Jack Siemiatycki, the epidemiologist who helped to defeat Big Tobacco

In 5 seconds

Science tipped the balance. The testimony of the epidemiologist Jack Siemiatycki, CRCHUM researcher and University of Montreal professor, was a deciding factor in an historical judgment against Big To

On May 27, the Superior Court of Quebec ordered Imperial Tobacco, Rothmans, Benson & Hedges and JTI-Macdonald to pay $15 billion in punitive and moral damages to smokers and ex-smokers in Quebec. This victory was achieved in part through the work of Jack Siemiatycki, who was an expert witness for tobacco victims in the two class actions. The researcher developed a new approach to respond to Justice Brian Riordan's main question in the trial: how many people with the specific diseases mentioned in the class action (lung cancer, throat and larynx cancer, and emphysema) does it take for smoking to have, "more likely than not," caused these diseases? "We presented a new way to calculate the number of cancers caused by smoking, according to which 90% of lung cancers can be considered legally attributable to smoking," Siemiatycki explained. Siemiatycki is affiliated with Centre de recherche du Centre hospitalier de l'Université de Montréal and the university's École de santé publique de l'Université de Montréal (ESPUM.)


We already know that smoking causes these diseases; however, as the well-known adage by Paracelsus goes, “only the dose makes the poison.” The challenge met by Siemiatycki was to calculate what the critical dose was, and how many patients in Quebec have exceeded this threshold of proof.

He used the concept of “pack-years” to determine how many cigarettes you need to smoke to face a more than 50% risk of disease caused by smoking. A pack-year equates to smoking a pack of 20 cigarettes per day for one year (or less over a longer period) for a total of 7,300 cigarettes. According to Siemiatycki's testimony in court, and based on his calculations, a smoker diagnosed with lung cancer has to have smoked 5 pack-years, or the equivalent of 36,500 cigarettes, for smoking to have, “more likely than not,” caused the disease. He then estimated how many cancer patients have exceeded this critical threshold and could legally attribute their disease to smoking. He concluded that 90% of lung cancer cases in Quebec can be considered legally attributable to smoking. On this basis, tens of thousands of Quebec victims could claim the right to compensation.

After a two-and-half-year trial and 17 years of legal proceedings, the judge ruled for the victims of tobacco. The tobacco companies and their experts argued that smokers and ex-smokers are responsible for their health problems because they knew the risks of smoking. The Court, on the other hand, concluded that Imperial Tobacco, Rothmans, Benson & Hedges and JTI-Macdonald put profits ahead of the health of their customers.

Despite the testimony of five US experts hired by the companies to contradict or discredit the work of Siemiatycki, in his lengthy, 276-page judgment, Justice Riordan expressed his full confidence in the scientist's analysis. He used Siemiatrycki's innovative calculations to determine the amount of compensation payable. “His testimony was central for tobacco victims. It's a great example of science serving the public good,” said Pierre Fournier, Dean of the Université de Montréal's School of Public Health (ESPUM).

The tobacco companies intend to appeal. Whatever happens, this decision should set a legal precedent throughout the world, largely because of this innovative approach for estimating health risks.

About Jack Siemiatycki

Jack Siemiatycki is a researcher at the CHUM Research Centre (CRCHUM) and professor of Social and Preventive Medicine at the University of Montréal's School of Public Health, and holds the Guzzo Environment-Cancer Research Chair of the Cancer Research Society. His work on the new methodology presented in court to quantify the number of lung cancers was funded by this research chair and the Canadian Institutes of Health Research (CIHR). Siemiatycki is also known for his previous studies on the causes of cancer in the workplace and the risk of developing brain cancer with the use of cellular phones. The University of Montreal is officially known as Université de Montréal.

Source: Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM)

Media contact:
William Raillant-Clark
International Press Attaché
University of Montreal (officially Université de Montréal)
Tel: 514-343-7593