Researching child exposure to environmental hazards

In order for those concerned with child health issues to properly diagnose and treat conditions caused by environmental health hazards it is necessary to develop a better understanding of what constitutes environmental health hazards. Research that identifies patterns of environmental diseases in children, assesses children's exposures to environmental toxicants, determines developmental periods of vulnerability, and quantifies dose-response relationships will bring us closer to prevention oriented interventions.

Many of the health threats to children arising from environmental exposures are to a large extent preventable, although there remain unanswered questions on the roles of the different exposures involved. In view of the very serious and long-term possible health consequences of these exposures, the lack of full scientific certainty should not serve to justify inaction. Public policy should be based on the precautionary principle and seek to prevent childhood diseases by reducing exposures to environmental agents and by considering children's characteristics and susceptibilities in legislation covering health and the environment.

Children are more vulnerable than adults to many pollutants. The cellular immaturity of children and the ongoing growth processes account for this elevated risk. Children breathe more rapidly and inhale more pollutant per pound of body weight than do adults. Their airways are much more narrow than those of an adult. Thus, minor irritation caused by air pollution, which would produce only a slight response in an adult, can result in a dangerous level of swelling in the lining of the narrow airways of a child.

If during early childhood a person is highly exposed to air pollutants, the risk of long-term damage to the lungs increases. Ozone and particulate matter in the air can cause disease in children and aggravate preexisting respiratory conditions. Incidence of asthma in US children has nearly doubled from 1980 to 1993.

Evidence that sunburn in childhood is linked to developing skin cancer later in life is now very strong. Because children spend a quarter of their time at school outside, schools are being advised to reschedule outdoor activities away from the middle of the day and provide sunscreen lotions and shaded playgrounds to help prevent pupils developing skin cancer. Overexposure to the sun and sunburn under the age of 15 are major risk factors for skin cancer, so teaching children about the need to avoid burning is vital to stop the increase in skin cancer cases.

Field studies in the US suggest ozone effects on the pulmonary function in children are much greater than would be predicted from chamber studies. Decreased peak flow in children has been reported to persist for up to a week following exposure to ozone concentrations lower than 0.2 ppm, suggesting the presence of damage to the respiratory tract. Repeated exposures may result in persistent bronchial hyperresponsiveness.

Epidemiologic studies in the US suggest that repeated exposures of children to ozone and other photochemical oxidants and particulates are associated with an accelerated decline in lung function and with symptoms of chronic respiratory disease; however, the quantitative aspects of such a relationship have not been adequately explored. There is a substantial body of experimental evidence in animals indicating that air pollution can lower resistance to infection, facilitate sensitization and airway responses to airborne allergens, and act synergistically with airborne acidity to damage deep lung tissues.

At the 1997 US research conference, "Children's Environmental Health: Research, Practice, Prevention, and Policy," experts on pediatric environmental health outlined the research agenda to protect the nation's children from environmental health risks. The agenda included current research in four priority areas: asthma and respiratory diseases; endocrine disruption; childhood cancers; and nervous system and developmental effects.

It is proposed that a platform or network of partnerships be established by the WHO European Centre for Environment and Health to conduct research on environmental hazards facing children. The terms of reference of this coordinating body would be to: (a) conduct and coordinate research, surveillance and monitoring activities in the priority areas identified in this document, as well as conduct research to assess the effectiveness of public health interventions; (b) serve as a channel for countries to exchange information on effective public health interventions, public education measures and research activities; (c) provide Member States with technical assistance in developing and implementing public health policies and intervention programmes and educational measures; (d) provide medical and health professionals and teachers' and parents' associations with education and training in environmental health issues affecting children; (e) serve as a channel for countries to exchange information on children's environmental health legislation, policies and regulation; (f) coordinate regional meetings and workshops on children's environmental health issues (including research, policy and education aspects); and (g) coordinate its work with that of other organizations and sectors involved in disseminating information on the issue, including the use of electronic communication (i.e. web sites, list servers, etc.).