CANCER: Health effect of air and water pollution
Lela Gary, Margaret Mroziewicz, Altaf Ghori
"From the right to know and the duty to inquire flows the obligation to act."
You are welcome and encouraged to share, copy and excerpt this report, provided it is referenced.
Cancer does not discriminate.
It may affect any organ of our body and may develop into rare types of cancer as reported by Dr. John O'Connor in 2006 of the increased incidence of the bile duct cancer affecting the Native population living in the vicinity of the Alberta oil tar sands in Fort Chipewyan. Toxins from the tailing ponds travel downstream into the lake which provides the village with drinking water.
This report concentrates on Lung, Breast, and Brain Cancer.
Cancers are on the rise, many of which are linked to environmental and occupational exposures. The Canadian Cancer Society in their 2010 report estimate 173,800 new cases this year, up 2,800 from last year, and 76,200 deaths, up 900. Leukemias and lymphomas have been linked to petroleum products, including VOCs, dioxin-like chemicals, and other hydrocarbons. Biliary cancers have been linked to petroleum and to PAHs (Polycyclic Aromatic Hydrocarbons) chemicals in tar and soot. There are over 80,000 industrial chemicals in the environment but few are tested for their danger level and less emphasis has been given to their synergistic effect created, which is greater than its parts. Over 80% of “Priority substances” in emissions are toxins not reported. We are exposed to about 10,000 different chemicals a day.
Air pollution kills.
The following are the most common carcinogens:
Canadians have a 1 in 11 chance of developing lung cancer, and a 1 in 13 chance of dying from it.1 Lung cancer accounts for 8% of all Canadian deaths being the second most common and the leading cause of cancer death (27% of all cancer mortalities).2 Although smoking is the primary cause of lung cancer, 25% of all cases worldwide are not attributed to smoking.3 Air pollution from industrial sources, power plants, and vehicle emissions is a prominent factor in causing lung cancer.
Scientific studies worldwide suggest that air pollution causes lung cancer. Fine particles (particularly PM2.5 and PM10), which are made up of hazardous materials (e.g. metals), and carcinogens PAHs (Polycyclic Aromatic hydrocarbons) also stick to their surface.4 And when inhaled, they may initiate lung cancer. Long-term studies have demonstrated the association between lung cancer and air pollution. A study in the US (with 500,000 participants in over 100 cities) assessed long-term exposure to fine particulates and lung cancer5, and that increased air pollution led to an increased risk for lung cancer mortality (for each 10-µg/m3 increase in fine particulate air pollution, lung cancer mortality increased by 8%). This effect was largest in non-smokers. The researchers concluded that there are no safe levels of air pollution, and as fine particulate air pollution increases, the risk of lung cancer mortality also increases. Lung cancer death rates can be reduced if air pollution is reduced.
Ten European countries (Sweden, Denmark, Norway, Netherlands, UK, France, Germany, Spain, Italy, Greece) were also part of a study (with over 500,000 study participants) to assess the role of air pollution in lung cancer in never smokers and ex-smokers.6 The study revealed that 5-7% of lung cancers in European non-smokers were due to high levels of air pollution from vehicles, specifically by nitrogen dioxide (NO2, an index of traffic pollution) or proximity to heavy traffic roads; but, due to strict NO2 thresholds used in their study, in reality, the percentage of lung cancers due to heavy pollution was likely higher than 5-7%. Smaller studies on urban air pollution and lung cancer, in Stockholm, Sweden, particularly from traffic(NO2) increased lung cancer risk.7 Likewise, a study in Denmark concurred on the association between traffic air pollution and lung cancer.8 In the Netherlands, scientists also reported an association of exposure to black smoke and traffic intensity with lung cancer incidence, particularly in people who had never smoked.9
Different types of lung cancers were reported in a study in Trieste, Italy, with respect to living in the polluted city center relative to a suburban area increased the risk of small cell and large cell lung cancer, while living in an industrial area increased the risk for adenocarcinoma9 and that lung cancer risk increased with increasing levels of air pollution. Exposure to metal air pollutants was associated with various types of lung cancer incidence in Texas, US10 Specifically, zinc was associated with primary and non-small cell lung cancers, and chromium and copper were associated with non-small cell lung cancer.
The effects of air pollution in lung cancer have also been studied in Asian cities. A study in Shizuoka, Japan, concluded that long-term exposure to traffic pollution (indicated by NO2) increased the risk of lung cancer mortality in non-smokers.12 Researchers in Taiwan showed a correlation between traffic-related air pollution (measured by nitrous oxides and carbon monoxide) and incidence of lung adenocarcinoma.13 An increased risk of lung cancer in women compared to men was reported in a study in seven Korean cities on long-term exposure to PM10, was significantly associated with only female lung cancer incidence and mortality.14 In Taiwan researchers used petrol station density as an indicator of exposure to gaseous petrol chemicals or vehicle emissions. The results of this study indicated a significant relationship between petrol station density and risk of lung cancer in females.15 Lung cancer is also linked to power plant emissions. Researchers in the United States used an air pollution index correlated with coal power-plant emissions, and found that the index correlated with lung cancer (among many other cancers).16 They warned that combustion of coal, diesel fuel and wood releases particles carrying PAHs, cause many types of cancers. Scientists in Spain also reported that proximity to fossil fuel power-plants was associated with increased lung cancer mortality.17
All of the above studies have ascertained the effect of air pollution from industrial sources, power plants and vehicles, on lung cancer and that lung cancer risk increases as air pollution increases. This prevalent and lethal disease can be reduced if air quality is improved.
