“The negative effects of PCB153 in neurodevelopmentare mainly attributed to prenatal exposure”

08/03/2013

Interview with Mireia Gascón, author of the study “Evaluating the neurotoxic effects of lactational exposure to persistent organic pollutants (POPs) in Spanish children”.

What motivated you to do this study?
To date, many studies have shown an association between exposure to organochlorine compounds (OCs in English) during pregnancy, such as PCBs, HCB and DDE, and effects on the neurodevelopment of children. However, postnatal effects of exposure to these compounds, which is mainly due lactation were less clear. One of the factors that limited the study of the effects of postnatal exposure was the exposure estimate was done in a very simple, and did not take into account the variation of exposure along the different months of life the child after birth. In the current study, we had the opportunity to apply some models, called pharmacokinetics, which allowed us to calculate exposure, month by month during the first year of the infant. Thus, we could study whether exposure to OCs, specifically PCB153, DDE and HCB, during lactation had a negative effect on neurodevelopment of children, and also see which month or months of the first year of life giving this effect.

What are the main findings of the study?
In this study we found that, although during lactation increases exposure to OCs regarding exposure during pregnancy, the negative effects of PCB153 in neurodevelopment, particularly in psychomotor development, are mainly attributed to prenatal exposure. In other words, the results indicate that during the prenatal stage the baby is more susceptible to the effects of prenatal exposure to PCB153. We saw no effects for DDE or HCB, pre-or postnatal.

What are the most common stages of exposure to these contaminants?
Actually we are exposed to these contaminants from before birth through the umbilical cord, and for the rest of our lives mainly by diet. In the case of infants, breast is a major source of exposure, as these compounds accumulate in fatty tissues or fluids, such as milk. Still, we recommend feeding a child, and that breast milk has many benefits even though they may contain CBs.

“The results indicate that during the prenatal
stage the baby is more susceptible to the effects
of prenatal exposure to PCB153.
We saw no effects for DDE or HCB, pre-or postnatal.” 

What carries more risk period high exposure to POPs, in prenatal or postnatal?
The results of previous studies and this study indicate that during the prenatal neurodevelopment of children are more susceptible to these compounds.

Are there external factors-social or geographical-that determine the risks of exposure?
So far it had been believed that individuals belonging to lower social classes were in danger of being more exposed to these contaminants, but the same study INMA has shown that this is not always true. In fact, in this population was that the levels of PCBs were higher in mothers of high social class, for example. Moreover, it was estimated that only social class explained between 1{3effe4377b6f02be2524d084f7d03914ac32a2b62c0a056ca3444e58c1f10d0b} i 5{3effe4377b6f02be2524d084f7d03914ac32a2b62c0a056ca3444e58c1f10d0b} of exposure, while other factors such as region of residence (Basque Country, Valencia, Asturias and Catalonia), the country of origin of the mother or The age of this, were much more decisive.

“The results of previous studies, and also this study,
indicate that during the prenatal neurodevelopment
of children are more susceptible to these compounds”. 

What effect this may have exposure to infant development? To what age can begin to “detected”? Can they have therefore also in the long run?
A level of neurodevelopmental effects we see already in the second year of life in these children at risk. The detection is therefore very early. Regarding the pattern of effects was observed eg PCBs, initially act more globally and as the child grows and their repertoire of cognitive skills increases, there are difficulties especially in areas such as executive functions which are vital for the control of behavior and cognition. Effects have also been observed in preteen age children, in very specific functions like processing speed. It is very important to remember that these effects of which we speak are not in any neurodevelopmental clinics deviations. That is, we can not predict that a child with high levels of OCs will develop neurodevelopmental pathology. The effects are detected at the population level and we refer to them as effects “sub-clinical”. That means, for example, we can see that those children exposed to higher levels of PCBs during pregnancy (as a group) scored X points lower on an IQ test. Clinically, this difference would not be significant, but at the population level are saying that this group of children, from exposure to the compounds, X points less developed cognitive ability. That can be translated in terms of productivity, mental capital, human development, etc..

The main problem is that the CBs be persistent,
may take many years to degrade completely.
They also have the capacity allocated by the ecosystem…”

What measures can be promoted, and who should do it, to temper or reduce these exposures?
Most of these compounds and were banned for years (PCBs, HCB or DDT) in our and many other countries, but, for example, in malaria endemic countries currently using DDT (the precursor of DDE) to kill mosquito transmitting malaria. This makes for fairly high populations exposed. The main problem is that the CBs be persistent, may take many years to degrade completely (can last up to 15 years). On the other hand, has the ability to be distributed by the ecosystem, so that compounds used in one part of the planet can reach our plates, and today, and we eat products from around the world every day. It would therefore be necessary to properly inform the public to be aware of the problem and have greater control of the use of these substances not only in his country but worldwide. In countries where DDT is used for the control of malaria mosquito alternatives should more sustainable, environmentally and economically, and implement those that are already proven to work.
Mireia Gascón has a degree in Biology (UAB). Masters in Biomedicine, specialty Toxicology and Environmental Health (Utrecht University). Coordinator Ribera d’Ebre cohort.
To read the study: ‘Evaluating the neurotoxic effects of lactational exposure to persistent organic pollutants (POPs) in Spanish children’