This study assesses the potential human health risks posed by six heavy metals (Hg, As, Pb, Cd, Cu, and Zn) found in five of the most consumed fish species (Mugil incilis, Centropomus undecimalis, Cathorops mapale, Eugerres plumieri, and Elops smithi) collected by the riverine population living in Ciénaga Grande de Santa Marta (CGSM), the largest estuary in Colombia. Metal concentrations were low compared with those reported in other regions around the world and the maximum value established by international monitoring organizations. The estimation of the potential risk (HQ) indicated that Cu and Hg could generate negative effects in groups of women of childbearing age (WCA) and the remaining population (RP), because they exceeded their related reference doses, with HQ values > 1; however, Cu and Hg concentrations were not high in fish and EWI, MFW, or MeHgPSL values shows that there is no evidence of a potential health risk from MeHg exposure in the study population. Therefore, the recommendations are to establish continuous monitoring of heavy metals together with strategies that address the high fish consumption, as well as to implement mechanisms for the mitigation of contamination of the watershed, to ensure the safety of organisms in the ecosystem and human health, not only of populations who depend on aquatic resources in the area but also of those that market and consume these resources in the Colombian Caribbean.

Anomalously cold conditions in the tropical Pacific, related to a strong La Niña event, affected numerous countries in 2010. Several areas in Colombia were severely impacted, including agricultural fields in La Mojana floodplain that were completely flooded for almost 2 years. This study assesses the effects of flooding on the levels, spatial distribution, and sources of trace metals in 222 agricultural topsoils of this floodplain. Our results show that mean concentrations of Cu 48.4 mg kg⁻¹ (11–103 mg kg⁻¹), Zn 79.2 mg kg⁻¹ (6–207 mg kg⁻¹), Ni 58.1 mg kg⁻¹ (17–101 mg kg⁻¹), Pb 3.2 mg kg⁻¹ (0.13–14 mg kg⁻¹), Cd 0.56 mg kg⁻¹ (0.05–1.4 mg kg⁻¹), Mn 411 mg kg⁻¹ (55–1,277 mg kg⁻¹), and Hg 0.10 mg kg⁻¹ (0.05–0.22 mg kg⁻¹) were higher than the world's averages. Topsoils revealed different degrees of pollution depending on the metal, of which Pb was the most problematic element, with 82% of the soil samples classified as heavily contaminated. Principal component analysis suggests that soil contamination was primarily derived from poor agricultural practices and contaminated river overflows from upstream mining areas. Our results show that an extreme flood event might increase the bioavailability of metals (especially Pb) for crops in most (66%) of the agricultural soils, posing a potential threat to human health.