By Jessica Tyrrell, University of Exeter
Many people buy high-end, free-range and organic products in a bid to cut down on the amount of chemicals in their bodies. But chemicals can accumulate from a range of sources, and new research suggests that people from poorer backgrounds may not be the only ones suffering harmful effects.
Findings from a study we carried out at the University of Exeter, show that the accumulation of potentially harmful chemicals in the body affects people of all social standings – and that the type of toxicant can change according to economic status.
Using ten years of data from the US National Health and Nutrition Examination Survey, we analysed possible links between a person's socioeconomic status and the prevalence of chemicals in their body. We found a range of different chemicals and a pattern across different economic groups.
We weren't expecting our findings to contradict the standard environmental justice hypothesis – the belief that poor and minority communities suffer greater exposure to environmental pollution and a disproportionate share of the burden.
Instead, as people become better off, changes in their lifestyle alter the types of chemicals in their bodies, rather than reducing the overall amount. This has a profound impact on the way we treat chemical build-ups. At present the major focus is on reducing exposures in individuals from poorer backgrounds.
While the environmental justice hypothesis rings true in many areas, our research suggests that individuals of all social standings are at risk of high levels of specific types of chemicals and that we need to look at lifestyles to reduce exposure rather than focusing solely on those at the bottom of the poverty scale.
Not the usual suspects
The team initially considered the potential associations between poverty income ratio, a calculation used to measure wealth and standard of living, and 179 chemicals. We then narrowed our focus to 18 chemicals that showed strong links with income over several sets of the survey data.
The results of the analysis came as a surprise. Although around half of the 18 chemicals linked to income were associated with lower socio-economic status (as anticipated), the other half were more prevalent in wealthier individuals.
People with higher socioeconomic status had higher levels of serum and urinary mercury, arsenic, caesium, thallium, perfluorooctanoic acid, perfluorononanoic acid, mono(carboxyoctyl) phthalate and benzophenone-3.
Our research suggested that eating more fish and shellfish contributed to an increase in mercury, arsenic, thallium and perfluorononanoic acid. We also demonstrated that the use of sunscreen is an important factor in the accumulation of benzophenone-3, with people from higher socioeconomic groups more likely to use products containing the chemical.
Lower socioeconomic status was associated with higher levels of serum and urinary lead and cadmium, antimony, bisphenol A and three phthalates (substances mainly used in plastics to increase flexibility and transparency): mono-benzyl, mono-isobutyl, mono-n-butyl.
We demonstrated that cigarette smoking, poor diet and occupation were among the factors likely to contribute to the build-up of cadmium and lead in those from groups with lower earnings.
Exposures to environmental pollutants have been associated with a wide range of diseases. For example increased levels of mercury can cause adverse neurological development in unborn babies. Perfluorooctanoic acid is linked to thyroid dysfunction in adults. Cadmium and lead are linked an increased risk of cancer, diabetes and cardiovascular disease.
Exposures to environmental pollutants have been associated with a wide range of diseases including diabetes and cardiovascular disease, but very little is currently known about the impact of small, yet long-term accumulations of chemicals.
We know even less about how complex mixtures of potentially harmful elements will affect our health in the longer term and these cocktails are building up in all of our bodies, regardless of wealth or lifestyle.
Populations living in poverty or of lower socio-economic status have previously been considered especially at risk from the possible harmful effects of chemical accumulation.
But these new findings indicate that despite not living near to heavily industrialised areas or landfill sites (for example), affluent members of society are similarly at risk from pollutant exposure, even if the specific chemicals involved are different.
A growing mix of novel chemicals, and materials such as nano-particles, are being used in consumer products, including cosmetics, medicines and clothing, and ultimately released into the environment.
Science is currently struggling to keep our understanding of the risks from these elements up-to-date.
With the expanding high-end consumer market, exposure to chemicals is likely to increase the toxicant burden in more affluent members of society. Worryingly we do not know what potential adverse health effects some of these chemicals, either individually or as part of the chemical cocktail, may cause.
Exeter University's European Centre for Environment and Human Health is part financed by the European Regional Development Fund Programme and the European Social Fund Convergence Programme for Cornwall and the Isles of Scilly.