Coal debate must be informed by robust scientific data. Studies that draw on maximum exposures to toxic substances are not relevant to public health policy.
Apr 8, 2014
Vancouver Sun
By Len Ritter
April 7, 2014
Five hundred years ago, Paracelsus, the Swiss-born scientist considered the father of modern toxicology, observed: “Poison is in everything, and nothing is without poison. The dose makes it either a poison or a remedy.” What Paracelsus was telling us is the dose or exposure is the critical factor in determining the risks from potentially toxic chemicals.
This principle is the basis for how governments and international agencies establish safe levels of human exposure for a wide array of pharmaceuticals, food additives and environmental contaminants.
This is an important consideration that garners little attention in the debate in Metro Vancouver about rail transport of coal.
A fundamental principle of the scientific method is the need to inform public health policy with credible and relevant data to address complex scientific questions. Matters of public health and environment cannot be resolved through fear or rhetoric, but rather through a dispassionate and disciplined scientific approach, as accepted and practised by government regulatory authorities around the world.
This approach has been widely adopted by prestigious and respected international agencies including the World Health Organization, the International Agency for Research on Cancer, and the U.S. Environmental Protection Agency, as well as Health Canada and the government of British Columbia, to name just a few.
All these organizations are neutral and work exclusively in the public interest to protect public health and ensure that human exposure to potentially toxic chemicals (even prescription drugs can be toxic, or lethal, at inappropriate doses) is minimized enough to ensure even the most sensitive subset of the population is adequately protected.
This is how Health Canada and the government of B.C. assess and establish ambient air quality standards for all substances, including those related to all aspects of coal handling; it’s all about the exposure.
This is why it is difficult to understand the relevance of high occupational exposure studies, studies that focus on urban pollution or studies that are based on questionable assumptions and draw conclusions that are simply not supported by the data, and often cited in the debate by opponents of rail transport of coal.
Much of the scientific evidence relating to adverse health effects from handling of coal is drawn from lifelong, repeated exposures to very high contaminant levels in occupational settings, such as coal miners. These data, while telling an important story, are simply not relevant to the much lower environmental exposure to the public predicted to be associated with coal handling activities in Metro Vancouver.
Similarly, exposures to high contaminant levels in urban traffic settings aren’t helpful in understanding the consequences of much lower exposures specifically related to coal activities.
Regulatory agencies establish ambient air-quality guidelines through a process of careful evaluation of all of the available scientific evidence, and an objective determination of exposure levels that are not expected to be associated with an adverse health effect even in the most sensitive sub population.
This safe exposure level then becomes the ambient air quality standard, and ambient air levels are continuously monitored to ensure compliance with the standard. It is these standards against which the safety of all coal handling activities is judged.
It is important to note these standards, established in compliance with internationally accepted protocols, are not predicted to be exceeded by any of the coal-handling activities proposed in B.C.
Utilizing adverse health outcomes resulting from urban traffic or lifelong occupational exposures to very high contaminant levels to assess the potential for adverse effects in the general population who may not be exposed at all, or exposed at much lower levels, violates Paracelsus’ axiom of “the dose makes the poison,” and this is, simply stated, not good science.
We can all agree we expect the best science to be applied in the policies and decisions that are intended to protect our health.
Dr. Len Ritter is a fellow of the Academy of Toxicological Sciences and professor emeritus (Toxicology) at the University of Guelph.
Click here to view the original opinion column in the Vancouver Sun.
