Tag Archives: chemical toxins

To eat or not to eat….organic foods

by Peggy Olive

A recent Stanford study has received a lot of attention because it finds that organic foods are no more nutritious than those grown “conventionally”. Apparently this comes as a surprise to many, although there have been similar reports in the scientific literature over the years. Leaving aside the fact that until the 20th century all food was grown organically, does this mean that we’re wasting our money paying extra for organically grown foods?

It’s not obvious to me why crops grown organically should contain more vitamins and minerals. That’s determined genetically for the most part. Popeye eats spinach and not green beans because of the higher vitamin and mineral content of spinach. The level of vitamins is also closely tied to the time since harvest. Vitamin C levels drop precipitously in many vegetables held at room temperature or even some kept in our refrigerators for a few days. If concerned only about nutrition, eating freshly-picked vegetables from your local gardens makes more sense than buying organic foods from afar.

Food safety issues are no different for organic and non-organic foods, although many people think the higher price paid for organic foods should make them safer to eat. There’s also no reason to believe that organic meat comes from animals that have been treated more humanely than animals fed hormones or antibiotics.

So why should we choose to eat foods grown organically if they aren’t more nutritious, they aren’t safer to eat, and the animals haven’t led happier lives?

An excellent reason to eat organic foods is because they are grown without the use of pesticides, additives, and hormones that we should avoid for health reasons. Just as important, organic refers not only to the food itself, but how it was produced. Organic foods are grown using methods that recycle resources and promote biodiversity, considered key elements of environmentally sustainable agriculture. Monoculture and intensive farming methods using petroleum-based fertilizers depletes the soil of important organisms that supply nutrients to growing plants. Soil degradation has been of concern for a long time in Canada and elsewhere, and ultimately conventional farming practices result in reduced crop yields, now exacerbated by climate change.

The argument has made that organic farming methods cannot increase agricultural productivity because they are too inefficient. However, the UN Environmental Program reported in 2008 that organic farming practices in Africa outperformed industrial, chemical-intensive conventional farming, and improved soil fertility, retention of water, and resistance to drought. Scientific studies support the conclusion that organic farming methods are better at retaining soil productivity than conventional methods.

Ten benefits of organic farming/ organic food

  • Better for our environment, by definition: A production system that integrates cultural, biological, and mechanical practices that foster cycling of resources, promote ecological balance, and conserve biodiversity.
  • Not treated with pesticides, hormones, or potentially toxic additives
  • Safer for farm workers (limits exposure to toxins)
  • Safer for farm animals
  • Safer for crop pollinators
  • Better for soil (fosters biodiversity, water retention, productivity)
  • Animals not fed animal by-products
  • Not genetically modified (when labelled 100% organic)
  • Not treated with antibiotics so organic meat contains less antibiotic-resistant bacteria
  • More likely to be farmed locally (fresher)

The major disadvantage of organic food is the price you will pay at your supermarket checkout, typically 10-40% higher. Organic foods are more expensive because production costs are higher. Production costs are higher because farming methods are more labour intensive and there is potentially greater crop loss from pests. Because the price is higher, the choice to eat organic foods is not always available to those on limited incomes, and this could be viewed as a social equity issue. Certifying that the organic food you buy has actually been grown organically and is chemically free is an ongoing concern. To counter this problem, Canadian organic food now bears a logo but more oversight is required.

Fortunately, not all the foods we eat need to be grown organically if we want to significantly reduce our exposure to pesticides. The Environmental Working Group, a U.S. based non-profit organization specializing in research and advocacy to protect public health and the environment, has given us a list of the dirty dozen fruits and vegetables that are likely to present with the highest levels of pesticides, so it makes sense to use your “organic dollars” to buy these ones. Now, if only my aging mind could remember which ones are best to buy ‘organic’ when standing in front of the vegetable displays and fruit bins.

