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 http://www.basel.int/convention/bc_glance.pdf).

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:
http://www.guardian.co.uk/news/datablog/interactive/2011/jun/27/data-store-water)

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.