Systematic Review of Chromium and Nickel Exposure During Pregnancy and Impact on Child Outcomes.

Some forms of chromium (Cr) and nickel (Ni) are toxic, especially with chronic elevated exposure, and certain forms such as hexavalent chromium or nickel carbonyl were labeled as carcinogens. Since both metals are naturally occurring, and used in industrial processes, individuals may be exposed through ingestion of contaminated food or water, inhalation, or dermal contact. This study focused on the impact of toxic forms of Cr and Ni during pregnancy and outcomes in newborn and young children. A systematic literature review following "The Navigation Guide" was applied, and 16 reports that satisfied the inclusion criteria were scored. Six papers studied birth weight, prematurity, or gestational age: one found an association between Ni and small for gestational age, while another linked Ni with low birth weight; however, four reported no marked associations. Of six studies that examined birth defects, three found no significant associations; one noted an association between Ni and neural tube defects; one showed an association between Ni and structural birth defects; and one reported a weak effect for Cr exposure and musculoskeletal defects. In the remaining four studies, weak associations were found for hexavalent Cr and neuroblastoma, Ni and autism spectrum disorder, Cr and Ni and DNA damage, and Cr and lymphocyte damage. Among the studies that were rated as good for execution and reliability, there was weak evidence of an association between Ni and autism spectrum disorder and small for gestational age, but no significant association between Cr and a child outcome.