Making the Environment Healthier 

for Our Kids

An overview of environmental challenges

 to the health of North America’s children

Commission for 

Environmental Cooperation

of North America

April 2002
The Commission for Environmental Cooperation (CEC) was 

established under the North American Agreement on 

Environmental Cooperation to address environmental issues in 

North America from a continental perspective, with a particular 

focus on those arising in the context of liberalized trade. 

This publication was prepared by the Secretariat of the CEC. 

The views contained herein do not necessarily reflect the 

views of the CEC, or the governments of Canada, Mexico or 

the United States of America.

Reproduction of this document in whole or in part and in any 

form for educational or nonprofit purposes may be made 

without special permission from the CEC Secretariat, provided 

acknowledgement of the source is made. The CEC would 

appreciate receiving a copy of any publication or material that 

uses this document as a source.

Published by the Communications Department

of the CEC Secretariat.

For more information:

Commission for Environmental Cooperation

393, rue Saint-Jacques Ouest, bureau 200

Montréal (Québec) Canada H2Y 1N9

Tel.: (514) 350-4300 Fax: (514) 350-4314

http://www.cec.org

Disponible en français – Disponible en español
Foreword

As parents, and as adults in a caring society, we do everything we can to protect children 

from harm. We vaccinate them against disease, teach them to be wary of strangers, restrict 

their freedom to work or drink alcohol. But what can we do when the danger lurks in the 

grass of a public park or in the air that they breathe? 

Almost every day we learn more about the hazards of environmental contaminants. We know that 

lead from chipping paint or pottery can depress IQ and create disturbances in the central 

nervous system. We know that PCBs and dioxins from municipal incinerators can promote 

cancer and cause developmental, reproductive, and metabolic damage. Just recently we

learned that second-hand tobacco smoke plays a major role in SIDS. And for every

association that we have been able to prove, there are dozens more that we strongly suspect. 

Children are especially vulnerable to environmental assault. Their bodies are changing

rapidly, which opens many windows of opportunity for chemicals to subvert the process. 

They take in more air—pollutants and all—and absorb more pesticide residue and other 

contaminants in their food than adults do, relative to size. Impoverished children are at even 

higher risk. With limited access to health care and proper nutrition, and with a greater 

likelihood of living in polluted, industrial areas, they are less able to withstand attack. In all 

three North American countries, children make up the largest age group living in poverty.

We have a problem that transcends borders. And this report is the first step toward addressing 

it in a collective manner, capitalizing on our varied perspectives and experiences. Before we 

can begin to propose solutions, we need to understand the challenges we each face within the 

context of our different countries.

One challenge is already clear: Environmentally induced disorders are typically chronic, 

difficult to treat, and harder to reverse. Prevention is key. The CEC’s children’s environmental 

health initiative gives us the chance to take preventive action to improve the health of future 

generations of parents and decision makers.

While there is abundant literature on the acute toxicity of many chemicals, we have scant 

information on the effects of chronic, low-dose exposures or on how various chemicals act in 

combination. We need to promote scientific and clinical research to help regulators make 

evidence-based decisions. But we also need to find the courage to take precautionary action 

while awaiting further data. In this we have a strong precedent. Consider the warnings we 

give pregnant women about drinking, even though we understand little about how alcohol 

affects the developing fetus. Precautionary approaches of this nature are what we need to be 

working on. 

Children are our most precious resource in North America. They are our adult population of 

tomorrow who will create the children of the next generation. Protecting them by protecting 

our environment is a double investment in the future.
Irena Buka, M.B. Ch.B. F.R.C.P. ( C )

Chair, Expert Advisory Board on Children’s Health and the Environment in North America

Table of Contents

I. INTRODUCTION ........................................................................................................1

II. WHY A HEALTHY ENVIRONMENT IS IMPORTANT FOR HEALTHY 

CHILDREN...................................................................................................................3

III. WHY CHILDREN ARE AT GREATER RISK..........................................................5

A. Overview............................................................................................................................................................. 5

B. Physical Vulnerabilities.................................................................................................................................. 5

1. Development.....................................................................................................................................................5

2. Diet .....................................................................................................................................................................6

C. Behavioral Vulnerabilities.............................................................................................................................. 7

D. Factors for Additional Susceptibility ............................................................................................................ 8

1. Poverty...............................................................................................................................................................8

2. Ethnicity...........................................................................................................................................................10

IV. THE NORTH AMERICAN CONTEXT...................................................................12

A. Urban and Rural Populations........................................................................................................................12

B. Births................................................................................................................................................................12

C. Mortality and Morbidity.................................................................................................................................12

Leading Mortality Rates for Children Aged 1- 4, 1997 ..................................................................................14

V. ENVIRONMENTAL THREATS TO CHILDREN'S HEALTH.............................15

A. Sources of Exposure—Types of Hazards....................................................................................................15

1. Chemical Pollutants........................................................................................................................................15

2. Chemical Pollutants........................................................................................................................................15

3. Consumer Products........................................................................................................................................15

4. Pesticides.........................................................................................................................................................16

5. Toxic Metals....................................................................................................................................................17

6. Asbestos .........................................................................................................................................................19

7. Ozone ...............................................................................................................................................................20

8. Particulate Matter...........................................................................................................................................20

9. Second-hand Tobacco Smoke......................................................................................................................21

10. Hazardous Air Pollutants..............................................................................................................................21

11. Airborne Agents ............................................................................................................................................21

12. Microbiological Agents ................................................................................................................................21

B. Routes of Children’s Exposure.....................................................................................................................22

1. Food .................................................................................................................................................................22

2. Water................................................................................................................................................................22

3. Air.....................................................................................................................................................................24
VI. HEALTH CONSEQUENCES ....................................................................................26

A. Asthma..............................................................................................................................................................26

B. Childhood Cancer ...........................................................................................................................................26

C. Neurodevelopmental Effects..........................................................................................................................27

D. Birth Defects ...................................................................................................................................................28

E. Immunological Effects....................................................................................................................................29

F. Reproductive Conditions and Endocrine Disruption................................................................................29

VII. POLICY CONSIDERATIONS ..................................................................................31

A. Overview...........................................................................................................................................................31

B. Scientific Gaps and Emerging Issues related to Children’s Environmental Health..........................32

C. Areas of Opportunity for North American Action....................................................................................33

VIII. APPENDIX: INTERNATIONAL INITIATIVES .................................................36

IX. SELECTED REFERENCES ......................................................................................39
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

I. Introduction 

Over the past several years it has become increasingly clear that environmental hazards pose a 

particular threat to children. At the same time, we have deepened our understanding of how 

pollutants like mercury, lead, DDT, dioxins and other persistent organic pollutants are transported 

vast distances by wind, water or commerce. Given that children are increasingly being exposed to 

environmental contaminants of foreign origin through long-range transport of contaminants such as 

persistent organic pollutants (POPs), coupled with the knowledge that children are a more

susceptible population to the effects of these and other environmental contaminants, it is clear that 

there is a strong need for global cooperation and a well-coordinated regional effort in order to 

truly protect our children. 

Conscious of the need for greater cooperation, the Commission for Environmental Cooperation 

(CEC) Council, comprising the federal environmental ministers (or their delegates) from Canada, 

Mexico and the United States, announced a special CEC initiative in this important area. Already, 

the CEC is actively helping to eliminate or reduce persistent organic pollutants and other

substances, is tracking data on toxic releases to the environment, and is involved in other initiatives 

relevant to the children’s health agenda. 

The CEC Symposium on North American Children’s Health and the Environment, held in Toronto 

in May 2000, was an important first step towards identifying a common agenda for the three 

countries. The symposium brought together scientists, policymakers, and environmental and

children’s health advocates to discuss recent scientific findings, emerging issues, gaps in our 

understanding, and new directions in policymaking. Participants were able to identify areas of 

common interest and to exchange ideas for a regional plan.

The outcomes of the symposium provided important groundwork for Council Resolution 00-10 

on Children’s Health and the Environment, which was adopted by the CEC Council during its 

session in Dallas, Texas, in June 2000. The Resolution commits the three governments to work 

together as partners to develop a cooperative agenda to protect children from environmental 

threats, with an initial focus on asthma and other respiratory diseases, the effects of lead, including 

lead poisoning, and the effects of exposure to other toxic substances. The Resolution also called 

for the formation of an Expert Advisory Board to provide advice to Council on matters of

children’s health and the environment. This board was convened in October 2001.

This paper is intended to paint a broad picture of children’s environmental health issues, with a 

specific focus on the situation in North America. The main elements of its structure are as follows: 

Section II is a general introduction to the subject. Sections III and IV present an overview of child 

development and examine how pollutants affect children at various stages of their lives—

something that is critical not only for assessing risk but for crafting targeted solutions. Sections V 

and VI provide an overview of environmental hazards and their consequences to children. Finally, 

Section VII outlines some policy considerations and possible opportunities for trilateral action, 

with a view to stimulating dialogue among interested individuals and groups throughout civil society 

about what can be done to better protect children from environmental threats in North America.
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

II. Why a Healthy Environment is Important for Healthy 

Children

Environmental concerns affecting children’s health is a relatively new field incorporating the child, 

the environment and health—three interrelated and dynamic components that involve many

disciplines and sectors. However, a basic tenet of this new field is that the child, and his/her health 

and development, is at the center of the paradigm. Children constitute 30% of the world’s 

population but they are 100% of our future (United Nations 1998). Their growth and

development is therefore of primary concern.

The connection between the external environment and human health is acknowledged by

institutions such as the World Health Organization (WHO), which has stated “...human health 

ultimately depends on society’s capacity to manage the interactions between human activities and 

the physical and biological environment” (WHO 1992). More recently, WHO has concluded that 

about one quarter of the global disease burden is attributable to environmental factors (WHO 

1997), and many environmental threats to health are preventable. One example of this is lead 

poisoning. In the United States, the Centers for Disease Control and Prevention (CDC) helped to 

initiate federal activities to reduce lead in gasoline, which brought about declines in average blood 

lead levels in the US population. Data from the most recent National Health and Nutrition

Examination Survey (NHANES) show that the percentage of US children with elevated blood 

lead levels has dropped from 88.2% in the late 1970s to 4.4% in the early 1990s (Brody et al. 

1994). 

Our world has seen sweeping changes over the past 50 years. Technological innovations in life 

sciences, communications, medicine and other areas have revolutionized the way we live. Part of 

that revolution has led to the discovery and manufacture of thousands of chemicals previously 

unknown to the world. These substances are now virtually everywhere, because they are

transported by natural forces and the growing commerce among nations. While we have reaped 

many positive benefits from our use of minerals and chemicals, new and old, we are just beginning 

to explore and understand some of the other impacts that these substances may have on human 

health and on the health of our children. In light of our increased scientific understanding of child 

development, environmental toxicants, and human health, there is a need to assess our protective 

strategies to ensure that they protect children’s health.

There are several unique aspects to environmental impacts on children’s health:

• Most children have a longer life expectancy than adults do, so that impacts from environmental 

exposures early in life have a longer time to manifest in adverse health consequences later on.

