Environmental Hazards and Toxins that are Affecting the Health of our Children

by Lawrence D. Rosen, MD 

It has been often said that children are our most precious natural resource. Ensuring the optimal health of this generation and future generations of children is not a choice we have—it is an absolute necessity.  Yet today, we are witnessing a public health crisis of historical proportions that threatens the well-being of children across the world. Everywhere, there are a growing number of children suffering from environmentally related diseases. Furthermore, the children at greatest risk are those living in poverty – those already facing the greatest uphill battles. The following snapshot of the state of our children’s health portrays a very disturbing picture of how our failure to make children’s health a priority is producing disastrous consequences and threatening our future.

• Cancer remains the leading cause of death by disease in children.  The age-adjusted annual incidence of cancer in children increased from 129 to 172 cases per million children between 1975 and 2005. (1)
• One in eight babies is born prematurely, an increase of more than 30% since the early 1980’s. A lack of prenatal care and poor nutrition may account for 40% of premature births in developed countries. Preterm birth contributes to more than one third of all infant deaths and costs the United States more than $26 billion per year. (2)
• Obesity is epidemic.  Data from NHANES surveys (1976–1980 and 2003–2006) show that the prevalence of obesity has increased: for children aged 2–5 years, prevalence increased from 5.0% to 12.4%; for those aged 6–11 years, prevalence increased from 6.5% to 17.0%; and for those aged 12–19 years, prevalence increased from 5.0% to 17.6% (3)
• Diabetes now affects one in every 500 children.  Of those children newly diagnosed with diabetes, the percentage with type 2 (“adult-onset”) has risen from less than 5% to nearly 50% in a ten-year period. (4)
• Asthma is the most prevalent chronic disease affecting American children, leading to 15 million missed days of school per year.  From 1980 to 2007, the percentage of children with asthma has almost tripled, from 3.6% to 9.1%. (5)
• Approximately 1 in 25 American children now suffer from food allergies.  From 1997 to 2007, the prevalence of reported food allergy increased 18% among children under age 18 years. (6)
• One in six children is diagnosed with a significant neurodevelopmental disability, including one in twelve with ADHD. (7,8)  Autism affects 1 in 91 children in the U.S., an extraordinary rise in prevalence widely publicized but poorly understood.(9)
• Children and adolescents are suffering from mental health disorders at alarming rates. Nearly 20% of young adolescents report symptoms of depression, with even higher rates in Native American youth.(10) Suicide is the third leading cause of death in youth aged 10 to 19, (11) and suicide rates in Native American adolescents are three times greater than the national average.(12)

Children as a Unique Population
Children, for a variety of reasons, are particularly vulnerable to changes in their environment.  Consumption of environmental chemicals is magnified as children routinely consume more food and water and breathe more air than adults. Children also play close to the ground and continuously engage in hand-to-mouth behavior, exposing themselves to a vast array of toxins. Infants are exposed as well to toxins in utero and ex-utero based on parental exposures. For example, before taking their first breath, babies are exposed to large amounts of toxins, placing them at a higher risk for health disorders. In July 2005, the Environmental Working Group released the findings of a landmark study that revealed an average of 200 industrial chemicals and pollutants in babies’ umbilical cord blood. The study identified 287 chemicals in the cord blood of 10 children, 180 of which cause cancer in animals and humans; 208 of these chemicals are known to cause birth defects or abnormal development in animals, and as many as 217 are recognized to be toxic to the developing brain and nervous system. (13) Once born, babies are exposed to a variety of secondhand environmental exposures that greatly influence health. Breast milk, long considered to be the ideal source of nutrition for newborns, may actually expose babies to increased levels of a variety of toxins, including flame retardants (polybrominated diphenyl ethers [PDBEs]).(14) If new parents smoke, their child is more likely to develop a variety of physical and behavioral problems, including asthma and neurodevelopmental disorders.(15,16) Newborns, as well, differ in their ability to excrete toxins compared with adults, due to developmental differences in respiratory, digestive, and urinary system physiology.(17)

ENVIRONMENTAL FACTORS RELATED TO PEDIATRIC ILLNESSES

Cancer
One of the greatest increases in children’s cancer rates has been seen in adolescents.  The largest increase in adolescent cancers is in the gonadal tumor category, specifically testicular and ovarian germ cell tumors. (18)  We have long suspected that increased exposure to endocrine-disrupting chemicals such as polychlorinated biphenyls (PCBs) may be responsible for the rise in gonadal tumor cases. Polychlorinated biphenyls are mixtures of 209 chemical compounds which have been used to manufacture flame-resistant materials, electrical insulators, heating coils, caulking compounds, and various other related materials. They are chemically stable and remain in the environment for long periods of time. Sources of exposure to PCBs can come from direct use of PCB-containing products and leaching from landfills often found close to or under low-income neighborhoods. Indeed, we do have evidence of the impact of PCBs on gonadal development in boys. Male genital abnormalities on the rise, including hypospadias, undescended testis, poor semen quality, and testicular cancer, are seen as part of an underlying testicular dysgenesis syndrome, conclusively linked to PCB exposure. (19) The PCB exposure may also occur vertically, across generations. It has been demonstrated that men born to mothers with higher blood concentrations of PCBs are four times more likely to develop tes¬ticular cancer than controls. (20)

Prematurity
Poor birth outcomes, including infant mortality, low birth weight and prematurity, are more frequent in populations living in poverty. (21,22) There are many environmental factors that influence these birth outcomes, but recent research has focused on air pollution as a contributing factor. It has been shown that women living in U.S. counties with greater air pollution, including ozone and carbon monoxide, are more likely to deliver babies prematurely. (23,24) Many of these babies come from families with genetic predisposition toward allergic disorders, and then they are exposed in utero to higher levels of ambient air pollution. They are born too early, weighing too little. Their lungs are immature and they often cannot eat and digest breast milk due to gastrointestinal immaturity; they are nutritionally deficient as a result. They eventually go home to indoor and outdoor environ-ments, pushing them further down the road toward chronic respiratory problems. Exposed to crowded living conditions, ripe with cockroach dander and tobacco smoke, (25) and living in neighborhoods with excessive outdoor air pollution, many of these children are doomed to a lifetime of asthma-related emergency room visits.

