Around the world, children are exposed to environmental hazards ranging from famine to pollution. Children are more susceptible than adults to toxic exposure to chemicals found in food, water, dirt, and air. Environmental problems negatively affect children's health directly and indirectly, both in the short and the long term.
The World Health Organization (WHO) estimates that one-third of the diseases among children are due to environmental factors. In developing countries, death from environmental causes is 12 times higher than in developed countries. Children are in need of protection from environmental threats to their health, according to the WHO.
The vulnerability of children to illness and disease is increased in degraded and poor environments. Neglected and malnourished children develop more diseases and have less access to healthcare than do well-fed children who are not neglected.
Governments and international organizations, including the United Nations (UN), the European Union (EU), and the U.S. government, are revising and changing laws and policies to protect children from environmental health problems and environment-related hazards. The UN has mandated that all agencies and researchers specifically consider health impacts on children apart from health impacts on adults.
In the past, mainstream research and surveys were focused on adults, considering children too infrequently or only in the same terms as adults. For example, the U.S. Environmental Protection Agency (EPA) noted that environmental regulations were originally written with the average American adult in mind, without consideration for the unique developmental issues faced by children. Because of the focus on adults, health impacts and developmental effects on children from environmental pollution have not been well researched or documented.
Children are at greater risk from environmental impact for several reasons. Relative to their size, they eat, drink and breathe more than adults. Their immune systems are still developing, and they are in close contact with floors, carpets, grass, and dirt. Children tend to put their hands in their mouths. They are less aware of dangers, especially if they cannot read. They live according to the decisions, habits, and cultures of their parents (e.g., second-hand smoke). Exposure to toxicants during certain periods of development may permanently alter the structure or function of organ systems. Other responses to environmental threats by children's bodies and minds are distinct from those of adults.
The EPA lists the following as its four children's health protection priorities: asthma, lead exposure, childhood cancer, and developmental disabilities. Other high priorities identified by researchers and agencies include pesticides, diabetes, mercury, exposure to ultraviolet radiation from sun, mold and moisture (in buildings), unintentional injuries, allergies and autoimmune problems, ozone, particulate matter, autoimmunity and endocrine disruption syndromes, perchlorate, and obesity. Sources of concentrated environmental threats to children include lawns, playgrounds, schools, school buses, toys, clothing, and bedding.
Most governments include agencies that deal directly with childhood (schools, recreation, etc.). These agencies may not address child safety and health. Publicly funded scientific and medical research could better address the needs of the public if they explicitly addressed children's health protection issues.
Environmental laws have tended to not include children. For example, warnings and standard labels in use on pesticides were set for adults, despite the fact that children were also being exposed to harmful chemicals (especially in agriculture).
Information distribution and consumer education are other responsibilities of government in protecting children's health. For example, research on chemicals in toys is increasingly being made available, as it has been by the Michigan-based Ecology Center. At its website, consumers can compare how products rank in measures of lead, cadmium, polyvinyl chloride (commonly known as PVC), and other chemicals that are associated with reproductive problems, developmental and learning disabilities, hormonal disorders, and cancer.
Government response may take many forms. Some healthcare experts and children's health advocates emphasize intervention by centralized authorities. Others propose shifting emphasis away from hospital-based professional care and toward care that is centered in family settings.
An example of a multipronged government response is described in a joint report on pesticide poisoning published in 2004 by the United Nations (UN) Food and Agriculture Organization (FAO), the UN Environment Programme (UNEP), and the World Health Organization (WHO). An estimated 1-5 million cases of pesticide poisonings occur every year, resulting in several thousand fatalities. To reduce pesticide poisoning, the FAO, UNEP, and WHO urge that governments take steps to reduce pesticide exposures to children at home and at work. The report also urges correctly storing and labeling pesticides, using integrated pest management (IPM) instead of pesticides, training healthcare providers about pesticide poisoning, and training agricultural workers on how to use pesticides and prevent exposure. Governments should, according to the report, run information and education campaigns via TV and radio programs and address the whole pesticide life cycle from manufacturing to disposal.
