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During pregnancy and infancy, environmental chemicals have a stronger influence on the human body than at any other time. What does that mean for brain development? What is the link to environmental, social, and economic inequality?
By Kam Sripada
Toxic environmental chemicals have been in the European public eye for decades. Think of Chernobyl, the clean-up of asbestos, or before that, the industrial revolution: biology textbooks still use the example of peppered moths in England which changed colour from light to dark during the 19th century, as pollution from burning coal in cities darkened their environment.
Researchers have uncovered important links between our health and what we are exposed to in our environments, such as air pollution, heavy metals, pesticides, and hazardous waste. A critical factor is at what age these exposures take place. Pregnancy and the first years of life are the most sensitive for exposure to toxic chemicals.
How environmental pollution affects development
During pregnancy and childhood, body systems develop rapidly. Children eat, drink, and breathe more than adults, relative to their body weight. Yet their body’s natural defences are not as effective as those of adults. This means that traces of certain toxic chemicals in food, air, and water can pass into the body more easily in children. At the same time, child-specific activities like crawling on the floor, putting objects in their mouths, and breastfeeding mean children are exposed to chemicals in different ways than adults. Levels of chemicals that may be tolerable for adults may have health-damaging effects for infants and children (Grandjean 2013).
This is especially true for early brain development, which lays the foundation for the human capital we depend on for the rest of our lives (Lanphear 2015). Early exposures to toxic heavy metals, such as lead and mercury, are linked to lowered intelligence, learning disabilities, impaired hearing, shorter attention span and hyperactivity. These effects can be permanent.
Environmental pollution from energy production, vehicles, industry, and food is a threat to the health of children living in Europe. To take the case of air pollution, researchers in Barcelona have reported that exposure to the air pollutant nitrogen dioxide (NO2) during pregnancy and to a lesser extent after birth, is associated with reduced attention in children at age 4 and 5 (Sentís et al., 2017). The European Environment Agency (EEA) annually assesses the sources of pollution in Europe and has published the 30 most polluting industrial facilities in Europe. Although there have been successes in reducing pollution, the EAA’s evaluation shows that around Europe, “air quality still needs to improve in order to reduce harm to human health and the environment”.
Inequalities in environmental health
The health burden from hazardous environmental chemicals falls disproportionately on disadvantaged groups. This means that some children are more affected than others. A clear example of this environmental injustice is proximity of homes to waste incinerators, landfills, and legal and illegal dumps. Poorer, less educated, disadvantaged people, and ethnic minorities tend to live closer to waste treatment facilities, and when health-damaging effects are detected, they are often worsened by social disadvantage (Martuzzi et al., 2010). The World Health Organization recently released its “Environmental health inequalities in Europe” second assessment report, with many examples of how social determinants interact with environmental health.
European consumers and policies also play a role in pollution in other places around the world. Toxic, flammable, explosive, or corrosive materials labeled as damaged goods, recycling, or waste are regularly exported by high-income countries to low- and middle-income countries. Processing may be less expensive, but many locations lack the facilities and oversight for proper disposal of toxic chemicals. The dumping of 500 tons of toxic waste in Abidjan, Cote d’Ivoire, by the vessel Probo Koala in 2006, and hazardous burning in Agbogbloshie,
Ghana, of electronic waste (known as e-waste, such as computers and refrigerators) from European ports, are two recent examples of transnational transfer of pollution (Landrigan et al., 2019). Toxic dump sites are often located near areas where children live, learn, and play. The recent Lancet Commission on Pollution and Health found that pollution from air, water, soil, and toxic chemicals was responsible in 2016 for 940,000 child deaths, of which 92% occur in low- and middle-income countries (Landrigan et al., 2017, 2019).
Steps to protect children’s environmental health
Our environment has changed dramatically from the days of the peppered moths’ color adaptation in England.
Many new regulations have been passed to reduce the amount of hazardous chemicals entering our environment each year and to clean up chemicals that persist over many years and decades. The Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation in the EU, along with the Stockholm Convention on Persistent Organic Pollutants and Minamata Convention on Mercury are major success stories in global health collaboration.
But new chemicals are also released each year and can be transported over long distances in air, water, and consumer products and mix with existing chemicals. What has not changed is children’s unique vulnerability to toxic chemicals in their environment, and the need to prioritize children’s health at the intersection of policy, research, and industry.
Grandjean P. Only One Chance. Oxford University Press; 2013.
Landrigan PJ, Fuller R, Fisher S, Suk WA, Sly P, Chiles TC, Bose-O’Reilly S. Pollution and children’s health. Sci Total Environ. 2019 Feb 10;650(Pt 2):2389-2394.
Landrigan, P.J., Fuller, R., Acosta, N.J.R., Adeyi, O., Arnold, R., N, Basu, et al., 2017. TheLancetCommission on pollution and health. Lancet.
Lanphear BP. The impact of toxins on the developing brain. Annu Rev Public Health. 2015 Mar 18;36:211-30.
Martuzzi M, Mitis F, Forastiere F. Inequalities, inequities, environmental justice in waste management and health. Eur J Public Health. 2010 Feb;20(1):21-6.
Sentís A, Sunyer J, Dalmau-Bueno A, Andiarena A, Ballester F, Cirach M, Estarlich M, Fernández-Somoano A, Ibarluzea J, Íñiguez C, Lertxundi A, Tardón A, Nieuwenhuijsen M, Vrijheid M, Guxens M; INMA Project. Prenatal and postnatal exposure to NO2 and child attentional function at 4-5years of age. Environ Int. 2017 Jul 6; 106:170-1779
World Health Organization (2019). “Environmental health inequalities in Europe”, second assessment report. Available online: http://www.euro.who.int/en/publications/abstracts/environmental-health-inequalities-in-europe.-second-assessment-report-2019
Recommended further reading
Silent Spring, by Rachel Carson (1962).
Quest for environmental justice: Human rights and the politics of pollution, by Bullard RD (2005).
The Precautionary Principle in the 20th Century: Late Lessons from Early Warnings, by David Gee (2002).
Kam Sripada PhD is a researcher based at CHAIN - Centre for Global Health Inequalities Research. She studies brain development, environmental health, and the long-term impact of early experiences.