Living in a city and caught up in the cross-currents of our daily living dilemmas and demands, we barely notice the pollution that is there all around us, inside us, sometimes in deafening forms, but mostly in a surreptitious manner. If truth be told, pollution, which is clearly one of the leading contributing factors to death and disability in the world, has gained a good degree of acceptance among us city dwellers. We tolerate it far more than should be the case. Sometimes, when we find it staring us in the face, we give it a curious glance (oh, you are here to stay, are you?), acknowledge its presence with a sideways nod (suit yourself, will you?), and move on with whatever it is that we have to do to make the ball of living rolling.

So, most of us know that urban air pollution not only exists but also thrives. How about car battery recycling, though? And contaminated surface water and groundwater? Do we suspect that metal processing smelters or facilities can have negative fallout on what we consume as food?

A report titled ‘World’s Worst Pollution Problems’, work on which was undertaken by New York-based Blacksmith Institute and Green Cross Switzerland, identifies six toxic pollutants that impact the health of tens of
millions of people, primarily children. The six pollutants in order of the impact they have are lead, mercury, chromium, arsenic, pesticides, and radionuclides.

The focus on specific pollutants reflects a more sophisticated understanding of the scope of toxic pollution globally. The 2010 report provides evidence of the scope of pollution and the global distribution of each pollutant, as these toxic substances originate from a number of different sources. Lead, the world’s worst toxic threat, comes from leaded gasoline for transportation, metal smelters, battery recycling, sinker production for fishing, colour and ceramics manufacturing, and lead mats for radiation protection. Due to its many different sources, lead is a health risk for people on every continent.

Read ahead and learn more about the world’s worst pollution problems.

Groundwater contamination
Groundwater is rainwater or water from surface water bodies, like lakes or streams, which soaks into the soil and bedrock and is stored underground in the tiny spaces between rocks and particles of soil. Groundwater is almost 97 per cent of the world’s accessible freshwater resource. About two billion urban and rural people depend on groundwater for everyday needs.

Groundwater pollution occurs when hazardous substances come into contact with the water that has soaked into the soil. Groundwater can be polluted by municipal, industrial, agricultural, and individual sources. Municipal sources of groundwater contamination include open dumpsites, poorly constructed landfills, latrines, and other waste sites. Industrial pollution can emanate from dumping of wastewater or waste, from untreated effluents, from mining activities, and from leakage or spillage from other industrial processes.

Wastewater disposal practices of certain types of businesses, such as automobile service stations, dry cleaners, electrical component or machine manufacturers, and metal platters or fabricators are particularly suspect because the waste they generate is likely to contain toxic chemicals. Other industrial sources of contamination include cleaning off holding tanks or spraying equipment on the open ground and storing hazardous materials in
uncovered areas or in areas that do not have pads with catchment basins. Mining of fuel and non-fuel minerals can create many channels for groundwater contamination through the mining process itself, disposal of wastes, and processing of the ores and the wastes it creates.

Agricultural contamination is primarily due to spillage of fertilizers and pesticides during handling; runoff from the loading and washing of pesticide sprayers or other application equipment; using chemicals uphill from or within a few hundred feet of a well; storage of agricultural chemicals near conduits to groundwater, such as open and abandoned wells, and sink holes; and chemicals stored in uncovered areas or in locations where the groundwater flows from the direction of the chemical storage to the well.

Individuals pollute groundwater by improperly disposing of household chemicals such as paints, synthetic detergents, solvents, oils, medicines, disinfectants, pesticides, batteries, and motor oil.

Industrial mining activities
The report ‘World’s Worst Pollution Problems’ uses industrial mining activities to include mines that are currently engaged in mineral and metal extraction operations. The materials can range from common to precious and from inert to hazardous. Mining for precious metals, coal, and other commodities forms an important part of many countries’ economies. Developing countries such as Brazil, China, India, and Peru contribute a large proportion of the world’s mining products. For example, of the total world production of
iron ore (1,020,000 metric tons), 21% is produced by China, 19% by Brazil, and 7% by India (USA National Mining Association 2002).

