Mercury Contamination in Sediments and Fish from an Urban Tropical Estuary: Ecological and Human Health Risks

This work examined mercury concentrations in Rodrigo de Freitas Lagoon (RFL; Rio de Janeiro, Brazil) to support ecological and human health risk assessments associated with the consumption of Hg-contaminated fish. Sediments and fish samples (Mugil liza and Geophagus brasiliensis) were collected for total Hg determination. Potential application of a model for estimating Hg in fish was also evaluated by comparing estimated Hg contents with those found in fish muscle samples. To assess human health risks for non-carcinogenic effects, the hazard quotient (HQ) was calculated for fishermen and market consumers. Hg contents in human hair and blood were estimated by using a single-compartment model proposed by WHO, based on the frequency of fish ingestion and mercury concentration in fish. No sediment sample (0.122 +/- 0.079 mg/kg; n = 17) exceeded the safety Brazilian limit for aquatic biota (0.3 mg/kg). The northern section of RFL presented the highest Hg contents correlated with organic enrichment and mud. Mercury concentrations in M. liza (0.0065 +/- 0.0050 mg/kg; n = 30) were lower than those found in G. brasiliensis (0.0580 +/- 0.0745 mg/kg; n = 31), probably due to the sampling of younger M. liza organisms, which are also at a lower trophic level. Estimated mercury concentration in fish was consistent for G. brasiliensis. Potential hazard on fishermen's health was detected (HQ = 2.1). Hg estimation in fishermen's hair (14.93 mu g/g) exceeded the safe limits indicated by WHO. Regarding market consumers, no potential risk was detected (HQ = 0.3), and the Hg concentrations in blood (2.11 mu g/L) and hair (0.53 mu g/g) were in accordance with the limits established by WHO.

Automated summary

This study investigated the mercury concentrations in Rodrigo de Freitas Lagoon in Rio de Janeiro, Brazil to assess the ecological and human health risks associated with consuming contaminated fish. Sediments and fish samples were collected for mercury determination, and a model for estimating mercury in fish was evaluated. For human health risk assessment, the hazard quotient was calculated for fishermen and market consumers. The results showed high mercury concentrations in the northern section of the lagoon, posing a potential health hazard for fishermen but no risk for market consumers.