It is true that some of the benefits of organic food might be accomplished by no-till farming methods and by the use of genetically modified foods (GMFs) that are naturally pesticide-resistant or tolerant to environmental stresses. No-till methods will improve the soil, but many GMFs are grown to be resistant to the drugs used to kill the weeds or pests, and we, like honeybees, are not resistant. The potential of GMFs to add new toxins, allergens and genetic hazards to our food supply is a concern for many consumers and the paucity of studies on the long-term safety of GMFs has been reported in the scientific literature.

As demand for organic food grows, economies of scale will reduce cost to the consumer and cost to the farmer who implements organic farming practices. Before we complain about the price of organic foods, we need to be reminded of how little of our income we actually spend on food. In 1961, Canadians spent on average 19% of their income on food, but by 2005 this had dropped to 9.3%. In comparison, Europeans spend about 15% of their income on food, South Americans about 30%, and Africans more than 40%. Also, we shouldn’t forget how much food we waste. Total losses and wastage in the food chain can reach 50% in Western countries, so we would pay much less for our food if we simply reduced waste. With the benefits of organic foods listed above (which do not include nutrition per se) and the low relative cost for food in this country, price alone becomes a poor excuse for not choosing to eat organic foods.

Is there a cancer threat from the Oil Sands industry?

by Peggy Olive

Those of us who watched “Tipping Point: The Age of the Oil Sands” on The Nature of Things at the end of January [1] are legitimately concerned by this question.  The Kelly and Schindler publication in the prestigious scientific journal PNAS [2] provided evidence that mining the Athabasca Oil Sands has increased the levels of carcinogens in the environment downstream of the industry, and it follows that more carcinogens in the environment could mean a higher risk of developing cancer for the exposed population.

Demonstrating that the Oil Sands have caused an increase in cancer incidence is another matter.  This is largely because cancer is so prevalent; one in three of us can expect to develop cancer over a lifetime and one in five may die from it.  According to the 2010 Canadian Cancer Statistics [3], the incidence rates for all cancers have not changed much across Canada in thirty years, and the current incidence of cancer in Alberta is somewhat lower than that in the Atlantic Provinces.  Rates of incidence for all cancers between 2004-2006 in the Northern Lights Regional Authority, which includes the small town of Fort Chippewyan downstream of the Oil Sands development, are lower or equal to the Alberta provincial average [4].  However, in 2009, The Alberta Health Services presented a comprehensive study of cancer incidence in the Fort Chipewyan residents between 1995 and 2006, concluding that there was an increase in cancer incidence (51 cases observed with 39 expected in about 1200 individuals); this included two cases of a very rare form of bile duct cancer [5].  With so few total cases, caution was correctly placed on the interpretation of this observation and whether the increase could be attributed to the Oil Sands chemicals alone.  Nonetheless, continued monitoring of this population was advised because of the unexpected cancer incidence.

What we really need are answers to more difficult questions: Can the current cancer risk be considered “acceptable”, as suggested by the 2010 Royal Society report on the Oil Sands [6], are all reasonable efforts being made to mitigate the risk, and will prompt regulatory action be taken when the risk is no longer considered acceptable (if it currently is)? These are not simple questions to answer because first we need to know:

  1. The chemical nature of the toxins from the tar sands industry (there are potentially dozens, each with its own distribution within the environment).  Unfortunately, it is not possible to know pre-industry levels of these chemicals, and the adequacy and credibility of results obtained by the industry-supported regional aquatic monitoring program (RAMP) have come under serious question [7].
  2. Which chemicals have been tested and classified as human carcinogens.   Ideally, any interactions between different chemicals that may affect cancer risk should also be known.
  3. The doses of carcinogens delivered to the population (including information on the concentration, duration of exposure, and route of exposure).   Ideally, biomonitoring of individuals (for example, in hair or urine) should also be performed where warranted by higher levels in the environment.
  4. Regulations concerning exposure limits for each carcinogen, and whether these limits have been approached or exceeded downstream of the Oil Sands industry
  5. The number of individuals exposed to the carcinogens in order to estimate the number of excess cancer cases that can be expected, and the significance one can place on this estimate
  6. What has been done, and what can be done, to mitigate the risks of developing cancer