• Effects from environmental exposures can permanently alter or damage developing systems 

in a child, whereas an adult experiencing the same exposures might not experience any ill 

health effects (the reverse can also be true).
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

To insure that children live in a healthy environmental is an issue that lies at the very heart of 

sustainable development. In general, healthy children grow into healthy, capable adults. Investing 

in environmental conditions that protect and enhance children’s health today will provide North 

American society with long-term dividends in terms of reduced demands on health and social 

services and increased productivity in the future.

If we create an environment that is safe and healthful for children, possibly the most vulnerable and 

sensitive among us, we create an environment safe and healthful for all. 

Children’s Health and the Environment—Definitions of Terms

Children

Children are “dynamic organisms,” growing and changing with great rapidity. For the 

purposes of this paper, a child is defined as 18 years of age and under, after which most 

biological systems are fully developed, with the recognition that parental reproductive 

health has an enormous impact on the future healthy development of both fetus and child. 

Environment

Many environmental factors influence children’s health, including the quality of water, air, 

food housing and the safety of the places in which children live, learn and play. Each of 

these factors is important in its own right, but they also interact with each other, and with 

the additional determinants of health, which include social and economic factors, health 

practices, genetic factors and access to health services (Federal/Provincial/Territorial

Advisory Committee on Population Health 1994).

Health

Over the last 50 years, the World Health Organization has revised and expanded its

definition of health from “a complete state of physical, mental and social well-being and 

not merely the absence of disease” to “a positive concept emphasizing social and personal 

resources, as well as physical capacity.” 
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

III. Why Children Are at Greater Risk 

A. Overview

Children are not little adults. From conception on, the fetus, infant, child, and adolescent are in 

dynamic states of growth. These involve the brain, skin, kidneys, and liver, and the respiratory, 

immune, endocrine, reproductive, gastrointestinal, skeletal, and nervous systems. The elegance 

and complexity of this development allows the body to mature. But it also opens windows of 

vulnerability that can divert, alter or permanently damage these developing systems. 

We therefore need to consider when during a child’s development an exposure takes place—not 

just the toxicants involved, sources and routes of exposures, and the dose of a contaminant. The 

fetus, for example, is perhaps the most vulnerable to environmental insults. We now know that a 

variety of toxic substances can cross the placenta, including polychlorinated biphenyls (PCBs), 

polycyclic aromatic hydrocarbons (PAHs), carbon monoxide (CO), lead (Pb), and ethanol

(Bearer 1995; Etzel and Balk 1999). These toxicants can cause serious health problems in

exposed children (Jacobson et al. 1990). We also know that the blood-brain barrier is not fully 

matured in the fetus or newborn, allowing some toxic substances to pass freely, for example, 

alcohol.

Adults and children differ in behavior, physiology, metabolism, and diet. Kilogram for kilogram of 

body weight, children breathe more air, drink more fluids, and consume more food than adults, 

proportionately increasing their exposure to whatever contaminants may be present. Generally, 

children are more active than adults and engage in a range of behaviors that can place them at 

higher risk of exposure.

B. Physical Vulnerabilities 

1. Development

The brain and nervous system develop through adolescence and into the mid-twenties, and are 

extremely sensitive to exposures at critical times in development (Rodier 1995). We have learned 

through experience in Canada, the United States and Mexico that lead and methylmercury can 

profoundly affect intelligence and central nervous system development. Subtle effects, including 

impaired language skills, attentiveness and memory, as well as motor and visual-spatial functions, 

can be measured in children exposed to even low doses, when exposure occurs during specific 

stages of development. The effects of lead on IQ have been well documented (McKeown-Eyssen 

et al. 1983b; Needleman et al. 1990; WHO 1990; Grandjean et al. 1999). In Canada and the 

United States, subtler effects and developmental disabilities such as attention deficit hyperactivity 

disorder (ADHD) are being observed, and have been linked with various environmental toxicants 

such as enviromental tobacco smoke, alcohol, lead, mercury and PCBs (Chen et al. 1992). There 

is also research that shows a possible link between environmental exposures (for example, to 

lead) and juvenile delinquency (Needleman 1996).
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

At times, an infant’s developing systems (such as the nervous, immune, reproductive,

gastrointestinal and respiratory systems) can protect against exposure to toxicants, since his or her 

body is not able to break these toxic compounds into harmful metabolites. Such is the case with 

acetaminophen (Etzel and Balk 1999). But more often, infants and children are at greater risk 

because they cannot metabolize, detoxify and excrete toxins as efficiently as adults (Echobichon 

and Stevens 1973; Landrigan et al. 1998).

Infants grow and develop rapidly and are more prone to adverse effects from low-dose 

exposures, as growing and dividing cells are at greater risk of influence by chemicals (McBride 

1998). Typically, they double their birth weight within the first 4–6 months, and triple it by their 

first birthday. Although the newborn weighs only one-twentieth of an average adult male, the 

infant’s surface area is one-eighth as great, creating a much larger dermal surface per mass ratio. 

As a result, infants and children could be at greater risk from dermal contact with environmental 

contaminants—a risk which in turn is increased by the behavior of infants and children (see 

Section IIIC, Behavioral Vulnerabilities).

Children absorb and metabolize nutrients at different rates from adults. For example, children 

require more calcium than adults for bone growth and thus absorb more through the

gastrointestinal tract. Children who are deficient in calcium, iron and protein can absorb lead faster 

than a child who is well nourished. It is estimated that while an adult will absorb 10% of ingested 

lead, a one- or two-year-old will absorb 50% (Royce 1992; Bearer 1995). Manganese and iron 

are other examples. Children need iron and manganese for oxygenation, and they absorb it 

through the intestinal wall. Lead and other metals can interfere and replace needed nutrients in the 

absorption process (Peraza et al. 1998).

The health risks from air pollutants are also greater in children. Young children breathe more 

rapidly, with newborns taking 60 breaths per minute—versus 12 for adults—and therefore they 

take in a larger volume of air per minute of breathing time (Bearer 1995). Consequently, children 

are likely to take in greater quantities of air pollutants. And, because their lungs continue

developing alveoli through adolescence (Etzel and Balk 1999), they may be more susceptible to 

permanent damage.

Puberty and adolescence is another time of rapid growth and change. Aside from tobacco, there 

has been little research on the risks of environmental toxins at this stage of development. Some 

scientists believe it is ripe for study.

2. Diet

For many infants in North America, breast milk is their primary food. It is an ideal source of 

nutrition, providing them with high protein, fat, and natural immunities. Unfortunately, it may also 

be providing them with heavy metals (such as lead, cadmium and mercury), chlorinated pesticides 

(such as hexacholorobenzene, DDT and its metabolites and trans-nonachlor), and industrial

organic chemicals (such as PCBs and dioxins) (Jensen and Slorach 1991; Newsome et al. 1992; 

Bearer 1995; Sonawane 1995; Lopez-Carrillo et al. 1996; Polder et al. 1998; CEC 1999; 

Nashashibi 1999; Waliszewski et al. 1999). Many of these chemicals are transported through the 
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

atmosphere and deposited in distant regions, by a process known as the “Grasshopper Effect” 

(CEC 1997), and eventually accumulate in the fatty tissue of animals and humans. It is partly 

because of this and other transport processes that persistent and bioaccumulative chemicals have 

been found in the breast milk and fatty tissues of humans and animals residing far from the point of 

initial chemical use. The presence of contaminants in mothers’ milk is of concern because it is 

typically the only source of food for infants during the first few months of life. Nevertheless, 

analyses conclude that the benefits of breastfeeding outweigh the risks associated with the

presence of contaminants.

The average infant consumes 5 ounces (148 mls) of formula per kilogram of body weight, which is 

the equivalent of an average male adult drinking 30 twelve-ounce (355 mls) glasses of milk per 

day (Etzel and Balk 1999). Infants and children drink 2.5 times more water daily than adults, by 

percentage of their body weight (Plunkett et al. 1992). Children between ages 1 and 5 eat three to 

four times more than adults, per unit of body weight. And children tend to eat diets higher in fruits 

and vegetables, which may increase their relative exposures to any pesticide residues that may be 

present. Proportionate to body weight, the average one-year-old in the United States eats two to 

seven times more grapes, bananas, pears, carrots, and broccoli than an adult (National Research 

Council 1993). 

C. Behavioral Vulnerabilities 

It is part of the natural course of development for children to explore their surroundings. Infants 

instinctively bring objects from their hands to their mouths as part of this discovery process. Later, 

as they begin to crawl, whatever is near floor level becomes a candidate for ingestion and 

experience. From dirt to dust, and anything in between.

Even though children may live in the same home as their family, they experience different

environments within the home. For example, infants are often indoors in cribs or on the floor. 

Toddlers are crawling, and small children also occupy space close to ground level. By contrast, an 

adult’s breathing zone is 4–6 feet above the ground. Heavier chemicals, such as lead, as well as 

particulates, radon, mercury vapors, and pesticide vapors settle close to the floor—increasing the 

possibility of children’s exposure (Bearer 1995; Mott 1997; Etzel and Balk 1999; Fenske et al. 

1990). It has also been noted that up to 3% of the displaceable residues of some pesticides 

applied on lawns are introduced into the home on the shoes of residents and accumulate in carpets 

(Nishioka et al. 1996). According to one study (Whitmore et al. 1994), these residues can persist 

for as long as four years, which increases the exposure of children to these toxic substances since 

they tend to live closer to the floor than adults. 

Children frequently eat soil as part of their explorations, and they ingest along with it whatever 

toxicants are present. In at least one risk assessment, the Centers for Disease Control and 

Prevention (CDC) in the United States used the following estimates of soil ingestion: 0–9 months, 

0 mg/d; 9–18 months, 1,000 mg/d; 1.5–3.5 years, 10,000 mg/d; 3.5–5 years, 1,000 mg/d; and 

5–70 years, 100 mg/d (Paustenbach, undated).
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

As children get older, their environments may include daycare, school, recreational spaces and 

work. Some children help their parents do craft jobs at home (Olaiz et al. 1995) and many others 

in North America join their parents in the fields as agricultural workers. Children in both urban and 

rural settings may live in homes that are part of the family business, where chemicals, solvents, 

paints, and pesticides are used or stored (Stansfield and Shepard 1993; Riojas et al. 1998). As 

children reach adolescence, many take part- or full-time jobs that may further expose them to 

occupational hazards (Pollack et al. 1990). In all of these situations, exposure to chemicals and 

other environmental pollutants may occur.

D. Factors for Additional Susceptibility

All children are exposed to a variety of toxicants at different developmental stages of their lives. 

Some children, however, are disproportionately exposed to environmental health threats due to 

poverty, and in some cases, to their ethnicity.

1. Poverty

The poverty rates in Canada and the United States are higher for children than for all other age 

groups. Today, there are approximately 1.3 million children living in poverty in Canada (Statistics 

Canada 1999). In the United States, the figure is 13.5 million, with African-Americans and 

Hispanics accounting for 26.1 and 25.6 percent respectively (US Census Bureau 1999). 