The most common pollution problem for an active mine arises from the disposal of mineral wastes, mainly mine waste rock and tailings. Economic ore deposits contain many chemical elements in addition to those that are extracted for sale. Some of these are toxic and they are often present at concentrations that pose risks to the environment and human health. They can be leached from both sources, transported by wind, or taken up by plants and animals in the human food chain. Physical agents such as asbestos and crystalline silica can also be windborne, and radioactive minerals pose their own set of risks. Substances emitted from or present at mine sites can enter the body in a variety of ways such as inhalation, absorption through dermal contact, or ingestion of contaminated food and water.

Metal smelters and processing
Metal processing smelters or facilities extract metals from ore to create more refined metal products such as copper, nickel, lead, zinc, silver, cobalt, gold, and cadmium. Smelting specifically involves heating the ore with a reducing agent such as coke, charcoal, or other purifying agents.

Emissions of high quantities of air pollutants such as hydrogen fluoride, sulphur dioxide, oxides of nitrogen, offensive and noxious smoke fumes, vapours, gases, and other toxins can be found near facilities that carry out metal and smelting processes.A variety of heavy metals like lead, arsenic, chromium, cadmium, nickel, copper, and zinc are also released by the facilities.

Inhalation of pollutants occurs as a consequence of gaseous emissions and fine dust or particulate matter (pm). Metal-bearing dust particles can travel distances to pollute the soil and surface waterways. Layers of dust can settle on to nearby agricultural fields, causing crop intake of pollutants and later consumed by humans. Particulate matter emissions, sewage waters, and solid wastes also enter waterways used for drinking water.

Radioactive waste and uranium mines
As explained in the report ‘World’s Worst Pollution Problems’, radioactive materials are used for power generation, military purposes, treatment and analyses in the medical sector, material control and treatment in industry, products of daily life, and scientific applications. Radioactivity is the sign that matter is decaying in order to reach, according to the law of physics, a better energetical state.

As materials decay, they emit radiation, eventually disintegrating entirely and becoming innocuous. For some materials, this process can happen in a fraction of a second. For others, however, it can take as long as millions of years.

Radioactive waste is categorized broadly as high- or low-level waste. The former results primarily from fuel used in civilian or military reactors, and the latter from a range of processes including reactors and industrial and commercial uses. High-level waste typically refers to ‘spent’ fuel from a nuclear reactor. Most reactors are powered by uranium fuel rods, which are at the beginning only slightly radioactive. However, when the fuel rod is ‘spent,’ or used, it is both highly radioactive and thermally hot.

Radioactive materials cannot be treated. Areas contaminated with radioactive waste are uninhabitable for the lifetime of their radioactive contents, which can amount to half a million years. There are worldwide efforts to find ways that high-level wastes can be reliably sealed off from the biosphere for at least a million years in so-called final repositories. Isolation from the biosphere is provided by placing several containment barriers between the waste materials and the external environment, arranged in succession so that each barrier reinforces the preceding one (multi-barrier system). However, there is no permanent storage site that is free from the hazards of radioactive waste. Nuclear waste has been dumped into oceans, rivers, and lakes, and into the ground. Leaking containers of radioactive wastes add to this on a daily basis, endangering the earth’s groundwater.

There is no ‘safe’ level of radiation exposure. In the words of Dr Helen Caldicott (1994), all it takes is one cell and one radioactive decay for the possibility of cancer, or a genetic defect. Radioactivity impacts the human metabolism in a wide variety of ways. Its effects can be dramatic, attacking all body functions in cases of severe exposure but more commonly seen as causing a range of cancers from exposure over a period of time or impacting the genetic code, which can result in health problems transmitted to the following generations.

Untreated sewage
Sewage refers to liquid wastes containing a mixture of human faeces and wastewater from non-industrial human activities such as bathing, washing, and cleaning. In many poor areas of the world, sewage is dumped into local waterways, for the lack of alternatives. For instance, it is estimated that in Latin America only 15 per cent of wastewater is treated, and sewage treatment is virtually unheard of in sub-Saharan Africa.