Taking the position that no increase in cancer risk is acceptable fails to acknowledge the many risks to our health that we accept each day, including risks of developing cancer from lifestyle choices.  The government sets limits on the levels of known carcinogens in the environment, but these limits are often meant to be “as low as reasonably achievable” and therefore are typically greater than zero.  For ionizing radiation, perhaps the best understood carcinogen (and my own area of expertise), the current dose limit is 1 mSv per year for the general public.  Yet a single medical imaging procedure can deliver ten times that dose, and the natural background dose (which is highly variable from one place to another) averages three times higher [8,9].  To put these amounts into perspective, exposure to 1 mSv would be expected to produce five extra cancer deaths in 100,000 people [9].   It would be impossible to demonstrate a statistically-significant increase in cancer incidence by exposure of small numbers of  individuals to 1 or even 10 mSv per year, yet we are still able to estimate the probability for a large population provided we know the exposure.

It often comes back to risk versus benefit.  We all find it easier to accept risk when it is our choice to make, but First Nations and others who make their homes downstream of the Oil Sands may not have that option.  Both risks and benefits need to be shared fairly, and that is not often the case.

Dozens of toxic chemicals are emitted and distributed during the mining and processing of the Oil Sands.  Arsenic is a known human carcinogen, yet a 2006 report prepared by Cantox Environmental for Alberta Health and Wellness concluded that there was a negligible risk of cancer from exposure to inorganic arsenic in the Woods Buffalo region of Alberta that contains the Oil Sands [11].  Although the levels of arsenic used for those cancer risk estimates were provided by the Oil Sands industry, in independently-funded studies, arsenic levels were rising in that area but did not exceed the regulatory limit [2,12].  However, seven of twelve other toxic metals exceeded guidelines for the protection of aquatic life by 5 -300 fold [2].  Heavy metals, including cadmium and mercury, are considered ‘possible’ human carcinogens, a different designation that limits what can be said about the risk for developing cancer.

Polycyclic aromatic hydrocarbons (PAHs) include known human carcinogens that are found downstream of the Oil Sands.  Twenty-six out of twenty-eight measured PAHs showed, on average, a six fold increase in concentration downstream compared to upstream [13].  Canada Health and Welfare and the World Health Organization recommend drinking water levels for total PAHs of 0.2 mg/L, and for the most carcinogenic PAH, benzo(a)pyrene, the limit is set at 0.01 mg/L.  The estimated lifetime risk associated with the ingestion of drinking water containing 0.01 µg/L benzo[a]pyrene is considered “essentially negligible” by Health Canada, and 1 in 100,000 by the World Health Organization [14].   In a study conducted in 2007 by Timoney [15], concentrations of PAHs near the Oil Sands varied greatly, but at times exceed guidelines suggesting potential danger to exposed individuals.  Perhaps we should be asking, “How dangerous is the exposure to PAHs from the tar sands industry relative to smoking cigarettes or living in an urban environment?  How rapidly are levels increasing downstream of the Oil Sands?  What are the peak levels as well as average levels?”  Answering these questions requires a reliable environmental monitoring program which is currently lacking.

Simply demonstrating that the amount of any one carcinogen is lower than government mandated limits fails to acknowledge the possible interactions between different chemicals.   Co-exposure of fish to arsenic and benzo(a)pyrene can increase rates of genotoxicity eight to eighteen times above rates observed after exposure to either carcinogen alone [16].  Currently, there is little if any information on additive or multiplicative risks of cancer from exposure to several carcinogens, so the possibility is largely ignored in assigning ‘safe’ limits.