A recent UNICEF report entitled The Progress of Nations 2000 indicates that Mexico and the 

United States now top the list of OECD countries where children live in ‘relative’ poverty. It 

states that more than one in four children in Mexico (26.2%) and more than one in five in the 

United States (22.4%) are poor. The report defines relative poverty as living in a household where 

income is less than half of the national median. 

Impoverished children often have limited access to clean water and health care, and live in substandard housing. Their parents or other adult family members may work in the dirtiest, most 

hazardous jobs, increasing the likelihood of “take home” exposures (Chaudhuri 1998). And poor 

children are more likely to live in areas where there is pollution and environmental degradation. 

Poverty is also associated with poor nutritional status, which affects proper growth and

development as well as the body’s ability to withstand environmental insults. A child’s nutritional 

status can help determine whether certain toxicants are readily absorbed or whether they will 

interfere with the absorption of needed nutrients. For example, low dietary levels of calcium, 

potassium, zinc, copper and iron have been associated with increased lead absorption (Skerving 

1988; Mahaffey 1995). 

The combination of poverty, nutritional status, and exposure to environmental toxicants places 

great stress on developing children, putting them at much greater risk of illness and chronic health 

problems (Bleyl, 1990; Chaudhuri, 1998). These interactions may be of particular importance in 

Mexico, where poverty is more widespread and severe malnutrition has not been eradicated. In 
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

one sampling of a semi-rural population of about 11 million, there were 79,217 registered cases of 

malnutrition—99 percent of whom were children ages 14 and under (IMSS SOLIDARIDAD 

2000). Malnutrition rates for 1999 are presented in Table 1 (IMSS SOLIDARIDAD 2000).
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

Table 1. Malnutrition Rates for Mexican Children, 1999

Age Severe Moderate Low

(years old ) cases rate cases rate cases rate

Total * 2,432 22.76 16,217 151.74 60,568 566.73

Under 1 ** 406 150.85 1,910 709.67 7,608 2,826.79

1–4 ** 1,755 144.83 12,395 1,022.91 45,085 3,720.70

5–14 ** 228 7.59 1,786 59.45 7,286 242.54

15–24 ** 14 0.66 74 3.46 401 18.77

*Rate per 100,000 inhabitants in the Program IMSS SOLIDARIDAD, June 1999

**Rate per 100,000 inhabitants in the Program IMSS SOLIDARIDAD, June 1999, 

according to age group (estimation with base on the percentage of Work Units) 

2. Ethnicity

In Canada, children (0–14 years of age) who belong to a visible minority (defined there as nonCaucasians or non-whites, other than Aboriginal peoples) account for 13 percent of the

population—a significant proportion. Breaking that down further, children of Asian and MiddleEastern origin account for 8.9 percent of the population, and Black and Latin American children 

account for 2.8 and 0.7%, respectively. Aboriginal people account for approximately 2.8% 

(Statistics Canada 1996). Aboriginal children and youth represent 50% of the total Aboriginal 

population (Statistics Canada 1996). 

Compared to the general population, Inuit in northern Canada are at higher risk of exposure to 

persistent organic pollutants due to a diet rich in traditional country foods including marine 

mammals—animals whose fat provides ideal storage for the various toxins and chemicals. Arctic 

regions, such as Nunavut and Nunavik, are at the highest risk, as contaminants deposited by air 

and water currents accumulate in the cold climate and break down at a much slower rate. In fact, 

high levels of PCBs and DDT have been found in the breast milk of Inuit women in the remote 

Arctic regions of Canada (Dewailly et al. 1993). Although the health risk to Inuit children has not 

yet been established, some scientists have concluded that they show compromised immune

systems and higher rates of illness (Repetto 1996).

In the United States, the ethnic breakdown of the under-18 population is 14% Hispanic, 15%

African-American, 4% Asian/Pacific Islander, 1% Native American, and 66% white/non-Hispanic 

as of 1996 (US Census Bureau 1999). Several studies have demonstrated that proportionately 

more landfills, power plants, toxic waste sites, bus depots, railyards, sewage treatment plants, and 

industrial facilities are in non-white, impoverished communities (Bullard 1994; Brynant 1995). 

Similarly, it has been documented that children living in ethnic communities in the United States are 
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Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

more exposed to air pollution and lead than their white counterparts (Wernette and Nieves 1992; 

Centers for Disease Control, undated).

In Mexico, it has been estimated that 10% of the total population is composed of indigenous 

people (Valdés 1996), and a relationship between ethnic background and life expectancy seems 

to exist. Counties with an indigenous population of more than 70%, for instance, have mortality 

rates that are 13% higher than the national average (Bronfman et al. 1994). Contributing factors 

are unclear, however.
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Making the Environment Healthier for Our Kids

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IV. The North American Context

Children make up a large part of the population throughout North America, and particularly in 

Mexico. Children, birth through 18 years of age, make up 28% of the national population in 

Canada for the year 1996, 28.8% of the national population in the United States for the year 

1997, and 45.6% of the national population in Mexico as of 1997 (Statistics Canada 1997; US 

Census Bureau 1999; INEGI, 1999). 

A. Urban and Rural Populations

An overwhelming majority of North Americans live in urban areas. The United States is the most 

heavily urbanized, with 80% of its population living in or near cities as of 1993 (United Nations 

1996). In Canada, 78% live in urban areas, but here too there is a sizable rural population of 22% 

(Statistics Canada 1997). Mexico is urbanizing the fastest of the three countries. While 73% of the 

population lived in or near cities in 1993, that percentage has been growing at the rate of 2% a 

year—versus 1% for Canada and 1.2% for the United States (Latin American Center for 

Demography 1997).

B. Births

In 2000, the birth rate (per 1,000 population) in Canada, the United States and Mexico was 11.3, 

13.5 and 23.4, respectively (PAHO 2000). As reported in UNICEF’s State of the World’s 

Children 2000, the crude birth rate is declining in all three countries (UNICEF 2000) and is 

expected to decline further.

C. Mortality and Morbidity

Clean water, sanitation, vaccines, antibiotics, education, the quality and accessibility of health care 

services, and a heightened public awareness in Canada and the United States have led to a steady 

decline in infant and child mortality from infectious diseases, as well as in child mortality from 

injuries. Currently, there is increasing attention being paid to chronic illnesses in infants and young 

children because exposures during infancy and childhood may be associated with adult onset 

diseases.

In Mexico, patterns of sickness vary throughout the country, with poorer communities more 

susceptible to infectious diseases. Although the number of deaths from respiratory illness continues 

to grow (Riojas and Santos-Burgoa 1998), mortality from infectious intestinal diseases has 

declined, due to efforts by the Health and Environment Ministries to chlorinate water, lower 

reservoirs, and improve health education. 

Leading mortality rates in Canada, the United States and Mexico are shown in Table 2 (SSA 

1999; WHO 2001). In 1997, the top two causes of death for infants under 1 were congenital 

anomalies and conditions that originated during the perinatal period. For age groups 1–4 and 5–
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14, accidents (other than traffic accidents) and adverse effects were the main cause of death in the 

three countries. In Canada and the United States, traffic accidents were second on the list; in 

Mexico, it was pneumonia and influenza, with infectious intestinal diseases ranked third for these 

age groups.

Table 2. Leading Mortality Rates in Canada, United States and Mexico (1997)

Age Group Country

<1* 1–4** 5–14** 15–24**

Conditions originated 

in the perinatal period

Accidents and adverse 

effects

Accidents and adverse 

effects

Accidents and adverse 

effects

254.4 8.0 6.5 27.1

Congenital anomalies

Signs and symptoms 

and other ill-defined 

conditions

Motor vehicle traffic 

accidents

Motor vehicle traffic 

accidents

147.7 4.3 3.1 18.6

Signs and symptoms 

and other ill-defined 

conditions

Malignant neoplasms Malignant neoplasms Suicides and selfinflicted injuries

Canada

77.5 3.2 2.7 13.7

Conditions originated 

in the perinatal period

Accidents and adverse 

effec ts

Accidents and adverse 

effects

Accidents and adverse 

effects

333.3 13.1 8.7 36.5

Congenital anomalies Motor vehicle traffic 

accidents

Motor vehicle traffic 

accidents

Motor vehicle traffic 

accidents

159.2 4.3 4.8 27.4

Sign and Symptoms 

and other ill-defined 

conditions

Accidental drowning 

and submersion Malignant neoplasms

Homicide and injuries 

purposely inflicted by 

other persons

United 

States

97.2 3.0 2.7 16.6

Conditions originating 

in the perinatal period Accidents Accidents Accidents

734.5 21.9 12.2 34

Congenital anomalies Pneumonia and 

influenza Malignant neoplasms

Homicide and injuries 

purposely inflected by 

other persons

267.7 12.5 4.7 18.4

Pneumonia and 

influenza

Intestinal infectious 

deseases Congenital anomalies Malignant neoplasms

Mexico

199.2 12.0 2.0 6.7

*Infant death rates per 100,000 live births

**Death rates per 100,000 inhabitants per age group

Sources: World Health Organization (WHO). 2001. Mortality Data; Secretaría de Salud (SSA). 1999. 

Estadísticas Vitales, Mortalidad.
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Leading Mortality Rates for Children Aged 1- 4, 1997

Source: WHO, 2001; SSA, 1999

21.9

12.5

12.0

10.7

7.4

0 5 10 15 20 25

Rates (per 100,000 inhabitantes aged 1-4)

ACCIDENTS

PNEUMONIA AND INFLUENZA

INTESTINAL INFECTIOUS

DISEASES

CONGENITAL ANOMALIES

NUTRITIONAL DEFICIENCIES

Causes of death

MEXICO 

15.2

10.8 4.5

4.0

3.9

2.0

3.1

2.6

2.7

2.2

0 2 4 6 8 10 12 14 16

Rates (per 100,000 inhabitants aged 1 - 4)

ACCIDENTS AND ADVERSE

EFFECTS

MOTOR VEHICLE TRAFFIC

ACCIDENTS

ACCIDENTAL DROWNING AND

SUBMERSION

MALIGNANT NEOPLASMS

HOMICIDE AND INJURY

PURPOSELY INFLECTED BY

OTHER PERSONS

Causes of death

UNITED STATES 

MALE FEMALE

9.1

6.8

5.5

3

3.7

2.7

3.5

2.1

2.7

1.7

0 1 2 3 4 5 6 7 8 9 10

Rates (per 100,000 inhabitants) 

ACCIDENTS AND ADVERSE

EFFECTS

SIGNS AND SYMPTOMS AND

OTHER ILL-DEFINED CONDITIONS

MALIGNANT NEOPLASMS

MOTOR VEHICLE TRAFFIC

ACCIDENTS

MALIGNANT NEOPLASMS OF

OTHER SITES

Causes of death

 CANADA 

FEMALE

MALE
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Making the Environment Healthier for Our Kids

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V. Environmental Threats to Children's Health 

A. Sources of Exposure—Types of Hazards

1. Chemical Pollutants

Children are exposed to a number of different hazards from a variety of sources, ranging from 

naturally occurring hazards such as UV radiation and microbiological agents, to human-made 

hazards such as pesticides. The following is a brief overview of some of the hazards children in 

North America encounter through their food, as a result of air and water contamination, and in the 

places where they live, learn and play.

