Man's health is being impaired by activities which contaminate the air, water, food, soil and biota. These activities include harmful discharges resulting from uncontrolled industrial development, the indiscriminate use of pesticides and fertilizers and the poor or non-existent planning of water supply and waste disposal in human settlements, resulting in certain endemic diseases. People are increasingly exposed to overcrowding and noise, to an atmosphere polluted by smoke and exhaust fumes in towns and cities, to chemical and physical hazards at work to food that may contain residues of insecticides and fungicides, and to polluted water in many rivers and lakes and even the oceans. In spite of all that has been done to improve basic environmental conditions, the pollution of much of the world's natural water resources by sewage, household refuse, industrial effluents and agricultural wastes, and run-off containing organic matter, pesticides and fertilizers, makes it more and more difficult to provide growing populations, or even relatively static ones, with enough safe water to meet their needs.
The system of government of a country, its geographic characteristics and size, its political philosophy, its economic situation and its stage of development, affect the way that environmental health services have developed and how they function. In contrast to public health and food safety services, which have a history stretching back more than a century, the problems of the environment as a whole have been recognized for only about two decades. Certain aspects of the environment, notably water pollution and emissions from chemical works, have been the subject of legislation that dates back to the 19th century but only recently has an attempt been made in a few countries to consider the environment as an integrated whole. Many countries are trying to consolidate responsibility for environmental services with varying degrees of success. While protection of the environment in theory works to the general benefit, the measures taken to this end are inevitably considered detrimental to certain interests and will therefore be resisted. The result, in many cases, has been a highly fragmented set of laws and regulations with exceptions and special conditions introduced to secure overall approval.
Because monitoring is often divided among various agencies, none has overall responsibility for coordinating the results or setting standards to cover all the routes of intake (air, water, food, tobacco, occupational exposure, etc.) of toxic substances into the body. Only rarely are standards based on local conditions of exposure backed up by the biological monitoring of tissue and epidemiological surveillance. Indeed, the trend is to rely on multinational standards or guidelines, employing a safety factor to cover local variations. Standards for lead in water, air, petrol, paint and food, for example, are the responsibility of up to five different agencies, each of which may monitor its own medium, while the monitoring of soil around the home - a major source of intake by smaller children – may be no one's responsibility. Many other examples of divided responsibility can be found. The reasons for dispersed authority lie in the legislative history of the countries surveyed. Agencies and ministries have been set up over the years on an ad hoc basis to deal with water, food, industrial resources, occupational exposure, etc, as each one came to be seen as a problem. The responsibility for monitoring was frequently assigned to an existing body that was already dealing with supply or distribution, sometimes with the requirement that the health aspects be coordinated with the ministry responsible for public health. Even when several agencies have been combined under one ministry responsible for the environment, certain strongly entrenched departments have successfully resisted efforts to transfer their activities to that authority. In fact, a division of responsibility may exist even within a ministry if it is organized with separate departments for air, water supply, waste disposal, etc.
In countries where development is at a relatively low level and where the problems of the human environment are closely linked to poverty and to the very lack of development itself, human health and life are continually jeopardized by biological pollution resulting from insanitary conditions, both in congested urban areas and in rural areas. The absence of safe water supplies and of facilities for the sanitary collection and disposal of human excreta, refuse and industrial waste, and the prevalence of vectors of disease, with the consequent high incidence of sickness from communicable diseases, are still the prime environmental problems in these developing countries.