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Human Health Risk Assessment for Diesel Exhaust

Health Canada completed the Human Health Risk Assessment for Diesel Exhaust, a comprehensive review and analysis of the potential adverse health effects associated with diesel fuel use in Canada. The report focuses on diesel exhaust (DE) emissions from on-road and off-road vehicles (excluding rail and marine applications) and targets impacts resulting from general population exposures. The assessment includes a review of diesel fuels, engines and emissions, a review of exposure to DE, an evaluation of the health effects associated with DE exposure, as well as a quantitative analysis of the population health impacts associated with the contribution of DE to criteria air contaminant concentrations in Canada. This report does not address the health risks of diesel fuel itself, which is under review as part of the Chemicals Management Plan of the Government of Canada and will be reported elsewhere.

Internationally, the potential health effects of DE exposure have long been recognized, and great effort has resulted in substantial reductions in diesel emissions, including in Canada. A key accomplishment has been the introduction of stringent emission regulations for new diesel vehicles and engines, resulting in improved engine and emission control technologies in both the off-road and on-road diesel fleets. In addition, the quality of diesel fuel used in on-road, off-road, rail, marine and stationary engines has improved, particularly in terms of the sulphur content. Some jurisdictions have undertaken additional initiatives to mitigate in-use diesel engine emissions and human exposure to them, such as inspection and maintenance programs, retrofit and scrappage programs and idling restrictions. However, the Canadian in-use diesel fleet is still dominated by engines pre-dating the most recent emission standards.

Diesel-powered vehicles are pervasive on major roadways and in urban centres in Canada. It is reasonable to assume that most Canadians are regularly exposed to DE. Because of the variable and complex nature of DE and the fact that DE constituents are emitted by other pollution sources, it has been difficult to quantify general population exposure to DE. Several surrogates have been used to represent DE, all of which have had their limitations. The respirable fraction of elemental carbon is considered to be one of the better options used to date.

This risk assessment considered the reviews and conclusions of the California Environmental Protection Agency (1998)Footnote1 and the United States Environmental Protection Agency (2002)Footnote2 human health risk assessments for DE and provided detailed review of the health effects literature published since 2000. The available information supports the conclusion that DE emissions have direct effects on human health.

The newly published health studies along with supporting evidence from work published prior to 2000 provide sufficient evidence to conclude that DE is carcinogenic in humans and is specifically associated with the development of lung cancer. Although the risk estimates are generally small, the population health risks are considered to be significant given the ubiquitous presence of DE emissions in Canada. The evidence is also suggestive that DE may be implicated in the development of cancer of the bladder in humans, but further research is required to allow definitive conclusions to be drawn. A limited number of studies have investigated other cancers in association with DE exposure, but the evidence is inadequate to draw conclusions regarding causality. Overall, these conclusions are consistent with the categorization of DE as a human carcinogen (Group 1) by the International Agency for Research on Cancer.Footnote3,Footnote4

Regarding non-cancer health effects and the potential causal role of DE in their development, a number of conclusions are drawn from the existing literature. The evidence supports a causal relationship between acute exposure to DE at relatively high concentrations and effects on the respiratory system, including increases in airway resistance and respiratory inflammation. Under conditions of chronic exposure, DE exposure is likely to be causal in the development of respiratory effects. It was concluded that DE exposure is likely to be causal in the development of adverse cardiovascular outcomes following acute exposure and in the development of adverse immunological responses. The evidence reviewed is suggestive of a causal relationship between DE and 1) adverse cardiovascular outcomes following chronic exposure, 2) adverse reproductive and developmental effects and 3) central nervous system effects following acute exposure to DE. Currently, there is inadequate evidence to draw conclusions regarding the potential neurological impacts of chronic DE exposure.

Based on traditional risk assessment methodologies and with regard to general population exposures, a short-term exposure guidance value of 10 µg/m³ and a chronic exposure guidance value of 5 µg/m³ have been derived based on diesel exhaust particulate matter (PM) to protect against adverse effects on the respiratory system. The available evidence indicates that respiratory effects occur at lower concentrations of DE than those associated with other non-cancer adverse effects, and so these guidance values are considered protective against the non-cancer health impacts of DE exposure. However, it is recognized that there have not been adequate large scale epidemiological studies of non-cancer effects associated with either short-term or chronic DE exposure to conclusively characterize the exposure-response relationships. More research is needed to elucidate this and to evaluate the potential role of DE in the observed non-threshold population health effects of fine particulate matter (PM2.5).