With known carcinogens being distributed over a large region of Alberta, reducing exposure and subsequent risk should be an industry priority.  In the 1970s, stack precipitators were instrumental in reducing airborne particulates, but subsequent industry expansion means that overall levels are now similar to those measured before precipitators were installed [2].  Levels will continue to rise in coming years if no efforts are made to further reduce emissions.  Tailings ponds should not leak as they do now [13], and they should be guarded against storm damage.  River water flow should be monitored so that it is adequate to dilute particulates, and climate change effects and usage effects on river flow should be taken into consideration for future expansion.  Technology should be developed to recover toxic heavy metals.

What is needed to make this happen is a world-class, government-sponsored environmental monitoring system that can keep pace with the oil sands developments, is transparent but informative to the public, and examines a full range of potential environmental effects.  Water testing should be as good if not better than the air quality measurements now provided by the Woods Buffalo Environmental Association, a multi-stakeholder group that publishes readouts on their web site from more than a dozen sites in the Oil Sands region [17].  Information on levels of carcinogens present in plants, animals and people living in the region are also needed.

A special review panel recently convened by the Alberta Government has already concluded that more stringent oversight of environmental contamination in the Athabasca Oil Sands is necessary [18].  Their full report is due in June 2011, but recognizing that the current monitoring program is flawed and doing something about it are two separate things.  Maximum toxic contaminant levels need to be set, and not just for water, but also for soil, sediment, plant and animal life.  There should be recognition that adhering to these levels may mean curtailing expansion at some future point.  The pressure to accomplish these goals must come from many directions, and should not rest exclusively on the inhabitants of Northern Alberta.

Coming back to the question, is there a cancer threat from the Oil Sands, the answer is yes, because the levels of known carcinogens in the regions downstream of the industry have increased.  Have these increases actually caused cancer?  Perhaps, but the available data do not support an unequivocal conclusion.  Cancer is too prevalent, and the number of exposed individuals is too small to be sure.  Does this mean that there is no reason for concern, at least at present?  Absolutely not.  Cancer can take many years to develop and levels of carcinogens from the industry continue to increase.  Until a reliable monitoring system is in place, we will have insufficient information to base estimates of cancer risk.

The Oil Sands industry has the opportunity and the responsibility to mitigate these risks, but we have a responsibility to understand these risks in relation to others we encounter in our daily lives.  Hall, in an earlier edition of his book [9] examined the chances of dying from a radiation-induced cancer in relation to the risk of dying from smoking cigarettes or driving a given number of highway miles.  I’ve used his analogy to compare PAH-induced cancer with these risks.  If drinking water containing 0.01 mg/L benzo(a)pyrene causes one additional fatal cancer in 100,000 people, this would be equivalent to the risk of dying from smoking 73 cigarettes or driving 178 miles.  This doesn’t sound too bad until we remember that we are also exposed to many carcinogens not only in drinking water but in the air we breathe and the food we eat.  One of those chemicals is arsenic.  The risk of dying from cancer by drinking water containing 0.01 mg/L arsenic (the government mandated limit) is equivalent to the risk of dying by smoking 1500 cigarettes or driving 3500 miles.  If you’re wondering why maximum allowable arsenic levels are so high, it’s partly because of the difficulties in estimating both exposure and risk from cancer caused by arsenic.  However, Health Canada also states that their regulation represents “the lowest level of arsenic in drinking water that can be technically achieved at reasonable cost” [19], which is even more reason for close monitoring of the carcinogens produced by the Oil Sands industry.


1.     Tipping Point: The Age of the Oil Sands.  Documentary film aired Jan 27 and Feb 12, 2011 on CBC-TV. http://www.cbc.ca/documentaries/natureofthings/2011/tippingpoint/

