From 13th to 16th September 13 to 16 Barcelona hosted the 2011 ISEE (International Society for Environmental Epidemiology) congress. More than a thousand researchers from all over the world met to share the ongoing and concluded research on all aspects related to health and environment.
Prof. Sunyer, in your opinion which are the most outstanding outcomes from this congress in terms of new issues and new perspectives?
There is an issue that had been announced earlier but has been much emphasized in the studies presented here which is how exposures in utero and in early life affect children's health and diseases throughout life. Another one is the concept of built environment, which has to do with how the environment in which one lives, i.e. noise, social networks, access to green spaces, do affect people in spite of their individual attitudes, such as playing sports or following a healthy diet.
A lot has also been said on new pollutants and hormone disrupters, which can come from building materials such as perfluorinated compounds (PFOS), or compounds that come from the use of wrapping materials such as phthalates. According to animal models these can have an endocrine disrupting activity –that is simulating sex hormones and prevent them from working - and affect male fertility or female sexual maturation. Others, like bisphenol A, for example, have been associated with obesity. Nevertheless, I have to say that the results presented here on hormone disruptors are still contradictory. Finally, the main topic of this congress still is air pollution and climate change. The technology for measuring air pollution has improved significantly and the results are becoming more evident. As for the vascular techniques in use, a study on how blood flow that reaches the brain changes depending on air pollution (‘Exposure to ambient fine Particulate Matter Alters Cerebral blood flow in the Elderly : The Boston study mobilize’, Gregory Wellenius) is very interesting in my opinion.
On climate change, we discussed the relations between heat events and problems during pregnancy, like urinary infections. While so far we have been discussing only about problems caused by heat on old people, now the target has changed.
It is known that children are more exposed than adults to environmental nuisances. According to the World Health Organization childhood environmental exposures may increase health inequalities at an older age. Children's health is known to be related to fetal health but little is known on fetal exposure and how this affects their adult life. Why is that?
Because of chemical limitations. For example, something that came out strongly from this congress is that while older pesticides were persistent, that is they were not eliminated from our body, the new ones, such as organophosphates, leave our body in a few hours. Therefore when we want to distinguish between a person who is exposed and one who is not, we need to have markers and look at the level of these compounds. What happens is that there is great intra-individual variability in exposure levels and it becomes difficult to establish if a person is more exposed than another.
Do you think that having more studies on pregnant women could help improving our knowledge on fetal exposure?
Yes, but in order to characterize the exposure of a pregnant woman a lot of money is needed, this is the problem.
Currently in Europe there are 35 cohorts with pregnant women that have started during the last 7, 8 years and for which now their children are receiving follow up. Maybe right now what we need is to use more extensively the material that has been collected in these cohorts instead of creating a new one.
Would it help to have a global biobanking?
No doubt, if instead of throwing away blood and urine samples taken from pregnant women these could be saved, we would have a very useful material to evaluate all the fetal exposures from there.
It is known both that disadvantaged people have a differential exposure and a differential susceptibilty to environmental health risks and that gender inequalities also affect the degree to which someone might be exposed to and affected by environmental nuisances. Do you think that it would be important for environmental epidemiology to have socio-economic and gender perspective transversally present in its studies or not?
Indeed, but I think they already are. All our studies have social class markers and the first table shown in the presentations is always how contaminations are distributed through education, social class and gender. Moreover, the studies on built environment have to do basically with people's socio-economic conditions. Perhaps in some topics, such as infertility, there is an exaggeration of the chemical and environmental factors in detriment of the well-known social ones, but I think that in this kind of research agenda social and gender aspects are already very important.
Has any of the studies presented here especially struck you?
Yes, one on ‘cognitive decline’ - that is basically dementia, Alzheimer- and air pollution and one on traffic related air pollution and autism. Autism is growing and until now we knew alcohol could bring to it but not air pollution... Another very interesting study presented here deals with the relationship between levels of acrilamida, an organic compound produced when oil fries, and the baby weight at birth.
Could you summarize which are the effects of environmental pollutants in children's neurobehavioral development?Yes. Lead for instance was removed from gas because it produced a six-points difference in the IQ between children who were exposed and those who were not. Six points in a child does not cause illnesses nor problems of school performance, but economic calculations were made on its impact at social level and it was decided to remove it.Afterwards it has been shown that mercury has a similar behaviour, especially in communities that have a diet very rich in fatty fish and that also persistent compounds used in pesticides, solvents etc. do interfere with the nerve connection. The time frame in which the brain develops is very large – starting from the first trimester of pregnancy until 25 years of age - and so is the chance that these compounds interfere with the cells while they are maturing. Organochlorides (pesticides used in agriculture and industry), for instance, join fatty acids and can therefore delay the signal or have to do with nerve conduction limitations, all things that cannot be seen unless you do a psychometric test or so.
Other phenomena no longer related to cognitive development, executive function or memory capacity but to clinic disorders, have also been studied. For example, these children may have a lower social competence, that is their ability to relate with others and can have a greater degree of hyperactivity or other clinical situations that might even lead to autism.
What we do not know is whether these compounds are affecting the cells because they interfere with the nerve conduction or because they inflame some specific cells, something we are now researching into thanks to the help of toxicology and animal studies.
Until now we only knew of occupational neurotoxicity while the role of pollutants in the daily life of children and adults is something completely new.
Do you see socio-economic, gender-based differences in these kind of effects of pollutants?
The socio-economic status is an important determinant on development but that contaminants interfere differently depending on social classes is something we have contradictory information about.
For example, someone of a higher economic level who eats more vegetables and fruit not clean enough from pesticides or more fish that has mercury may be at higher risk than someone poorer who does not that much.
Perhaps socio-economic vulnerabilities are clearer in air pollution?
No, because city centers, at least in the Mediterrean area, are the places where most pollution concentrates and they are usually not exactly where disadvantaged people live. Nevertheless there are other aspects that are clearly mediated by social class and where poorer people undoubtedly are more at risk, like physical exercise and obesity, diabetes or cardiovascular problems.
In your opinion, what are the main challenges of environmental epidemiology today?
A very good thing of environmental issues is that in theory they could become easily preventable; It is much more difficult to change people's behavior than making a filter for a chimney. The thing is that these findings are difficult to communicate, we do not do it well or it is not known how to transform the findings into interventions. This is certainly a big challenge.
Another one is that we must know how to communicate with basic science to understand for instance epigenetic mechanisms, but since extremely expensive instruments are needed there is a risk that all the resources are put into labs and that we lose focus. There is a huge pressure by research agencies and the industry to make large investments in this regard, but I believe we must balance the investments well because it is as much or more important to characterize the environment and to understand exposure variations than maybe to understand the epigenetic mechanisms.
Is there anything relevant you would like to add?
Yes. There is a saturation of negative messages and I think it would be interesting to explain that we have found that fish consumption increases children performances. So, it is worth eating fish despite it has mercury. White and little blue fishes counterbalance the role of mercury in fatty acids and I believe this should be said to give also positive messages. If we saturate people only with negative ones it ends up causing a total lack of awareness and I believe that knowing how to communicate and managing risk is a major challenge.
A challenge shared with the media, right?
Absolutely.