Environmental contaminants may reduce immunity
Exposure to environmental contaminants during pregnancy is associated with an increased risk of infections during the first three years of life and a reduced response to childhood vaccines. This was found in two studies from the Norwegian Mother and Child Cohort Study (MoBa) at the Norwegian Institute of Public Health from 2013 and 2012.
The environmental contaminants PFAS, PCBs and dioxins are found in small amounts in foods and the adverse health effects come as a result of accumulated substances slowly breaking down. These substances cross the placenta and are present in breast milk, so foetuses and young children may be more susceptible to their effects.
200 participants from MoBa took part in the BraMat Study and their children were followed until the age of three. PFAS levels in maternal blood at birth were measured, and the intake of PCBs and dioxins was calculated based on a dietary questionnaire that was completed in mid-pregnancy. Episodes of common childhood infections were recorded and the effects of childhood vaccines (Hib, tetanus, measles and rubella) were measured in blood samples at three years of age.
- Colds and gastrointestinal infections were more frequent among the children with mothers who had higher PFAS levels.
- The children of mothers with elevated levels of PFAS had a poorer response to rubella vaccination (German measles).
- The highest intake of PCBs and dioxins in mothers was associated with a risk of respiratory infections and wheezing episodes among the children.
- The response to the measles vaccine was lower in the children of mothers with the highest intake of PCBs and dioxins in pregnancy.
There was no association between maternal levels of PFAS, PCBs and dioxins and asthma and allergies in the children.
As the foetal and neonatal immune system is still developing, these groups may be particularly vulnerable to contaminants.
“A previous study of Faroese children suggested that elevated PFAS levels in maternal blood were associated with a reduced immune response to routine childhood vaccination, and our study supports these findings. However, further research is needed to investigate the immunotoxic effects of PFAS” says Berit Granum, project coordinator of the BraMat study.
About the BraMat study
BraMat is a sub-cohort of the Norwegian Mother and Child Cohort Study, a unique collection of questionnaire data and biological samples from over 100,000 children and their mothers and fathers. The work was supported by the EU Integrated project NewGeneris, 6th Framework Programme, Priority 5: Food Quality and Safety.
What are PFAS
- PFAS (Perfluoroalkyl compounds) are found in impregnated consumer products, textiles, carpets and food packaging.
- Fish and shellfish are the most common dietary sources.
- Breast milk is the main source for breastfed children.
- The indoor environment can contribute to PFAS intake.
- Use has declined substantially over the past decade, but PFAS can be found in the blood of mothers and newborns.
- PFAS degrade very slowly and can harm living organisms.
What are dioxins and PCBs
- Dioxins form at high temperatures during industrial processes and through combustion where both chlorine and carbon are present.
- PCBs (polychlorinated biphenyls) are synthetic chlorinated compounds that were previously produced for use in a variety of products.
- Due to the adverse environmental and health properties, the use of PCBs in new products was banned in Norway in 1980, but still exists in some older products.
- Animals and humans accumulate dioxins and PCBs in adipose tissue and the liver, and they degrade very slowly.
- The main dietary source is oily fish and seafood, and more than 90 per cent comes from fat-containing foods (including meat and dairy products).
- Granum B et al. Pre-natal exposure to perfluoroalkyl substances may be associated with altered vaccine antibody levels and immune-related health outcomes in early childhood. J Immunotoxicol 2013. doi: 10.3109/1547691X.2012.755580.
- Stølevik S et al. Prenatal exposure to polychlorinated biphenyls and dioxins from the maternal diet may be associated with immunosuppressive effects that persist into early childhood. Food Chem Toxicol 2012;51C:165-172.
- Stølevik et al - Prenatal exposure to polychlorinated biphenyls and dioxins from the maternal diet may be associated with immunosuppressive effects that persist into early childhood (PubMed)
- Granum et al - Pre-natal exposure to perfluoroalkyl substances may be associated with altered vaccine antibody levels and immune-related health outcomes in early childhood (PubMed)