10:40am Monday 21 August 2017

Certain environmental pollutants slow down infant motor development

Dr Aritz Aranbarri, a researcher in the UPV/EHU’s Department of Basic Psychological Processes and their Development, has analysed the relationship between prenatal exposure to certain organochlorine compounds and the cognitive and motor development of two-year-old children. He has found that there is a correlation between this exposure and reduced motor development; the difference is not clinically relevant, although it is statistically significant in population terms. However, no effects on cognitive development were found.

Organochlorine compounds are pollutants that, despite being currently banned, continue in the atmosphere owing to their use in the past: they are persistent, are in the food chain, in the soil, etc. Within the framework of the INMA (Infancy and Environment) project which studies the effects that various chemical pollutants present in the environment may have on infant development, the UPV/EHU researcher Dr Aritz Aranbarri has studied the impact of three types of organochlorine compounds on early neuropsychological development: hexachlorobenzene (HCB), dichlorodiphenyldichloroethylene  (p,p’-DDE) and polychlorinated biphenyls (PCBs). And the fact is, as the researcher explained, the developing functions -like language, fine and gross motor skills, attention, memory, etc.- besides being guided genetically, are influenced by everything surrounding the child, as well as by the baseline exposure, which he/she has had in the prenatal phase, in other words during foetal development.

This research is underpinned by an epidemiological study, for which a whole host of data needed to be obtained. Data on the mothers were obtained: the level of these compounds in their blood during the first trimester of pregnancy as well as in the blood in the umbilical cord at birth; and by taking advantage of routine Osakidetza (Basque Autonomous Community Public Health Service) visits, further information was obtained on their lifestyle, diet, etc. Foetal development was also monitored -by monitoring the whole pregnancy- and, after that, a series of data were collected during the different phases of the child’s growth: data extracted from the routine visits to Osakidetza (anthropometric measurements, etc.), and an additional neuropsychological assessment (cognitive and motor development) was done at 26 months. Specifically, the researcher assessed 537 children at this age.

The study was conducted in the catchment area of the Hospital de Zumarraga (Hospital de Zumarraga and Osakidetza health centres in Zumarraga, Beasain and Azkoitia) with the collaboration of the whole team involved in pregnancy processes. This area for the study was chosen as it is closest to the industrial heart of Gipuzkoa and because it is a district hospital. Furthermore, participation in the study was on a voluntary basis and, as Dr Aranbarri confirmed, “it had a representativeness of 71%; a very good result for a public study of these characteristics”.

Results not alarming but significant nonetheless

The results obtained from the contamination measurements in the blood show that the levels of these organochlorine compounds are very similar to those in other developed countries where similar studies have been conducted; “the levels are very, very low,” concluded Dr Aranbarri. Within these very low levels, there is a higher level of PCBs in Gipuzkoa than elsewhere across Spain, because they are associated with the province’s industrial background.

In a study of these characteristics, everything that influences the variable being studied has to be taken into account to avoid reaching false conclusions. So, after monitoring the effect of variables associated with child development, like the social position and the family context, as well as various characteristics of the pregnancy and the anthropometric development of the children, the researcher has concluded that there is a significant relation between prenatal exposure to organochlorine compounds and reduced motor development. In other words, it was found that children in whom reduced motor development was detected -although always within normal levels- had been associated with higher prenatal levels of these compounds. The difference in the motor development between some and others is not clinically relevant nor pathological, but it is statistically significant in terms of the population, “since it is within the normal development parameters”, he pointed out. By contrast, these compounds were not found to have any effect on cognitive development. It should be pointed out that the neurotoxic properties attributed to these compounds derive mainly from laboratory studies and studies carried out on humans who have been acutely exposed, either through the occupational sphere or following environmental accidents.

Besides biological effects, the person’s social environment has a great influence on brain development. The conclusions of this study corroborate the positive, significant association exerted by the quality of the family context on early cognitive development, while this influence has not been seen in motor functions which are more susceptible to biological effects.
As the researcher concluded, “the results are important for public health since considering that the levels found are low, these compounds point to sufficient neurotoxicity to reveal an effect that can be detected on a population level”. These conclusions support the idea worldwide to drive forward the strategy to find out about and lower the risk associated with exposure to substances of this type and, what is more, will help to encourage habits and conduct designed to protect health.

Additional information

Aritz Aranbarri-Paredes (Azkoitia, Basque Country, 1982) is a doctor in Psychology (UPV/EHU, Donostia-San Sebastian). He studied Psychology at the UPSA of Salamanca and has done two Master’s degrees: a Master’s in Neuropsychology and Neurology (UAB, Barcelona) and an official Master’s in Psychology Research (UPV/EHU, Donostia-San Sebastian). He wrote up his thesis Impact of prenatal organochlorine compounds on early neuropsychological development at the Department of Basic Psychological Processes and their Development of the UPV/EHU’s Faculty of Psychology in collaboration with the Environmental Epidemiology and Child Development research team at the BioDonostia Institute of Health Research, under the supervision of Eduardo Fano and Jesus Mª Ibarluzea.

During his pre-PhD training, he completed a research internship at the University of California’s Mind (Medical Investigation of Neurodevelopmental Disorders) Institute in Davis.

Right now, he is a paediatric neuropsychologist and researcher at BioDonostia IIS (Institute of Health Research) in the area of neuroscience research in the Mental Health and Psychiatric Care research team.  He is working on a project for the early detection of early neurodevelopment pathologies in the Bidasoa district. He also collaborates with the Environmental Epidemiology and Child Development research team of IIS BioDonostia, and lectures at the UPV/EHU in the area of Psychobiology. 

Bibliographical reference:

J. Forns, N. Lertxundi, A. Aranbarri, M. Murcia, M. Gascon, D. Martinez, J. Ibarluzea (2012). “Prenatal exposure to organochlorine compounds and neuropsychological development up to two years of life”. Environment International, 45, 72-77. doi:10.1016/j.envint.2012.04.009

J. Forns, A. Aranbarri, J. Grellier, J. Julvez, M. Vrijheid, J. Sunyer (2012). “A conceptual framework in the study of neuropsychological development in epidemiological studies”. Neuroepidemiology, 38(4), 203-8. doi:10.1159/000337169

 

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