DOI 10.1515/reveh-2012-0033 Rev Environ Health 2013; 28(1): 59–65 Review Rosana E. Norman* , David O. Carpenter , James Scott , Marie Noel Brunea and Peter D. Sly Environmental exposures: an underrecognized contribution to noncommunicable diseases Abstract: Previous attempts to determine the degree to of Queensland, Herston, Queensland, Australia; and Institute for which exposure to environmental factors contribute to Health and the Environment, University at Albany, Rensselaer, NY, USA James Scott: Children ’ s Health and Environment Program, noncommunicable diseases (NCDs) have been very con- Queensland Children ’ s Medical Research Institute, The University servative and have significantly underestimated the actual of Queensland, Herston, Queensland, Australia ; and Metro North contribution of the environment for at least two reasons. Mental Health, Royal Brisbane and Women’s Hospital, Herston, Firstly, most previous reports have excluded the contribu- Queensland, Australia; and The University of Queensland Centre for tion of lifestyle behavioral risk factors, but these usually Clinical Research, Herston, Queensland, Australia involve significant exposure to environmental chemicals Marie Noel Brune: Public Health and Environment, World Health Organization, Geneva, Switzerland that increase risk of disease. Secondly, early life exposure Peter D. Sly: Children ’ s Health and Environment Program, to chemical contaminants is now clearly associated with Queensland Children ’ s Medical Research Institute, The University an elevated risk of several diseases later in life, but these of Queensland, Herston, Queensland, Australia connections are often difficult to discern. This is especially true for asthma and neurodevelopmental conditions, but there is also a major contribution to the development of Introduction obesity and chronic diseases. Most cancers are caused by environmental exposures in genetically susceptible indi- Quantifying the disease burden caused by the environ- viduals. In addition, new information shows significant ment has been difficult given the relative lack of evidence associations between cardiovascular diseases and diabetes on causal links between environmental exposures and and exposure to environmental chemicals present in air, health outcomes as well as lack of reliable data on popu- food, and water. These relationships likely reflect the com- lation levels of exposure (1) . Nevertheless, several reports bination of epigenetic effects and gene induction. Environ- have attempted to determine what proportion of the mental factors contribute significantly more to NCDs than global burden of disease is attributable to environmental previous reports have suggested. Prevention needs to shift factors (1 – 7) . In the World Health Organization ’ s (WHO) focus from individual responsibility to societal responsibil- Comparative Risk Assessment, environmental risk factors ity and an understanding that effective prevention of NCDs accounted for approximately 9.6% of the total global ultimately relies on improved environmental management disease burden for 2000 (2) . Building on this analysis, to reduce exposure to modifiable risks. Pr ü ss- Ü st ü n et al. then published estimates of the envi- ronmental disease burden for 2002, which also involved Keywords: burden of disease; children; environment; surveys of expert opinion with large uncertainty around exposure; noncommunicable diseases. these estimates. About 24% of the global disease burden and an estimated 23% of all deaths were attributable to aAn author is a staff member of the World Health Organization. environmental factors. For children 0 – 14 years old, the The authors alone are responsible for the views expressed in this proportion of deaths attributed to the environment was publication and they do not necessarily represent the decisions, as high as 36% (4) . The authors also reported the fraction policy, or views of the World Health Organization. *Corresponding author: Dr. Rosana E. Norman, Children’s Health of disease that could be attributed to the environment and Environment Program, Queensland Children’s Medical Research for 85 diseases. These estimates provided an overview of Institute, The University of Queensland, Herston, Queensland, opportunities for prevention through healthier environ- Australia; and School of Population Health, The University of ments with a focus on health gains that could be achieved Queensland, Herston, Queensland, Australia, through environmental interventions. The WHO Envi- Phone: + 61-7-3346-4619, Fax: + 61-7-3365-5442, E-mail: [email protected] ronmental Burden of Disease series also provides practi- David O. Carpenter: Children ’ s Health and Environment Program, cal guidance to estimate the burden from selected risks Queensland Children ’ s Medical Research Institute, The University at country level (8) and a country-by-country analysis of Bereitgestellt von | Universitätsbibliothek der RWTH Aachen Angemeldet Heruntergeladen am | 22.04.16 12:52 60 Norman et al.: Environmental contributions to noncommunicable diseases the health impact of environmental factors (9) . Several to recognize that for children, exposure to lifestyle risk national-level estimates of environmental burden of factors like diet and tobacco smoke are not lifestyle choices disease have also been conducted (10 – 12) . The problem is but rather environmental exposures imposed on them by that these analyses are, by their nature, conservative and, others. There is no question that diet, habits, and exercise for the most part, have dealt with exposures from only influence susceptibility to disease. However, these sources limited sources with estimates based on traditional well- of exposure should not be excluded from the category of established environmental risk factors like unsafe water, environmentally induced diseases. Clearly, smoking and sanitation and hygiene, indoor and outdoor air pollution, excessive alcohol consumption involve exposure to chem- lead exposure, and occupational exposures. ical agents known to increase risk of developing cancer In a more recent analysis, 8.3% of deaths were as well as cardiovascular and liver disease. However, as attributable to chemical exposures including indoor and detailed below, exposure to certain chemicals, primarily outdoor air pollutants, second-hand smoke, lead, arsenic through diet, has also been linked to risk of cancer, type in drinking water, chemicals in occupational exposures, 2 diabetes, hypertension, cardiovascular disease, and and acute poisonings due to pesticides and other chemi- obesity. These diseases have not generally been consid- cals (6) . Notably, this analysis did not consider exposure to ered to be “ environmental ” in the past, although about chemicals in food, personal care products or other house- 8% – 10% of cardiovascular disease has been attributed to hold items, or the effects of prenatal exposure leading to environmental causes through consideration of only air diseases later in life. pollution and occupation (7) . The aim of this review is to revisit the question of how Furthermore, we know much more about gene-envi- environmental exposures contribute to disease, drawing ronment interactions today and understand that genetic on new information and using a broader definition of susceptibility is an essential factor for the development of what constitutes an “ environmental disease ” . The focus is many chronic diseases. An environmental exposure is often on noncommunicable diseases (NCD), including diseases responsible for triggering disease in susceptible individu- that either present or have their origins in childhood. als. There is emerging evidence that the origins of many Thinking needs to change in these areas to make progress adult diseases are found during fetal development and in reducing the burden due to such disorders. The need early childhood (14) . These early life experiences and expo- for a change in thinking is highlighted by a recent com- sures can affect adult mental and physical health either by mentary written on behalf of the Lancet NCD action group cumulative damage over time or by the biologic embed- in which a call for action was made to the United Nations ding of adversities during sensitive developmental periods (UN) high-level meeting on NCDs to stimulate a coordi- (15) . However, due to the long lag between exposure and nated global response to major NCDs including heart outcome, these connections are sometimes difficult to disease, stroke, cancer, diabetes, and chronic respiratory establish. NCDs should be recognized as largely “ environ- diseases (13) . These authors highlight key risk factors that mental diseases ” and doing so will allow the environmen- cause NCDs, namely, tobacco use, including second-hand tal contributions to NCDs to be appropriately recognized. smoke, diets high in fats, salt, and sugar, environments that prevent physical activity, and alcohol consumption. In addition, they include the intermediate risk factors like Definition of environment and obesity, increased blood pressure, and glucose, and cho- lesterol concentrations. However, the issue of low-dose environmental disease chronic exposure to a variety of environmental exposures, including chemical toxicants, was lacking. The environment has been defined as all that which is The so-called lifestyle behavioral risk factors have external to the human host and can be divided into physi- traditionally been excluded from consideration when cal, biologic, social,