Untreated sewage contains waterborne pathogens that can cause serious human illnesses including cholera, typhoid, and dysentery. Other diseases resulting from sewage contamination of water include hepatitis A and
intestinal nematode infections. The World Health Organization (WHO) estimates that 1.5 million preventable deaths per year result from unsafe water and inadequate sanitation or hygiene. WHO also estimates that 2.6 billion people lacked access to improved sanitation facilities in 2008, with the lowest coverage in sub-Saharan Africa (37%), Southern Asia (38%), and Eastern Asia (45%).

Untreated sewage also destroys aquatic ecosystems. Increased organic matter (from the sewage) breaking down in the river reduces the amount of dissolved oxygen in the water body as the decomposition process uses up the
available dissolved oxygen. Fish and other aquatic life need that dissolved oxygen in the water to live.

Eutrophication, which refers to the excessive deposition of chemical nutrients in water bodies, is one of the numerous problems created by sewage water pollution. Degradation of the quality of water, reduction in the
number of fish, and increase in biological oxygen demand (BOD) are the effects of eutrophication.

Urban air quality
Airborne pollutants are emitted into the atmosphere by burning fossil fuels such as petrol and natural gas, vehicle engines, and industrial production; by combustion of biomass for agricultural or land-clearing purposes; and by natural processes such as windblown dust, volcanic activity, and biologic respiration. Studies have shown that air pollutants from carbon-based fuels include such contaminants as carbon monoxide, nitrogen oxides, and other harmful gases and particles.

Various studies suggest that gas and aerosol pollutants are routinely transported by winds across and between continents and can affect the air and climate of areas far from their source. However, specifics of climate and
geography play an important role in the persistence and severity of the pollution. In warm and sunny climates, air in the upper atmosphere can become warm enough to inhibit vertical air circulation and the dispersion of air
pollutants, trapping smog in the lower atmosphere.

Major health effects associated with outdoor air pollution include respiratory and cardiovascular disease, lung cancer, asthma exacerbation, acute and chronic bronchitis, restrictions in activity, and lost days of work. The WHO estimates that 865,000 deaths per year worldwide can be directly attributed to outdoor air pollution. Most studies on the health effects of outdoor air pollution have focused on urban environments (>100,000 people). People living in large urban areas, especially in developing countries, where the health risks of air pollution may be underappreciated and pollution controls lacking, are routinely exposed to concentrations of airborne pollutants.

Other greenhouse gases include methane—which comes from such sources as swamps and gas emitted by livestock—and chlorofluorocarbons (CFCs), which were used in refrigerants and aerosol propellants until they were banned because of their deteriorating effect on Earth’s ozone layer.

Ozone can be both beneficial and harmful to life on Earth. In the stratosphere, it prevents most of the harmful ultraviolet rays from reaching the Earth’s surface. But in the troposphere, near the Earth’s surface, the ozone is a pollutant.

Used lead acid battery recycling
Lead acid batteries are rechargeable batteries made of lead plates situated in a ‘bath’ of sulphuric acid within a plastic casing. They can commonly be recognized as ‘car batteries’. About 6 million tons of lead is used annually, on a worldwide basis, of which roughly three-quarters goes into the production of lead-acid batteries, which are used in automobiles, industry, and a wide range of other applications. Much of this existing demand for lead is
met through the recycling of secondary material and in particular from lead recovered from used lead-acid batteries. Once the lead acid battery ceases to be effective, it is unusable and deemed a used lead acid battery (ULAB), which is classified as a hazardous waste under the Basel Convention (‘The Basel Convention at a Glance’. Basel Convention. United Nations Environmental Programme. Available at

Recycled lead is a valuable commodity and for many people in the developing world the recovery of car and similar batteries (ULABs) is a profitable business. Many developing countries have entered the business of
buying ULABs in bulk in order to recycle them for lead recovery. ULAB recycling and smelting operations are often located in densely populated urban areas with few (if any) pollution controls. In many cases, the local recycling operations are not managed in an environmentally sound manner and release lead-contaminated waste into the local environment and ecosystems in critical quantities. Despite efforts by government agencies and the industry to establish safer and more efficient practices, ignorance of the risks of lead contamination combined with a lack of viable economic alternatives has led to the systemic poisoning of many poor populations throughout the developing world. Blacksmith Institute estimates that over 12 million people are affected
by lead contamination from processing of used lead acid batteries throughout the developing world.

