An initiative of the Canadian Association of Physicians for the Environment.

"People who wouldn't dream of abusing a child think nothing of giving their children and grandchildren an environment that has been abused."

Richard J. Jackson, MD, MPH, Director, National Center for Environmental Health, Centers for Disease Control and Prevention, USA

Children have greater risk of exposure and greater risk of harm compared to adults for many reasons that are unique to each developmental stage.

Environmental health researchers increasingly recognize that a variety of health problems may be attributed in part to exposure to environmental factors.

What kinds of effects, clinical or otherwise, can be due to exposure to environmental factors?

Environmentally influenced health problems are a challenge to diagnose since most present with non-specific symptoms that are commonly missed and very few have been adequately characterized.

What can the
clinician do?

What can
parents do?

Introduction

The Children’s Environmental Health Project was designed by the Canadian Association of Physicians for the Environment (CAPE). It is intended to introduce clinicians (and their patients) to the fundamentals and broad context of children’s environmental health issues. Information on the health effects from environmental exposures is presented in a systems approach.

Five units summarize the current scientific research regarding environmental influences on: 1) respiratory health, 2) neurobehavioural development, 3) cancer and immune functioning, 4) dermatological health, and 5) reproductive health and congenital anomalies in the young. The project also covers environmental history-taking and provides links to additional resources that may be useful to the interested individual. Lastly, we provide a commentary on the physician’s role in primary prevention of environmental health problems in children.

What is environmental health?

• The field of environmental health focusses on the relationships between human health and well being and the influence of the physical, social and societal environments. The physical environment encompasses both natural and built aspects. The latter has the greatest influence on human health since we are largely an urban society and spend the vast majority of our time indoors, in homes, buildings or cars. In industrialized countries, environmental health research has come increasingly to focus on the impact of the physical, chemical and biological contaminants that abound in the environment as a result of our consumer and industrial society.
• Our understanding of the environment–health interface has progressed because of two relatively recent insights: First, we recognize that the unprecedented environmental changes of the last half-century (i.e., global warming, reduction in atmospheric ozone, loss of biodiversity, pervasiveness of toxic environmental contaminants, etc.) are affecting global population health. The second and arguably equally significant insight has been that children have greater vulnerability to environmental hazards and are inadequately protected by current regulatory standards. Efforts to redress this situation have shaped the current thrust in environmental health research toward preventing further harm to children’s health.

How are children unique?

• Children are not "little adults." We know that children have greater risk of exposure and greater risk of harm compared to adults for many reasons that are unique to each developmental stage.
• Their behaviour and activity patterns bring them into greater contact with toxins.
• Children have important biological differences. Immature developing organs and tissues are more vulnerable to harm from toxic exposures. Immature metabolic and physiological systems less effectively protect the child from toxic exposure and effects.
• Children have additional pathways of exposure that are not applicable to adults, e.g., in utero, via breast milk and via products such as toys, clothing, etc.
• In the words of the former US EPA scientist Dr. Lynn Goldman, children also have a longer "shelf life." They have much more of their life ahead of them during which time they will be exposed and may develop health problems as a result.
• Finally, children are more often involuntarily exposed and unable to avoid exposures of their own accord.

What kinds of environmental factors can have an effect on children’s health?

• There is a daunting array of environmental agents to which people are exposed through various means. Many of these agents can be considered harmful to humans, especially children.
• Chemical and metal pollutants alone account for several tens of thousands of substances that are in use annually. Pesticides are an important category of such contaminants that are commonly present in the environment.
• Physical agents that have been studied for their effects on children’s health include electromagnetic frequency, radiation, ultraviolet radiation, radon and radionuclides.
• Examples of biological agents that influence children’s health include molds, fungi, bacteria and allergens such as pet dander and dust mites.
• Environmental tobacco smoke (ETS) is a mixture of several toxic compounds and is the primary cause of poor indoor air quality and respiratory health problems in children.
• Many potential factors exist in the built environment, including unsafe housing, poor indoor air quality (contributed by many of the factors above such as dampness and mould) and unhealthy communities (where there is substantial traffic, lack of safe play areas, unsafe streets, noise, etc.)
• Finally, poor children generally experience the worst in environmental influences on health. Poor communities are most often downwind, downstream and downhill from major sources of environmental contamination. Their communities and homes frequently are in the worst condition and their parents often work at jobs that expose them to contaminants or other hazards that may be brought home from the workplace.

