Environmental health

Environmental health is the branch of public health that is concerned with all aspects of the natural and built environment that may affect human health. Other terms that refer to the discipline of environmental health include environmental public health and environmental health and protection.

Environmental health practitioners may be known as sanitarians, public health inspectors, environmental health specialists or environmental health officers.

Nutrition and Health
There are six main nutrients that the body needs to receive: carbohydrates, proteins, fats, vitamins, minerals, and water. It is important to consume these six nutrients on a daily basis to build and maintain healthy body systems.

Ill health can be caused by an imbalance of nutrients, producing either an excess or deficiency, which in turn affects body functioning cumulatively. Moreover, because most nutrients are, in some way or another, involved in cell-to-cell signalling (e.g. as building block or part of a hormone or signalling 'cascades'), deficiency or excess of various nutrients affects hormonal function indirectly. Thus, because they largely regulate the expression of genes, hormones represent a link between nutrition and how our genes are expressed, i.e. our phenotype. The strength and nature of this link are continually under investigation, but observations especially in recent years have demonstrated a pivotal role for nutrition in hormonal activity and function and therefore in health.

Soil contamination is the presence of man made chemicals or other alteration to the natural soil environment. This type of contamination typically arises from rupture of underground storage tanks, application of pesticides, percolation of contaminated surface water to subsurface strata, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals. This occurrence of this phenomenon is correlated with the degree of industrialization and intensity of chemical usage.

The concern over soil contamination stems primarily from health risks, both of direct contact and from secondary contamination of water supplies.

Health effects
The major concern is that there are many sensitive land uses where people are in direct contact with soils such as residences, parks, schools and playgrounds. Other contact mechanisms include contamination of drinking water or inhalation of soil contaminants which have vaporized. There is a very large set of health consequences from exposure to soil contamination depending on pollutant type, pathway of attack and vulnerability of the exposed population. Chromium and many of the pesticide and herbicide formulations are carcinogenic to all populations. Lead is especially hazardous to young children, in which group there is a high risk of developmental damage to the brain and nervous system, while to all populations kidney damage is a risk.

Chronic exposure to benzene at sufficient concentrations is known to be associated with higher incidence of leukemia. Mercury and cyclodienes are known to induce higher incidences of kidney damage, some irreversible. PCBs and cyclodienes are linked to liver toxicity. Organophosphates and carbamates can induce a chain of responses leading to neuromuscular blockage. Many chlorinated solvents induce liver changes, kidney changes and depression of the central nervous system. There is an entire spectrum of further health effects such as headache, nausea, fatigue, eye irritation and skin rash for the above cited and other chemicals. At sufficient dosages a large number of soil contaminants cause death.

Drinking water is water that is intended to be ingested by humans. Water of drinkable quality is termed potable water, whether it is used as such or not. Although many fresh water sources are utilised by humans, some contain disease or pathogens and cause long-term health problems if they do not meet specific water quality guidelines. Water that is not harmful for human beings is sometimes called safe water, water which is not contaminated to the extent of being unhealthful. The available supply of drinking water is an important criterion of carrying capacity, the population level that can be supported by planet Earth.

As of the year 2006 (and pre-existing for at least three decades), there is a substantial shortfall in availability of potable water, primarily arising from overpopulation in lesser developed countries. Many nations have water quality regulations for water sold as drinking water, although these are often not strictly enforced outside of the developed world. The World Health Organization sets international standards for drinking water.

Environmental health services
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 behaviours. They also have a leading role in developing and suggesting new policy areas.

Environmental Tobacco Smoke (ETS), is a serious and deadly environmental health issue facing workers across the world. On June 27, 2006, the U.S. Surgeon General released an in-depth report which analyzed the body of science relating to the disease and death caused by secondhand smoke.

Sanitary sewer overflow (SSO) is a condition whereby untreated sewage is discharged into the environment, escaping wastewater treatment. This situation, also known as Wet Weather Overflow, is primarily meaningful in developed countries, which have extensive sewage treatment facilities. The main causes of SSO are:


 * Infiltration of excessive stormwater into sewer lines during heavy rainfall
 * Rupture or blockage of sewerage lines
 * Malfunction of pumping station lifts or electrical power failure
 * Human operator error at treatment plant facilities

Since a number of countries have essentially 100 percent treatment of domestic wastewater, an SSO episode is viewed as a significant breakdown in environmental control of water resources; for example, the USA, Japan, the United Kingdom and some other European countries strive for complete secondary treatment of all effluent and pursue vigorously shortcomings in the sewerage systems.

By far the most prevalent cause of Sanitary Sewer Overflow stems from heavy rainfall events which can cause massive infiltration of stormwater into sewerage lines. This circumstance is most prevalent in older cities whose subsurface infrastructure is quite old; Inflow into the sanitary lines can be caused by tree root rupture of subsurface lines or by mechanical fracture due to age and overpressure from trucks and buildings above.

Other modes of system failure can include power outage which may disable lift station pumps or parts of the treatment plant operations themselves; in fact, any mechanical system failure within a treatment plant can create a circumstance leading to overflow: breakdown of rotating arms of trickling filters, jamming of line gates, clogging of filters or grates etc. Furthermore, some forms of human error can infrequently lead to diversion of sewage and result in an overflow event.

Decentralized failures in dry weather mainly occur from collection sewer line blockages, which can arise from a debris clog, line rupture or tree root intrusion into the line itself. One of the main problems of a decentralized line failure is the difficulty of defining the location of overflow, since a typical urban system contains thousands of miles of collection pipage, and the central treatment plant has no way of communicating with all the lines, unless expensive monitoring equipment has been installed.

Human health and ecological consequences
Human health impacts include significant numbers of gastrointestinal illness each year, although death from one overflow event is uncommon. Additional human impacts include beach closures, swimming restrictions and prohibition against consumption of certain aquatic animals (particularly certain molluscs) after overflow events. Ecological consequences include fish kills, harm to plankton and other aquatic microflora and microfauna. Turbidity increase and dissolved oxygen decrease in receiving waters can lead to accentuated effects beyond the obvious pathogenic induced damage to aquatic ecosystems. It is possible that higher life forms such as marine mammals can be affected since certain seals and sea lions are known to experience peaks in pathogenic harm