Exposure to lead through inhaling dust, fumes or vapours dispersed in the air can cause impaired physical growth, kidney damage, retardation, and in extreme cases even death. Lead poisoning can lead to tiredness, headache, aching bones and muscles, forgetfulness, loss of appetite, and sleep disturbance.

Contaminated surface water
With growing populations and an overall increase in living standards, not only is the overall demand for freshwater pushing limits (one third of the world now lives in areas of ‘water stress’), but increasing pollution from urban, industrial, and agricultural sources is also making available resources either unusable or dangerous to health. Water stress occurs when the demand for water exceeds the available amount during a certain period
or when poor quality restricts its use. Water stress causes deterioration of freshwater resources in terms of quantity (aquifer over-exploitation, dry rivers, etc.) and quality (eutrophication, organic matter pollution, saline
intrusion, etc.).

Every human needs about 20 litres of freshwater a day for basic survival (drinking and cooking) and an additional 50 to 150 litres for basic household use. Rural communities around the world traditionally take
their water supply from rivers or from shallow dug wells. Growing concentrations of people combined with the increasing industrialization of land use have resulted in many major rivers becoming highly polluted. Key pollutants in the water systems are typically pathogens arising from human waste (bacteria and viruses), heavy metals, and organic chemicals from industrial waste.

Water pollution is one of the greatest causes of mortality that can be linked to environmental factors. Almost five million deaths in the developing world annually are due to water-related diseases.

According to Population Action International, based upon the UN Medium Population Projections of 1998, more than 2.8 billion people in 48 countries will face water stress by 2025. Of these countries, 40 are in West Asia, North Africa, or sub-Saharan Africa. By 2050, the number of countries facing water stress or scarcity could rise to 54, with a combined population of four billion people – about 40 per cent of the projected global population of
9.4 billion (Gardner-Outlaw and Engleman 1997; UNFPA 1997).

(Click here for an interactive map on global water stress:

Indoor air pollution
The most significant cause of indoor air pollution in the developing world is the burning of coal or unprocessed biomass fuels for cooking, heating, and light.

The practice of cooking with wood or cow dung inside houses exposes millions of women to fine particles of air pollution in developing countries. This can cause premature death and lung disease. In poorly ventilated dwellings, indoor smoke can exceed acceptable levels for small particles 100-fold. Biomass fuels are typically burned in rudimentary stoves. Few of these fully combust the fuel, resulting in inefficient use of fuel and
unnecessarily large air emissions.

University of Wisconsin-Madison researchers have linked indoor air pollution with increased blood pressure among older women. Indoor air pollution mostly affects health through inhalation, but can also affect the
eyes through contact with smoke. This category of pollution contributes to nearly three million deaths annually and constitutes four per cent of the global burden of disease. There is strong evidence that chronic exposure to
indoor air pollutants increases the risk of a range of respiratory illnesses, including acute lower respiratory infections (ALRI) in children and chronic obstructive pulmonary disease (COPD) in adults. In addition, chronic exposure to coal smoke results in increased risk for lung cancer. Women and young children are at greatest risk because they spend the most time indoors. Studies have shown that improved stoves or cleaner fuels can cut indoor air pollution by 50 per cent to 75 per cent.

Artisanal gold mining
Artisanal and small-scale mining (ASM) refers to mining activities that use rudimentary methods to extract and process minerals and metals on a small scale. Artisanal miners frequently use toxic materials in their attempts to recover metals and gems. They work in mostly hazardous conditions. Further, in the absence of knowledge or any regulations or standards, toxic materials can be released into the environment, posing great health risks to the miners and surrounding communities.

Artisanal gold mining releases mercury into the environment in its metallic form during amalgamation and as mercury vapour during the burning process. It is one of the most significant sources of mercury release into the environment in the developing world. According to United Nations Industrial Development Organization (UNIDO), as much as 95 per cent of all mercury used in artisanal gold mining is released into the environment. UNIDO estimates that mercury amalgamation from this kind of gold mining results in the release of an estimated 1,000 tons of mercury per year, which constitutes about 30 per cent of the world’s anthropogenic mercury emissions. It is estimated that there are between 10 million and 15 million artisanal and small-scale gold miners worldwide, including 4.5 million women and 600,000 children.