2. Chemical Pollutants

A new chemical is discovered about every nine seconds of the working day (McGinn 2000). On 

15 June 1998, chemists identified the 18-millionth synthetic chemical substance known to science 

(McGinn 2000). Yet, only 2000 new chemicals are taken to US EPA for review each year, 

implying that the capacity to produce new chemicals has far surpassed our ability to monitor them 

(Landrigan 1998). It is likely, then, that many chemicals of common use have not been examined 

for their health consequences—particularly to children (Roe et al. 1997; Schaefer 1994). 

Some of these chemicals are known as persistent organic pollutants (POPs), because they remain 

in the environment for long periods of time, accumulate in the tissues of living species, and often 

are transported far from their sources. As discussed earlier, they can be detected in human beings 

worldwide and may be passed from one generation to the next through breast milk. POPs include 

industrial chemicals such as PCBs, pesticides such as DDT and chlordane, and unintentional byproducts of industrial processes such as dioxins and furans. Some POPs are known endocrine 

disruptors and neurotoxins. The Stockholm Convention on POPs, signed by over 100 countries 

worldwide since May 2001, seeks the elimination or phase-out of POPs, with an initial focus on 

twelve substances: aldrin, chlordane, dieldrin, endrin, heptaclor, hexachlorobenzene, mirex,

toxaphene, PCBs, DDT, dioxins and furans.

3. Consumer Products

A variety of seemingly innocuous household products can expose children to toxic or hazardous 

substances. Possible sources include: chemically treated building materials (e.g., particle board 

and insulation); upholstery and furnishings (e.g., carpets, curtains, and wall decorations);

appliances (e.g., gas and wood stoves, and kerosene heaters); cleaning products; and materials 

used for hobbies (Metropolitan Toronto Teaching Health Units and the South Riverdale

Community Health Centre 1995). Even toys and other items made specifically for children can be 

hazardous. A recent example is soft-vinyl toys that use phthalate esters as plasticisers. While 
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scientists are still debating the health risks, some companies are removing the chemical from their 

products and some countries are acting to ban its use. 

4. Pesticides

North America continues to be the world’s leading consumer of pesticides. Under NAFTA, 

pesticides can be traded tax-free among the three partners. Over the past three decades, sales 

have jumped by 50% (US EPA 1997) and have been growing at a rate of about 6% a year since 

1990, particularly for so-called cosmetic use—that is, to make lawns and gardens weed-free and 

attractive (Agrow 1997). In the United States alone, this translates to 4.6 billion pounds of active 

ingredients in a typical year (US EPA 1999b), including wood preservatives and disinfectants. 

Mexico also has registered a steady increase in sales of pesticides. In 1960, 14,000 tons were 

sold within the country; by 1986, sales had climbed to 60,000 tons (Ortega-Ceseña J. et al. 

1994). From 1999 to 2000, pesticide imports grew by 28.2% from 1999 to 2000 (Subcomité de 

Comercio y Fomento Industrial 2001).

Canada is one of the only OECD nations that does not require reporting of pesticide sales (Boyd 

2001). Nevertheless, according to OECD data, pesticide use in Canada appears to be declining, 

by 26% since 1985 (OECD 1999), whereas Statistics Canada recently published figures

indicating that pesticide use in Canada rose over 400% between 1970 and 1995 (Statistics 

Canada 2000). This discrepancy may be due to the fact that Canada’s survey coverage has 

varied greatly (different active ingredients, registrants and products); therefore, survey trends may 

not reflect actual trends but simply changes in the survey coverage (OECD 1999, as cited in Boyd 

2001).

Pesticides have the potential to contaminate food and ground and surface waters and can

bioaccumulate in the food chain. Also, the dangers of acute pesticide poisoning are well

documented, with up to 5 million people being poisoned annually, worldwide (WHO 1990). 

There is now growing concern about chronic, low-level exposure to persistent residues, which 

may interfere with immune, thyroid, respiratory and neurological processes in children (NRC 

1993; IPCS 1998) and may be linked to childhood cancers, endocrine disruption, and

developmental neurotoxicity. 

Children, like other members in the general population, are exposed to pesticide residues in their 

diets; however, children eat more fruit and vegetable products per kilogram of body weight than 

adults do. A report entitled Pesticides in the Diets of Infants and Children (National Research 

Council 1993) concluded that the differences in diet and, thus, in dietary exposure to pesticide 

residues, account for most of the differences in pesticide-related health risks that have been found 

to exist between children and adults.

Foods commonly consumed by children, such as apples, tomatoes, grapes and peas, among other 

food crops, are likely to carry more than one pesticide. One US study analyzed twenty-two fruits 

and vegetables for pesticide residues. The results showed 108 different pesticides; forty-two 

different pesticides were detected on tomatoes, thirty-eight were detected on strawberries, and 
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An overview of environmental challenges to the health of North America’s children

thirty-four were detected on apples (Wiles et al. 1999). The study also indicated that twenty 

million children aged five and under eat an average of eight pesticides a day; a total of more than 

2,900 pesticide exposures per child each year from food alone. These numbers may be higher, 

particularly in agricultural areas were children may be exposed to pesticides in the air from aerial 

spraying, as well as from clothing of parents who work with pesticides (Health Canada 1996).

Each year, more than 100,000 children in the United States accidentally ingest pesticides (US 

EPA 1998b), either directly or by putting contaminated objects into their mouth. In Mexico, 

where acute poisonings dropped by 27% from 1997 to 1999 (IMSS SOLIDARIDAD 2000), 

one rural area of 11 million people reported 592 pesticide poisonings in 1999, 141 of which 

occurred in children 14 and under (IMSS SOLIDARIDAD 2000). According to data for

Canada, accidental pesticide exposure accounts for about 4% of all reported childhood

poisonings (Health Canada 1995a).

Far more often, though, children are exposed less acutely through inhalation or absorption through 

their skin. Parents or landlords may spray their home and their lawn, and their pets may wear flea 

collars. Schools and daycare facilities may use pesticides in classrooms and food preparation 

areas, as well as to maintain playgrounds and sports fields. Public buildings and parks also are 

frequently sprayed. In rural areas, some children may be directly involved in the application of 

pesticides, or they may be exposed by playing in treated fields or by family members who bring it 

home on their clothing. 

5. Toxic Metals

Lead

Lead is a potent neurotoxin that can cause significant health problems in children. It has no known 

function in the human body and as a systemic toxin exerts its effects in a variety of ways, for 

example, by forming bonds with negatively charged groups of enzymes and proteins. It is

absorbed into the bloodstream and can accumulate in tissues, particularly in the bones and teeth. 

Children and the fetus are particularly at risk because they absorb lead more efficiently than adults, 

and because immature organs and tissues are thought to be more susceptible to lead. Lead can 

damage a child’s developing brain, kidneys and reproductive system; even low levels are

associated with learning disabilities, hyperactivity, behavioral problems, impaired growth, and 

hearing loss (Needlemann and Bellinger 1991). 

Much of the debate over low-level exposure centers around the effect it may have on childhood 

intelligence. Although studies consistently suggest a negative impact on IQ, it is a challenge in 

epidemiological studies to control for the many social factors that have a strong influence on 

children’s intelligence (Wasserman et al. 1997). Currently, researchers have not been able to 

determine a threshold of exposure below which lead does not have an effect on human health 

(Federal/Provincial Committee on Environmental and Occupational Health 1994).

Although historical uses of lead have been shown to result in widespread distribution (for example, 

through analysis of ice cores from remote areas), the most extensive example of its pervasiveness 
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in the environment was through the introduction of lead in gasoline and industrial products. Other 

sources of exposure can include: (1) lead-based paint, which children may i) directly ingest, ii) 

indirectly ingest through the hand-to-mouth route via contact with contaminated dust in the home, 

or iii) encounter in soil contaminated with flaking paint; (2) hazardous waste sites including lead 

which may originate from many different industrial or commercial processes; (3) drinking water 

from lead pipes, or copper pipes with lead solder, used in older homes, or faucets with leadcontaining alloys; or corrosive water leaching lead from bedrock; (4) low-temperature-glazed 

pottery inappropriately used for food preparation or storage; (5) home environments associated 

with a parent who works in a lead-related industry or cottage industry, has artisan applications, or 

has a hobby involving lead use; and, (6) industrial emissions from a host of different processes. In 

the US, the EPA has published guidelines to determine if any of these source areas represent a 

hazard.

For children in the United States, sources identified as important are paint chips and lead in dust 

(US EPA 1996b). In Mexico, among the priorities are food prepared in leaded pottery and 

contamination of the environment around mining industries and waste treatment facilities (Rojas et 

al, 1994). Both countries saw a 90% drop in the levels of lead in the air after banning leaded 

gasoline (US EPA 1996b; Rothenberg, et al. 2000). This is anticipated to have a considerable 

impact on children’s health: for example, blood lead levels dropped a corresponding 75% in the 

United States after the ban (US EPA 1996b). Nevertheless, historical evidence of ancient bone 

and teeth samples collected from past civilizations suggest modern day exposures may still be 

several orders of magnitude higher than background values (US EPA 1984; Patterson 1983). 

Consequently, efforts which result in the reduction of exposure further still are likely to result in 

reduced risk of health effects in susceptible individuals.

Mercury

The most toxic form of mercury is methylmercury (WHO 1990), which has been found to be a 

strong teratogen (a substance able to cause birth defects) and to affect the central nervous system 

(Etzel and Balk 1999). Most mercury released to the environment is in the inorganic form, as a

result of mining, smelting, and other industrial discharges, or of coal-fired power plants, which in 

the United States are responsible for 34% of mercury arising from human activities (Grant et al. 

1999). Bacteria then convert inorganic mercury to organic methylmercury, making it available for 

uptake into the food chain, where it bioaccumulates and biomagnifies (Lindberg et al. 1987). 

Food, such as tuna and other types of predatory fish, is considered to be the primary route of 

exposure for children and adults, while marine mammals remain the main source of exposure for 

Inuit. This is of particular concern because methylmercury in food is almost totally absorbed into 

the bloodstream by the gastrointestinal tract (WHO 1990). 

Health Canada has established a guideline level of 0.5 parts per million (ppm) for mercury in most 

commercial fish, whereas the current guideline for methyl mercury in the United States is 1.0 ppm. 

Certain fish species sold in Canada and the United States, namely, shark, swordfish, and fresh and 

frozen tuna, contain mercury at levels which are known to exceed the guidelines. Based on current 
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An overview of environmental challenges to the health of North America’s children

data available, average mercury levels in these species are at or near 1.0 ppm with a typical range 

of 0.5–1.5 ppm (Health Canada 1999).

