Environmental health


Environmental health is the branch of public health concerned with all aspects of the natural and built environment affecting human health. Its study determines the requirements for a healthy environment, with the goal of effective control over the factors that affect health. The major sub-disciplines of environmental health are environmental science, toxicology, environmental epidemiology, and environmental and occupational medicine.

Definitions

WHO definitions

Environmental health was defined in a 1989 document by the World Health Organization as:
Those aspects of human health and disease that are determined by factors in the environment. It is also referred to as the theory and practice of accessing and controlling factors in the environment that can potentially affect health.
, the WHO website on environmental health states that "Environmental health addresses all the physical, chemical, and biological factors external to a person, and all the related factors impacting behaviours. It encompasses the assessment and control of those environmental factors that can potentially affect health. It is targeted towards preventing disease and creating health-supportive environments. This definition excludes behaviour not related to environment, as well as behaviour related to the social and cultural environment, as well as genetics."

Other considerations

The term environmental medicine may be seen as a medical specialty, or branch of the broader field of environmental health. Terminology is not fully established, and in many European countries they are used interchangeably.
Other terms referring to or concerning environmental health include environmental public health and health protection.

Disciplines

Five basic disciplines generally contribute to the field of environmental health, with some overlap between them:
  • Environmental epidemiology studies the relationship between environmental exposures and human health. Observational studies, which simply observe exposures that people have already experienced, are common in environmental epidemiology because humans cannot ethically be exposed to agents that are known or suspected to cause disease. While the inability to use experimental study designs is a limitation of environmental epidemiology, this discipline directly observes effects on human health rather than estimating effects from animal studies. Environmental epidemiology is the study of the effect on human health of physical, biologic, and chemical factors in the external environment, broadly conceived. Also, examining specific populations or communities exposed to different ambient environments, Epidemiology in our environment aims to clarify the relationship that exist between physical, biologic or chemical factors and human health.
  • Toxicology studies how environmental exposures lead to specific health outcomes, generally in animals, as a means to understand possible health outcomes in humans. Toxicology has the advantage of being able to conduct randomized controlled trials and other experimental studies because they can use animal subjects. However, there are many differences in animal and human biology, and there can be a lot of uncertainty when interpreting the results of animal studies for their implications for human health.
  • Exposure science studies human exposure to environmental contaminants by both identifying and quantifying exposures. Exposure science can be used to support environmental epidemiology by better describing environmental exposures that may lead to a particular health outcome, identify common exposures whose health outcomes may be better understood through a toxicology study, or can be used in a risk assessment to determine whether current levels of exposure might exceed recommended levels. Exposure science has the advantage of being able to very accurately quantify exposures to specific chemicals, but it does not generate any information about health outcomes like environmental epidemiology or toxicology.
  • Environmental engineering applies scientific and engineering principles for protection of human populations from the effects of adverse environmental factors; protection of environments from potentially deleterious effects of natural and human activities; and general improvement of environmental quality.
  • Environmental law includes the network of treaties, statutes, regulations, common and customary laws addressing the effects of human activity on the natural environment.
Information from epidemiology, toxicology, and exposure science can be combined to conduct a risk assessment for specific chemicals, mixtures of chemicals or other risk factors to determine whether an exposure poses significant risk to human health. This can in turn be used to develop and implement environmental health policy that, for example, regulates chemical emissions, or imposes standards for proper sanitation. Intervention strategies from engineering and law can be combined to provide monitoring and risk management of exposure, and achieve the objective of protecting human health.

Pediatric environmental health

Children's environmental health is the academic discipline that studies how environmental exposures in early life—chemical, biological, nutritional, and social—influence health and development in childhood and across the entire human life span. Pediatric environmental health is based on the recognition that children are not "little adults." Infants and children have unique patterns of exposure and vulnerabilities. Environmental risks of infants and children are qualitatively and quantitatively different from those of adults. Pediatric environmental health is highly interdisciplinary. It spans and brings together general pediatrics and numerous pediatric subspecialties as well as epidemiology, occupational and environmental medicine, medical toxicology, industrial hygiene, and exposure science.

Concerns

Environmental health concerns include:
According to recent estimates in Europe, about 5 to 10% of disability-adjusted life years lost are due to environmental causes. By far the most important factor is fine particulate matter pollution in urban air. Similarly, environmental exposures have been estimated to contribute to 4.9 million deaths and 86 million DALYs globally. In the United States, Superfund sites created by various companies have been found to be hazardous to human and environmental health in nearby communities. It was this perceived threat, raising the specter of miscarriages, mutations, birth defects, and cancers that most frightened the public.

Air quality

includes ambient outdoor air quality and indoor air quality. Large concerns about air quality include environmental tobacco smoke, air pollution by forms of chemical waste, and other concerns.

Outdoor air quality

is globally responsible for over 6.5 million deaths each year, as of 2022. Air pollution is often a risk-factor for diseases like lung cancer, respiratory infections, asthma, heart disease, and other forms of respiratory-related illnesses. Reducing air pollution, and thus developing air quality, has been found to decrease adult mortality.
Common products responsible for emissions include road traffic, energy production, household combustion, aviation and motor vehicles, and other forms of pollutants. These pollutants are responsible for the burning of fuel, which can release harmful particles into the air that humans and other living organisms can inhale or ingest.
Air pollution is associated with adverse health effects like respiratory and cardiovascular diseases, cancer, related illnesses, and even death. The risk of air pollution is determined by the pollutant's hazard and the amount of exposure that affects a person. For example, a child who plays outdoor sports will have a higher likelihood of outdoor air pollution exposure than an adult who tends to spend more time indoors, whether at work or elsewhere. Environmental health officials work to detect individuals who are at higher risks of consuming air pollution, detect risk factors present in communities, work to decrease overall community exposure.

Indoor air quality

contributes to diseases that kill almost 4.3 million people every year, as of 2014. Indoor air pollution contributes to risk factors for diseases like heart disease, pulmonary disease, stroke, pneumonia, and other associated illnesses. For vulnerable populations, such as children and elderly populations, who spend large amounts of their time indoors, poor indoor air quality can be dangerous.
Burning fuels like coal or kerosene inside homes can cause dangerous chemicals to be released into the air. Dampness and mold in houses can cause diseases, but few studies have been performed on mold in schools and workplaces. Environmental tobacco smoke is considered to be a leading contributor to indoor air pollution since exposure to second and third-hand smoke is a common risk factor. Tobacco smoke contains over 60 carcinogens, where 18% are known human carcinogens. Exposure to these chemicals can lead to exacerbation of asthma, the development of cardiovascular diseases and cardiopulmonary diseases, and an increase in the likelihood of cancer development.