Association between prenatal cadmium exposure and child development: The Japan Environment and Children's study

Cadmium is a heavy metal that can be found in soil, air, food, and water. Cadmium has toxic effects on the kidneys, bones, and respiratory system. Prenatal exposure to cadmium has been found to affect the mental development of children, but inconsistent results have been found in different studies. Therefore, it is unknown that prenatal cadmium exposure associated with child development after birth. To elucidate whether cadmium affect the child development or not, we analyzed nation-wide cohort study data, the Japan Environment and Children's Study. Prenatal cadmium concentrations in blood from mothers in the second or third trimester were determined by inductively coupled plasma mass spectrometry. Child development was evaluated using "Ages and Stages" questionnaires. The association between cadmium and child development were investigated by performing logistic regression analyses, multinomial logistic regression analyses and generalized linear mixed model using the child development parameters as dependent variables and the cadmium concentrations in maternal blood as the independent variable. There were significant associations between the cadmium concentration and child development at 6 months, 1 year, and 1.5 years after birth. However, the effect had disappeared at 2 years after birth or later. The number of developmental delays was positively associated with the cadmium concentration after adjusting individual difference. The results indicate that prenatal exposure affects child development, but the effect decreases with age.