- Fetuses exposed to heavy metals may have an increased risk for the development of asthma and allergic diseases in childhood.
- The findings are particularly important with regard to cadmium which remains widely used in batteries and pigments and is also a component of tobacco smoke.
Why this matters
- Heavy metal exposure is known to have detrimental health effects even at low doses; however, little is known about their role in early childhood, especially in relation to asthma and allergies.
- Children from the French EDEN birth cohort were followed up yearly until the age of 8 years.
- Levels of heavy metals were assessed in maternal blood during mid-pregnancy (n=706) and in cord blood (n=658).
- Funding: None disclosed.
- Incidence rates (per 1000 years) at 8 years of age were as follows:
- Asthma: 29.5 (95% CI, 24.1-35.0);
- Allergic rhinitis: 38.6 (95% CI, 32.3-44.9);
- Eczema: 100.1 (95% CI, 88.5-111.8); and
- Food allergy: 18.9 (95% CI, 14.6-23.2).
- The average levels of cadmium in the maternal blood and cord blood were 0.8 µg/L and 0.5 µg/L, respectively.
- Higher levels of cadmium in cord blood (>0.7 µg/L) were associated with an increased risk for asthma in childhood (HR per 1 standard deviation [SD] increase, 1.24; 95% CI, 1.02-1.51) and food allergy (HR per 1 SD increase, 1.44; 95% CI, 1.13-1.83).
- Higher levels of manganese in maternal blood (>1.1 µg/L) were associated with an increased risk for eczema (HR per 1 SD increase, 1.14, 95% CI, 1.04-1.26).
The presenter, Professor Isabella Annesi-Maesano said: "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."