  1. Kelly, EN, Schindler, DW, Hodson PV, Short JW, Radmanovich, R. Oil Sands development contributes elements toxic at low concentrations to the Athabasca River and its tributaries.  Proceedings of the National Academy of Sciences, 107: 16178–16183 2010.
  2. Canadian Cancer Society’s Steering Committee: Canadian Cancer Statistics 2010, Toronto: Canadian Cancer Society, 2010. http://www.cancer.ca/canada-wide/about%20cancer/cancer%20statistics/~/media/CCS/Canada%20wide/Files%20List/English%20files%20heading/pdf%20not%20in%20publications%20section/Canadian20Cancer20Statistics2020102020English.ashx
  3. Alberta Health Services, Report on Cancer Statistics in Alberta, 2009. http://www.albertahealthservices.ca/poph/hi-poph-surv-cancer-cancer-in-alberta-2009.pdf
  4. Alberta Cancer Board, Report on the Incidence of Cancer in Fort Chipewyan, 1995-2006 http://www.albertahealthservices.ca/rls/ne-rls-2009-02-06-fort-chipewyan-study.pdf
  5. Royal Society of Canada Expert Panel, Environmental and Health Impacts of Canada’s Oil Sands Industry, December, 2010. http://www.rsc.ca/documents/expert/RSC%20report%20complete%20secured%209Mb.pdf
  6. Main, C.  2010 Regional Aquatics Monitoring Program Scientific Review http://www.ramp-alberta.org/UserFiles/File/RAMP%202010%20Scientific%20Peer%20Review%20Report.pdf
  7. The 2007 Recommendations of the International Commission on Radiological Protection.  ICRP #103;  Wrixon, AD. New ICRP recommendations.  Journal of Radiological Protection, 28:161-168, 2008. http://iopscience.iop.org/0952-4746/28/2/R02/pdf/jrp8_2_R02.pdf
  8. Hall EJ and Giaccia, AJ, Radiobiology for the Radiologist, Sixth Edition, Lippincott Williams & Wilkins, Philadelphia, 2006.

10.  Smith AH, Lopipero PA, Bates MN, Steinmaus CM.  Arsenic epidemiology and drinking water standards.  Science 296: 214l5-6, 2002;  Kaiser J. Second Look at Arsenic Finds Higher Risk, Science 293, 2189, 2001; Arsenic in drinking water. National Academy Press, 2001 Update. http://www.nap.edu/openbook.php?record_id=10194&page=203

11.  Report prepared by Cantox Environmental for Alberta Health and Wellness.  Assessment of the Potential Lifetime Cancer Risks Associated with Exposure to Inorganic Arsenic among Indigenous People living in the Wood Buffalo Region of Alberta, 2007.

12.  Timoney, KP and Lee P.  Does the Alberta Tar Sands industry polute?  The Scientific evidence.  The Open Conservation Biology Journal 3:65-81, 2009.

13.  Kelly EN, Short JW, Schindler, DW, Hodson PV, Ma M, Kwan AK,  and Fortin, BL.  Oil sands development contributes polycyclic aromatic compounds to the Athabasca River and its tributaries.  PNAS 106:22346-22351, 2009.

14.  Ministry of Environment, Lands and Parks, Province of British Columbia. Ambient water quality criteria for polycyclic aromatic hydrocarbons (PAHs) http://www.env.gov.bc.ca/wat/wq/BCguidelines/pahs/index.html#TopOfPage

15.  Timoney, KP. A study of water and sediment quality as related to public heath issues, Fort Chipewyan, Alberta.  A report conducted on behalf of the Nunee Heath Board Society, Fort Chipewyan, Alberta. http://energy.probeinternational.org/system/files/timoney-fortchipwater-111107.pdf

16.  Maier A, Schumann BL, Chang X, Talaska G, Puga A. Arsenic co-exposure potentiates benzo(a)pyrene genotoxicity. Mutation Research, 517: 101-11, 2002.

17.  Wood Buffalo Environmental Association Website: http://wbea.org/component/option,com_frontpage/Itemid,1/

18.  Jones, J.  (Reuters) Water checks deficient at Canada Oil Sands: Report, March 10, 2011 http://solveclimate.com/news/20110310/water-checks-deficient-canada-oil-sands-report

19.  Health Canada Environmental and Workplace Health, Arsenic, Application of the Guideline. http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/arsenic/application-eng.php