Presumptive lists and cancer-relevant policies

The presumptive lists (Schedule 3 and 4) and many of the policies that are specifically related to cancer need updating. In particular, the list of presumptions is very limited compared to other jurisdictions and to the lists of well-established associations identified by agencies such as IARC and ILO. Increasing the use of presumptive lists can reduce the reliance on purely case-by-case review, increase the speed of adjudication and improve transparency by making it clear what the WSIB regards as causal associations. While some of the policies of the WSIB are very clearly written, there are gaps and some policies and presumptions are specific to employers, rather than to carcinogenic exposures, which could be applied more widely. In addition, there is the perception that some key adjudication procedures are not included in the policy manual or in the publicly available documentation. One example of this is how adjudicators handle exposure to multiple carcinogens: adjudication staff told us that they factor it into their determination, but some stakeholders we consulted with believe that is not the case.

Many workers' compensation systems, including the WSIB, use estimated latent periods as a scientific criterion for establishing work-relatedness of disease. In Ontario, there is no general policy on how to factor latency into the adjudication process. For certain cancers, minimum latency requirements that establish the minimum interval between first exposure and diagnosis of disease are set out in the applicable policiesfootnote 43. Workers are generally not entitled to compensation if the interval between the date they were first exposed to the carcinogen(s) and the date of diagnosis is less than the minimum interval established in policy. While establishing such intervals is a useful tool for facilitating adjudication for the majority of cases, it should not be used as an absolute barrier because some cases can fall outside this range. It is important to consider this when there are no other risk factors for the cancer in question, or the circumstances for the claimant are unusual, such as when exposures were particularly high or the patient unusually young.

In determining work-relatedness, decision-makers are required to weigh the evidence and be satisfied that work exposure was a significant contributing factor in the development of the worker's cancer. However, the assessment of work-relatedness is often complicated by the fact that workers are rarely exposed to just one workplace hazard. Most workers' compensation systems, including the WSIB, rely on the findings of epidemiological studies to inform their decision-making. However, this approach has limitations because the majority of existing occupational epidemiologic studies from which evidence can be drawn have traditionally focused on the effects of single workplace hazards in isolation. In Ontario, the policies are generally silent on how to factor multiple exposures into the determination of work-relatedness and adjudicators are faced with having to make assessments of work-relatedness on a case-by-case basis. This may lead to invalid assumptions about causal interactions between multiple exposures and inconsistency in decisions.

When determining entitlement, decision-makers are required to consider not only the worker's work-related exposures, but also non-occupational factors. Although there is research available that suggests that a range of non-occupational factors can influence disease risk, the most common and contentious is smoking. There is a widely held perception that, more often than not, a worker's history of smoking is used to dismiss occupational disease claims. If true, this practice would run counter to what the science says about the interaction between smoking and exposure to carcinogens. The conclusions of IARC's 2004vevaluation of the carcinogenicity of tobacco smoke are particularly relevant and should be factored into the adjudication process. This evaluation, which was published over 15 years ago, concluded that smoking was a potential confounder of the association between exposure to various workplace carcinogens and lung cancer, but that there was evidence of synergy between smoking and some important causes of lung cancer (e.g., asbestos, radon, arsenic, nickel) (66).

In most jurisdictions, including Ontario, workers' compensation legislation and policy are generally silent on the synergistic relationship between smoking and certain exposures. Two of the six lung cancer policiesfootnote 44 specifically mention smoking, but only in the context of minimum cessation requirementsfootnote 45. In both of these policies, the cessation interval must be 15 years or less for a smoker or 20 years or less for a confirmed non-smoker or ex-smoker. Implicit in the use of cessation intervals is the assumption that there is no synergy between smoking and exposure and indeed that a cancer in a recent smoker was due only to smoking. There are two other policies that mention smoking. The first, Policy 23-02-02: Laryngeal Cancer and Asbestos Exposure states "in considering the individual merits of each case, a claimant's cigarette smoking and alcohol consumption habits before the diagnosis of laryngeal cancer should be considered". The second, Policy 23-02-03: Lung Cancer Among Workers in the Uranium Mining Industry, states "a worker's non-smoking status can provide evidence of work-relatedness in the weighing of evidence on the individual merits and justice of the case". No further guidance is given.

