The State of World Population 2001 The State of World Population 2001
Chapter 5: Health and the Environment

United Nations Population Fund

Environmental conditions help determine whether people are healthy or not, and how long they live. They can affect reproductive health and choices, and they can help determine prospects for social cohesion and economic growth, with further effects on health. Changes in the environment—pollution and degradation, climate change, extremes of weather—also change prospects for health and development.

Martha Cooper, Still Pictures
Women in India carrying pots. Rural poor women often carry heavy loads over long distances, contributing to ill-health.

Environmental conditions contribute significantly to communicable diseases, which account for about 20-25 per cent of deaths annually worldwide. The illnesses most closely related to environmental conditions—infectious and parasitic diseases and respiratory infections and diseases—endanger development prospects, particularly in poor countries and among poor people in any country. Unclean water and associated poor sanitation kill over 12 million people each year. Air pollution kills nearly 3 million more.

Changes in land use can create new breeding grounds. Irrigation or dam construction, for example, can encourage waterborne diseases: schistosomiasis established itself in Egypt and Sudan after the building of the Aswan dam. The clearing of tropical forest creates hardpan on which rainwater can collect and mosquitoes can breed. Malaria results in over 1 million deaths each year and accounts for some 300 million new clinical cases each year. Malaria causes 10 per cent of the total deaths in sub-Saharan Africa.1

It has been estimated that roughly 60 per cent of the global burden of disease from acute respiratory infections, 90 per cent from diarrhoeal disease, 50 per cent from chronic respiratory conditions and 90 per cent from malaria could be avoided by simple environmental interventions.2

In more-developed countries, these conditions contribute a lower proportion of the total burden of illness but still are responsible for outbreaks, especially in communities poorly served by sanitation and other clean-water services. Outbreaks of diphtheria in Central and Eastern Europe reflect poorer public health services (including low levels of vaccination) and greater migration of infected and susceptible populations in the wake of political change.3

Changes in health conditions directly affect development prospects and the chances for eradicating poverty. These are affected by a wide variety of conditions in the human and social environment.

Demographic Change and Health

Environmental change can dramatically improve urban health, as in European cities in the 19th century, when piped water and treated sewage eliminated the ancient threat of cholera. In Sri Lanka and other Asian countries in the 1940s a combination of spraying DDT and removing mosquito breeding places temporarily wiped out malaria. Such public health interventions hold down the burden of disease in many developing countries, especially in great cities, but they often fight a losing battle against growing populations, polluting industry, deteriorating infrastructure and housing stock, and shortage of resources.

Crowded living conditions, particularly in urban areas, spread infection. People living in poverty are the most crowded because of the cost of housing and the larger size of their families. Infants in poorer and more crowded portions of cities are at least four times more likely to die than infants in more affluent neighbourhoods. Environmentally related diseases, notably tuberculosis and typhoid, contribute to these differentials.

Trade links between large cities and the surrounding rural areas and smaller cities are accelerating with the integration of economies into the global system. Better transport to centralized markets has helped spread sexually transmitted diseases, including HIV/AIDS. Infection rates are markedly higher along lorry routes and at border towns where drivers congregate.

Ease of transport also allows diseases to travel between regions or continents within human hosts, other animals or cargo. Cholera has travelled from Bangladesh to Chile in the ballast tanks of a freighter. Cholera outbreaks following disasters in India have been spread by infected people leaving the area.

Migration to newly opened lands, sometimes as part of government-approved and -assisted colonization programmes,4 often removes settlers from the reach of health systems, including reproductive health services. Incentives for doctors and nurses to move to rural locations are generally insufficient and ineffective. Equipping and re-supply of remote facilities is difficult and their inadequacies deter settlers from using them.

Health services in settlements around cities are similarly poor. Mortality rates for the young can be higher than in more-established rural settlements.

Maternal mortality, though difficult to measure, is clearly much higher in rural areas—where fewer births are attended by trained staff and transport in case of pregnancy complications is difficult—than in cities, and higher still in new rural settlements.

Large families in new settlements also have a greater effect on their immediate environment than smaller ones. Their needs for food, fuel and water are greater and, with additional resource scavengers, so are their impacts.