What kinds of effects, clinical or otherwise, can be due to exposure to environmental factors?

• Environmental health researchers increasingly recognize that a variety of health problems may be attributed in part to exposure to environmental factors. The focus here is on chronic, low-level exposures, where the evidence for causation remains somewhat elusive and yet there is potential for many children to be affected.
• Some studies have noted increases in spontaneous abortion, stillbirth rates and congenital birth defects in the babies of women exposed during pregnancy to various contaminants such as solvents, pesticides, PCBs, metals, chlorine disinfection by-products in drinking water and ionizing radiation.
• Impairment of behavioural, cognitive and neurological development may result from exposure early in life to neurotoxins such as lead and methylmercury. Lowered IQ, reduced attention span, learning disabilities and behavioural problems such as aggression are subclinical symptoms associated with exposure to low levels of lead.
• There have been substantial increases in childhood asthma, allergies and respiratory problems in recent decades. There is good evidence that air pollutants trigger attacks in asthmatic children causing them to miss school and attend at hospital or their doctor.
• An increase in certain childhood cancers such as leukemia and bone and brain tumours has also been documented and may be related to exposure to a variety of chemical and physical agents.
• Immune system functioning may be compromised by exposure to contaminants, either by heightening the immune response or by suppressing it, thereby leaving the body more vulnerable to infections and cancer.
• Finally, there is considerable concern that some environmental chemicals may act as endocrine disruptors, altering reproductive development and thyroid or immune system functioning. Studies of wildlife and laboratory animals have convincingly documented hormone disruption from certain contaminants. The effects in humans are not fully confirmed, although trends observed in industrialized countries (e.g., declining sperm counts, increasing prevalence of prostate, testicular and breast cancers, reproductive organ abnormalities and fertility problems) may be linked with the presence of endocrine disruptors in the environment.

How does this relate to clinical practice?

• Environmentally influenced health problems are a challenge to diagnose since most present with non-specific symptoms that are commonly missed and very few have been adequately characterized. This web resource provides basic background information to enhance the physician’s understanding of the scope of the problem. References and links to appropriate sources for in-depth diagnostic and treatment information are provided as far as possible.
• Health professionals can also provide parents and patients with greater understanding and the awareness to prevent hazardous exposures to their children. One strategy for such patient education is to incorporate key questions into the history-taking routine.
• The primary tenet of the Hippocratic Oath is to do no harm. The medical profession therefore fundamentally endorses a precautionary approach that strives to protect the child when there is profound uncertainty and incomplete understanding of the risks from environmental toxins.
• As such, physicians are also lending a powerful leading voice to the health advocacy organizations influencing environmental policy – the ultimate means of ensuring protection of children’s health. Of note, in December, 1999, Dr. Kelly Martin gave testimony on behalf of CAPE to the federal standing committee on environment and sustainable development, conveying why Canadian physicians are concerned about the policies regulating pesticide use.
• Precaution and prevention require action at a broader level. CAPE also urges all physicians to ensure that their own hospitals and practices are not adding to the burden of environmental damage that may affect the health of children and future generations. CAPE has been particularly active in urging that the health care system become more environmentally sustainable and less harmful to ecosystem health via the Greening Health Care theme.

What can the clinician do to better understand the environmental determinants of childhood illness?

• The volume of scientific literature on children’s environmental health issues is enormous. This web resource aims to summarize some of the more salient details from a practical, clinical and preventive perspective and suggests further references and resources for the interested physician.
• A first step might be to become a member of the Canadian Association of Physicians for the Environment (or other NGO focussing on children’s environmental health) and take advantage of the networking and information-sharing that extends from that affiliation.

What can parents do to better understand how the environment can impact on their children’s health and well being?

• Knowledge is power. Parents are encouraged to make use of the information on prevention in this site.
• Parents may also find the suggested links to be of value. Several sites geared specifically for the lay public are highlighted as relevant links for parents.

Seana Brennan, age 6

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