Our knowledge of what causes workplace cancer is constantly evolving and presumptive lists and policies need to keep pace to retain credibility. This updating requires both internal scientific capacity (see below) and independent scientific review. In the past, the WSIB had the Industrial Disease Standards Panel to conduct reviews. Currently, it handles major scientific questions on an ad hoc basis, sometimes using internal reviews (e.g., rubber workers), sometimes external consultants (e.g., McIntyre Powder), and on occasion independent panels (e.g., herbicides). Creating a standing scientific panel would allow for the continuous review of scientific information as well as new and emerging issues.

Recommendation: The WSIB should update and greatly expand the list of presumptions regarding cancer in Schedules 3 and 4 to reflect the current state of scientific knowledge. Presumptions should be based on exposure to carcinogenic agents or processes, and not specific employers, in order to be more broadly applicable. In updating and expanding its presumptive lists, the WSIB may want to consider using criteria such as that used in independent scientific review undertaken of Australia's deemed diseases list (2). Similar to that review, we would recommend that the following three criteria be used:

  • Evidence of a strong causal link between the disease and occupational exposure, defined on the basis of inclusion in IARC Group 1 (i.e., definite human carcinogen), a systematic review of the evidence, or multiple good quality studies showing a causal relationship between the disease and the occupational exposure.
  • Clear diagnostic criteria for any disease included in a scheduled list to ensure questions don't arise as to whether the claimant really has the disease that is the subject of the claim.
  • The occupational disease comprises a considerable proportion of the cases of that disease overall in the exposed population.

Recommendation: The WSIB should update and expand all of the policies relevant to adjudication of cancer claims to reflect the current state of scientific knowledge. We have identified two areas for which new policies are needed:

  • A policy that explains how exposure to multiple carcinogens is handled. Given the current state of knowledge regarding the impact of multiple exposures, the effects of exposure carcinogens impacting the same cancer site should be considered additive, unless there is evidence to the contrary.
  • A policy that states clearly how non-occupational exposures, particularly cigarette smoking, are weighted relative to occupational exposures. As with multiple occupational exposures, the relationship should be considered additive unless there is evidence for a synergistic effect.

Recommendation: The WSIB should create an independent, standing Scientific Review Panel to review and recommend changes to the schedules and policies, to review and approve scientific reports, and to assist in the selection of external consultants and researchers. The Panel should be composed of independent scientists with a broad range of expertise, including epidemiology, toxicology, occupational medicine, and occupational hygiene. The process for choosing members should allow for stakeholder input, including the opportunity for worker representatives and employers to nominate scientists. Scientists with expertise in occupational cancer and occupational disease are a scarce resource in Canada and the scientific challenges are similar across the country. Ontario could consider sharing the support of such a panel with other jurisdictions. This would not only increase efficiencies and leverage other resources, but also increase the independence of the panel.

Enhancing scientific capacity

Our knowledge of what causes workplace cancer is constantly evolving and presumptive lists and policies need to keep pace to retain credibility. Although both the WSIB and the MLTSD have highly trained professionals, the current level of internal scientific capacity in both organizations is grossly inadequate. For example, in contrast to the over 10 research staff it had a decade ago, the WSIB currently has only 2 dedicated research staff, and the MLTSD, which had the ability in the 1980's to investigate clusters and conduct independent studies, is now almost entirely reliant on external resources. While the WSIB, through the MLTSD, funds scientific research centres, including the Occupational Cancer Research Centre, it does not always take full advantage of their research expertise or their findings.

Capacity needs may be partially addressed by enhancing existing and developing new research partnerships, but internal staff are also needed at both the WSIB and the MLTSD. There is currently no capacity to investigate clusters or to identify potential high-risk industries. There is also too little capacity to translate the results of scientific studies into a form that can be used to drive policy and to support the activities of the Scientific Review Panel.

