Effects of Cadmium Exposure on Lactating Mice and Rats: A Systematic Review of Breastfeeding Experiments

Abstract

Cadmium (Cd) is a widely spread pollutant in the environment and its identification in human breast milk has caused concern. Children are particularly vulnerable, since their detoxification mechanism is not fully developed and their organs still being formed. Human- and animal-based studies demonstrate health issues and adverse pregnancy outcomes related to prenatal and postnatal Cd exposure. However, investigations of the effects, mechanisms, and treatments are still required. Thus, this systematic review compiled studies of Cd effects on lactating mice and rats focusing on experimental features and reported effects. The search was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA), using PubMed, SciELO, and ScienceDirect databases. After identification, screening, and inclusion process 52 research articles were recovered and data, such as animal strain, metal compound, dose or concentration, administration route, exposure time, litter size normalization, lactation days, organs or samples examined, and effects reported were organized in tables. Three general schemes of Cd exposure on dams were identified: pregnancy, lactation, or pregnancy-lactation. The effects evaluated included neurotoxicity, sexual maturation, biochemical parameters, and Cd transfer and retention. Experimental features most common were Cd exposure during the pregnancy–lactation scheme and Cd administration by drinking water, while the most evaluated effect on offspring was Cd-neurotoxicity.