Prenatal Exposure to Metals May Increase Risk of Atopic Dermatitis in Children

Prenatal exposure to inorganic arsenic and cadmium may significantly increase the risk of atopic dermatitis (AD) in young children, according to study findings published in JAMA Network Open.

With AD diagnoses affecting approximately 20% of children and 3% of adults globally, risk factors associated with the condition include genetics, obesity, climate factors, and environmental pollutants. In recent studies, heavy metals such as lead and chromium have also been shown to be associated with both AD symptoms and severity in infants.

“Another recent study found that prenatal inorganic arsenic exposure was associated with allergic airway inflammation in children up to 14 years,” said the study authors. “However, the association between multiple metal exposure during pregnancy and the risk of AD in young children remains unknown.”

As environmental exposures during gestational development may increase susceptibility to disease later in life, researchers sought to further assess how prenatal exposures to arsenic, cadmium, lead, mercury, and chromium may influence risk of AD in young children.

They conducted an analysis of 1152 pregnant women enrolled in the original Taiwan Maternal and Infant Cohort Study (TMICS), a multicenter birth cohort study conducted at 9 hospitals in northern, central, southern, and eastern Taiwan from October 2012 to May 2015.

From those enrolled in TMICS, 370 eligible mothers and children aged 4 years agreed to participate in follow-up questionnaires from August 2016 to January 2019 (mean [SD] age, 3.94 [0.59] years; 208 children (56.2%) were male; 267 children (72.2%) were from the central region of Taiwan).

Parent-reported AD history among children served as the primary outcome, with concentrations of arsenic, cadmium, lead, cobalt, copper, nickel, thallium, and zinc measured in maternal urine during the third trimester of pregnancy using an inductively coupled plasma mass spectrometer.

“Estimated total inorganic arsenic exposure was calculated using a model that included data on both total arsenic and arsenic species (arsenite, arsenate, monomethylarsonate, and dimethylarsenate) obtained from a previous TMICS cohort,” added the study authors.

Of the study cohort, 110 children were found to develop AD at age 4 years. After adjusting for potential confounders, including parental allergies, child’s sex, and geographic area, every doubled increase of total inorganic arsenic exposure during pregnancy was associated with a more than 2-fold increased risk of AD in children (odds ratio [OR], 2.42; 95% CI, 1.33-4.39).

All other maternal urinary metal concentrations were not associated with higher odds of AD.

Furthermore, every increased unit in the weighted quantile sum (WQS) index of maternal metal exposure was significantly associated with AD (OR, 1.63; 95% CI, 1.28-2.07), in which arsenic (40.1%) and cadmium (20.5%) accounted for most of the WQS index.

“Prevention of exposure to inorganic arsenic and cadmium during pregnancy may be helpful for the control of AD and other potential allergic diseases in young children,” concluded the study authors. “Environmental improvements and reductions in contact with sources of exposure are important to reduce the risk of metal exposure among this susceptible population.”

Reference

Tsai TL, Wang SL, Hsieh CJ, et al. Association between prenatal exposure to metals and atopic dermatitis among children aged 4 years in Taiwan. JAMA Netw Open. Published online October 27, 2021. doi:10.1001/jamanetworkopen.2021.31327