Persistent organic pollutants (POPs) are chemical compounds which can naturally occur in the environment, but mostly come from human activity. They are chemically very stable, which means that they can stay in the environment long after they have been produced and released and, moreover, they can stay long periods of time in the adipose tissue of animals and human beings.
An international team of researchers to whom the University of Granada (UGR) belongs has analysed the effects of prenatal exposure to three of those compounds on the birth weight of babies: polychlorinated biphenyls (PCBs, specifically PCB-153), DDT pesticide, and its metabolite DDE. The results have been published in Environment International magazine.
For that purpose, they analysed a huge database from eleven European birth cohorts, from which they extracted 9377 mother-child pairs. The researchers assessed the levels of exposure to this pollutants in the mother's blood and milk, as well as in the newborn's umbilical cord blood.
Umbilical cord blood
The results showed that newborn babies with higher PCB-153 level in umbilical cord blood have a higher risk of being born with lower birth weight than babies with lower levels. "Moreover, this association was stronger if the mother smoked during pregnancy", researcher Mariana Fernández Cabrera, from the Department of Radiology and Physic Medicine of the UGR, explains. However, no relation between DDE and birth weight was observed.
Low birth weight is associated with breathing problems during infancy, as well as with other diseases suffered throughout life. Therefore, these results indicate that "regulating the use of and exposure to PCBs and eliminating wastes which could contain PCBs is very important, so we can prevent potential risks for human health as well as for the environment", the author stresses.
The UGR researcher reminds us that infants are specially vulnerable to environmental pollutants due to their anatomic and physiologic immaturity, and because their detoxification mechanisms are not completely developed until their organs are completely formed.
Forbidden in the 70's
Although POPs were banned in most countries during the decades of the 70's and 80's, "environmental exposure has led to them accumulating in human bodies (specially in adipose tissue), so most Earth inhabitants have stored them in great proportion", says Mariana Fernández.
With the exception of individuals exposed to POPs in their job posts, most exposures take place by means of the diet. POPs exposure comes mainly from animal sources, but they are also present in water, air and soil.
"Exposure to environmental pollutants during the early stages of life may have negative consequences when born, such as, for example, delay in the fetal development (which manifests in the form of lower birth weight), delay in intrauterine growth, preterm labour or congenital malformation", the researcher concludes.