptable limits as per the Ministry of Environment and Forests (MoEF) Notification, New Delhi, dated August 30, 2005. After chronic exposure (for 55 days) to used SBM, higher mean values of PAHs accumulation were obtained from the Tilapias exposed to higher SBM concentration. The highest level of accumulation was noted for Naphthalenes and the lowest for Benzo (a) pyrenes. Liver was the primary organ for PAH accumulation, while least was observed in muscle. From the observations made on PAH levels in control as well as exposed fish, we found SBM concentration dependant bioaccumulation, suggesting the potential high risk of PAH toxicity to the fish inhabiting in the vicinity of disposal site.