Rene (Ray) Matthey, 1923 - 2003
(This page is dedicated to the late Ray Matthey who passed away on November 27, 2003 in Ottawa. He was the founder of the Saunders-Matthey Foundation for cancer research. He wondered why hundreds of millions of dollars spent on cancer research has not produced a reduction in cancer incidence. Mr. Matthey felt that more research on environmental pollutants that cause cancer is needed.) from a Globe and Mail obituary, March 31, 2004
Pollution and Cancer: Stunning and Striking? December 1999
A. C. Goddard-Hill.
In the late sixties three Ontario biologists, Drs. Donald Chant, Bryce Kendrick and David Suzuki founded the environmental public interest group Pollution Probe. These men taught us to think about the effect of environmental factors on biological systems. Since then in the field of human biology cigarette smoking has been accepted as the cause of about one quarter of human cancers. This example of chemical carcinogenesis has led many to wonder what other human cancers are related to chemical exposures. In the last decade evidence around this question has been accumulating in the general and specialist medical literature. One review found almost five hundred articles relating environmental pollution to human health in the last seven years editions of five general medical journals.
Now, thirty years later, Pollution Probe is alive and well but public health officials have yet to board the environmental health train. For example environmental carcinogens have been absent from the mandate of the prevention unit of the provincial cancer control agency in Ontario.
Environmental and occupational carcinogens include industrial effluents, household chemical products, pesticides and radionuclides.
There are approximately 70,000 chemicals in use in modern industrialized countries, 3000 of these in high volume use as defined by the U.S. EPA. Some 667 of these compounds are known carcinogens and of those 84 are in high volume use. The release of these compounds into the environment raises questions about implications for human health. However such questions are difficult to answer as in the overwhelming majority of cases the chemicals of concern have never been adequately if at all tested for chronic toxic or carcinogenic effects. In Canada some 23,000 chemicals are approved for use and of these a meagre 31 have completed toxicity testing. There are currently about 200,000 tonnes of voluntarily reported releases of toxic chemicals into the Canadian environment annually and of these 13,000 tonnes are suspected or known carcinogens. 50,000 tonnes of pesticides are used each year in Canada. One pound of dioxins are released.
One consequence of this pollution is that breast milk in Canada contained 25 times the safe level of dioxin (compared to the WHO standard) when last assayed in 1992. Since then there has been no further Canadian data on this primal matter of mothers milk. However in the U.K. the World Wildlife Fund recently reported that British breast milk contains forty times the safe level of dioxin. This is uncertain nourishment for the next generation.
Another consequence of environmental pollution is that 200 synthetic chemicals are now measurable in the human body. The organic chemicals are of particular interest. These include the non chlorinated varieties such as benzene and benzo(a)pyrene, and the chlorinated organics which number some 11,000 and which include vinyl chloride, trichlorethylene, pcbs and dioxins. Chlorinated organic chemicals, the so-called persistent toxic substances, were first produced on an industrial scale in the forties. The bad news about them began arriving in the sixties when Rachel Carson collared the chlorinated pesticides. The following decades brought further revelatory waves of negative news about the pcbs and cfcs in the seventies, the dioxins and furans in the eighties and the APEs, bisphenols and pthalates in the nineties. Most of these compounds have their origins in the chlorine chemical industry. They include byproducts from the use of chlorine as a bleaching agent by the pulp and paper industry, PVC plastics production, pesticides, fugitive dichloromethane from the pharmaceutical industry, various intermediates, refrigerants, and solvents. They are also produced by the hundreds through the incineration of chlorinated (PVC) plastic waste.
Researchers and activists interested in chemicals have made much of their non-cancer health effects including perturbations of human sexuality, brain injury, and immune dysfunction. However lay epidemiologists, a.k.a. the general public, still regard these effects with a certain comedic skepticism. When we look down our collective pants or gaze at the video screen the sexual vigour of the human race is hardly in question. (Indeed the idea that environmental pollutants could reduce the fertility of our prolific species has a certain attraction.) When we observe the computer industrys ingenuity in propagating the global neural network the collective brain power of our race seems assured.
By contrast cancer remains a dread disease about which the public has a serious concern. Citizens increasingly link chemicals with cancer.