Over time, industrial pollution may have hampered the mental and physical development of millions of children worldwide, according to children's health researchers. Older estimates of the cost of lead poisoning in children in the United States are about $43 billion annually, and estimates of the cost of methylmercury toxicity in children are about $8.7 billion. Recent research suggests that these costs are actually higher.
Prenatal and postnatal exposure to pesticides and polychlorinated biphenyls (PCBs) has been implicated as a possible cause of impaired immune function in children. Studies suggest that children exposed to PCBs and related compounds from their mothers' diets have reduced concentrations of immunoglobulins and more childhood infections.
Recently, research has focused on whether exposure to pollutants is likely to travel across the placenta in pregnant women to affect the fetus. A Bristol University study of babies with leukemia whose mothers had been exposed to pesticides during pregnancy suggested that this may be the case.
A 2006 study suggests that children exposed to PCBs may have reduced immune responses to childhood vaccinations, adding to the growing evidence that PCBs may be associated with developmental immunotoxicity (DIT). DIT reflects the heightened immune vulnerabilities that exist during early life.
Asthma: About one in 13 school-aged children in the United States has asthma, and the percentage is rising most rapidly among preschool-aged children. The annual societal cost, including emergency room and hospital visits and missed days at school and work, amount to about $19 billion. The number one reason for hospitalization in children in North America is for respiratory conditions.
Children exposed to high levels of air pollutants, including ozone, particulate matter, nitrogen dioxide, and other traffic-related emissions, show clinically important adverse effects on asthma pathogenesis, lung function development, respiratory symptoms, and infections.
After birth, the developing lungs are susceptible to damage after exposure to environmental toxins, suggesting the importance of keeping babies away from air pollution. Also, studies have found potential links between air pollution and preterm birth, infant mortality, deficits in lung growth, and possibly the development of asthma.
Lead: Children are most often exposed to lead through ingestion of contaminated soil or paint dust. Additionally, lead traces in drinking water may be caused by old lead pipes. Food may be contaminated through contact with lead-glazed ceramic dishes.
Because of public education and changes in law, children are more protected now from lead poisoning. Lead was removed from gasoline and paint, after which lead levels plummeted. The concentration of lead in blood of children (age five and younger) dropped from 15 micrograms per deciliter during 1976-80 to 1.7 micrograms per deciliter during 2001-2002, a decline of about 85 percent.
Mercury: Research suggests that women and children may have more mercury in their systems than men. Contamination from pesticides, polychlorinated biphenyls (PCBs), heavy metals, and other chemicals has been measured in women and children at levels that may result in pre- or postnatal impairments. Industrial emissions, especially from coal-fired power plants, are the main source of mercury in the environment. Mercury seeps into soil and surface waters, drains into rivers, and accumulates in fish. The consumption of large amounts of fish has been linked to elevated levels of mercury.
Pesticides: Pesticides are used liberally to rid agricultural fields, public spaces, and buildings from pests. They may be inhaled, ingested, or touched directly. Pesticide levels in children's blood and urine remain at levels that concern U.S. and international health agencies.
A study of the long-term effects of pesticides on mothers and children focused on children whose mothers lived in California's Central Valley, near known pesticide-treated fields (particularly the organochlorines dicofol and endosulfan). Children of mothers who lived within a distance of 1.75 kilometers from these fields were more likely to have autism spectrum disorders than children whose mothers lived farther away.
There is evidence that banning pesticides may improve overall child health. The ban by the U.S. Environmental Protection Agency (EPA) of two household pesticides (diazinon and chlorpyrifos), for example, resulted in a rapid decrease in exposures in New York City.
While children may come into contact with pesticides, the targeted pests may also be bad for them. Allergens associated with dust mites and cockroaches can be important in both triggering and worsening of asthma symptoms for children.
Ozone: Ambient ozone is formed when sunlight acts on nitrogen oxides and reactive hydrocarbons, which are emitted by motor vehicles and industrial sources. Levels are highest on warm, sunny, windless days, peaking in mid-afternoon, when children are most likely to be playing outside. Ozone exposure may cause shortness of breath, chest pain upon inhaling deeply, wheezing, and coughing. Effects on children may include a impaired lung function, increased respiratory tract symptoms, and aggravation of asthma symptoms.