1 in 9 women are expected to develop breast cancer in their lifetime
About 22,000 women are diagnosed with breast cancer every year, as reported by the Canadian Breast Cancer Network, and bear huge financial burdens on top of the physiological challenges.
In both sexes the manifestation of breast cancer is similar suggesting a common origin of the disease.7 Mutations may be inherited or induced by chemical carcinogens.21 Route, timing, frequency of exposure to carcinogens contribute to the overall susceptibility to breast cancer development.1
A Scandinavian study of twins done in 2000 found that al¬though inherited factors accounted for 27% of breast can¬cer risk, 73% of the risk was linked to environmental factors, suggesting that environment plays a major role in determining risk.14 A 1991 study conducted on rural Asian women immigrating to the United States found that the daughters and granddaughters of these women had a higher chance of developing breast cancer. Within two generations, breast can¬cer rates of their offspring were as high as those of Western white women.20 Research has been done worldwide to prove that pollutants increase the risk of breast cancer in both women and men.1
Epidemiologic studies suggest 50% to 500% increases in risk in women exposed to pollutants such as polychlorinated biphenyls (PCBs), dichlorodipheny-ltrichloroethane (DDT), polycyclic aromatic hydrocarbons (PAHs), and chemical solvents.16 In 2007 Rudel et al published an article on environmental carcinogens causing the development of tumors in the mammary gland of animals. By compiling data from 450 primary epidemiology research articles from the International Agency for Research on Cancer (IARC), the U.S. National Toxicology Program (NTP), and other sources, 216 carcinogenic compounds were found. Chemicals were mutagenic and most caused tumors in multiple organs in animal species.16 Of the 216 chemicals on the list, 35 are outdoor pollutants (ambient) or indoor (residential) air, 25 have involved occupational exposures to more than 5000 women.16 Researchers found that risk assessment and regulatory documents have not been developed for these chemicals. 4
The evidence to date supports the association between breast cancer, PAHs and PCBs.3 PAHs are lipophilic chemical carcinogens mainly formed by incomplete combustion of fossil fuels that are absorbed into the fat cells of the body.10 Benzo[a]pyrene, a type of carcinogenic PAHs, has been shown to be activated by xenobiotic-metabolizing enzymes to highly mutagenic and carcinogenic metabolites that initiate cell transformation.10 If exposure to PAH is high or the detoxification pathway is insufficient, PAH-DNA adducts are formed, which increase the risk of breast cancer.18 Based on models of PAHs estimates attributed to vehicular traffic, it is reported that there is over a two-fold increase in risk for exposure for breast cancer.9
The Long Island Breast Cancer Study Project (LIBCSP) multi-institutional collaboration research in 2002 in Long Island, New York, observed a 50% elevation in the risk of breast cancer in relation to the highest amount of PAH-DNA adduct levels.10 A 2004 study in New York supported the data that PAHs increase the risk of developing breast cancer, indicated a 35% increase in breast cancer risk in individuals that lived in polluted locations.8 A 2003 study reported that higher levels of PAH-DNA adducts were found in individuals that lived in areas with high pollution compared to those that lived in less polluted locations.11 A 1996 study in New York recorded a higher risk of cancer associated with living in areas with air pollution from industrial facilities.13
Occupational exposure to gasoline and vehicular exhaust has been identified with elevated risk in both female and male breast cancer in individuals that work in these conditions. 12, 15 Organochlorine compounds, such as PCBs, chlorinated dioxins, furans, and pesticides, are frequently detected in food, soil, and dust.15 These chemicals concentrate up the food chain, and have been found in human breast milk and adipose tissue.3
Extensive evidence has been presented on the effect of air pollution on breast cancer by damaging DNA, promoting tumour growth, and increasing susceptibility by altering mammary gland development.15 Recognizing the effect of environmental chemicals on breast cancer will bring awareness to governments, the medical profession, and the public about the dangers these pollutants place on our health and economy. The government should act proactively to encourage safe environmental corporate practices and to improve public health policies.22
The link between air pollution and brain cancer has been reported in studies on both adults and children.
This report refers to the primary brain cancer regarding the effect of chemicals at the molecular level, excluding metastases. Brain tumours develop as a consequence of cellular genetic alterations that evade and destroy the immune system. Only a small proportion of brain tumours has been attributed to inherited predisposition, as is the case in other cancers, where only up to 6% is attributed to the genetic factor.