There is quite a spectrum of opinion with respect to the cause of cancer. At one end is for example the Canadian Cancer Society which concluded that the main culprit is the aging of the population and that toxics and bad habits are not the cause. By contrast in Ontario the provincial cancer agency is concerned about bad habits and lifestyles while across the street at the Ontario Ministry of Health their Statement of Environmental Values calls for the elimination of pollutants and carcinogens as causative agents of cancer. (An independent environmental commissioner found there has been little action predicated on these sentiments.) Similarly the federal environment department has called for a reduction in public exposure to toxics and carcinogens through decreased industrial discharges of compounds such as benzene, lead, mercury, dioxin and chromium. (The government plans to achieve that goal by voluntary limits on pollution which industry itself has said are unlikely to be effective.) At the other end of the spectrum Epstein speaks darkly of the cancer establishment and their propensity to ignore the effluvia of industry which he says accounts for the majority of human cancers.
The general medical literature has had much to say about toxics. The recurring theme is that carcinogens cause cancer. Dixon identified the disease as one in which genes are triggered into mischief by carcinogens. Miller recalled the long lag time between exposure in early life and the appearance of the disease decades later. Kessler focused on the overexposure of children to carcinogens and Davis expanded the envelope by noting critical periods of exposure during pregnancy and adolescence when timing can be more important than dose. Rassool returned to the interaction between carcinogens and genes and hinted at the gradient of differential susceptibility and resistance to carcinogens found in human populations as a function of complex genetic factors.
What has the literature said about common cancers and carcinogens? Tang identified the damage to tumour suppressor gene DNA from exposure to benzo(a)pyrene in cigarette smoke, suggesting one mechanism of carcinogenesis. The International Joint Commission of the Great Lakes revealed that this compound has sources other than cigarette smoke when it identified benzo(a)pyrene as one of eleven critical contaminants found throughout the Great Lakes basin. This polyaromatic hydrocarbon is a legacy of historical industrial activity in the area. A study of workers exposed occupationally to dioxins confirmed the carcinogenic nature of these compounds when higher rates of lung and other cancers were found in the workers. Canadian and U.S research found higher incidences of bowel cancers in populations drinking chlorinated water over decades attributable to trihalomethane content. Great interest in the relationship between organochloride exposures and the rising incidence of breast cancer was reported. One group found that women so exposed happened to achieve some degree of protection from that scourge by breast feeding their infants. Thus the fundamental human gesture of lactation apparently flushes toxics from the maternal breast. The recipient is the newborn breast feeding infant.
Next the uncommon and rare cancers. Some of these increased by stunning increments of 1 4% per year. Would these tumours be uncommon and rare today if they had sustained such increases over long intervals of time or is this only a recent phenomenon? Epidemiologic trends in non Hodgkins Lymphoma and testicular cancer may prove more instructive in teaching the lessons of environmental epidemiology than have the common cancers. In these uncommon tumours the effects of chemical exposures may be less confounded by other factors than are the common cancers. Non Hodgkins Lymphoma and testicular cancers rose at 2 4 % per year and pcbs and pesticides proved popular in the literature as putative causes. Melanomas doubled in the southern hemisphere due to chlorofluorocarbon destruction of protective ozone. Brain cancer in the elderly doubled due in part to occupational and nonoccupational chemical exposures.
The shifting epidemiology of the childhood cancers has been striking. Their overall incidence in Canada and the U.S. increased twenty per cent in twenty years as did the incidence of the leukemia subgroup. One researcher focused on leukemia and prenatal and infant exposures to EMF radiation, and the big increase in childhood brain tumors seen at an Ontario childrens hospital was attributed in part to industrial and other environmental exposures. A review paper listed 185 references variously making the connection between childhood cancer and environmental toxics. A British study related the occurrence of childhood cancer to proximity to hazardous industrial sites.
These findings suggest that Barkers hypotheses on programming of non-cancer diseases by environmental exposures during the prenatal and infant stages could also apply to cancers.
