Children's environmental health: a critical challenge of our time

Abstract

In studying a cohort of inner city children in New York City, my colleagues and I are finding that many of the children were exposed prenatally to various air pollutants, pesticides, endocrine-disrupting chemicals, and metals. By age 7 years, 25% of the children were overweight or obese, more than 25% had a diagnosis of asthma, and 15% had experienced delayed cognitive or motor development that could affect their ability to learn. One boy in the study is affected by asthma and developmental problems. Biomarkers in his cord blood showed measurable exposure to a number of toxic chemicals. But he comes from a low-income family and with that goes a host of nutritional and social stressors known to play a part in childhood illness and developmental problems. Is there a connection between each of these prenatal exposures and his poor health? What about the combination of these insults? As researchers in children's environmental health we are challenged to unravel the mystery and share our knowledge because the stakes for the children are so very high. Now, for the eager student, physician, researcher, or policy maker, there is a landmark textbook on the many facets of children's environmental health edited by two eminent pioneers in the field, Philip Landrigan and Ruth Etzel. Both are paediatricians and have long experience in bridging the worlds of research and policy.The Textbook of Children's Environmental Health is timely and provides a comprehensive and informative overview of this discipline. Recent statistics tell us that, by some indicators, the health of children worldwide is worsening, with serious implications for their future wellbeing and that of society as a whole. In recent decades, rates of developmental disabilities, asthma, obesity, diabetes, and certain cancers in children have increased. As with all diseases, their aetiology is complex, requiring the concerted efforts of not only epidemiologists, statisticians, and exposure scientists but also molecular biologists and geneticists to tease out the various factors involved. In addition to genetics, environmental factors, including toxic contaminants and pollutants in the air, water, and food, nutritional deficits, and psychosocial stress, have emerged as important causal factors, capable of interacting with genetic predisposition and with each other to inflict harm. The co-occurrence of such factors in low-income and minority populations has resulted in shocking disparities in child health and development that are only now beginning to attract the attention they have long deserved. The overarching environmental threat of climate change, resulting from the burning of coal and other fossil fuels, has already inflicted disproportionate suffering on the health of poor children and is endangering their future wellbeing.Children bear the brunt of the failure of governments to address environmental threats: according to WHO, 36% of all childhood deaths globally are attributable to environmental causes and 43% of the total environmental burden of disease falls upon children younger than 5 years. The solution to this problem is the integration of social and environmental policies centred on the protection and nurturing of the developing child.There is mounting interest in understanding the contribution of environmental contaminants because by definition these are preventable once identified. A growing wave of longitudinal studies of pregnant women and children points to the fetal developmental window and early childhood as particularly susceptible to the multiple adverse effects of toxic exposures, stress, and nutritional deficits. There are now many examples of the fetus, infant, and young child being affected by low levels of environmental toxicants, inadequate nutrition, and stress that have no apparent effects in adults. This is because, in early life, detoxification and repair pathways are immature, and the complicated, rapid process of early development is easily disrupted, often with lasting consequences. There has also been much progress in understanding the mechanisms by which environmental exposures can lead to disease, not only by inflicting genetic damage that results in alterations in the structure and sequence of genes, but also by dysregulating the epigenetic programming of gene expression during critical developmental stages. Evidence is emerging that environmental exposures that occur prenatally can affect health and disease over the life course and even over future generations. This is a promising moment for translation of scientific evidence to preventive policy, starting with meaningful reform of laws that regulate toxic chemicals and pesticides.Landrigan and Etzel state at the outset of the textbook that “The goal of research is evidence-based blueprints for the prevention of disease and the protection of children's health”. Accordingly, in addition to focusing on the generation of rigorous scientific data, the Textbook of Children's Environmental Health constantly reminds us of the importance of translation of scientific data to practice, advocacy, and regulatory and other strategies for prevention. This challenge is underscored at the outset and repeated throughout the book with the sobering statistics that, for example, there is no information on developmental toxicity or potential to harm infants and children on about 80% of the 3000 chemicals produced or imported into the USA; neurodevelopmental disorders affect one in every six children in the USA, similar to rates in other industrially developed countries; children from lower income and minority groups in the USA bear the greatest burden of asthma; the global prevalence of overweight and obesity in preschool-age children has nearly doubled in the past 20 years; and the cost of environmentally attributable disease in children in the USA in 2008 alone was US$76·6 billion whilst the corresponding estimate for the European Union was $70·9 billion.The textbook takes the reader from the chemical, nutritional, social, and built environments in which children are conceived and develop through to the various methods involved in generating the data in these areas and also to a review of the chemicals associated with chronic diseases and neurodevelopmental impairment in childhood. The list includes the best characterised toxicants, such as lead, mercury, polychlorinated biphenyls, and arsenic, as well as those more recently studied such as organophosphate pesticides, polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers, the volatile organic chemicals benzene and formaldehyde, and the endocrine-disrupting chemicals bisphenol-A and phthalates. The book's contributors assess the nature and quality of the evidence linking these exposures to specific diseases and disorders in childhood—in some cases definitive, in others suggestive. The final chapters describe the need for environmental justice and strategies to prevent and control diseases of environmental origin in children. These strategies include early identification by health professionals, changes in public policy to reduce or eliminate toxic exposures, global treaties that are essential to control the fundamentally transnational problems of pollution and climate change, and advocacy informed by science. By covering the many facets of children's environmental health, this textbook will help to inform and engage participants in