All fish are an excellent source of high-quality protein and are low in saturated fat, which makes 

them a healthy food choice. Health Canada advises pregnant women, women of childbearing age 

and young children to limit the consumption of shark, swordfish and fresh and frozen tuna to no 

more than one meal per month; whereas, the US Food and Drug Administration’s Center for 

Food Safety and Applied Nutrition advises that pregnant women and women of childbearing age 

do not consume shark, swordfish, King mackerel, or tilefish (US FDA 2001). They also advise 

that it is prudent for nursing mothers and young children not to eat these fish as well.

Cadmium

Cadmium has been designated a ‘probable human carcinogen’ by the International Agency for 

Research on Cancer, and chronic exposure to it has been associated with anemia, softening of the 

bones, cardiovascular disease, and kidney damage. Food is a principal route of non-occupational 

exposure for children and adults, though adults are exposed through tobacco as well (Buchet et al. 

1990). Due to its toxicity, cadmium may pose significant risks to the respiratory system even at 

low ambient air concentrations (Wadge and Zelikoff 1999). 

Arsenic

Arsenic is a known human carcinogen and is highly acutely toxic (ASTDR 2000). It is also a 

chemical element and a natural constituent of the Earth’s crust. It occurs naturally in rocks and 

soil, water, air, and plants and animals. When in the natural environment, arsenic usually binds to 

other molecules, such as those found in soils, and does not tend to travel very far. Arsenic can be 

released into the environment through natural occurrences such as volcanic activity, erosion of 

rocks, and forest fires, or through human actions. Agricultural practices, mining, and smelting also 

contribute to arsenic releases in the environment. Approximately 90 percent of industrial arsenic in 

the United States is currently used as a wood preservative, but it is also used in paints, dyes, 

metals, drugs, soaps, and semiconductors (ASTDR 2000).

6. Asbestos 

Asbestos is a group of minerals that is found naturally as a bundle of strong and flexible fibers. 

Due to their insulating, fireproofing, and sound absorption properties, asbestos fibers have been 

used extensively since the late 1800s in the clothing, shipbuilding, and construction industries (NCI 

2001). Many schools, homes, public buildings, and offices—especially those constructed between 

the 1950s and the 1970s—contain asbestos. Widespread public concern over its health

implications led to a decline in its use starting in the late 1970s. 

Asbestos is known to cause mesothelioma (a rare cancer of the lining of the chest or abdominal 

cavity), asbestosis (scarring of the lung which makes breathing difficult), and lung and other 
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An overview of environmental challenges to the health of North America’s children

cancers. The risk of developing these diseases depends on the level and duration of exposure to 

asbestos dust, on fiber size, and the mineralogical type of the fiber. Asbestos fibers may be 

released, for example, especially if the material is damaged, exposed and flaking. There is a very 

long latency period associated with mesothelioma—up to 30 years or more. 

Some evidence points to elevated risks for children and other family members of workers who are 

heavily exposed to asbestos. Asbestos dust may be brought into the home on clothing, shoes, and 

the body or hair of workers (NCI 2001).

7. Ozone 

Since children spend more time outdoors than adults, they are the group most at risk to ozone at 

levels measured in the air of many cities. Ozone can cause breathing difficulty, inflammation of the 

airways, susceptibility to respiratory infection, impaired pulmonary function (Castillejos et al. 

1992; Gold et al. 1999), and a variety of respiratory symptoms (e.g., cough, chest pain, nose and 

throat irritation, shortness of breath). 

8. Particulate Matter 

Particulate matter is one of the most pervasive air pollutants, posing a threat to all age groups. 

Toxicity is most likely related to its physical or chemical properties, including particle size, number, 

shape, composition, and reactivity. Particles are classified by size, based on their sources and on 

their ability to penetrate and deposit on the lungs. The PM10 fraction (particles of less than ten 

microns in diameter), also called thoracic or inhalable particles, can penetrate and deposit in the 

respiratory tract (Lippmann 1989) and includes both fine (PM2.5) and coarse (PM2.5-10) particles.

Fine particles are formed during high-temperature processes and by chemical reactions in the 

atmosphere, and include nitrates, sulfates, ammonium, organic compounds, and trace metals 

(Hinds 1982; Koutrakis and Sioutas 1996; US EPA 1996a). Coarse particles, by contrast, are 

typically produced mechanically and through erosion and soil resuspension, and include elements 

such as calcium, potassium, sodium and silicon, as well as pollen, mold, and plant spores 

(Spengler and Thurston 1983; Chatigny et al. 1989; US EPA 1996a; Spengler and Wilson 1996). 

Studies conducted in the United States, Mexico and the Czech Republic have all found a link 

between particulate exposure (measured as fine or total suspended particles) and child mortality 

(total infant mortality or deaths due to respiratory causes) (Woodruff et al. 1997; Bobak and 

Leon 1999; Loomis et al. 1999). A host of respiratory ailments have been associated with fine 

particulate matter in particular. These include symptoms such as cough, shortness of breath, and 

throat and nose irritation; labored breathing; asthma; and vulnerability to lung infections. In

addition, several studies have associated fine particles with higher mortality rates in the elderly 

(Dockery and Schwartz 1995; Pope et al. 1995; Schwartz et al. 1996; Laden et al. 2000). 
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9. Second-hand Tobacco Smoke 

Exposure to environmental tobacco smoke (ETS), commonly referred to as “second-hand 

smoke,” has been linked to a variety of respiratory symptoms, including asthma. Children who live 

with at least one smoking parent have a higher incidence of bronchitis, pneumonia, otitis media 

(middle ear infection), and viral respiratory infections than unexposed children (Landrigan et al. 

1998). Also, maternal smoking during pregnancy has been associated with low-birth-weight 

infants, and a greater risk of pulmonary hypertension and lower respiratory tract infections in the 

newborn (Erlich et al. 1996; Landrigan et al. 1998). 

Smoking is still permitted in many restaurants, shops and other public places throughout North 

America. Many states in the United States have banned smoking in public places. In Canada, it is 

banned in many public buildings, and municipal by-laws in some cities require non-smoking 

sections in restaurants. Mexico enacted in a federal law in 1992 that prohibits smoking in federal 

buildings. Still, all three countries allow children in smoking areas, where they may be subjected to 

acute ETS exposure associated with bronchial hyperreactivity (Etzel and Balk 1999). 

10. Hazardous Air Pollutants 

Commonly referred to as air toxics, hazardous air pollutants (HAPs) include substances that are 

known to cause or suspected of causing cancer or other serious health problems, such as 

reproductive impacts and neurological damage. Examples of air toxics include heavy metals like 

mercury, lead and chromium; and organic chemicals like benzene, 1,3-butadiene, formaldehyde, 

perchloroethylene, and dioxins. Benzene, for example, is a known human carcinogen. Long-term 

exposure to high levels of benzene in the air can cause leukemia, cancer of the blood-forming 

organs (ATSDR 1997).

Dangerous exposures to HAPs can occur from nearby facilities, from distant sources whose 

emissions are carried through the atmosphere, or from a mixture of pollutants in urban settings. 

The great number of HAPs and the scarcity of evidence about their toxicity under nonoccupational conditions limit a fuller evaluation of their health risks. 

11. Airborne Agents 

These include pollen, bacteria, and fungal spores—all of which affect children’s health and can be 

particularly harmful in closed, indoor environments. Exposures have been associated with reduced 

lung function and higher incidence of respiratory illness.

12. Microbiological Agents 

Food and water are the main sources of microbiological contamination in children. For foodborne illnesses, the major causes are bacteria, protozoa and parasites, as well as shellfish–borne 

toxins produced by algae. Improper food handling, storage, and cooking practices may lead to the 

growth and multiplication of bacteria like Salmonella, Campylobacter, E. coli, Listeria, and
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Clostridium, which can cause diarrhea, dehydration, abdominal pain, mild fever, nausea, and 

vomiting. The most commonly contaminated foods include vegetables, meat and poultry (see 

Water section, under Routes of Children’s Exposure, for water-borne illnesses.)

Food poisoning statistics for children are not available in Canada, Mexico or the United States in 

a concentrated and valid manner, although some data are available at a population level. Canada 

records about 10,000 cases of bacterial food poisoning in adults and children every year, but 

there may be up to 100 unreported cases for each reported one (Health and Welfare Canada 

1992a; Health and Welfare Canada 1992b; Health Canada 1994). In fact, Salmonella poisoning 

alone is thought to be responsible for about 600,000 cases of illness a year in Canada (Health 

Canada 1997).

One report from the United States estimated that food-borne diseases cause 76 million illnesses, 

325,000 hospitalizations, and 5,000 deaths every year, among all age groups. Known pathogens 

account for only 14 million of those illnesses, 60,000 hospitalizations, and 1,800 deaths (CDC 

1999). Escherichia coli alone is thought to cause 73,000 cases of infection and 61 deaths per 

year (CDC 1999). 

B. Routes of Children’s Exposure

1. Food

Food provides the nutrients for children to grow. It is also an effective conduit for microbiological 

agents, persistent organic pollutants, pesticides, food additives, and metals, including mercury, 

lead and cadmium.

Some of the most toxic pollutants enter the food chain through farmland—after being either 

deposited by air currents, applied through sewage sludge and untreated water, or sprayed on 

crops directly. These include persistent organic pollutants (POPs), such as PCBs, chlorinated 

dioxins, furans, and organochlorine pesticides; and polycyclic aromatic hydrocarbons (PAHs). In 

Canada, it has been estimated that food accounts for 80–95% of our daily intake of persistent 

organic pollutants (Health Canada 1995b). 

Food additives, including nitrates/nitrites and sulfites, are another concern for children’s health. 

Nitrates and nitrites are used as anti-microbial preservatives in cured meats like sausage, but most 

human exposure is through vegetables (Health Canada 1995b). Sulfites are used as preservatives 

in a wide variety of foods that appeal to children, including fruit juices, snack foods, ketchup, 

candy, and jams and jellies. Some children, especially those with asthma, are highly sensitive to 

sulfites. Allergic symptoms include hives, nausea, and even fatal shock (Health Canada 1995b).

2. Water 

Children are vulnerable to a range of hazards from water, such as microbial contaminants, 

disinfection by-products, metals, and chemical contaminants. Exposure can occur in seemingly 
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innocuous ways—from drinking to hand-washing or by inhalation of contaminants in steam while 

showering. Swimming in contaminated surface waters can put children at particular risk of

exposure to harmful microbes. Those risks may include pathogens like Entamoeba, Giardia, and 

Cryptosporidium (protozoans), as well as Escherichia coli, Salmonella, Shigella spp., Vibrio 

cholerae (bacteria), Hepatitis A (virus), and Enteroviruses.

One likely source of microbial contamination is human fecal waste that has leaked from septic 

systems. The disinfection of drinking water is a critical safeguard, particularly in rural areas where 

it can be the sole affordable treatment. As discussed earlier, children are especially vulnerable to 

contaminated water, because they consume more for their body weight than adults. In Canada, 

where about 87% of the population receives treated municipal drinking water, the incidence of 

serious waterborne diseases has been among the lowest in the world (Health Canada 1997). 