In general, it has been shown that sensitive subpopulations, such as the elderly, children and asthmatics, can be at greater risk of adverse respiratory effects due to DE exposure. Exposure of the elderly and asthmatics to traffic-related DE has been shown to increase respiratory inflammation. Also, pulmonary function decrements have been demonstrated in asthmatics exposed to traffic-related DE. Furthermore, traffic-related DE exposure in children has been implicated in potential asthma development later in life. The guidance values for short-term and chronic DE exposure presented above account for the enhanced sensitivity of subgroups in the population.

Overall, it is concluded that DE is associated with significant population health impacts in Canada and efforts should continue to further reduce emissions of and human exposures to DE.

As part of this assessment, efforts were also made to quantify the population health impacts associated with the contribution of DE to criteria air contaminant concentrations in Canada. The analysis of population health impacts was conducted in a stepwise manner with the use of computer simulation tools to 1) estimate emissions from the Canadian diesel fleet, 2) estimate the impact of those emissions on ambient concentrations of criteria air contaminants across the country and 3) estimate population health impacts resulting from the incremental contribution of DE to air pollution levels. This was undertaken for calendar year 2015, and results were assessed on a national, provincial/territorial and regional basis. This analysis is complementary to the traditional risk assessment approach presented above.

The air quality scenarios modelled with A Unified Regional Air Quality Modelling System (AURAMS) and the Air Quality Benefits Assessment Tool (AQBAT) were selected in order to provide an indication of the potential air quality and health impacts associated with diesel fuel use in on-road and off-road applications in Canada. On-road and off-road diesel applications are responsible for substantial levels of pollutant emissions. Compared with other mobile sources, diesel vehicles and engines contribute significantly to nitrogen dioxide (NO2) and PM2.5 emissions, whereas gasoline mobile sources contribute the majority of carbon monoxide (CO) and volatile organic compound (VOC) emissions. Diesel source emissions are notably important in large urban areas, such as Greater Vancouver, Toronto and Montréal, where a large fraction of the Canadian population resides. Diesel emissions are also important along major trucking routes and roadways connecting major cities (e.g. Windsor-Québec corridor), as well as in agricultural and mining areas (e.g. Alberta). The characteristics of the mobile fleet and the dominating economic sectors in a particular region determine the influence of diesel emissions. The concentration of diesel emissions in specific geographic areas leads to distinct air quality impacts across Canada.

Diesel emissions are estimated to contribute significantly to ambient concentrations of NO2, PM2.5 and ground level ozone (O3). The air quality modelling results show that on-road diesel emissions contribute significantly to air pollutant concentrations in urban and economically active areas and along major transportation routes. Off-road diesel emissions, which are more widely distributed than on-road diesel emissions, affect air quality in both rural and urban areas. The combination of on-road and off-road emissions leads to greater air quality impacts in the largest Canadian urban centres, notably Greater Vancouver, Edmonton, Calgary, Winnipeg, Toronto and Montréal. Off-road diesel emissions also have a relatively large impact in less developed areas characterized by few other sources of pollutant emissions (e.g. remote mining communities).

Based on the current health impact analysis, on-road and off-road diesel emissions result in significant and substantial population health impacts and societal costs in Canada via the contribution of DE to ambient concentrations of criteria air contaminants. The modelling undertaken estimates that on-road diesel emissions are associated with 320 premature mortalities for 2015 (valued at $2.3 billion), with 65% and 35% of the estimated mortalities attributable to ambient PM2.5 and NO2, respectively. On-road and off-road diesel emissions are associated with 710 premature mortalities (valued at $5.1 billion), with 65%, 32% and 3% of the estimated mortalities being attributable to ambient PM2.5, NO2 and O3, respectively. Diesel emissions are also associated with significant numbers of acute respiratory symptom days, restricted activity days, asthma symptom days, hospital admissions, emergency room visits, child acute bronchitis episodes and adult chronic bronchitis cases across Canada. Results from the AQBAT simulations for the current assessment suggest that on-road and off-road emissions each contribute approximately equally to population health impacts. The results also indicate that both on-road and off-road diesel applications have significant health impacts in major Canadian urban centres. Diesel emissions have higher health impacts in the most populated provinces, such as British Columbia, Alberta, Ontario and Quebec, and in the most populated census divisions, which correspond to the Greater Vancouver, Calgary, Winnipeg, Toronto and Montréal areas. The greatest air quality impacts are also observed in those areas. Overall, it is concluded that efforts should continue to further reduce emissions of DE in Canada, particularly in areas with large populations.

