Environmental Contaminants, Iron Deficiency, and Iron-Deficiency Anemia: A Review of the Literature.

Iron deficiency (ID) and ID anemia (IDA) are global health concerns that tend to affect vulnerable populations, including women, children, and those living in areas disproportionately affected by environmental health hazards. A review of the literature was conducted using the top ten chemicals of public health concern as identified by the World Health Organization (WHO) in 2020, in combination with the terms "iron deficiency" and "anemia." Both epidemiological and controlled experimental studies were considered. Eight contaminants or exposure classifications were ultimately considered to be within the scope of this review: lead, cadmium, arsenic, mercury, indoor and ambient air pollution, asbestos, dioxin and dioxin-like polychlorinated biphenyls (PCBs), and fluoride. Lead, cadmium, indoor and ambient air pollution, and fluoride are reliably linked to higher IDA prevalence and lower hematological parameters, including hemoglobin, hematocrit, and red blood cell count, all indicators of anemia. Direct measures of ID are less frequently reported. Further research studies, particularly controlled exposure studies, are needed to determine the importance of arsenic and mercury in contributing to the global ID and IDA burden. There is limited evidence that supplemental or dietary iron fortification can ameliorate the effects of lead, but not fluoride, and the efficacy of fortification has not been widely studied in the context of the remaining contaminants. Asbestos, dioxin, and dioxin-like PCBs are linked to anemia; however, the role of iron homeostasis is more complex and tends to include iron bioaccumulation. The narrative review has identified a need for renewed effort to address environmental factors beyond diet and nutrition when implementing ID and IDA interventions.