Environment and Health

Environmental health is a branch of public health concerned with 
all aspects of the natural and built environment that may affect human health. 
Other phrases that concern or refer to the discipline of environmental health 
include environmental public health and environmental health and protection.
Environmental health is defined by the World Health Organization as:


  Those aspects of the human health and disease that are determined by factors 
  in the environment. It also refers to the theory and practice of assessing and 
  controlling factors in the environment that can potentially affect health. 
  Environmental health as used by the WHO Regional Office for Europe, includes 
  both the direct pathological effects of chemicals, radiation and some 
  biological agents, and the effects (often indirect) on health and well being 
  of the broad physical, psychological, social and cultural environment, which 
  includes housing, urban development, land use and transport. 

Environmental health services are defined by the World Health Organization as:
  those services which implement environmental health policies through 
  monitoring and control activities. They also carry out that role by promoting 
  the improvement of environmental parameters and by encouraging the use of 
  environmentally friendly and healthy technologies and behaviors. They also 
  have a leading role in developing and suggesting new policy areas.

Environmental health practitioners may be known as sanitarians, public health 
inspectors, environmental health specialists, environmental health officers or 
environmental health practitioners. In many European countries physicians and 
veterinarians are involved in environmental health. Many states in the United 
States require that individuals have professional licenses in order to practice 
environmental health. California state law defines the scope of practice of 
environmental health as follows:

"Scope of practice in environmental health" means the practice of 
  environmental health by registered environmental health specialists in the 
  public and private sector within the meaning of this article and includes, but 
  is not limited to, organization, management, education, enforcement, 
  consultation, and emergency response for the purpose of prevention of 
  environmental health hazards and the promotion and protection of the public 
  health and the environment in the following areas: food protection; housing; 
  institutional environmental health; land use; community noise control; 
  recreational swimming areas and waters; electromagnetic radiation control; 
  solid, liquid, and hazardous materials management; underground storage tank 
  control; onsite septic systems; vector control; drinking water quality; water 
  sanitation; emergency preparedness; and milk and dairy sanitation pursuant to 
  Section 33113 of the Food and Agricultural Code.

The environmental health profession had its modern-day roots in the sanitary and 
public health movement of the United Kingdom. This was epitomized by Sir Edwin 
Chadwick, who was instrumental in the repeal of the poor laws and was the 
founding president of the Association of Public Sanitary Inspectors in 1884, 
which today is the Chartered Institute of Environmental Health.
Environmental medicine may be seen as the medical branch of the broader field of 
environmental health. Terminology is not fully established, and in many European 
countries they are used interchangeably.

Disciplines


Three basic disciplines generally contribute to the field of environmental 
health: environmental epidemiology, toxicology, and exposure science. Each of 
these disciplines contributes different information to describe problems in 
environmental health, but there is some overlap among them.


Environmental epidemiology studies the relationship between environmental 
    exposures (including exposure to chemicals, radiation, microbiological 
    agents, etc.) 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. 




    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.


Information from these three disciplines can be combined to conduct a risk 
assessment for specific chemicals or mixtures of chemicals 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.