Recently, however, Escherichia coli contamination of municipal water in Walkerton, Ontario, led 

to seven deaths in the small rural community. Similarly, in the United States, a 1993 outbreak of 

cryptosporidiosis in Milwaukee, Wisconsin, caused over 400,000 persons to be affected. More 

than 4,000 people were hospitalized, and over 50 deaths (some counts are as high as 100) were 

attributed to exposure to the bacteria through drinking water. Both of these cases have helped put 

the issue of drinking water quality on the public agenda in Canada and the United States. 

In Canada, drinking water guidelines are revised and updated on a continuing basis by the federal 

government in collaboration with the provinces and territories. The Guidelines for Canadian 

Drinking Water Quality outline maximum acceptable concentrations and/or aesthetic objectives 

for the physical, microbiological, chemical and radiological parameters of drinking water supplies, 

both public and private (Health Canada 1995b). Since supervision of drinking water is a

provincial responsibility, the guidelines are not applied nationally except in those areas that fall 

under federal jurisdiction. Provinces and territories may develop enforceable standards based on 

the national guidelines, and many provincial and territorial governments have established their own 

measures of water quality based on the guidelines.

In the United States, the Safe Drinking Water Act gives the Environmental Protection Agency 

(EPA) the responsibility for setting national drinking water standards. While EPA and state 

governments set and enforce standards, local governments and private water suppliers have direct 

responsibility for the quality of drinking water. Water systems test and treat their water, maintain 

the distribution systems that deliver water to consumers, and report on their water quality to the 

state. States and EPA provide technical assistance to water suppliers and can take legal action 

against systems that fail to provide water that meets state and EPA standards (US EPA 2001b). 

EPA issues drinking water standards, or Maximum Contaminant Levels (MCLs), for more than 

80 contaminants. The standards limit the amount of each substance allowed to be present in 

drinking water. 

In the United States, about 95% of the population was served by filtered water systems as of 

1995, and was, at least in principle, protected against microbiological contaminants (US EPA 

1996b). Similarly, the Mexican government has implemented programs to improve the percentage 

of households served as well as the quality of drinking water. From 1991 to 1998, the percentage 
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of households with access to drinking water increased from 79% to 86.4%, and the percentage of 

water that is disinfected increased from 84.5% to 93.4% (CNA 1999). For that same period, the 

mortality rate for children under 5 from infectious intestinal diseases declined by 70.5% (SSA 

1999), which may attest to the effectiveness of such programs. 

It should be noted that while disinfectants are an effective weapon, they pose their own problems. 

Some can react with matter from plant and animal decay, forming disinfection by-products 

(DBPs). Epidemiological studies have found a possible association between certain DBPs and a 

slightly elevated risk of reproductive and developmental effects (US EPA 2001a). Toxicological 

studies have shown that several trihalomethanes found in drinking water can cause cancer, and 

other epidemiological studies have indicated that chlorinated drinking water may be associated 

with bladder cancer (King and Marret 1996). 

A number of other water contaminants can cause health problems for children. Nitrates found in 

drinking water—a product of municipal wastes, urban and agricultural runoff, and the erosion of 

natural deposits—may lead to acute toxicity in bottle-fed infants, causing methaemoglobinaemia. 

This disease is life threatening in infants under six months unless they receive immediate medical 

attention (US EPA 2001a).

Arsenic, which is a human carcinogen in its inorganic form, may also be found in drinking water, 

introduced from industrial runoff, from the dissolution of mineral and ores, and from atmospheric 

deposition. Studies conducted in the United States have linked exposure to arsenic in drinking 

water to miscarriages (Aschengrau et al. 1989). In Mexico, chronic exposure to arseniccontaminated water has been associated with skin cancer, cutaneous lesions, peripheral vascular 

diseases, abdominal pain, diarrhea, and nausea (Tseng 1977; Cebrian et al. 1983).

Another serious hazard sometimes found in drinking water is inorganic mercury compounds. 

Long-term exposure at levels above the maximum contaminant level (0.002 mg/L) can cause 

kidney damage (US EPA 2001a). But there is inadequate evidence to say whether a lifetime 

exposure to drinking water can cause cancer (US EPA 2001a). 

Chemical contaminants, including pesticide runoff, chemical discharges from industrial facilities, 

and even consumer products and pharmaceuticals, can also be found in drinking water sources. 

While the main health effects associated with some of these chemicals are known, there are other 

potential effects, including more subtle, long-term effects such as endocrine disruption, that may 

be caused by some of these chemicals and which are not yet fully understood.

3. Air

Literally thousands of studies have documented the health effects of indoor and outdoor air 

pollutants, both in human and laboratory animal research. Conducted over the past three decades, 

these studies have shown that inhaled air pollutants modulate the lung immune system response 

(Thomas and Zelikoff 1999) and are associated with a variety of health problems in children. 

These range from relatively minor ailments, such as small changes in the ability to breathe normally 
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or nose and throat irritation, to asthma and cancer, resulting in hospitalizations or even death 

(Woodruff et al. 1997; Borja et al. 1999; Loomis et al. 1999).

Indoor air pollution is a very serious concern—one of the five biggest environmental hazards, 

according to the Science Advisory Board of the US EPA—because children are indoors so much 

of the day (Moeller 1997; US EPA 1998a). One Canadian study reported that young children 

spend almost 90% of their time indoors (Leech et al. 1996), a percentage that an earlier US study 

found applies for people of all ages, throughout the industrialized world (US EPA 1989). In 

Mexico, researchers concluded that children ages 9 to 12 are indoors 85% of the time (RojasBracho 1994). 

Levels of certain pollutants can also be much higher indoors. In some US cities, the EPA says, 

concentrations of nitrogen oxides, carbon monoxide, suspended particles, and volatile organic 

compounds can be two to five times higher indoors than outdoors. But even when levels are low, 

the longer duration of exposure could have a significant impact. 

Pollutants that are thought to pose the greatest threat to children are carbon monoxide, pesticides, 

respirable particles, volatile organic compounds, microbiological agents (mites, fungal spores, 

etc.), cigarette smoke, and asbestos. Potential sources of contamination are diverse, including 

such things as kerosene heaters, cooking and heating stoves, tobacco, cleaning products,

furniture-finishing materials, building insulation, humidity, poor hygiene, and the presence of pets. 

And exposure risks are virtually everywhere: home, school, day care, and any public place.

Indoor air problems in industrialized countries seem to differ from those in developing areas. In 

Canada or the United States, for example, indoor air pollution basically arises from low ventilation 

rates and emissions from a large variety of compounds. In developing countries, the principal 

problems may be related to the use of biomass fuels for cooking and heating in rural areas. A 

recent Mexican study showed that PM10 levels inside the homes in two rural towns were on 

average five times higher than national standards (Riojas-Rodriguez et al. 2001). These unhealthy 

conditions are thought to contribute to the very high rates of infectious respiratory diseases found 

in children in rural Mexico (Riojas-Rodríguez et al. 2001). For instance, in one predominantly 

rural state, respiratory diseases are the third leading cause of death overall and the main cause of 

death among children (SSA 1995).

As for outdoor air, the chief sources of pollution are the burning of fossil fuels in power plants, 

industry and industrial operations (e.g., paper and pulp mills, smelters), agricultural practices, 

petroleum refineries, gasoline stations, dry cleaners, and motor vehicles (Moeller 1997).

Contaminants include the six so-called criteria pollutants (carbon monoxide, lead, ozone,

particulate matter, sulfur dioxide, and nitrogen dioxide), as well as a large number of chemicals. 
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VI. Health Consequences

C. Asthma

Asthma has been epidemic in large portions of North America for the past 15 to 30 years, 

affecting all ages, races, and ethnic groups—but none more than children (GPO 1999).

Industrialized areas seem to have fared the worst: Reported incidences of asthma are higher in the 

United States and Canada (up to 17% of the population) than in Mexico (6%) (ISAAC 1998). 

Although the relationship between exposure to contaminants and onset of the disease is still

unknown, the rising rates and concentration in industry-heavy areas point to an environmental 

trigger (Becklake and Ernst 1997).

As it is now understood, asthma is a disease of chronic airway inflammation and

hyperresponsiveness to a variety of stimuli, resulting from a complex interplay between

environmental exposures and genetic and other factors (GPO 1999). While the initial cause 

remains something of a mystery, the triggers of subsequent attacks in children are well

characterized. Allergens such as house dust mites, cockroaches, fungal spores, and animal dander 

all can provoke asthma symptoms (National Asthma Education and Prevention Program 1997; 

Platts-Mills et al. 1997; Warner et al. 1996), whereas tobacco smoke can either trigger an

episode or worsen the effects of allergens (US EPA 1992). Parental smoking during the first year 

of life has also been associated with an increased risk of childhood asthma (Strachan and Cook 

1998). Upper respiratory viral infections are also recognized as important triggers for asthma 

episodes (Busse et al. 1997). 

Children with asthma have long been recognized as particularly sensitive to outdoor air pollution. 

Many common pollutants, such as ozone, sulfur dioxide, nitrogen dioxide, and particulate matter, 

are respiratory irritants that may exacerbate the disease (Koren 1995; Romieu et al. 1995; 

Landrigan et al. 1998). Recent data further suggests that exposure to dense traffic is a risk factor 

for asthma as well as other respiratory symptoms in children (van Vliet et al. 1997; Brunkreef et 

al. 1997; English et al. 1999).

D. Childhood Cancer

Childhood cancers represent a range of diseases affecting different organ systems and tissues, all 

of which are characterized by chaotic cell growth and multiplication. About 10-20% of cancers 

are genetically determined, according to scientists. The remaining 80% have some environmental 

component. The environment here is broadly defined to include lifestyle choices, socio-economic 

status, and what we eat, drink, breathe, and are otherwise exposed to during the course of our 

lives (Needleman and Landrigan 1994; Carroquino et al. 1998). This includes exposure in utero, 

which may play a key role in childhood cancers (Herbst et al. 1971; Zahm and Devesa 1995; 

Perera et al. 1998).
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Scientists believe that cancer involves a series of steps. Step one is a change or mutation in genetic 

material, possibly resulting in greater susceptibility and sensitivity to further mutations; next is the 

activation of oncogenes, causing cells to grow at a rapid rate; and finally the deactivation of tumor 

suppressor genes, which normally slow down the growth of cells. Critical factors in this scenario 

are the type of carcinogen (some are known to initiate cancer while others are known to promote 

it), the duration of exposure, routes and dose of exposure, and the stage of development when a 

child’s exposure occurs.

In Canada, leukemia is the most common of the childhood cancers, followed by brain and spinal 

cord cancers (National Cancer Institute of Canada 1999). Similarly, in the United States, where 

cancer is the second most common cause of death after age 1, leukemia and brain cancers are the 

most prevalent in childhood (Landrigan et al. 1998). Mexico’s cancer morbidity data suffers from 

under-reporting, making mortality statistics better indicators of health trends. According to 1996 

data, cancer was the eighteenth cause of death in children age 5 and under, and the eighth cause 

of death in children 4 to 14 (SSA 1997). Of all childhood cancers, brain cancer was the most 

frequent cause of death.

