Scientists in the USA have found that exposure to toxic chemicals early in life can have an impact on the way we respond to the tuberculosis (TB) vaccine.
The study, published in the journal, Environmental Health Perspectives, focused on two toxic chemicals: polychlorinated biphenyls (PCBs), which have been used in manufacturing and consumer products, and the main chemical compound of the insecticide DDT, which has been commonly used to stop the spread of malaria through mosquitos.
Several countries have banned the use of these chemicals but, due to the fact that they are not easily broken down, they can remain a health threat long after their use is stopped. They can be passed on to a baby from their mother when they are in the womb, as well as through breastfeeding.
The researchers wanted to investigate whether exposure to these chemicals would have an impact on the way babies would respond to the TB vaccine. Their study involved 516 mother-and-baby pairs from an area of eastern Slovakia heavily polluted with these chemicals.
Blood samples were taken from participants and analysed for levels of the toxic chemicals. Over 99% of samples were found to contain the chemicals.
Each baby was given the TB vaccine 4 days after birth. This involved injecting them with a weakened form of a bacterium closely related to human TB. This stimulates the body’s immune system to produce antibodies, which are then able to recognise and effectively destroy the TB infection when they are next exposed to it.
The researchers measured the babies’ immune antibody response 6 months after vaccination. The babies with the highest levels of chemicals in their blood tended to have the lowest number of TB-fighting antibodies.
The scientists believe that these findings could also apply to other vaccinations and pollutants, and state that further research is needed.
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