Environmental health encompasses all issues of public health that might be affected by any aspect of the built or natural environment.
A more detailed definition comes from the World Health Organisation (WHO):
Environmental health addresses "... all 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-supporting environments."
In addition to including the pathological effects of chemicals, radiation and some biological agents on health and wellbeing, WHO also includes the often indirect effects of the broad physical, psychological, social and aesthetic environment including housing, urban development, land use and transport.
According to WHO, environmental hazards are responsible for about a quarter of the total burden of disease worldwide, but in regions such as sub-Saharan Africa this can be as much as a third. It is estimated that as many as 13 million deaths could be prevented each year if environments could be made healthier.
Environmental health services implement environmental health policies through monitoring and control activities. Depending on their location, environmental health practitioners may be known as sanitarians, public health inspectors, environmental health specialists or environmental health officers. In many European countries physicians and vets are also involved in environmental health.
The environmental health profession owes its roots to the sanitary and public health movement that grew up in the United Kingdom as a result of work by Sir Edwin Chadwick. Chadwick was a great social reformer, although in fairness much of his work was centred on a desire to reduce the costs of supporting a population that was unable to work due to ill health. He was convincedthat active measures such as cleaning, drainage and ventilation would make people healthier and therefore less dependent on welfare.
Following outbreaks of cholera, influenza and typhoid in London during the 1830s the government to ask Chadwick to carry out a new enquiry into sanitation. Chadwick used quantitative methods to show that there was a direct link between poor living conditions and disease and life expectancy. This investigation inspired the Public Health Act of 1848 and the establishment of the general Board of Health, of which Chadwick was the first director. He was the founding president of the Association of Public Sanitary Inspectors, which today is the Chartered Institute of Environmental Health.
There are many environmental health-related issues that affect modern life in both the developed and the developing worlds. These include, in no particular order:
Environmental health must also be aware of the impact that changes to ecosystems can have on human health. Examples of these changes and their impacts abound. Common examples include increases in the rates of asthma due to a rise in air pollution levels, PCB contamination of game fish in the Great Lakes of the United States and habitat fragmentation that has led to increased rates of Lyme disease.
Human interference with ecosystems has been found to cause a number of new infectious diseases such as SARS, Ebola virus, Nipah virus, Bird flu and Hantavirus. These diseases have high death rates and very few effective therapies.
It is important to bring together experts who will comprehensively study and understand how human health is negatively impacted by ecosystem changes. These experts will include physicians, vets, ecologists, economists, social scientists and planners. The aim will be to provide innovative, practical solutions to reduce or reverse the negative health impacts of ecosystem change.
A good example of the way such a project can act positively is with respect to malaria in Mexico. During the 1940s and 1950s every year 2.4 million people caught malaria and nearly 24,000 died as a result. The accepted method of dealing with the problem was to try to kill mosquitoes with DDT. Although some progress was made, the problem was far from being solved and the many of the harmful effects of DDT began to manifest themselves.
After 2002, when DDT was banned, a new approach was needed and a team of specialists began to gather evidence. Data from powerful geographical information systems enabled the team to conclude that mosquitoes do not travel very much. They also foundthat while women are more likely to be bitten by mosquitoes early in the morning when they go to fetch water, the men are likely to be bitten in the coffee plantations at night.As a result of the project, several preventive actions have been taken. The scientists have proposed a new insecticide that, unlike DDT, does not persist in the environment. They have also developed a more effective pump that can spray 40 homes a day instead of 8, and uses less insecticide.
Volunteers use a new malaria testing kit that detects the presence or absence of parasites in a patient's blood in only a few minutes instead of three to four weeks, so there is no longer a need to treat everyone who shows vague symptoms of the illness.
Mosquito larvae live in algae that is found on areas of water and every two weeks the algae is removed before the lavae have a chance to hatch. As a result of these actions, the number of cases of malaria in the state of Oaxaca has dropped from 15 000 in 1998 to only 400 today and all without using any DDT.
Other health hazards result from mankind's constant search for new sources of energy. An issue that currently has enormous potential for becoming an environmental health hazard is a process known as hydraulic fracturing or fracking. This is a process used to obtain natural gas from shale rock.
Natural gas is hailed as being the least polluting of all the fossil fuels and there are vast reserves worldwide.The problem is that it needs to be extracted from the shale in which it rests. Basically the fracking (hydraulic fracturing) method involves drilling a hole down to the seam of shale and then drilling at right angles along the seam. A controlled underground explosion at the end of the tunnel splits the rock and millions of gallons of water with a mix of chemicals are then pumped down at high pressure. This releases the shale gas, which rises to the surface along with all the waste water.
A New York Times investigation of gas wells in Pennsylvania reported that during the past three years more than 1.3 billion gallons of wastewater was produced. More than 179 wells were producing waste water with high levels of radiation and at least 116 reported levels of radium or other radioactive materials 100 times as high as the levels set by federal drinking-water standards. At least 15 wells produced waste water carrying more than 1,000 times the amount of radioactive elements considered acceptable.
Not only is the public water supply being contaminated, but so is rich farmland. The chief fear is what happens when the mystery slurry gets into the water supply. Activists and scientists reckon that if the process is safe, the companies should come clean about the chemical composition of the waste.
Most of the waste water was sent to treatment plants that are not equipped to remove many of the toxic materials in drilling waste. At least 12 sewage treatment plants in three states accepted gas industry waste water and this is discharged into rivers, lakes and streams after it has only been partly treated. Meanwhile the environmental health experts are keeping a very close eye on the situation.
Our world is in a continuing state of development but we seem to be beset by one potential environmental health crisis after another. Many of of these crises would have been beyond the wildest imaginings of Sir Edwin Chadwick, but it is to his successors that we look to for help in safeguarding our future.