In Canada, the incidence of childhood cancer has been relatively stable over the past 15 years 

(Health Canada 1999a), whereas in the United States it rose 10% from 1974 to 1991

(Carroquino et al. 1998; Landrigan et al. 1998). During the last time period, 1990–1995, there is 

an indication of a leveling off, or a slight decline in the overall incidence rates for each of the fiveyear age groups (Ries et al. 1996). Death rates, though, have declined in the US. By contrast, 

Mexico has seen rising mortality rates during the same period. From 1986 to 1990, the number of 

deaths from cancer grew from 2.25% to 5.8% for children ages 1 to 4, and from 7.6% to 14% 

for those ages 5 to 14 (SSA 1991; SSA 1999). These increases in the United States and Mexico 

have been the subject of debate, as some scientists question if they really are a reflection of better 

diagnostics (Smith et al. 1998; Landrigan et al. 1998; Lent et al. 1999). Still, changes in lifestyle, 

diet and environment may play an important role (Carroquino et al. 1998; Landrigan et al. 1998; 

Schmidt 1998). 

Apart from exposure to ionizing radiation, the causes of childhood cancer remain unclear. The list 

of suspects includes, but is not limited to: genetic abnormalities, ultraviolet radiation,

electromagnetic fields, viral infections, certain medications, tobacco, alcohol, and industrial and 

agricultural chemicals (Zahm and Devesa 1995; Schmidt 1998).

E. Neurodevelopmental Effects

With no known cause for an estimated 70% of the developmental defects seen in children, there 

has been growing concern about the impact of chemicals and drugs on the developing nervous 

system (Wilson 1977). Learning disabilities, attention deficit hyperactivity disorder, developmental 

delays, and emotional and behavioral problems are among childhood disabilities of increasing 

concern. For example, in the United States nearly 12 million children under 18 years of age (17%) 

suffer from deafness, blindness, epilepsy, speech deficits, cerebral palsy, delays in growth and 

development, emotional or behavioral problems, or learning disabilities (Schettler 2001). Learning 
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disabilities alone affect 5–10% of children in public schools (Schettler 2001). Attention deficit 

hyperactivity disorder (ADHD) conservatively affects 3–6% of all school children and perhaps as 

many as 17% (Schettler 2001). 

Genetics clearly play a significant role in some developmental problems like attention deficit 

disorder, but there is mounting evidence that chemicals, nutrition and other environmental factors 

are primary causative factors. Such neurodevelopmental defects as delayed development, altered 

reactivity to the environment, and cognitive dysfunction have been reported in children exposed to 

any of a number of chemicals in utero or as newborn. These toxicants include methyl mercury, 

nicotine, PCBs, alcohol, toluene, phenytoin, and lead (Friedman 1998; Levin and Slotkin 1998; 

Rice 1998). In addition, children exposed to chronic, low-dose environmental neurotoxicants may 

show permanent and irreversible neuropsychiatric effects, including learning deficits and behavioral 

alterations (Landrigan et al. 1998).

Interacting genetic, environmental and social factors are important determinants of childhood brain 

development and function (Schettler 2001). Children of lower socio-economic status, for instance, 

may be at higher risk of mental retardation because of severe malnutrition, disease and proximity 

to environmental hazards, including known developmental neurotoxicants like mercury, cadmium, 

lead and PCBs. Still, even though exposure to chemicals, genetic background, and nutritional 

status are known to affect neurodevelopmental processes, we need to better understand how 

these three factors interact to produce neurodevelopmental deficits. 

F. Birth Defects

Birth defects are the second leading cause of infant mortality in Canada, the US and Mexico (SSA 

1999; WHO 2001), and are among the top five causes of premature death in people under 65 in 

the United States (CDC 1988). 

In most cases, there is no known etiology. One study found that almost 57% of birth defects were 

unexplained and that only about 5% percent were associated with chemical exposures (Nelson 

and Holmes 1989). Others have estimated that up to 80% of birth defects are of unknown

etiology. We expect to learn much more about the development of birth defects and the role 

played by environmental factors as information becomes available from the Human Genome 

Project, as well as from studies linking genes with particular birth defects (Khoury 2000). For 

instance, some studies have found an interaction between maternal cigarette smoking during

pregnancy and an uncommon allele of transforming growth factor alpha (TGF), resulting in as 

much as a ten-fold increase in the risk of cleft lip, with or without cleft palate, or cleft palate alone 

(Hwang et al. 1995; Shaw et al. 1996; Shaw and Lammer 1997). 

In the United States, there has been increased monitoring of birth defects over the past few years. 

The Centers for Disease Control and Prevention (CDC) has set up 10 regional tracking centers 

that will do some evaluation of contributing factors, including environmental exposures. Texas 

began its own extensive tracking program after several children living on the Mexican border were 

born with anencephaly—a condition where most or all of the brain is missing. The most likely 
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culprit in those cases was a vitamin B deficiency, which may easily be prevented with appropriate 

supplements including folic acid. Because of findings from several studies showing that folic acid 

can help prevent neural tube defects like anencephaly and spina bifida, the US Public Health 

Service raised its recommended dose of folic acid to 4 milligrams daily for prospective mothers 

(US Public Health Sevice 1995). Similarly, Health Canada suggests that a daily supplement 

containing 0.4 mg of folic acid together with the amount of folate found in a healthy diet is 

expected to reduce the risk for women who have not previously had a pregnancy affected by a 

neural tube defect (Health Canada 1998).

Better tracking of birth defects, exposures, and genetic factors will help us discover other 

preventive measures and reduce the incidence of birth defects in the population. There is also the 

need to include data from prenatal screening for abnormalities and elective abortions when

measuring birth defect rates.

G. Immunological Effects

The immune system is the body’s defense against infection from foreign agents. There is also some 

evidence that it may play a role in containing malignant cells, thus allowing the body to resist tumor 

formation and cancerous growths. However, there is little known about the immune system effects 

from exposure to environmental contaminants in humans. 

Two main immune system effects may be associated with exposure to toxins: 1) immune

sensitization or heightened function may allow for development of allergic reactions to antigens; 

and 2) immune suppression may render the individual more susceptible to infections and cancer 

(Vanderlinden and Abelsohn 1999). There is also some speculation that certain auto-immune 

disorders may be associated with environmental exposures (Pieters and Albers 1999; Sentzivanyi 

et al. 1995).

While the exact immunological effects from environmental contaminants are not well known, it is 

believed that some may be potentially immunotoxic to humans. For example, exposure to

compounds that may result in immunological effects include: pesticides; air pollutants such as 

ozone, nitrogen dioxide, environmental tobacco smoke; and metals such as cadmium, lead and 

mercury (Vanderlinden and Abelsohn 1999). 

H. Reproductive Conditions and Endocrine Disruption

A growing body of evidence suggests that a number of synthetic and naturally occurring organic 

chemicals such as phytoestrogens (Hughes 1998), dioxins, PCBs, phthalate esters, and DDT, may 

disrupt the endocrine systems of humans and wildlife. Children may be at a particularly high risk 

from even very low levels of endocrine-disrupting chemicals because of the importance the 

endocrine system plays in development (Longnecker et al. 1997). Research has indicated that 
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early exposure to endocrine-disrupting compounds can interfere with reproductive development 

(Schell 1997).

Human health effects believed to be linked to endocrine-disrupting contaminants include difficulties 

in fertilizing and conceiving, birth defects of the reproductive organs, lower sperm counts,

cryptorchidism and hypospadias, testicular cancer in young men, breast cancer, and premature 

puberty in girls (Foster 1998). Early life exposures to endocrine-disrupting substances and other 

environmental toxins have been proposed as possible causes of these effects.

Pre-natal exposure to endocrine disruptors has been implicated in reproductive tract defects and 

certain types of cancer. In men, it has been postulated that pre-natal exposure to endocrine 

disruptors could be causing increased incidences of cryptorchidism (Giwervcman et al. 1993), 

abnormal formation of the penis (hypospadias) (Giwervcman et al. 1993), reduced sperm counts 

(Auger et al. 1995) and testicular cancer (Giwervcman et al. 1993; Klotz 1999; DeVesa et al. 

1995). For example, in the United States, rates of hypospadias have increased more than 50% 

over the past three decades (Paulozzi et al. 1997). However, in Canada, increasing trends appear 

to have leveled off after 1985 (Paulozzi 1999). Hypospadias is one of the most common

congenital anomalies in the United States, occurring in approximately 1 in 250 newborns or 

roughly 1 in 125 live male births (Baskin et al. 2001). While the causes remain unknown, the 

relatively recent increase in this birth disorder suggests that some change in environmental factors 

may well be involved.

Early-onset puberty has been recorded in children exposed to both synthetic and naturallyoccurring endocrine disruptors (Gee 1999). For example, one study suggested that some girls in 

the US are entering puberty much earlier than normal (Herman-Giddens et al. 1997). This and 

several other studies (Boyce 1997; Walters et al. 1993; Gellert 1978) propose that exposure to 

estrogen-mimicking chemicals such as PCBs, DDT and methoxychlor might be involved. 

Endocrine-disrupting contaminants may also be associated with an altered human sex ratio.

Several recent reports indicate that the ratio of males to females being born has declined in several 

industrialized countries, including Canada (Davis et al. 1998). In the last 20 years, the male 

proportion of births in Canada has declined, resulting in a decrease of approximately 8600 male 

births (Davis et al. 1998). It has been suggested that this decline may be linked to endocrinedisrupting chemicals interfering with critical stages of sex determination (Davis et al. 1998). 

While some researchers have concluded that endocrine-disrupting compounds may produce 

adverse health effects in humans, the specific mechanisms of action are not well understood for 

most reported associations between various hormonally active agents and various biologic effects 

(National Research Council 1999). Thus, the biological significance of the findings for humans has 

yet to be established (Foster 1998). 
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VI. Policy Considerations

A. Overview 

Several basic conclusions can be drawn that are relevant in any policy discussion about children’s 

environmental health:

• Children cannot be regarded as little adults because their behavior, physiology, metabolism 

and diet are different. 

• Children have very different exposure patterns from those of adults, and different 

susceptibilities.

• Timing of exposure within a child’s development is a key determinant of toxicity for certain 

chemicals.

• Children can have very different health outcomes from those of adults exposed to the same 

toxicant.

The fact that children cannot be regarded as little adults has enormous implications for

environmental health policy because it means that children must be considered as a sensitive subpopulation. Environmental policy decisions that are based on the need to protect adults’ health 

may not be protective of children’s health.

We also now recognize that children cannot be protected through domestic policy alone.

Environmental contaminants know no boundaries and move freely on air and in ocean currents, in 

freshwater systems, as well as through foreign trade. To effectively safeguard the children of North 

America, the three nations—Canada, the United States and Mexico—must work together. 

The aim of this section is to outline some factors and opportunities for consideration as the three 

countries develop a cooperative agenda to reduce environmental threats to children’s health.

Some preliminary questions:

• What are the most important environmental factors affecting children’s health in the three 

countries?