Brain tumours, most devastating of all cancers, can be developed through neurotrans- mitter misregulation. One of the symptoms is “Brain fog” also experienced by migraineurs exposed to high level of pollution. A common cause of brain fog is the reduction of oxygen to the brain from the effect of air toxics, especially the ultrafine particles (http://www.ecopolitics.ca/airpol/migraine.php.
Breakdown of the nasal olfactory epithelial barrier contribute to brain inflammation by increasing the access of air pollution to the brain, both directly through the olfactory pathway and indirectly through the systemic circulation.1, 1a Chemical assaults on the brain, such as glutamate, NMDA, and formaldyhyde occur by neurotransmitters through the olfactory system, are implicated in brain-cell injury and death..2 ( Nasal olfactory and respiratory mucosae are targets for air pollutant-induced toxicity and carcinogenicity.) Formaldehyde, a colourless strong-smelling chemical that is used in building materials, household products, automobile tailpipe emissions, is a carcinogen that increases the risk of brain cancer and leukemia in individuals who have a prolonged exposure to this toxic.3
Another industrial pollutant, the carcinogen TCE (Trichloroethylene) has been detected in various human organs, brain, liver, etc.4 Additionally, neurological effects related to traffic air pollution in a study on the brain tissue of animals in Mexico City, indicated higher levels of nuclear factor-B activation and nitric oxide production and tumour necrosis factor (TNF: the presence of dead cells in the middle of the tumour) compared with the animals from non-polluted areas.
Drs. Keith Black and Julia Ljubimova in their research on brain tumours and air pollution at the Cedars Sinai Medical Center in California, observed that fine particle pollution passes through cell walls and triggers molecular changes to the same genes associated with brain cancer. Fine particles, like those in diesel soot, can switch on tumour genes that people inherit and jump-start the disease process and the destruction of the immune system.5 Studies have shown firefighters exposed to diesel exhaust in their fire stations are more likely to develop brain cancer than people in other occupations. Pollution particles enter through the damaged blood vessels and enter the brain walls, the blood brain barrier (BBB). The risk of cancer in firefighters examined in a study by the Division of Environmental and Occupational Medicine at the Mount Sinai School of Medicine in New York, noted the effect of carcinogens benzene, asbestos, PAHs, diesel exhaust, and formaldehyde have on prevalent cancers of brain and bladder, among others.14
The brain is particularly susceptible to toxins and free radical mediated insult, due to its inherent biochemical and physiological characteristics.6 In a study done in France on parental exposure to polycyclic aromatic hydrocarbons (PAH), which occurs primarily through air pollution, second hand smoke, and occupational exposure, increases the risk of all childhood brain tumours.7 Correspondingly, in a study by the Department of Environmental & Occupational Health at Emory University in Atlanta, Georgia, on the residential exposure to toxics during pregnancy, the researchers observed an extensive number of children diagnosed with brain cancer before 5 years of age and living within 1mile of a facility releasing mass carcinogens.8 In a 2009 study at the Division of Health Studies in Atlanta, Georgia, on parental exposure to pesticides and childhood brain cancer, they concluded that the exposures to herbicides from both residential and occupational sources had a significant elevated risk of brain cancer.9
To understand the cancer incidence due to airborne toxicants in anthropogenic pollution, an investigation in Indiana counties on the relationship between air emissions of volatile organic compounds (VOCs) and the incident of cancer, referred to strong correlations between VOC emissions and cancer of the brain, nervous system, and skin.10
Petroleum and petrochemical complexes have been identified for the significant excess deaths due to cancers, especially of the brain, bone, and bladder among children and adolescents in a residential district in Taiwan living within 3km of the facility.12 A follow-up case-control study was conducted in Taiwan from 1995 - 2005 regarding to residents' exposure to air emissions from petrochemicals. The subjects living in municipalities characterized by the highest levels of air pollution, had a statistically significant higher risk of developing brain cancer.13 Another study showed that genes associated with common brain tumours and degenerative brain diseases are more active in rat brains exposed to highway pollution for periods ranging from 2 weeks to 10 months.6,7
In contrast to the proven causes of hereditary syndromes or radiation, which account for a small proportion of cases, studies continue to associate brain cancer to workplace, personal, and residential exposures to carcinogenic toxics. Urban pollution has been identified in these studies to be a potential public health risk of great importance.15
"Our lives begin to end the day we stay silent about the things that matter"
The long-term consequences of carcinogenic air and water chemicals of urban pollution should be incorporated in multidisciplinary research and promoted actively by the Department of Public Health. Little has been done to act on what we already know. The impact urban pollution has on our health should not be discussed endlessly with no determination of action. Nor should the government kowtow to industry and introduce amendments to “streamline” their environmental assessment processes. If the public can not combat the powers of industry or ineffective governments that contravene in the prevention of disease, the Chief Medical Officer must protect public health by developing strategies on health, environmental and social determinants.
Health Protection is defined as Prevention.
* * * * * *
Bureaucracy marred by blind folly, benefits no one.
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