To obtain an electronic copy of the Human Health Risk Assessment for Diesel Exhaust, please contact .

Footnotes

Footnote 1

California EPA (1998). Part B: Health risk assessment for diesel exhaust. Office of Environmental Health Hazard Assessment, Air Resources Board, California Environmental Protection Agency, Sacramento, CA.

Return to footnote1referrer

Footnote 2

US EPA (2002). Health assessment document for diesel engine exhaust (final 2002). EPA/600/8-90/057F. National Center for Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, Washington, DC.

Return to footnote2referrer

Footnote 3

Benbrahim-Tallaa L; Baan RA; Grosse Y; Lauby-Secretan B; El Ghissassi F; Bouvard V; Guha N; Loomis D; Straif K; International Agency for Research on Cancer Monograph Working Group (2012). Carcinogenicity of diesel-engine and gasoline-engine exhausts and some nitroarenes. Lancet Oncol 13(7): 663-664.

Return to footnote3referrer

Footnote 4

IARC (2013). Diesel and gasoline engine exhausts and some nitroarenes. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 105. International Agency for Research on Cancer, Lyon, France.

OHS Futures – Grant Funding Program

On March 1, 2016, the Alberta Ministry of Labour launched the third year of the Occupational Health and Safety (OHS) Futures – Research Funding Program. OHS Futures is accepting research applications for projects that support the prevention of occupational injury, illness and disease in Alberta workplaces.

OHS Futures formalizes the way researchers, institutions, industry, and labour organizations across Canada access funding for OHS research. The program links government with experts with the purpose of enhancing OHS knowledge and capacity within the province.

A one-hour information session will be held via WebEx on March 17, 2016 at 2:00 pm MST. To register for the session, please email Amy Elefson – Research and Evaluation Associate at .

In the meantime, please visit the OHS Futures website (www.work.alberta.ca/ohsfutures) for information on research priorities, applicant eligibility, the application package, application assessment, data sharing, and the Freedom of Information and Protection of Privacy Act under which the information you provide is being collected.

The Application Package, consisting of an online application and application supplement, is now available on the OHS Futures website. The submission deadline is May 2, 2016 at 11:59 pm MST.

Should you have any questions, please do not hesitate to contact us directly at .

Sincerely,

 

 Dr. Lisa Ross-Rodriguez, MSc, PhD

Director | Occupational Disease and Injury Prevention

OHS Policy and Program Development | Alberta Labour

Phone: 780.638.1069 | Cell: 780.690.0410 | Fax: 780.644.2100

8th Floor Labour Building, 10808-99 Ave | Edmonton, AB  T5K 0G5

 

Oil and gas workers suffering hearing loss at double the rate of other noisy industries

Drilling and pipeline work is noisy business and according to a new report, it’s taking an alarming toll on the hearing of workers in B.C.’s gas and oil industry.

In a bulletin WorkSafeBC says those oil and gas patch workers are experiencing noise-induced hearing loss at a rate of 33 percent, over twice the rate of workers in other noisy jobs.

“It raises a few alarm bells,” said Budd Phillips, regional prevention manager with WorkSafeBC in Fort St. John. “Approximately one-third of workers were starting to show signs of noise-induced hearing loss.”

WorkSafe doesn’t know if ear protection is absent, improperly used, or just inadequate for all the noise. But Phillips says companies need to do a better job making sure their employees are protected.

Workers often don’t use the ear protection they are given, said Art Jarvis of Energy Services B.C. — which speaks for 1,600 companies working in B.C.’s gas patch.

“Definitely if you’re working beside a frac crew with screaming engines, that’s a noisy location,” said Jarvis.

