Are some cases of Parkinson's Disease work related?

Last week, I participated in a research project sponsored by the Pacific Alzheimer’s Research Foundation and Canadian Institute of Health Research.  It was conducted by the Pacific Parkinson’s Research Centre at the Health Sciences Centre Hospital – UBC.  I don’t have Parkinson’s or Alzheimer’s or other neurodegenerative disease (at least not yet) but believe research is essential if we are to improve the diagnosis and treatment of Parkinson’s, Alzheimer’s and related  neurodegenerative disorders.  As a subject in the study, I will not receive any direct benefit but the knowledge gained from me and other participants may benefit others. 

The study employed a technique known as PET (Positron Emission Tomography) scanning to determine the activity of brain nerve cells.  This involved the injection of a substance labeled with a tiny amount of radioactive isotope with a very short half-life.  As the isotope decays, it emits positrons. When a positron bumps into an electron, both are annihilated releasing two gamma photons in opposite directions which are detected in the scanner.  Three dimensional images of the brain can be constructed from the data sets collected from the scanner.

I had two scans during the course of the six hours I was at the hospital. Each scan involved my head being placed in the scanner.  Keeping my head still for the hour or so for each scan was made easier by a a very stylish custom-fitted mask. 

Such studies are not cheap to run.  The isotopes, technicians, medical staff involved to get one set of readings from one test subject like me, not to mention my occupying the very expensive PET scan for literally hours are clearly cost intensive.   The actual research on the scans of all subjects involved, the analysis, peer review and publication also carry significant costs. What could possibly justify the cost?  Well, to paraphrase a poster I once saw, “If you think research is expensive—Try disability and disease!”  Clearly, the human and financial costs of neurodegenerative disorders are staggering and, by that measure, financial and personal commitment to research is the far better and cheaper choice. 

Linking that personal experience and position to the world of workers’ compensation is not a huge leap.  We may not talk a lot about neurodegenerative disorders but just about everyone knows someone with one such neurodegenerative disorder:  Parkinson’s disease.  High profile sufferers of this chronic disorder include actor Michael J. Fox and fighter Mohamed Ali.  They have helped put a face on the characteristic and progressive tremors, stiffness, and slow movements that are often the most visible signs of this disease. 

Is Parkinson’s disease or Parkinsonism work-related? There is a lot of evidence that certain work exposures are associated with an increased risk for the development of Parkinsonism.  There is evidence that chemicals in the work environment may play a role in the development of the disease.   Certain pesticides and organic solvents are clearly implicated in the development of Parkinson’s and head trauma – as a result of a work-related injury, for example—increases the risk of Parkinson’s disease.  Manganese exposure and heavy metal exposure are also associated with the development of Parkinsonism. 

As far as occupational risks are concerned, work on farms and in gas stations or work as a welders and miners have been shown to have statistically higher risks for the development of this disease. 

In the US, the ASSE reports 10,000 lawsuits by welders who have developed manganese-induced Parkinson’s disease .   I know of only a handful of workers’ compensation claims ever being submitted  for Parkinson’s disease or Parkinsonism.  Aside from a few cases reported in the US press [like the 1996 win by a welder in the California Workers’ Compensation Appeal Board], few applications for workers’ compensation have been accepted.  

Why don’t we see more workers’ compensation claims for Parkinson’s disease, Parkinsonism, and other potentially work-related neurodegenerative disorders?  The onset of the disease is often diagnosed after work careers end.  Knowledge of the association between work and the disease may not be widely known in the occupations at elevated risk.  Temporary foreign workers in agriculture, for example, may not fully understand the risks they may be exposed to in applying pesticides; even if they are aware of the risks, it is unlikely that a temporary foreign worker who may have suffered exposure here will file a claim from their home country. 

Will we see more workers’ compensation claims for neurodegenerative diseases like Parkinson’s in the future?  I predict we will.  As more workers extend their work careers into their late sixties and beyond and as the association between work, certain work-related traumas and increased risks of occupational disease including Parkinson’s increase, we are going to see more cases presented as work-related, exacerbated by work,  recognized by diagnosticians as being work-related, and ultimately presented for consideration of workers’ compensation benefits.    

What is the true incidence of work-related disease?

The following story from New Zealand (NZ) caught my eye:

New figures reveal work kills 1000 a year
(by Tom Hunt, Fairfax News, 19/12/2011)

Work is killing 1000 of us a year.
New figures, which also show there are 17,000 new case [sic] of work-related disease in New Zealand each year.

