PCBs influence allergy risk.
Glynn, A, A Thuvander, M Aune, S Johannisson, PO Darnerud, G Ronquist and S Cnattingius. 2008. Immune cell counts and risks of respiratory infections among infants exposed pre- and post-natally to organochlorine compounds: a prospective study. Environmental Health 7:62.
Researchers describe that some chemicals may pack a stronger punch during the time when the immune system is developing than other chemicals -- a punch that can last a lifetime.
In the study, both the amount and type of PCBs a baby was exposed to in the womb, or in the first three months after birth, affected the number of respiratory infections a child had. Some types of PCBs seemed to be associated with increased respiratory infections; other types seemed be associated with fewer infections.
Respiratory infections early in life are linked with more severe allergies and asthma later on.
PCBs, or polychlorinated biphenyls, are industrial chemicals principally manufactured during the middle of the 20th century. PCBs are long-lasting. Even though they were banned in the early 1970s, people are still exposed to them, mostly via food.
About 209 different compounds are classified as PCBs. How they affect biological processes is highly variable and diverse. A number of adverse health affects are attributed to PCB exposure, including reproductive problems, nervous system and cardiovascular system problems, diabetes, obesity and immune deficiency.
In this new study, scientists measured the amount and type of PCBs in the umbilical cord of babies, in the breast milk of their mothers three months after giving birth and again in the babies at three months of age. This information was compared to the number of respiratory infections the babies had during the first three months.