Pollution and Health Threats

Air pollution kills an estimated 2.7 million to 3.0 million people every year, about 90 per cent of them in the developing world. The most critical components include: sulphur dioxide (from the burning of oil and high-sulphur coal); particulate matter (from domestic fires, power and industrial plants, and diesel engines); carbon monoxide and nitrogen dioxide (from petrol fumes from motor vehicles); ozone (from the effect of sunlight on vehicle emission-generated smog), and atmospheric lead (from burning leaded petrol or coal).

Outdoor air pollution harms more than 1.1 billion people and kills an estimated half million people per year, mostly in cities.5 Nearly 30 per cent of these deaths are in developed countries. Fine particulate pollution is responsible for up to 10 per cent of respiratory infections in European children (and twice as much in the most-polluted cities).6 The situation is particularly serious in the former Soviet Union where, despite reduced levels of industrial output, automobile transport has increased markedly.

Densely populated and rapidly growing megacities in developing countries subject their populations to levels of air pollution exposure far in excess of allowances recommended by the World Health Organization.7

The one hour per year maximum for specific concentrations (greater than 0.1 parts per million) and 30 days per year limit on generally high ozone exposure are exceeded in Mexico City regularly. The specific limits were exceeded for more than 1,400 hours over only 145 days in 1991. Similar excessive exposures are common in Santiago and São Paulo.

Asian megacities do better in ozone exposure, but worse with respect to WHO standards for suspended particulate matter and sulphur dioxide (for example in Beijing, Delhi, Jakarta, Kolkata and Mumbai). Cairo, Lagos and Tehran also show high exposure concentrations.

Automobile ownership is expanding rapidly in many developing countries. In Beijing, more than three quarters of survey respondents expect to purchase a car in the near future.8 India has recognized the growing contribution of automotive exhaust to city pollution. However, efforts in Mumbai to mandate use of liquid propane to power taxis have met strong opposition from drivers and fleet owners. (Similarly, efforts to regulate industrial emissions have generated a counter-response from small businessmen.)

Indoor air pollution—soot from the burning of wood, dung, crop residues and coal for cooking and heating—affects about 2.5 billion people, mostly women and girls, and is estimated to kill more than 2.2 million each year, over 98 per cent of them in developing countries.9

Air pollution's impact extends beyond direct health effects. Acid rain results from chemicals dissolved in precipitation. It increases the corrosive effect of rainfall on buildings and structures and makes the lands and waterways that receive it less productive. Alterations in the chemical balance of soils and water have widespread effects on plant and animal life. Air pollution also reduces food production and timber harvests by impairing photosynthesis. An estimate for Germany suggests that $4.7 billion in agricultural production is lost due to high levels of sulphur, nitrogen oxides and ozone.10

Heavy Metals

Heavy metals11 are released into the environment by metal smelters and other industrial activities, unsafe disposal of industrial wastes, and the use of lead in water pipes and petrol. The most dangerous metals, when concentrated above naturally occurring levels, include lead, mercury, cadmium, arsenic, copper, zinc and chromium. These have diverse effects relating to cancers (arsenic and cadmium), genetic damage (mercury) and brain and bone damage (copper, lead and mercury).

Shehzad Noorani, Still Pictures
Bangladeshi woman giving birth. Women weakened by environment-related health problems are more vulnerable in pregnancy and childbirth.

Lead pollution from leaded petrol (phased out in the United States and the European Community over the past three decades), worsened by use in inefficient or poorly maintained engines, causes widespread health problems in some countries. It contributes to lower levels of intelligence among exposed children and later loss of productivity in adulthood.

Nuclear Contamination

The contaminated areas around the Chernobyl nuclear facility in the Ukraine provide one of the starkest examples of the catastrophic dangers of unsafe nuclear power use.12 Over 2 million people were immediately affected, including 500,000 children. There has been a great increase in thyroid cancers, in some areas over a 100-fold higher incidence than expected. The full impact in thyroid and other cancers will develop over the coming years.

The 600,000 soldiers and civilians who worked to clean up the site over several years will also bear the burden of radiation exposure. The 50,000 who worked on top of the reactor building to put out the fire and build its new concrete containment were most seriously exposed and affected. Research suggests that some 30 per cent suffer from reproductive disorders (including higher levels of infertility and birth defects).