High ozone levels have been linked to respiratory or asthma hospitalizations, as well as school absences for respiratory problems. These problems have also been noted when ozone levels are below current warning standards. Protecting children from exposure to ozone may help improve their health, reduce the number of sick days, and reduce treatment costs for the community.
Traffic pollution: Vehicles pollute the air with carbon monoxide, particulate matter, nitrogen oxides, hydrocarbons, and other hazardous air pollutants, thereby contributing to ozone formation. Exhaust from traffic is the biggest polluter in most communities.
Among those living near busy roads, investigators have found increased adverse health effects, including wheezing, chronic productive cough, and asthma hospitalizations.
Some research has linked various childhood cancers to proximity to traffic. Other research suggests that there may not be a significant correlation between childhood cancers and nearby traffic. However, EPA-funded research suggests that children living close to major roadways in Southern California may be more likely to develop asthma.
Most of America's school buses run on diesel fuel. Diesel exhaust is a cancer-causing (carcinogenic) pollutant. The EPA and state agencies are trying to reduce children's exposure by banning unnecessary idling and using cleaner buses. Limited evidence suggests that a child riding inside a school bus may be exposed to four times as much diesel exhaust as someone riding in a car.
Millions of people in the United States spend every weekday in school buildings. More than half of these schools report structural or environmental problems. Schools often do not have the expertise or funding to address these problems. There is a lack of research available to determine whether student performance is linked to environmental exposures. Efforts to monitor indoor environmental issues are not standardized, and measurements are not shared among agencies.
Research performed at the University of Wisconsin at Madison examined the effects of lead, mercury, PCBs, pesticides, noise, and radioactive and chemical wastes on schoolchildren. These toxins affected memory, attention, learning, motor skills, intelligence, personality, and emotion.
Safety: The leading cause of death for children (ages 2-14) in the United States is motor vehicle crashes, according to the National Highway Traffic Safety Administration (NHTSA). However, in the United States, laws require that children be placed in car seats during driving. When child safety seats are used, they reduce the risk of fatal injury by 71 percent for infants and by 54 percent for toddlers in passenger cars, according to the NHTSA. However, researchers are still measuring the importance of factors like car seat placement, use of restraints, direction of placement, ages of children, sizes and designs of seats, and dangers from airbags.
Food and drug products for children have shown contamination problems, suggesting the need for greater regulation. In November 2008, 30 children aged between three months and four years died in Nigeria after taking a teething syrup contaminated with diethylene glycol (used in engine coolant and antifreeze). The children died of kidney failure. Forty other children were reportedly hospitalized with the same problem, but many cases are thought to have been unreported. The manufacturing firm was shut down, and the product was recalled. In 2006, in Panama, at least 50 children died (other estimates exceed 100) from use of a cough syrup containing diethylene glycol. The product was manufactured in China. After the deaths, Chinese and Panamanian sources blamed each other. In several Central and North American countries, diethylene glycol was found in Chinese-made toothpaste.
A 2008 case of milk containing melamine in China is another publicized violation of safety and quality standards. The extent of the problem was first reported to be limited, but later it was estimated that hundreds of thousands of children were made sick, and six Chinese children died. Reports from Bangladesh say four babies there died after use of Chinese powdered milk containing melamine. The largest milk producer in China was implicated, and a few officials in the dairy industry were put on trial.
FUTURE RESEARCH OR APPLICATIONS
Purchasers of most products are adults, not children. Therefore, testing the safety or health effects of products is typically directed at adults. Understanding the effects products have on children will require a shift in research toward children.
Short-term studies are not capable of detecting long-term effects of environmental damage to the maturing bodies of children. Longitudinal studies in which children's health is tracked well into adulthood would provide more information.
Environmental health issues, by definition, bring together many factors from the environment. Traditional medical research, however, tends to examine only one factor or one correlation between factors at a time. Some researchers argue, for this reason, that new experimental designs and new analytical methods are required to tackle the inherent complexity of environmental health questions. A relatively new approach is the thorough examination of environmental impacts on the immune systems of children. Autoimmune diseases in children include rheumatoid arthritis, multiple sclerosis, and type 1 diabetes. Genetic profiling may be used to identify children that are at a higher risk for developing autoimmune diseases that are likely to be triggered by environmental hazards.
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
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