WHO:Eliminating environmental health hazards

This text is taken from the WHO report "Health and Environment in Europe: Progress Assessment", 2010, ISBN 978 92 890 4198 0. [1]

Regional priority goal IV: We commit ourselves to reducing the risk of disease and disability arising from exposure to hazardous chemicals (such as heavy metals), physical agents (e.g. excessive noise), and biological agents and to hazardous working environments during pregnancy, childhood and adolescence.

Key messages

• Policies and action to limit exposure to persistent organic pollutants (POPs) and heavy metals in food, and to eliminate exposure to lead from leaded petrol have all achieved considerable success within the Region. Constant awareness is, however, needed. Moreover, there are still challenges in many countries, with a need for improved monitoring and enforcement.
• Iternational cooperation on food safety has proved efficient, as countries develop coherent standards and regulations aiming to ensure the same level of health protection for as many citizens as possible.
• There is a lack of appropriate publicly available environmental health data, especially regarding exposure to heavy metals but also regarding contamination of the food chain and the burden of foodborne disease.
• Consideration of health aspects in environmental policies for heavy metals is low in most countries and is not proportional to the risks to health which heavy metals may create.
• Environmental noise is perceived as the most common stressor: a quarter of the population in EU countries is exposed to noise levels leading to a wide range of health effects. Noise abatement policies in many Member States need to be strengthened to address health problems effectively.
• Safety in the occupational environment improved significantly in the 1990s, but in the last decade the improvement has levelled of in the eastern part of the Region.

Regional priority goal IV addresses a wider range of environmental health issues than goals I–III and is associated with diverse environmental health risks such as toxic chemicals, physical agents (e.g. harmful noise, and ionizing and ultraviolet radiation) and hazardous working environments. It focuses on policy action to reduce and prevent hazardous exposure with an emphasis on children and other age-specific sensitivity windows. Furthermore, this goal pays particular attention to child labour and advocates the elimination of its worst forms.

This chapter focuses on three areas, giving an assessment of the situation, progress and policy action regarding:

1. issues related to
   1. food safety, including exposure to hazardous chemicals in food;
   2. general exposure to lead; and
   3. chemical safety aspects of other heavy metals;
2. environmental noise;
3. occupational health, in particular work-related health problems.

Consideration is paid to the health burdens, public concerns, availability of data and evidence, and potential to take targeted action to benefit health. Despite their differences they are all of special concern for children’s health for similar reasons: the particular sensitivities of children in the pre- and postnatal periods due to their rapid development; their different metabolisms and behaviour compared to adults; and their longer life expectancy, which render them more vulnerable than adults to many environment hazards.

Chemical hazards

Exposure to chemical hazards

People are exposed to huge numbers of industrial and household chemicals, pesticides and metals in air, water, food and consumer products. Many of these chemicals can be hazardous to health, especially if they are used inappropriately. Children are particularly vulnerable to chemical hazards for various reasons including naïve behaviour and because their organ systems are rapidly developing. Symptoms arising from prolonged low-level chemical exposure may only appear later in life and may be chronic and irreversible. Global industrialization, urbanization and intensive agriculture, together with growing patterns of unsustainable consumption and environmental degradation, contribute to exposure to hazardous chemicals.

New chemicals are constantly synthesized for various purposes and the capacity rigorously to test the safety of all of them prior to use is very limited. The EU Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulation, introduced in June 2007, makes industry responsible for assessing and managing the risks posed by chemicals and providing appropriate safety information to their users. Adverse health outcomes are a result of many factors including the compound’s toxicity, and the exposure levels and characteristics of the exposed population. It is, however, assumed that many new chemicals will not take on public health importance.

Food safety is one of the most important factors for good health. Several serious accidental poisonings have arisen due to food contaminated by POPs or heavy metals, and long-term low-level exposure can cause chronic health effects. Furthermore, the microbiological safety of food is crucially important for public health. The surveillance of foodborne diseases and the monitoring of contamination in the food chain are, however, inadequate. Reporting of foodborne disease only represents the tip of the iceberg. A risk-based approach is needed in the management of exposure to chemical hazards. Priority should be given to assessing those chemicals with the greatest risks for public health, those that accumulate in the body and those to which chronic exposure at low levels cause adverse health outcomes.