Many area residents are afraid to have children from fear of defects, fears that are complicated by the continuing decline in the capacity of the health system. Observed effects are clearly related to proximity and exposure. Malformations (including cleft palate, Down's syndrome and deformed limbs and organs) increased 83 per cent in severely contaminated areas, 30 per cent in mildly contaminated areas and 24 per cent in "clean" areas. The worst-affected region in neighbouring Belarus has seen increases in childhood cancers (more than 60 per cent), blood diseases (54 per cent) and digestive organ diseases (85 per cent).

Contamination of the land has restricted agricultural production, killed trees and polluted waters. Close attention will be required to monitor and prevent contamination of nearby waterways that supply 35 million people.

With growing awareness of the health and climate impacts of oil-, gas- and coal-fuelled power plants, reliance on nuclear power for electrical generation may increase. Many countries still do not have the capacity to run and regulate these facilities properly, or to prepare and implement emergency plans to handle accidents.

Reproductive Health and the Environment

Environmental factors have a direct effect on individuals' reproductive health and communities' response to reproductive health conditions. They also affect service access and quality. They have their most serious impacts among the poor, who are more likely to live near sources of pollution and use polluted resources.

Impacts start at or before birth. Exposure to some agricultural and industrial chemicals and organic pollutants are associated with pregnancy failures and with infant and childhood developmental difficulties, illness and mortality. Exposure to nuclear radiation and some heavy metals has genetic impacts. Exposure to new interactions, with reproductive risks stretching down the generations, is increasing.

Anaemia is common among ill-nourished girls and women and can affect the age at menarche. Frequent childbearing intensifies the incidence and severity of anaemia.

Rural poor women frequently carry large loads of water and household fuel (wood, charcoal and other bio-matter), often for long distances. In many communities environmental damage has greatly increased the distance women must go for fuel or water. In addition to their general effect on health and the possibility of injury, these heavy loads contribute to low weight and proportions of body fat among women. Below certain levels low body weight contributes to the cessation of menses and reduced fertility.

Women weakened by general ill-health, and by infectious and respiratory diseases, are much more vulnerable in pregnancy and childbirth, especially if they are very young, near the end of their reproductive years, or have had many children. They may also be more vulnerable to HIV infection.

Reproductive Health Service Challenges

Peri-urban and marginal land use. The unplanned development of land around cities and the opening of new, often marginal, rural lands increases the number of people in areas without health delivery infrastructures. The reduced availability of reproductive health services in these areas increases the risks of maternal mortality and unwanted pregnancy.

Water availability. In poor countries and countries in transition with shrinking health budgets, lack of water or clean water at health facilities is a serious problem. Quality health care, including reproductive health care, is impossible without adequate supplies of clean water.

Seasonality burdens. Cases of many diseases increase when seasonal conditions favour their spread. This is true, for example, of water-borne and insect-borne diseases during and after rainy seasons; and infectious diseases in cooler times when more people are indoors or in overcrowded schools. Pregnancies similarly may follow a pattern related to breaks in the agricultural work schedule or certain holidays, for example. These patterns affect the flow of visitors to clinics and hospitals. Improved flow management and staff training are required to maintain appropriate service quality, including sufficient time for counselling and follow-up, throughout the year.

Exposure to Persistent Organic Pollutants

Pollution from emissions, industrial processes, fertilizers, pesticides and waste is exposing people to higher levels and a broader range of chemicals than ever before. Many chemicals that did not exist 50 to 100 years ago are now widely dispersed throughout our environment.

People are at the top of their food chain (living on agricultural products and on animals, birds and fish which themselves consume affected organisms, water and prey) and are exposed to concentrated levels of pollutants. Most of these chemicals have not been studied, either individually or in combination, for their health effects. Many questions remain about their possible impacts on early foetal and childhood development in particular.13

Developed countries, the major producers of the new substances, vary dramatically in their concern and attention to the issue. The European Community, for example, tends to take a more cautious approach to the regulation of new chemicals than does the United States.

Since 1900, industrialization has introduced almost 100,000 previously unknown chemicals into the environment. Many have found their way into the air, water, soil and food—and human beings. One category of these chemicals, endocrine disrupters, is now suspected as an important cause of human reproductive disorders and infertility.14

An endocrine disrupter is a synthetic chemical that, when absorbed into the body, interferes with normal hormone function, sometimes altering the amount of hormones inappropriately, sometimes mimicking or blocking their action. This interference can undermine intelligence, decrease disease resistance, or impair reproduction.