• What environmentally-related health impacts are of greatest concern in the three countries? 

Are there issues that all three countries share and that would benefit from joint actions that are 

not currently addressed by other trilateral initiatives?

• How are children’s unique susceptibilities taken into account when assessing risk and 

developing policy and regulations? 
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• Are there emerging issues that would benefit from a greater sharing of expertise and 

experience among the three countries?

• What mechanisms exist in North America to foster ongoing communication and collaboration 

on children’s environmental health? Are new mechanisms or approaches needed?

B. Scientific Gaps and Emerging Issues related to Children’s 

Environmental Health

There are many gaps in scientific data and understanding and numerous emerging issues related to 

children’s environmental health, some of which may provide opportunities for North America 

cooperation. These include: 

1. Child Development: There is a need to improve understanding of children’s

vulnerability at different stages of development, from conception onwards, including 

pre-puberty through adolescence. It is becoming increasingly clear that the timing of 

an environmental exposure can be a critical factor in whether a health impact will 

occur, and the nature of that impact.

2. Exposures: There is very little comprehensive information on children’s exposure to 

hazardous agents in the environment. Information is needed for different ages and 

stages of development, especially adolescence. 

3. Synergistic and Cumulative Effects: There is a need for improved understanding of 

the effects of exposures to multiple environmental hazards via multiple exposure

pathways, and for the development of methodologies to assess these complex

connections.

4. Nutritional Data: Patterns of food consumption for children at different stages of 

development need to be characterized. Information on contaminants in food (e.g., 

pesticide residues) is also important for assessing children’s exposure to hazardous 

agents.

5. Surveillance and Monitoring: There is a need for national and regional databases 

on children’s health conditions that are associated with environmental factors,

including asthma, childhood cancers, and birth defects, as well as for surveillance 

systems for neurodevelopmental outcomes. There is also a need for databases on 

environmental conditions that are associated with children’s health, such as

contaminant levels in different media (e.g., food, soil, water), as well as for

biomonitoring data. In addition, the three member countries need to reach consensus 

on diagnostic definitions and valid and reliable measurement tools for exposures and 

health conditions.
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6. Indicators of Children’s Environmental Health: Currently there are no continentwide indicators of children’s environmental health. Indicators can play an important 

role of raising the profile of children’s health concerns and encouraging and tracking 

improvements.

7. Risk Assessment/Risk Management: Children are not necessarily included in risk 

assessment and management methodologies in all three countries, with the exception 

of pesticides, which means they may not be adequately protected from the hazards of 

many substances. Methodologies for special consideration of children during risk 

assessments—even in the absence of perfect or complete data—need to be

developed and used in all risk assessments.

8. Public Access to Information: There is a need to expand and strengthen information 

channels to allow communities, families and other stakeholders to make informed 

decisions about environmental exposures and risks to their children.

9. Environmental Justice: There is a need to fully explore the relationship between 

poverty, ethnicity and environmental health threats, particularly exposures to toxic 

chemicals, in order to address the issue of disproportionate exposures to

environmental threats among lower socio-economic strata and certain minority

populations and disadvantaged groups.

10. Electromagnetic Fields: Studies conflict on the health consequences of exposure to 

electromagnetic fields. More research and prudent preventive action may be needed. 

11. Endocrine Disruptors: There is strong evidence from wildlife populations, and some 

evidence from humans, that various contaminants can disrupt normal endocrine

metabolism. There is a need for more study, as well as preventive strategies.

12. Climate Change: Climate change may affect children’s health through changes in 

disease vectors, environmental exposures, etc., and thus is another area requiring 

further research and preventive action.

C. Areas of Opportunity for North American Action

1. Persistent Organic Pollutants and other substances capable of transboundary 

movement 

There is strong scientific evidence of the long-range migration of certain pollutants, including DDT, 

mercury, dioxins and furans, and other POPs (CEC 1999). Several international protocols, such 

as the UN ECE POPs and Heavy Metals Protocols under the Convention on Long-Range 
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Transboundary Air Pollution, and the recently signed Stockholm Convention on POPs, recognize 

the need to address such substances through international action. 

The CEC is actively assisting the Parties to reduce or eliminate the use of these substances. To 

date, the Commission has developed Regional Action Plans committing the three countries to take 

concrete steps to reduce PCBs, chlordane, DDT, and mercury. Another regional plan for dioxins, 

furans and hexochlorobenzene is being developed by the Sound Management of Chemicals CEC 

Working Group. Work has also begun on a regional action plan on environmental monitoring and 

assessment. Work on a regional action plan for lindane is anticipated to commence in 2002.

2. Goods Traded in Commerce

Goods such as food, manufactured products, pesticides, and chemicals cross political borders as 

part of the flow of trade among the NAFTA countries. In some cases, goods that are banned or 

restricted for health and safety reasons in one country may be exported without restriction to 

another. More cooperative work is needed to ensure that exported goods are safe for children 

everywhere.

3. Environmental Hazards in Border Regions

Border areas are typically characterized by intense transboundary interaction. In addition to 

sharing airsheds, watersheds, coastal areas, and wildlife corridors, these areas are criss-crossed 

by shipments of hazardous products or waste for use or disposal. Degraded air quality in the 

vicinity of congested border crossings also poses a threat to public health, including the respiratory 

health of children.

4. Scientific Cooperation

Scientific cooperation is fundamental to, and often a precondition to, problem-solving in complex 

areas such as health and environment. The CEC strives to share knowledge and build consensus 

in a number of areas in its work program, including the Sound Management of Chemicals and the 

Conservation of Biodiversity. In the realm of children’s environmental health, opportunities for 

enhanced scientific cooperation may include exposure assessment methodologies, bio-marker 

technologies and research, epidemiological studies, diagnostic tools and common diagnostic

definitions, and/or other specific applied-research areas. Furthermore, collaboration with

organizations currently involved in international efforts to protect the health of susceptible subpopulations of children, such as Aboriginal and indigenous peoples, migrant workers, and others, 

provides additional opportunites for scientific cooperation.

5. Policy and Standard Setting

Important policy tools such as risk assessment and the application of the precautionary approach 

may strengthen the continental protection of children. The CEC serves as a forum in which the 
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governments and civil society can engage in a dialogue to advance the protection of children by 

strengthening the application of selected policy tools and approaches.

6. Public Education and Outreach

Participation of the public in research, policy development and communications strategies can 

strengthen the basis for educated decision-making and problem-solving. As part of the CEC, the 

Joint Public Advisory Committee (JPAC) together with the National Advisory Committees work 

to ensure active public participation and transparency in the actions of the Commission.
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VII. Appendix: International Initiatives

During the last decade, the relationship between the environment and human health, and

particularly the health of children, has been recognized in several key international reports,

conventions and agreements. Following are highlights of several of these initiatives.

1. The UN Convention on the Rights of the Child (1989)

Signed and ratified by almost every country in the world, including Canada and Mexico, the UN 

Convention of the Rights of the Child outlines basic principles that acknowledge the special needs 

of children and elevate their status within all societies. 

Article 24 outlines specifically that:

1. States Parties recognize the right of the child to the enjoyment of the highest 

attainable standard of health . . . 

2. States Parties shall pursue full implementation of this right, and in particular, 

shall take appropriate measures:

c) To combat disease and malnutrition, including within the framework of 

primary health care, through, inter alia, the application of readily available 

technology and through the provision of adequate nutritious foods and clean 

drinking water, taking into consideration the dangers and risks of

environmental pollution; [author’s bold]

e) To ensure that all segments of society, in particular parents and children, 

are informed, have access to education and are supported in the use of 

basic knowledge or child health and nutrition, the advantages of

breastfeeding, hygiene and environmental sanitation and the prevention 

of accidents . . . [author’s bold]. 

2. Agenda 21, Chapter 25 (1992)

The UN Conference on Environment and Development and the resulting Agenda 21 gives 

prominence to the protection of children from the effects of a deteriorating environment, and urges 

governments to develop programs to protect children from the effects of environmental and 

occupational toxic compounds.

Chapter 25 of Agenda 21 is on Children and Youth in Sustainable Development.

Among other areas, this program addresses the need to: reach child-related goals set in the areas 

of health, nutrition, education and literacy; seek the ratification and implementation of the

Convention on the Rights of the Child; promote Primary Environmental Care that benefits children; 
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expand educational opportunities; mobilize communities through schools and local health centers; 

and establish procedures to incorporate children’s concerns into environmental and development 

policies at the local, regional and national levels. 

3. Declaration of the Environment Leaders of the Eight on Children’s 

Environmental Health (G7 countries plus Russia, 1997)

This declaration provides the framework for domestic, bilateral and international efforts to

improve the protection of children’s health from environmental threats. It highlights lead,

microbiologically safe drinking water, air quality, environmental tobacco smoke, endocrinedisrupting chemicals, and global warming. The declaration also commits the eight to specific 

actions under each of these topic areas as well as to the general process of incorporating

characteristics of infants and children into environmental science, risk assessments, and protection 

protocols.

The problem and solution are eloquently stated in the first section of the Declaration:

We acknowledge that, throughout the world, children face significant threats to

health from an array of environmental hazards. The protection of human health 

remains a fundamental objective of environmental policies to achieve sustainable 

development. We increasingly understand that the health and well-being of our 

families depend upon a clean and healthy environment. Nowhere is this more true 

than in the case of children, who are particularly vulnerable to pollution. Evidence is 

growing that pollution at levels or concentrations below existing alert thresholds can 

cause or contribute to human health problems and our countries’ present levels of 

protection may not, in some cases, provide children with adequate protection . . .

We affirm that prevention of exposure is the single most effective means of

protecting children against environmental threats . . . 

4. Declaration of the Third European Ministerial Conference on 

Environment and Health (1999) (WHO European Region only)

The Declaration of the European Environment Ministers supports the principles in the Declaration 

of the Environment Leaders of the Eight, and focuses specific attention on injuries, environmental 

tobacco smoke, asthma and allergies, and emerging threats. The Declaration requests that: “ ... all 

Member States and the EC ... identify methods and mechanisms to promote the exchange of 

information and experience” concerning the above target health areas. Additionally, the request is 

also to:

d)promote and encourage public health measures in areas of emerging concern

about environmental impacts on children’s health, on the basis of the precautionary 

principle . . .
38

Making the Environment Healthier for Our Kids

An overview of environmental challenges to the health of North America’s children

f)develop an effective mechanism for monitoring and reporting progress annually 

throughout the Region on the basis of key indicators of the state of children’s health 

and the relevant environmental conditions.

The Ministers agreed to maintain this issue on their agenda for 2003.

The above agreements, conventions, and declarations all acknowledge the unique susceptibilities 

and vulnerabilities of children. Many identify specific health outcomes such as asthma, specific 

toxicants such as lead, or specific exposure pathways such as air pollution or unclean water. Some 

incorporate the precautionary principle. All acknowledge that children are at risk from exposure to 

environmental health threats, and all call for the protection of children through policy and action.
39

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An overview of environmental challenges to the health of North America’s children

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