Asthma
As noted, national asthma rates have surged to new highs in recent years. There are communities though, like New York City’s Harlem, where rates exceed by far even these troubling numbers. According to one study coordinated by Harlem Hospital Center and Harlem Children’s Zone, asthma is now diagnosed in one in four children in this region. (26) Low-income populations and children living in inner cities experience disproportionately higher morbidity and mortality due to asthma, as well. Both indoor and outdoor pollutants have been implicated in asthma development. Indoor allergens such as dust mites, molds, cockroach and pet dander, and tobacco smoke have been shown to influence asthma symptoms. (27,28)  More recently, there has been increased recognition of outdoor factors in the development of asthma.  A laundry list of air pollution contaminants are thought to be responsible for the trend, including ozone. (29-31) According to the last survey of the U.S. Environmental Protection Agency in 2004, approximately 41% of children lived in counties in which the eight-hour ozone standard was exceeded on at least one day per year. (32) Global climate change, too, has been associated with changes in air quality and ozone that negatively impact children with respiratory conditions.(33)

Obesity
The tremendous rise in obesity in today’s children and adolescents is reported in all racial groups and socioeconomic spheres. Still, certain populations—African Americans, Native Americans, and Latino Americans, report higher rates of obesity than matched community controls. (34) Much of this increased risk is due to a complex interplay of genetic factors and environmental triggers. Poor quality nutrition plays a role, as does reduced access to fitness opportunities. Related health disorders, type II diabetes and metabolic syndrome, have also been reported at startlingly higher rates in these same at-risk populations, leaving adolescents with poor health profiles reminiscent of elderly relatives. Hypertension, hyperlipidemia, and insulin resistance, all hallmarks of metabolic syndrome, are now developing at younger and younger ages. (35) Lack of access to safe play areas and restricted time to participate in free play furthermore contributes to the obesity epidemic. This dual threat – poor nutrition and reduced physical activity – must be addressed in a systemic, community-wide manner to effectively combat the obesity problem.

Neurodevelopment
The complexities of child development are profound. Our understanding of brain function remains in its infancy as we strive to develop better objective tools to measure neurologic differences and the physiological factors responsible for them. As autism spectrum disorders and attention-deficit/hyperactivity disorder continue to be reported at epidemic rates, we are searching for environmental factors that may be contributing to the alarming rise in neurodevelopmental disorders. As Drs Philip Landrigan and Philippe Grandjean point out, “The combined evidence suggests that neurodevelopmental disorders caused by industrial chemicals has created a silent pandemic in modern society.” (36)

It is not likely to be one single pollutant that influences the development of attention-deficit/hyperactivity disorder or autism in this way, but a toxic cocktail of small, persistent amounts of contaminants (in air, land, food, water, industrial, and pharmaceutical products) that affects a child in such a way that he develops clinically obvious neurodevelopmental symptoms. Several of these toxins have been identified, including the heavy metals lead and mercury, pesticides, and PCBs. (37) Both lead and mercury have been well-documented to disproportionately affect poor youth. (38,39) Less well described are the effects of pesticides and PCBs on the neurodevelopment of children living in poverty, both in urban and rural settings.

One example is the negative effect of PCBs on the cognitive functioning of Akwesasne Mohawk adolsecents. (40) The exposures in these case are most likely multi-generational. Polychlorinated biphenyls amass in the fatty tissues of animals and bioaccumulate through the aquatic food chain. Poor families often depend on fishing to provide a low-cost source of food. In many areas, fish is the primary diet for many low-income and Native American communities. The food meant to be a source of nourishment can actually be contaminated with toxic PCBs that seeped into rivers and streams. Fish can also contain high levels of mercury. The combination of mercury air pollution and a regular diet of fish caught in polluted streams can add substantial PCB and mercury exposure to children growing up in poverty. For pregnant women, both PCBs and mercury found in fish can cross the placenta and affect the fetus.

COMPLEX INTERACTIONS

The evidence presented here demonstrates the huge impact of the environment on children’s health. These examples, furthermore, represent only a small percentage of the numerous concerning findings being published with alarming regularity. An unpredictable and explosive mix of genetic susceptibility and environmental exposure often leads to disparate health woes for those children at highest risk. The concept of genetic susceptibility, as well, is under scrutiny. With new research elucidating the mechanisms of epigenetic phenomena (41),  it is likely that environmental factors are causing disease both via direct exposure and by altering DNA de novo, thereby increasing the effect of exposure at the same time – a double-edged sword, if you will.

A CALL TO ACTION

Children cannot protect themselves nor can they clean up an environment our society has created. Independently, they have no political or economic voice. It is our responsibility to insure that their environment is safe. A compassionate and successful society will invest its assets in the good health of its children—all of its children. Addressing these environmental inequities will require a substantial resource shift and a commitment from government, industry, and citizens. A paradigm shift directing our focus toward preventing disease is urgently needed. We must adopt a new way of looking at children’s health and cannot delay in addressing the environmental inequalities that are robbing our society of its future.

Note: Portions of this article were adapted from “Environmental injustice: Children’s health disparities and the role of the environment” (Rosen LD, Imus D. Explore (NY). 2007 Sep-Oct;3(5):524-8).


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