Virtually every person on earth has been exposed to endocrine disrupters—through direct contact with pesticides and other chemicals or through ingestion of contaminated water, food or air. Many are persistent, accumulating in fat and other tissues, so human exposure may increase from eating fatty foods or contaminated fish.

Assumed endocrine-disrupting chemicals include some of the most commonly used substances in the developed and developing worlds. For example:

  • Phthalates—plasticizers found in polyvinyl chloride, used in plastic bags and intravenous equipment, as well as in soaps, hair sprays, nail polishes and cosmetics.
  • PCBs—formerly used in electrical equipment and still found in contaminated watersheds, landfills and other disposal sites.
  • Dioxins—produced during waste incineration and by industrial processes such as paper production.
  • At least 84 pesticides—some of the most common are DDT, lindane, vinclozolin, dieldrin, atrazine, 2-4 D (agent orange), 2,4,5-t, some pyrethroids and malathion. Many have been banned in the United States and Europe, but are still exported to and used in the developing world. In fact, pesticide use and human exposure are rapidly growing worldwide.

Research about the effects of these ubiquitous chemicals is not conclusive, but mounting evidence links endocrine disrupters to a range of problems, including: infertility among women; miscarriage; declining sperm counts; testicular and prostate cancer; and other reproductive disorders such as hypospadias (malformed penises), cryptochidism (undescended testes) and early puberty in girls; endometriosis; and breast, ovarian and uterine cancers. Children exposed in utero are more likely to suffer development problems and difficulties in learning or cognition.

Some recent research findings:

  • A February 2001 University of North Carolina (U.S.) study found that foetal deaths are almost twice as likely among pregnant women in California farming communities who live near areas where certain pesticides were sprayed. Deaths appeared to be a result of exposure during the first trimester of pregnancy. These findings are relevant to developing countries where regulation of chemical application is less stringent and where even more dangerous chemicals banned in the developed world are still used in agriculture and disease control.
  • A 1996 study in the Great Lakes region of the United States and Canada found that children born of women who had eaten fish from the lakes, which contain extremely high levels of PCBs, showed delayed motor development and dramatically lower levels of intelligence. PCBs are ubiquitous around the globe, particularly in poorer nations.
  • In 1997 the International Association for Research on Cancer found high levels of dioxin in human breast milk in 29 of 32 countries studied, including France, Pakistan, the Russian Federation, the United States and Viet Nam. WHO has called for measures to control and reduce dioxin and other organochlorines in the environment to eliminate or minimize exposure.
  • A controversial set of studies of U.S. girls points to a nationwide trend towards earlier and earlier puberty. Other studies show that girls exposed to high levels of PCBs and DDE (a product resulting from the breakdown of DDT) in utero entered puberty 11 months earlier than did those without such exposure. 

Existing evidence points to the need for more extensive and rigorous testing of chemicals, as currently proposed by the European Union; effective "right-to-know" laws that inform individuals about the chemicals to which they are exposed; better detection of exposures; and reducing and eliminating exposure in the first place.

In an important step towards achieving the latter, the United Nations Treaty on Persistent Organic Pollutants, signed in May 2000 and set to go into effect when ratified by 50 countries, is intended to control or eliminate 12 toxic substances, all of which are endocrine disrupters.

HIV/AIDS and the Environment

The causes and consequences of the HIV/AIDS crisis are closely linked to wider development issues, including poverty, malnutrition, exposure to other infections, gender inequality and insecure livelihoods. The epidemic, with its direct and devastating impact on health and the family, complicates the problem of environmental protection, intensifies agricultural labour problems and adds to the burdens of women in rural settings.

The Food and Agriculture Organization of the United Nations has pointed to the impact of the epidemic on agricultural sustainability. Tenuous land rights and low access to resources already limit rural women's choices. These disadvantages are heightened by the death from AIDS of male heads of farm households.

The loss of labour to the epidemic cripples the household. Infection rates are higher among women, who comprise most of the agricultural labour force, produce more than 80 per cent of household food and gather and manage other vital resources for their families.

