A child gets his blood tested for lead poison levels at a clinic set up in Flint, Michigan, after the city’s drinking water became contaminated with dangerously high levels of lead. Photograph: Jim Young/Reuters
Nearly one in four deaths are linked to unhealthy environments and are avoidable, a new World Health Organisation study – the first major assessment of environmental risk since 2006 – has shown.
It suggests environmental risks now contribute to more than 100 of the world’s most dangerous diseases, injuries, and kills 12.6 million people a year – nearly one in four or 23% of all deaths.
Of these, two-thirds or 8.2m deaths are from non-communicable diseases (NCDs), such as strokes, cancers and heart illnesses, a significant rise in 10 years, say the authors.
While the number of deaths from infectious diseases, including diarrhoea and malaria, have fallen since 2006, those from NCDs linked to indoor and outdoor air pollution, climate change and exposure to synthetic chemicals have increased, the WHO report says.
The two biggest global environmental killers are strokes (2.5m a year), heart disease (2.3m), and unintentional injuries such as road accidents which kill 1.7 million people a year. Cancers linked to the environment kill 1.7 million people, respiratory diseases 1.4 million, and diarrhoeal diseases 846,000.
“A healthy environment underpins a healthy population,” says Margaret Chan, WHO director general. “If countries do not take actions to make environments where people live and work healthy, millions will continue to become ill and die too young.”
Many of the deaths are linked to poverty and rapid urbanisation, says the report, with indoor and outdoor air pollution increasingly significant.
“Decreases in air quality have been observed in many low- and middle-income cities around the world in recent years. Increased exposure to air pollution will mainly increase NCDs, but also respiratory infections in children under five years,”says the report.
“Modern risks, like ambient air pollution and unsafe use of chemicals, tend to increase in countries undergoing rapid development, before control over such factors is improved when full transition to high-income societies is made.”
Air pollution and rapid industrialisation in China, India and elsewhere in south-east Asia and the Pacific regions is now a major cause of deaths and illness, the report finds. The massive rise in industrial production, urbanisation and car ownership has lifted these regions to the top of the global unhealthy environment league table with 7.3m deaths a year. Most, says the report, are attributable to air pollution.
“Air pollution was associated with increased hospital admissions and deaths from stroke. The evidence for an association between stroke and both short-term and prolonged increased exposure to fine particles (PM2.5) is increasing. Also, short-term exposure to increased ozone levels was associated with stroke incidence. In 2012, 25% of the global stroke burden was attributable to ambient air pollution,” it says.
Cancers are now a leading cause of death worldwide, says the WHO, with one in five of all people and one-third in industrialised countries expected to develop the disease in their lifetimes. Around 19% of all cancers are estimated by the WHO to be attributable to environmental factors.
Smoking is the greatest risk for developing lung cancer, but more than 20 other environmental and occupational agents are proven lung carcinogens in humans.
Air pollution, for example from indoor burning of coal or biomass, was associated with substantial increases of lung cancer risk. Lung cancer caused nearly 1.6m deaths in 2012 and was the largest contributor to cancer related mortality.
About 18% of all heart disease was linked to household air pollution. About 35% of the total burden of heart disease was attributed to the environment.
However, great improvements to water supplies, sanitation and waste in Africa and other developing countries have been made in 10 years. Better access to immunisation, insecticide-treated mosquito nets and essential medicines have all reduced deaths from the environment, says the WHO.
“Total environmental deaths are unchanged since 2002, but show a strong shift to noncommunicable diseases,” say the authors. “The last decade has seen a shift away from infectious, parasitic and nutritional diseases, not only in terms of the environmental fraction but also the total burden.
“This shift is mainly due to a global decline of infectious disease rates, and a reduction in the environmental risks causing infectious diseases. A higher share of people have access to safe water and sanitation, and a lower share of households use solid fuels for cooking.”
But the death toll from infectious diseases is still very high, largely because of increased populations.
“Diarrhoeal diseases are one of the main contributors to global child mortality, causing 20% of all deaths in children under five years. WHO recently estimated that 58% of all cases of diarrhoea in low and middle income countries could be attributed to inadequate drinking-water (34%), sanitation (19%) and hygiene (20%).
“Malaria is estimated to have caused 584,000 deaths in 2012, mostly among African children. About 42% (28–55%) of the global malaria burden could be prevented by environmental management,” say the authors.
But rapid urbanisation my be leading to a rapid increase in other mosquito-born-diseases, says the report. “Dengue fever is the most rapidly spreading mosquito-borne viral disease in the world. Rapid urbaniation, unreliable drinking water supply services, increased population mobility and global trade are important determinants of the resurgence of the disease.”
A row of intravenous drips for parents taking their children to hospital in Beijing, China. Public anger is growing over dangerous levels of air pollution in the capital. Photograph: STR/AFP/Getty Images
But some of the greatest environmental risks come from everyday activities. People falling down was said to be the second cause of death from unintentional injuries with 690 000 deaths in 2012. Each year, 37m falls are severe enough to seek medical attention. A further 372,000 people are believed to have drowned in 2012, with drowning the leading ‘injury’ in children under five years.
In addition, about 268,000 deaths occur each year due to burns from exposure to fire, heat or hot substances; the vast majority occurring in low and middle income countries.
Other causes of environmental deaths include 193,000 deaths from unintentional poisonings by chemicals or other noxious substances, including drugs, and toxic vapours and gases, lead poisoning from informal recycling or gold extraction, or from industrial emissions.
Road accidents are now the largest cause of injury deaths, causing 1.25m deaths per year. Almost half of all deaths on the world’s roads are among those with the least protection – motorcyclists, cyclists and pedestrians.
Environmental risks to health are defined as “all the physical, chemical and biological factors external to a person, and all related behaviours, but excluding those natural environments that cannot reasonably be modified.”
“There’s an urgent need for investment in strategies to reduce environmental risks in our cities, homes and workplaces,” said Dr Maria Neira, WHO director, department of public health, environmental and social determinants of health. “Such investments can significantly reduce the rising worldwide burden of cardiovascular and respiratory diseases, injuries and cancers, and lead to immediate savings in health care costs.”