Recommendation: The WSIB needs to increase its internal scientific capacity to at least its previous levels. This should include scientists with graduate level training in epidemiology, toxicology and exposure science (such as occupational hygiene).

Recommendation: Stronger partnerships with external research centres, including those already funded with WSIB funds, are needed for research on emerging issues and gaps of importance to Ontario. Such partnerships should encourage the development of surveillance systems to support evidence-based decision making in adjudication and to assist in identifying emerging issues, including previously unrecognized excesses of cancer.

Recommendation: Provincial capacity needs to be developed to investigate cancer clusters and other emerging issues. Ideally that should be in the MLTSD, where it is independent of the WSIB, and could also focus on prevention of future disease as well as compensation. This would require increased research capacity within the Ministry. MLTSD could seek partnerships with other branches of government or, possibly, system partners. For example, Public Health Ontario currently investigates suspected clusters of environmental origin, and has appropriate expertise to provide assistance. Historically, Ministry physicians undertook these investigations.

Access to exposure data to improve compensation (and prevention)

A necessary component to making science-based judgements on the work-relatedness of occupational cancer is documenting or estimating exposure to workplace carcinogens. This is a major challenge for all workplaces though special efforts may be required for complex, high-risk industries. Ontario has many industries with a long history of contributing to the provincial economy of Ontario, but these industries also come with a long history of carcinogenic exposures. Large complex workplaces such as GE Peterborough create special challenges for reconstructing historical exposures. Special efforts may be needed to document exposure for these workplaces and may require a large investment of human and financial resources, but proper adjudication of large numbers of claims is expensive regardless of the methods. In addition, claims adjudicators need better and more timely access to exposure data. At present, claims adjudicators must submit Freedom of Information requests for documents relevant to workplace exposures held by the Ministry, which introduces delays in an already slow process.

Recommendation: Adjudication should be improved by better access to electronic exposure data. While MESU is useful, it could use a better interface and does not cover all circumstances or time periods needed. The WSIB should attempt to partner with the Canadian Workplace Exposure Database (CWED) which contains the MESU data, but also contains exposure data collected by other provinces to cover a wider range of exposure.  

Recommendation: MLTSD should lower data access barriers and create better mechanisms to provide exposure-related data to WSIB. In addition, exchange of data in both directions between MLTSD and WSIB could also contribute to prevention. The Ministry should  consider this in the context of the existing privacy regulatory framework in Ontario. Facilitating this may require the Ministry to computerize records and, potentially, statutory changes. The Ministry may want to consult other jurisdictions where mechanisms exist for the sharing of administrative datafootnote 46

Recommendation: MLTSD should collect copies of exposure-monitoring results from employers at the time of inspections and computerize those results to facilitate access to exposure monitoring data. As above, the Ministry should consider this recommendation in the context of Ontario's existing privacy regulatory framework and statutory changes may be needed.

Recommendation: WSIB should explore opportunities to work with external research organizations to digitize historical exposure or employment records for high-risk industries, such as was done with the Mining Master File. Such efforts could also be taken using internal resources.

Improving recognition through medical education

Even for well-established carcinogens there is an extremely large gap between the estimated burden of occupational cancer and submitted claims. Currently, Canadian medical students receive very little basic training in occupational health, including the need to collect an occupational history. Other than a few specialty clinics and some independent practices, there are very few occupational medicine specialists in the province, so the great majority of patients need to rely on their primary care providers for support on workers’ compensation claims.

General practitioners have acknowledged the value that additional training in occupational medicine could bring to their practice (67) and primary care provider targeted occupational health training could improve the rate of detection and reporting of occupational disease (68). For example, a recent study demonstrated that physicians who had been trained in occupational medicine or received training in occupational diseases were "more likely to refer a patient on suspicion of occupational disease" (69).

Recommendation: Physician education is a challenging area that deserves more investigation. While a detailed review of this issue is beyond the scope of this report, it is important that medical education be improved in Ontario to increase the recognition of occupational cancer.