Environmental politics in the province of Ontario was heated throughout this decade. The International Joint Commission of the Great Lakes with the support of the American Public Health Association began the decades debate with their 1992 report based on human health considerations. The binational commission called for elimination of PVC plastic production, elimination of chlorine use by the pulp and paper industry, and elimination of waste incineration. However despite those recommendations PVC plastic production continued apace with a sixty percent increase recorded by the end of the decade. For their part and in response the pulp and paper industry invented creative solutions to the problem of disposal of dioxin-contaminated waste pulp liquor rather than eliminating chlorine use from the process. They cleverly marketed the waste material as a dust suppressant for use on country roads and persuaded local governments to spread this toxic stew around huge areas of provincial watersheds. The Times Beach disaster in rural Missouri of two decades earlier was apparently forgotten.
Incineration of municipal, medical and hazardous waste was identified by the Canadian and U.S. governments as a major source of dioxins and metals entering the environment. However after a brief respite hearings in Ontario are now under way again for the construction of new incinerators. Proposed sitings are usually in rural and economically depressed areas of the province, a social phenomenon portrayed by activists as environmental injustice. British and American studies have both found higher rates of cancer in the vicinity of such facilities.
What happened to environmental research during the decade? Paradoxically the number of articles appearing in the general medical literature went into steep decline starting in 1996 after increasing interest registered in the first half of the decade. This decline began after the collapse of government environmental program funding in various jurisdictions. For example the budget of the Ontario Ministry of Environment fell by half in the second half of the decade. Governments became more and more uninterested in environmental health. There was little data on toxics and health as the century closed because there was no money to analyse and research. Academic research agendas were determined to a large extent by generous funding for cancer drug treatment trials by the large pharmaceutical companies. Corporations showed little interest in funding environmental research.
The problems in toxics and cancer are these. First, there is a research bias away from prevention in general and away from environmental health research in particular. Secondly, in the presence of plenty of existing evidence there is a lack of leadership in cancer prevention by pollution prevention in the Province of Ontario and presumably in other jurisdictions around the globe.
However this has not occurred in the complete absence of good advice. For example in 1995 Griers Task Force for the Primary Prevention of Cancer recommended that "government should establish timetables to sunset the use of chlorine-containing compounds as industrial feedstocks and examine the means of reducing or eliminating other uses of chlorine, bearing in mind the priority to ban substances established as carcinogens. We urge action now." Occupational and environmental carcinogens are a significant public health issue. They need to be put on the public agenda.
Dr. Ken Shumak, President, Cancer Care Ontario,
620 University Avenue
Toronto, Ontario M5G 2L7.
Dear Dr. Shumak,
Thankyou very much for meeting with our citizens group in July. We made the case for the inclusion of Environmental and Occupational Carcinogens in the mandate of the Cancer Care Ontario Prevention program .
The CCO Strategic Plan has now been approved by the Board of Directors
(November 25 1999). I am pleased to note that you have acknowledged the issues which we raised. Excerpted here are some statements from your document.
"Occupational cancer is an important concern. CCO will become involved
in preventing occupational cancers, beginning with improved surveillance. CCO will create a collaborative group of stakeholders and experts to make recommendations regarding the most effective means of surveillance of occupational cancer. A variety of surveillance strategies have been proposed, including routine reporting of occupation with incident cancer cases. The utility of these strategies must be assessed and the effective approaches incorporated into our cancer surveillance. Environmental carcinogens are a source of concern and controversy. CCO will identify opportunities for evidence-based interventions in this field."
With respect to evidence about environmental carcinogens, our province
and country should prove to be a real mother lode of opportunity for your epidemiologists.
For example at one end of the province we have recently learned that the Sarnia hazardous waste landfill is leaking into local ground water, while at the other end approval for the operation of a hazardous waste incinerator of doubtful efficiency has just been granted in Cornwall. At the local level the Ontario Ministry Environment last week confirmed that medical waste incinerators currently operate in communities in Ontario with no pollution controls or requirements for monitoring of emissions whatsoever. At the federal level the National Pollutant Release Inventory has recently documented a large increase in chemical pollutants released in Canada for the last reporting year of l997 (Ontario now having attained the No. 2 polluter status on the continent) and facilities in Swan Hills, Alberta and Chalk River Ontario are now preparing to receive international sources of hazardous and nuclear waste.
Appended to this letter is a review entitled "Pollution and Cancer: Stunning and Striking?".
Can you speculate as to when CCO will start to "identify opportunities for evidence-based intervention in the field of environmental carcinogens?"
Best wishes for the new century.