Pesticides are an example of contaminants deliberately introduced into the environment that have played a significant role in the decline of species and the loss of habitat diversity. They interfere with and cause the breakdown of fundamental biogeochemical processes that support life support systems, including decomposition, mineral oxidation, nitrogen fixation and photosynthesis.

Pesticides are chemical compounds used to control plants and animals that are classified as pests. They are most widely used on crops, but they are also used in and around the home on insects, rodents, weeds, and plant diseases; in wood processing and preserving; in paint; in food storage; and in public health programmes. Insect and weed control are the two most common uses. Some pesticides are applied directly to plants or soil. Soon after application, they are dispersed into the environment, so that applications are often repeated. As the pesticides accumulate in the soil and wash into streams and rivers, they can affect fish and birds. Because of the wide spectrum of life forms which they attack, some call these pesticides biocides.

Because of the toxicity of pesticides in concentrated form and because of the frequency of exposure, the most serious human health effects are found among agricultural and production workers. Long-term and chronic health effects occur as the chemicals are ingested and inhaled. Bioaccumulation (the buildup of toxic materials in tissues) is evident in fish and birds as well as in humans.

Two different sets of problems are posed by the occurrence of persistent pesticides in the environment: (1) localized problems, tending to be acute, leading to recognizable effects with assignable origins, which can be dealt with if successfully sorted out and if the will and powers exist; and (2) more widespread problems, tending to be inferential with postulated effects, due to the universal presence of the materials in question. There is, for example, growing evidence from the amount of pesticide residues found in specimens of affected species as well as in the animals, fish, invertebrates, or plankton they feed upon, that there is a process of pesticide concentration in the food chains. As small amounts of persistent pesticides become more and more widely spread throughout the entire natural environment, they are absorbed by low forms of life. Where large numbers of these species serve as food for higher animals, some of the total pesticide remains in the eater. This can lead to a certain concentration of pesticides in a form of life at the end of the food chain. Eventually lethal doses may be reached for certain populations, or the species may be reduced because of adverse effects on reproduction or behaviour.

The importance of changes in the environment is that they may be irreversible: species may disappear altogether. This will cause ecological imbalance - certain forms of life whose numbers are controlled by the disappearing species will no longer be held in check. Thus an apparently harmless species may become a pest. Another result of reduction of species diversity may be the loss of the genetic possibilities that each organism disturbance of the selective pressures of the environment will reduce the chances of future development of desired plants and animals. Furthermore, as humans are at the top of food chains, they too tend to concentrate residues in their bodies with as yet unknown effects on them. While perhaps sufficient attention has been directed to acute toxicity problems, too little attention has been paid to the effect of long term ingestion by human beings of small amounts of these chemicals.

A serious dilemma is that the cheapest pesticides are the organochlorines, known to accumulate in human fat. The substitution of organophosphorus pesticides brings both higher cost and a need for more carefully trained operators, both of which pose problems.

Malaria is a parasite of red blood cells and the world's number one infectious disease. It is caused by infection of the liver with parasites of the genus Plasmodium, transmitted by the bite of infected anopheline mosquitoes Anopheles bifurcatus. The parasites cause the rupture of red blood cells and, in its worse cases, life-threatening anaemia, coma or death. The disease is characterized clinically by recurrent paroxysms of chills, high fever, seizures, sweating and prostration. It can lead to anaemia, kidney failure or rupture of the spleen. In man, malaria is produced by four specific parasites: Plasmodium vivax, P. malariae, P. ovale and P. falciparum. Falciparum malaria is the most life-threatening and has a fatality rate in untreated cases of 25%; it is transmitted by its African mosquito vector Anopheles gambiae.

Malaria is worsening in many parts of the world. It is a major threat to health and development, is primarily an environmental and socio-economic problem. Past reliance on narrow strategies is increasingly seen as the reason for the resurgence of this debilitating disease. The P. falciparum] parasite has continued to evolve resistance to almost all drugs in use (chloroquine, sulfadoxine/pyramethamine, and mefloquine). In areas of mosquito control, research with bed nets impregnated with pyrethroid insecticide offers hope of at least partial control of transmission of the disease in certain epidemiological situations. However, many people cannot afford the mosquito nets, which cost $5-10. Patients can usually be saved if they receive prompt medical treatment, but many of them cannot afford doctor's fees or the cost of travel, in total often less than $20.

Corruption is a debasement or subversion of integrity or purity and may occur in ideology or personal morality, culture, commerce, civil service (including police) or in politics. It constitutes a barrier to progress, and promotes conflict as a result of frustration and alienation; instability as a result of apathy; violence and crime. It may lead to social, ethnic, political, national and ideological disintegration and possibly revolution.

Corruption feeds on itself. People involved in petty corruption become increasingly involved in more and larger amounts. Corruption has many victims. Public corruption offenses affect all citizens directly and personally, particularly those at the lower end of the income scale. Building inspectors paid small amounts of money to approve shoddy work results in dangerous construction, substandard electrical wiring, and inferior building materials, usually in the poorest areas of town. Judges and lawyers who line their pockets result in criminals set free to victimize citizens. Taxpayers pay for corruption. When officials are bribed to award construction contracts the cost of the bribe goes into the cost of the construction often with interest. In a corrupt system, good people avoid public service. Honest contractors refuse to bid on government contracts; honest lawyers refuse to become prosecutors or judges; honest citizens avoid participating in politics either as voters or candidates.

Corruption has been highly detrimental for development. It introduces an element of irrationality in all planning and plan implementation by distorting the actual course of development plans. A common method of exploiting a position of public responsibility for private gain is the threat of obstruction and delay; hence corruption impedes the processes of decision-making and execution at all levels. It increases the need for controls to check the dishonest official. Thus it tends to make administration cumbersome and slow, and prohibits rational delegation of authority. Corruption and the widespread knowledge of corruption counteract the strivings for national consolidation and in particular, decrease respect for and allegiance to the government.

In its most evident form, corruption affects dealings of the public with government bureaucracy and political hierarchies whereby money or favour is given in exchange for a benefit from the official. This extends to dealings between business enterprises and the bureaucracy and politicians. But corruption may also affect any transactions, notably with or between businesses, even where no governmental or political body is involved. In its simplest form corruption consists mainly of bribery and tipping. Generally bribes are negotiated payments made before a transaction, whereas tips, reflecting gratitude are paid afterwards based on the evaluation of the donor with regard to short-term and long-term interest in the relationship.

The capacity for industrialization and economic growth depends, to a large extent, on a nation's ability to develop the productivity of its manpower, in particular that of individuals in top managerial positions.

A chronic illness usually develops slowly, lasts for an indefinite period of time, can deteriorate overall health and usually requires intervention to resolve.  Many chronic diseases are uncertain in prognosis. Cure is problematic or impossible, so treatment concentrates in making the patient comfortable or relieving pain. Sometimes patients suffer from multiple diseases; and the side effects of medical treatments can lead to additional chronicity. Long-time use of drugs, routine monitoring and crisis requiring hospitalization make chronic diseases expensive. The extent to which patients succumb to the various effects of chronic disease depends upon numerous factors, in particular their psycho-social support, financial status, childhood experiences, sense of humour and determination to push on.