Polycyclic Aromatic Hydrocarbons in Seafood: Occurrence, Trophic Bioaccumulation, and Human Health Risks

Polycyclic aromatic hydrocarbons (PAHs) can enter the human body through the consumption of contaminated food, particularly seafood, which can bioaccumulate these toxic compounds. This study evaluated PAH contamination levels in fish, crabs, and shellfish from the Parnaiba River estuary following the 2019 oil spill that impacted over 3000 km of Brazil’s northeastern coastline with weathered, heavy crude. The results showed that PAH concentrations in 2019 were approximately 50% higher than those detected in 2021, indicating an acute contamination event linked to the spill. Among the sampled organisms, crabs had the lowest PAH levels, followed by shellfish with intermediate contamination levels, and fish with the highest concentrations. PAH profiles varied by species: shellfish were dominated by high-molecular-weight (HMW) compounds typical of pyrogenic sources; fish were primarily contaminated with low-molecular-weight (LMW) PAHs associated with crude oil; and crabs exhibited a balanced mix of both. Toxicity equivalency analysis revealed the presence of benzo[a]pyrene (BaP) only in 2019 shellfish samples, while BaP contamination was found in both fish and shellfish in 2021. Some samples exceeded regulatory limits for indeno[1,2,3-cd]pyrene. Mollusks collected during the 2021 dry season presented BaP and benzo[k]fluoranthene levels above the threshold of concern. These findings demonstrate the acute impact of the oil spill, characterized by a predominance of LMW PAHs, as well as a residual contamination pattern in 2021, likely associated with pyrogenic sources and driven by environmental degradation processes. This study also indicates that although overall carcinogenic PAH levels decreased, some carcinogenic PAHs continue to exceed legal limits in fish and shellfish samples, even 2 years after the oil spill. This work highlights the need for long-term monitoring and reinforces the importance of including food safety in environmental impact assessments, especially in vulnerable fishing communities.