Groups of chemicals that should be considered when assessing the safety of food are pesticide residues, veterinary drug residues, heavy metals, POPs and other organic contaminants, microbial toxins, food additives, compounds formed unintentionally during the processing of food, contaminants from packaging and storage and, last but not least, the major constituents of food itself, such as excess salt, sugar and fat. The inherent toxicity of a substance does not necessarily indicate high public health concern, as population exposure and vulnerability are also important determinants.

Persistent organic pollutants

POPs have been recognized as a serious concern since the 1960s and 1970s, when dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs) were banned or phased out in many industrialized countries. Over time, it became clear that this was not sufficient. Besides staying in the environment for long periods, POPs are prone to accumulate in higher organisms and to magnify in the food chain: levels increase by several orders of magnitude from sea plankton up the food chain to people. Owing to their semi-volatility and persistence, some are transported through air and water to locations where they have never been used, such as the Arctic. At high concentrations, POPs cause reproductive and developmental effects in wild and laboratory animals. There is more uncertainty about health effects in humans at typical levels of exposure, which can be lower than in some other species.

Among the POPs, polychlorinated dioxins (PCDDs) and dioxin-like chemicals (including polychlorinated dibenzofurans (PCDFs) and dioxin-like PCBs) appear to have the lowest safety margin and to be the most likely group to cause adverse effects in humans. During the 1970s, at concentrations 5–10 times higher than at present, they were possibly the cause of subtle effects such as effects on tooth development. The sources of these compounds were the incineration of municipal waste, chlorine gas bleaching of wood pulp and the metal industries, together with a number of minor sources. Until the 1980s, there were also important impurities in the production of certain chemicals (PCBs, chlorophenols and their derivatives). Advances in abatement have been greatest in areas such as waste incineration and the pulp and paper industry, resulting in the reduction of POP concentrations in environmental samples, including lake- and seabed sediment layers, fish, fish-eating birds and seals. The largest remaining sources are the metal and cement industries, landfill fires and small-scale wood and biomass burning. There may still be considerable variations among countries.

There is evidence that developmental effects occur even at the lowest measured POP concentrations. Dioxin levels in human milk provide a long-term average of the body burden because these persistent compounds accumulate in breast tissue. They are relevant both as an indicator of risk during pregnancy and for measuring the chemical intake by the breastfed baby. Both of these steps are believed to be crucial for assessing the risk of developmental effects for the whole population. The most systematic information on POPs in humans is based on four rounds of human milk analysis studies of dioxins and PCBs coordinated by WHO. Dioxin levels in human milk have decreased in all countries monitored since 1988. Several European countries with higher initial levels have made particularly dramatic and important reductions. In spite of the decrease, the margin between currently prevalent and known toxic levels is still narrow enough to be of concern.

WHO recognizes this concern. Nevertheless, the net beneficial effect of breastfeeding as the optimal food source for newborn babies should always be emphasized, especially when sharing information with the general public.

The body burden is clearly age-dependent and is lowest in younger age groups. For older populations with higher body burdens, the relative risk of cancer, while real, is not very high even at the highest industrial exposures. Recent results of studies on families of fishermen indicated that, despite much higher dioxin and PCB body burdens, mortality (including cancer mortality) was lower than in the general population, possibly due to the other, beneficial effects of consuming fish. In Seveso, Italy, after a very high level of accidental exposure, there were reports of developmental effects on teeth, altered sex ratios and a possible increase in some rare types of cancer.

It is more difficult to assess the health risks of compounds other than dioxins, as the data on both exposures and effects are less systematic. Organochlorine pesticides or their metabolites can still be found in human samples in Europe, but the concentrations are low and their health relevance has clearly decreased. Some compounds have more recently come into focus. Polybrominated diphenyl ethers (PBDEs – flame retardants used in plastics and textiles) were found in human milk at the end of 1990s. Certain brominated diphenylethers, such as tetra- to octa-congeners, are absorbed by different animal species and bioaccumulate to some extent. They were therefore banned by the European Commission in 2004 and their concentrations in Europe are now decreasing. Even so, continued monitoring is warranted because there is uncertainty about the metabolic fate of decabromodiphenyl ether (BDE-209), which is still in production. It is itself very poorly absorbed by biota and fairly rapidly eliminated in humans, but it may be broken down into more toxic forms.