Think about that for a minute. New Zealand is a country with a population of 4.3 million — almost identical to the population of British Columbia — yet work-attributed fatalities and diseases in NZ far exceed those we accept at WorkSafeBC. What accounts for the difference?

When I tracked down the source report for the headline, the reasons became clear. NZ is taking a holistic approach to the issue of occupational illness: on a population basis, the incidence of occupational disease that can be attributed to work will always be greater than incident rates calculated from individual cases where causation must be adjudicated.

On a population basis, NZ finds:
about 700–1,000 deaths occur every year in New Zealand from occupational disease, particularly cancer, respiratory disease and ischaemic heart disease (such as coronary artery disease) 2–4 percent of deaths of all people over the age of 20 are due to occupational disease, and 3–6 percent of all cancer deaths in people aged 30 or older are due to occupational cancer
there are about 17,000–20,000 new cases of work-related disease every year.

What the population-incidence approach illustrates is that workers and society are paying a huge price for work-related illness and disease. If B.C. has a similar population-incidence ratio then the true cost of work-related disease is far greater than the 2,750 occupational disease claims first accepted and paid in 2010.

Leaving aside the under-recognition and under-reporting of many occupational diseases, this high incidence alone requires action. The NZ Action Plan proposes a focus on five specific hazards:
• occupational carcinogens;
• respiratory hazards;
• noise;
• skin irritants; and
• psycho-social hazards.

Exactly what actions will be taken to address each of these hazards will depend to some extent on the sector. To assess whether any of the actions has been effective will require data on exposure to health hazards in the working population. NZ is actively developing a surveillance system through the Centre for Public Health Research at Massey University.

Recognizing the true incidence of occupation disease changed the dialogue in NZ. The focus is not on claims costs but human and societal costs. More importantly, there is a refined focus on prevention rather than jurisdiction. It will be interesting to see how their strategy and surveillance systems develop. There may be important lessons for other jurisdictions.

What constitutes an emerging OH&S risk?

Everyone who does environmental scanning in workers’ compensation and prevention gets asked the question, “What constitutes an emerging risk in OH&S?” Over the years, I have created lists of emerging risks based on many sources. Here is how I rationalize what makes the list.
I generally follow the European Risk Observatory’s approach, and consider for inclusion in my list of “emerging OH&S risks" any occupational risk that is both new and increasing. A couple of examples illustrate the sort of reasoning I apply to determining what that means.

“New” means the risk did not exist or was not recognized before. Nano-particles and their application in industry are new risks caused by a new technology and new processes. Workplace bullying and psychological stress are not new but are becoming more widely recognized as OH&S risks, (often newly recognized by legislators, regulators, or the Courts). Cyber-bulling is a relatively new social phenomenon that might fit this category.

The recognition of workplace mental or psychological stress is not really new. However, recognition of it being caused by the expectations for 24/7 connectedness via a smart phone might fit as a new type of workplace or organizational structure that would also fit the definition of “new.”

I am particularly concerned about highlighting those issues where new scientific knowledge allows a long-standing issue or common work practice to be identified as a risk. Historically, asbestos was widely used long after it was known to be carcinogenic. What is the new asbestos? IARC and others have identified shift work that interferes with circadian rhythms as a probable human carcinogen, and an important contributor to other health conditions. To my way of thinking, this should be considered new.

Emerging risks may also be long-standing issues that are seen in a new way, or are rising in society in a way that is increasing the OH&S risk. People have always aged and some people have been overweight or obese, but the aging workforce and the epidemic in obesity should be on the list as emerging OH&S risks. Mumps and Rubella have always been a threat to school staff such as teachers, teaching assistances, and administration but the decline in vaccination levels among school age students may be categorized as an increasing OH&S risk.

None of the above risks would make the list of emerging risks if the risk was not “increasing." Clearly the number of hazards, (like sedentary work, for example), leading to the risk , (obesity), is growing. Nano-particles and processes involving their use make the list because they have moved out of the lab, and are increasing in day-to-day operations in the workplace. The exposure to the hazard, (number of people working shifts that interfere with circadian rhythms), leading to the risk, (cancer), is increasing. In some cases the effect of the hazard on workers' health, (pace of work, mental stress), is getting worse, (more people affected or the magnitude of the effect recognized as more serious).

Creating lists of emerging risks is not an end itself. It is more important that we understand what is going on, apply the precautionary principle, and protect workers by education, design, substitution, work processes, and other strategies.

One of my biggest fears is that future professionals in workers’ compensation OH&S will look back at what we knew today about these emerging risks and ask, “What were they thinking? Why didn’t they recognize the emerging risk?” and more importantly, “Why didn’t they do something?”