The impacts are most severe in poorer communities, where farming is labour-intensive with little mechanization and few modern inputs. Land falls out of cultivation; tilling, planting and weeding are delayed; pests become more virulent. A farm may shift to crops needing less labour, and from cash to subsistence production. The loss of experienced farmers and agricultural extension workers deprives the community of their knowledge and management skills.

In severely affected areas, the numbers of surviving children and the elderly overload the community's systems of social support. Families are hard put to keep farms afloat, including their share of communal responsibility for land management, to feed and educate the children, or to care for the elderly. Loss of the male landholder may put even the survivors' tenure in question.

Adults and Children Living with HIV/AIDS, December 2000

The impact of the pandemic in urban centres limits prospects for development, including programmes for environmental protection. By killing workers in mid-life, including employees of productive industries and the public-sector workers such as doctors, nurses and teachers, the pandemic can negate a generation of investment in economic and social development.

Biodiversity Loss and Health

Most of the world's most effective pharmaceutical products have been discovered from compounds derived from plants or animals. These are frequently found in tropical climates, where biodiversity is greatest, and often in "biodiversity hotspots" subject to increasing human pressure.

Decreased genetic variability in agricultural crops also increases the vulnerability of the food supply to new pathogens. Resistance to pests and climate variation decrease without enough diversity in the strains of common food crops under cultivation. If crops were adversely affected, widespread hunger and disease would surely follow.

Ecologists have also rediscovered what many indigenous cultures and agriculturalists already knew—greater diversity among plants in a field can significantly increase their yields and resistance to pests. Population pressures, increasing consumption and the drive for cheap food have led to the intensification of agriculture. This change has often been achieved at the cost of a greater homogenization of cropping practices. Continuation of this trend could increase the risks to food security.

Great hopes have been placed on the development of genetically engineered crops suited to survive in difficult habitats (whether due to soil conditions, climate or pests). Slower population growth, consistent with the voluntary choices of women and men, could allow more time for the research, distribution and education efforts needed to ensure that such crops are safe and pose no long-term threats to sustainability; relaxing population pressure would also soften the blow of possible failures or reversals of progress.

Effects of Climate Change

There is no certainty about the effects climate change due to global warming might have on health, but what data there are suggest that countries should invest more in public health to meet possible hazards. Environmental change can increase the location, spread and intensity of insect- and water-borne diseases. Epidemics can develop when disease-carrying insects or animals reproduce out of control, or move to new locations where people have not developed immunities.

Higher temperatures may encourage insect hosts to breed and to move further up hillsides and mountains. They could also lead to changes in the geographical range of insect hosts as previously cooler areas become more hospitable. Exposure of new populations without prior immunity could lead to virulent outbreaks.15

Temperature variation could also shift the timing of seasons and the seasonal transmission of diseases. Changes in the timing of seasonal activities (e.g., harvest or planting times) could interact in complex ways to shift exposures and risks related to disease.

Higher rainfall could trigger mosquito-borne disease outbreaks, increase flooding (spreading parasitic diseases), increase the contamination of water supplies with human or animal wastes and increase exposures to run-off of pesticides and other chemicals.16 Studies in a lake region of Kenya show that malaria, acute respiratory infections and diarrhoeal diseases increase dramatically two or three months after heavy rainfalls.17

Arnaud Greth, Still Pictures
Geothermal plant in Iceland produces power without contributing to global warming. Climate change could increase outbreaks of various diseases.

Global warming will also increase the risks and danger of exposure to heat stress, especially in urban areas, which act as local heat traps because of their interference with air flow patterns, greater reflective surface area and local heat generation.18

Extreme weather events have a variety of effects on reproductive health, including an immediate short-term decline in fertility. This is largely the result of postponement or cancellation of marriages, decreased frequency of sexual relations and an increase in temporary separations. Fertility may subsequently increase as couples take up postponed or interrupted relationships, or respond to improving conditions and hopes.

Disasters also disrupt health services as infrastructure, equipment and drugs are lost, access becomes more difficult, and other immediate priorities supervene. Reproductive health, including safe motherhood, is an immediate victim, since pregnancy is not regarded as an emergency and contraception is not given priority in relief efforts. Extended settlement in temporary shelters or refugee camps exposes women and girls to sexual abuse, sexually transmitted diseases and unwanted pregnancies.19

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