Marine pollution is an escalating global concern, and marine mammals are widely recognized as sentinels of cumulative chemical and biological stressors in coastal ecosystems. South American otariids (family Otariidae), which occupy high trophic levels and inhabit nearshore environments, are particularly vulnerable to the bioaccumulation of trace elements (TEs), persistent organic pollutants (POPs), and exposure to infectious agents. This review provides a systematic synthesis of the available literature on environmental contaminants and pathogens in South American otariids published up to early 2026. Structured searches in PubMed and Google Scholar identified 104 eligible studies, which were classified according to contaminant type (TEs and POPs), pathogen group (parasites and viruses), species, life stage, tissue, and oceanic region (Southwestern Atlantic vs. Southeastern Pacific). Research effort was unevenly distributed, with 62% of studies conducted in the Southwestern Atlantic despite the greater species richness along the Pacific coast. Mercury and cadmium were the most frequently reported TEs, while PCBs and DDTs dominated POP studies. Higher mercury concentrations were consistently reported in liver, bone, and muscle, particularly in Atlantic populations. Parasitological studies documented 31 genera, with higher diversity in the Southeastern Pacific, whereas viral investigations identified 16 viral taxa, showing greater richness in the Southwestern Atlantic. Pups and juveniles often exhibited higher contaminant burdens and parasite occurrence, highlighting the relevance of early-life exposure and maternal transfer. Overall, the literature remains fragmented, with most studies addressing contaminants or pathogens in isolation. This review identifies key gaps and emphasizes integrated approaches to assess cumulative pollution-disease impacts health.
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