Fetal exposure to heavy metals linked to childhood asthma, allergies
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Exposure to cadmium in the womb may impact the development of asthma and allergic diseases in childhood, according to research presented at the virtual European Respiratory Society International Congress.
“Heavy metals, to which people can be exposed to in everyday life through food, water, air, can have a damaging effect on health even at low doses,” Isabella Annesi-Maesano, MD, PhD, DSc, research director at the French National Institute of Health and Medical Research and professor of environmental epidemiology at Sorbonne University, Paris, said during a presentation. “However, studies investigating their role in early life in particular in relation to asthma and allergy — the common diseases in childhood — are scarce.”
Annesi-Maesano and colleagues analyzed maternal blood samples from 706 pregnant women in maternity units in France and cord blood after delivery. The researchers evaluated serum concentrations of lead, cadmium and manganese to investigate the association with fetal exposure and risk for developing asthma, allergic rhinitis, eczema and food allergy in childhood.
Researchers followed the children up to age 8 years. Parents responded to annual questionnaires on children’s health, asthma, allergic rhinitis, eczema and food allergy symptoms. Possible factors known to influence these conditions were also considered, such as parental smoking history and family medical history.
The researchers found heavy metals in both maternal blood and cord blood samples, with an average of 0.8 g/L of cadmium in maternal blood samples and an average of 0.5 g/L in cord blood samples.
At age 8 years, researchers reported that the incidence of asthma was 29.5 cases per 1,000 person-years, the incidence of allergic rhinitis was 38.6 cases per 1,000 person-years, the incidence rate of eczema was 100.1 cases per 1,000 person-years and the incidence rate of food allergy was 18.9 cases per 1,000 person-years.
Cadmium levels in cord blood samples were associated with increased risk for asthma (HR for highest vs. lowest quintile = 1.81; 95% CI, 1-3.29), eczema (HR = 1.6; 95% CI, 1.09-2.35) and food allergy (HR = 3.17; 95% CI, 1.36-7.38). Manganese levels in maternal blood were associated with increased risk for eczema only (HR = 1.55; 95% CI, 1.05-2.28).
“Our study suggests that exposure to cadmium in the womb could have a role in increasing the risk of asthma and allergies in children,” Annesi-Maesano said in an ERS press release. “Our study doesn’t tell us why this might be the case, but it could be that cadmium is interfering with babies’ developing immune systems, and we think this can have an impact on their allergic reactions in childhood.”
Annesi-Maesano and colleagues are continuing to study heavy metals and environmental pollutants and the related effects on development of asthma and allergies.
“We need more research to confirm these findings and to understand more about the links between exposure to heavy metals in the womb and children’s health in the longer term,” Annesi-Maesano said in the release.