this most critical issue of our time. In studying a cohort of inner city children in New York City, my colleagues and I are finding that many of the children were exposed prenatally to various air pollutants, pesticides, endocrine-disrupting chemicals, and metals. By age 7 years, 25% of the children were overweight or obese, more than 25% had a diagnosis of asthma, and 15% had experienced delayed cognitive or motor development that could affect their ability to learn. One boy in the study is affected by asthma and developmental problems. Biomarkers in his cord blood showed measurable exposure to a number of toxic chemicals. But he comes from a low-income family and with that goes a host of nutritional and social stressors known to play a part in childhood illness and developmental problems. Is there a connection between each of these prenatal exposures and his poor health? What about the combination of these insults? As researchers in children's environmental health we are challenged to unravel the mystery and share our knowledge because the stakes for the children are so very high. Now, for the eager student, physician, researcher, or policy maker, there is a landmark textbook on the many facets of children's environmental health edited by two eminent pioneers in the field, Philip Landrigan and Ruth Etzel. Both are paediatricians and have long experience in bridging the worlds of research and policy. The Textbook of Children's Environmental Health is timely and provides a comprehensive and informative overview of this discipline. Recent statistics tell us that, by some indicators, the health of children worldwide is worsening, with serious implications for their future wellbeing and that of society as a whole. In recent decades, rates of developmental disabilities, asthma, obesity, diabetes, and certain cancers in children have increased. As with all diseases, their aetiology is complex, requiring the concerted efforts of not only epidemiologists, statisticians, and exposure scientists but also molecular biologists and geneticists to tease out the various factors involved. In addition to genetics, environmental factors, including toxic contaminants and pollutants in the air, water, and food, nutritional deficits, and psychosocial stress, have emerged as important causal factors, capable of interacting with genetic predisposition and with each other to inflict harm. The co-occurrence of such factors in low-income and minority populations has resulted in shocking disparities in child health and development that are only now beginning to attract the attention they have long deserved. The overarching environmental threat of climate change, resulting from the burning of coal and other fossil fuels, has already inflicted disproportionate suffering on the health of poor children and is endangering their future wellbeing. Children bear the brunt of the failure of governments to address environmental threats: according to WHO, 36% of all childhood deaths globally are attributable to environmental causes and 43% of the total environmental burden of disease falls upon children younger than 5 years. The solution to this problem is the integration of social and environmental policies centred on the protection and nurturing of the developing child. There is mounting interest in understanding the contribution of environmental contaminants because by definition these are preventable once identified. A growing wave of longitudinal studies of pregnant women and children points to the fetal developmental window and early childhood as particularly susceptible to the multiple adverse effects of toxic exposures, stress, and nutritional deficits. There are now many examples of the fetus, infant, and young child being affected by low levels of environmental toxicants, inadequate nutrition, and stress that have no apparent effects in adults. This is because, in early life, detoxification and repair pathways are immature, and the complicated, rapid process of early development is easily disrupted, often with lasting consequences. There has also been much progress in understanding the mechanisms by which environmental exposures can lead to disease, not only by inflicting genetic damage that results in alterations in the structure and sequence of genes, but also by dysregulating the epigenetic programming of gene expression during critical developmental stages. Evidence is emerging that environmental exposures that occur prenatally can affect health and disease over the life course and even over future generations. This is a promising moment for translation of scientific evidence to preventive policy, starting with meaningful reform of laws that regulate toxic chemicals and pesticides. Landrigan and Etzel state at the outset of the textbook that “The goal of research is evidence-based blueprints for the prevention of disease and the protection of children's health”. Accordingly, in addition to focusing on the generation of rigorous scientific data, the Textbook of Children's Environmental Health constantly reminds us of the importance of translation of scientific data to practice, advocacy, and regulatory and other strategies for prevention. This challenge is underscored at the outset and repeated throughout the book with the sobering statistics that, for example, there is no information on developmental toxicity or potential to harm infants and children on about 80% of the 3000 chemicals produced or imported into the USA; neurodevelopmental disorders affect one in every six children in the USA, similar to rates in other industrially developed countries; children from lower income and minority groups in the USA bear the greatest burden of asthma; the global prevalence of overweight and obesity in preschool-age children has nearly doubled in the past 20 years; and the cost of environmentally attributable disease in children in the USA in 2008 alone was US$76·6 billion whilst the corresponding estimate for the European Union was $70·9 billion. The textbook takes the reader from the chemical, nutritional, social, and built environments in which children are conceived and develop through to the various methods involved in generating the data in these areas and also to a review of the chemicals associated with chronic diseases and neurodevelopmental impairment in childhood. The list includes the best characterised toxicants, such as lead, mercury, polychlorinated biphenyls, and arsenic, as well as those more recently studied such as organophosphate pesticides, polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers, the volatile organic chemicals benzene and formaldehyde, and the endocrine-disrupting chemicals bisphenol-A and phthalates. The book's contributors assess the nature and quality of the evidence linking these exposures to specific diseases and disorders in childhood—in some cases definitive, in others suggestive. The final chapters describe the need for environmental justice and strategies to prevent and control diseases of environmental origin in children. These strategies include early identification by health professionals, changes in public policy to reduce or eliminate toxic exposures, global treaties that are essential to control the fundamentally transnational problems of pollution and climate change, and advocacy informed by science. By covering the many facets of children's environmental health, this textbook will help to inform and engage participants in this most critical issue of our time.