Canadian Occupational Safety

22 Canadian Occupational Safety | www.cos-mag.com Parkinson's is a "major burden" for the working age population because it can affect people quite young, says Squires. While most people develop the disease around age 60, 20 per cent are diagnosed under age 50. Ali was diagnosed at 42. Young onset Parkin- son's (before age 40) occurs in fi ve to 10 per cent of those diagnosed, says Parkinson Canada. Because manual de xterity is affected early in the course of the disease, many offi ce workers have trouble typing and their occupational performance can take a hit. Some of Squires' patients have lost their jobs because they were not keeping up as well as they used to. Professionals in very cognitively demanding jobs have noticed issued with multi-tasking and cognitive pro- cessing, such as business executives. Other workers with Parkinson's have found balance to be problematic. "One individual worked for a tele- phone utility as a technician and he was up and down ladders as part of his job, but when he developed bal- ance issues, he was having to change jobs as a result of that," says Squires. It is estimated that 25 to 35 per cent of people diagnosed with Parkinson's are still in the workforce, says Parkin- son Canada. Employers have a legal duty to accommodate workers with Parkinson's disease. One diffi culty with the disease is that the causes remain largely unknown. While some cases may be inherited (about fi ve to 10 per cent), it is likely that the large majority of cases have an environmental basis, says Kay Teschke, a professor in the School of Population and Public Health at the University of British Columbia in Vancouver. Various studies show there are sev- eral workplace exposures that can increase the risk for Parkinson's dis- ease. Employers need to be well-versed in these risks and do their part to pre- vent their workers from developing this debilitating and chronic disease. HEAD TRAUMA One such exposure is head trauma, which doctors blamed for Ali's case. Head trauma is really well-known to be associated with Parkinson's dis- ease, says Harris, who was a part of a team of researchers who presented a report on Parkinson's workplace risk factors to WorkSafeBC in 2011. Their study found the strongest risk rela- tionships were for concussion injuries and head injuries that resulted in unconsciousness. "If we prevent head injuries at work, we will prevent Parkinson's disease," Harris says. "I believe that's true and I believe the results (of our study) bear that out. Fortunately, that's a great target because that's something we want to do anyway. Preventing head injuries is already a goal and you can get double bang for your buck because you also can prevent some future cases of neuro- logical disease." Teschke, who was the lead author of the report to WorkSafeBC, says workers' compensation boards should be particularly interested in the correlation between head injuries and Parkinson's. "Workers' compensation boards in Canada would be wise to do a review of that literature on head injur y and think about potentially compensat ing people who had documented head injur ies at work , if t hey develop Parkinson's disease later in life," she says. "I think it's worth at least examining that potential." The relationship between Parkin- son's and head injury is also making headlines in the class-action law- suit against the NFL, which accused the league of hiding the dangers of concussions. The lawsuit provides compensation for former players who suffered serious medical condi- tions associated with repeated head trauma. Retired players diagnosed with Parkinson's could receive up to US$3.5 million each. Workers in Canada can apply for workers' compensation and provide evidence of a link between their workplace exposure — such as head trauma — and the disease. Many people think the disease needs to be on a board's schedule of occu- pational diseases, but that's not the case, says Teschke. SOLVENTS In 2008, an Ontario worker was granted compensation for his Par- kinson's disease after "signifi cant exposure" to hydrocarbons in his work. He worked for a manufacturer of offi ce furniture components and had been using paints that contained organic solvents, including hexane, xylene and toluene. In 1983, the worker began his employment at the company. After seven years, he began to complain of weakness in his left arm. Ten years after that, in 2000, he was offi cially diagnosed with Parkinson's disease. Ontario's Workplace Safety and Insurance Board, as well as the appeals resolution offi cer, originally denied the claim, but the Workplace Safety and Insurance Appeals Tribunal panel ruled in the worker's favour. The panel said the evidence for and against the claim that exposure to hydrocarbons led to his Parkinson's disease was approximately equal in weight, there- fore, the claim must be granted. Various studies have made links between Parkinson's and toluene, xylene, n-hexane, carbon tetrachlor- ide, trichloroethylene (TCE) and tetrachloroethylene (also known as perchloroethylene or PERC). A 2012 study examined these six chemicals and found ever exposure to TCE was associated with signifi cantly increased risk of Parkinson's, and exposure to PERC and carbon tetra- chloride tended toward signifi cance. The researchers, who were from all over the world, including Toronto, studied 99 twin pairs, where one twin had Parkinson's and the other did not. Results were similar regardless of the exposure duration and cumulative life- time exposure, found Solvent Exposures and Parkinson's Disease Risk in Twins. TCE had been used extensively worldwide for decades — in coffee decaffeination and as an anesthetic — but today it is primarily used as a degreasing agent in metal parts fabrication. Carbon tetrachloride was formerly used as a dry cleaning solvent but has been almost entirely replaced by PERC. PESTICIDES One of the best-known potential risk factors for Parkinson's is pesticides. The chemicals have been found to wreak havoc by disr upting enzymes, proteins and neurons within the brain. The pesticides paraquat and rote- none are fairly well-established to cause an increased risk for Parkin- son's, and they should not be used in the workplace, says Squires. The problem of course, he adds, is there may be other offending agents, but we just don't know what they are yet. A study published in May in the Scandinavian Journal of Work, Envi- ronment and Health conducted a systematic literature review and meta- analyses on Parkinson's disease and occupational exposures. It concluded "there is now strong evidence that exposure to any pesticide involves at least a 50 per cent increased risk for developing Parkinson's disease." But Harris is not convinced. In her research with Teschke and colleagues, they found recall bias to be a concern — individuals with Parkinson's were more likely to report a history of pes- ticide exposure because they were aware of the suspected association between the two. Recall bias is a con- cern in any study where participants are asked to self-report. While many individuals said they were exposed to pesticides, once an industrial hygienist reviewed the data, only about one-half showed a true exposure. "This is a long suspected relation- ship and probably the best studied. Unfortunately, it doesn't mean that that information is totally clear. We don't necessarily have the answer as to whether or not pesticides are a cause of Parkinson's," says Harris. Pesticides can be worked with safely if proper precautions are fol- lowed. All Canadian jurisdictions have either set their own occupational exposure limits for some pesticides or follow the American Conference of Governmental Industrial Hygien- ists (ACGIH) threshold limit values (TLV). However, a number of com- monly used pesticides do not have such limits, so exposure must be kept as low as reasonably achievable. Parkinson's is a "major burden" for the working age population because it can affect people quite young.

• Cover