The report is based on tests conducted in 2014 and notes that young workers are most likely to forego hearing protection devices entirely, with 27 percent of those under-21 reporting they didn’t use hearing protection.

WorkSafeBC regulations require that employers provide workers with CSA rated hearing protection and test them annually when workplace noise exceeds a certain exposure limit.

Only 15 percent of oil and gas workers were tested in 2014.

This article originally published on CBC News Canada and can be viewed at by clicking here 

An Introduction to ANSI/ASSE Z88.2-​2015, Practices for Respiratory Protection

The new American National Standard Practices for Respiratory Protection, Z88.2-2015, which was approved by ANSI on March 4, 2015, overcame significant challenges during the past two decades. The updates to the 1992 revision of Z88.2 were substantially delayed while professional disagreements over appropriate assigned protection factors (APFs) for air-purifying half-mask respirators were addressed through a lengthy appeals process. In December 2010, the ANSI Board of Standards Review Panel denied the final appeal and recommended that a new subcommittee start the review process.

The new Z88.2 subcommittee was established in October 2011. It had the distinct advantage of the previous draft standard along with the many updates in related federal regulations and guidance documents, national consensus standards, and advances in relevant research.

RELATED GUIDANCE AND REGULATIONS

Subsequent to the ANSI approval of the 1992 version of Z88.2, NIOSH promulgated its final rule on Respiratory Protective Devices. That regulation updated performance standards for air-purifying particulate respirators, and NIOSH published several guidance documents addressing their selection, use, and limitations. OSHA revised its Respiratory Protection Standard in 1998. Later, the agency added definitions and requirements for APFs and Maximum Use Concentrations (MUCs). OSHA APFs were established after thorough evaluation of available peer-reviewed literature, including workplace protection factor studies, comments submitted to the public record, and testimony from hearings. Proper respirator selection is an important component of an effective respiratory protection program, and the OSHA APFs provide employers with necessary information for selecting respirators for employees exposed to airborne contaminants. OSHA also revised its fit-testing procedures in 2004. The agency published various guides in support of these updated regulations, including a guide on APFs. A recent update to the Department of Transportation’s specifications for shipping containers also informed the work of the Z88.2 subcommittee. Other national consensus standards considered in the preparation of Z88.2-2015 are listed in the “Resources” sidebar below. The subcommittee considered a substantial body of research that was published after the 1992 revision of Z88.2. This information related to the proper use and performance of respiratory protection in general, including workplace and laboratory evaluations of NIOSH-approved particulate respirators and the effectiveness of fit-testing.

BY RICHARD W. METZLER, JAMES S. JOHNSON, DAVID L. SPELCE, AND TIMOTHY R. REHAK 

Originally published in AIHA  Synergist September 2015

The Ethical Mentor

 Ethics are a critical aspect of our profession. As industrial hygienists, we are guided by the ethical guidelines published by industrial hygiene professional associations (and, for those certified by the American Board of Industrial Hygiene, the enforceable ABIH Code of Ethics).

The public maintains certain expectations of what members of our profession represent and how our ethical behavior should relate to the professional services we offer. Industrial hygienists are expected to provide advice based on our knowledge and expertise for the purpose of preventing injury and disease. We gain this knowledge and expertise through a lifelong process of education, work experience, and feedback.

We learn ethics through a similar process of interactions with peers, parents, mentors, and even our children regarding social and professional expectations and norms. The author George Head has written that right and wrong can be different for individuals and groups based on profession, life experiences, religious beliefs, and an infinite number of other confounding factors. In professional ethics, there may be multiple rights and multiple wrongs, and we may disagree with one another on how to resolve a particular ethical dilemma.

At the beginning of our career, we learn ethics first by the “right-and-wrong” method, usually through feedback from supervisors and peers. As we become more seasoned professionals, however, we often lack feedback loops for our behaviors. We become the “supervisor,” and we must ponder the ethical nature of some decisions by ourselves.

When I’m unsure about the resolution of an ethical dilemma, I often seek counsel from a mentor. At the beginning of my career, these mentors were older than I was. As my career has progressed and my experience broadened, I often seek ethical counsel from peers and younger professionals. Multiple perspectives help ensure that I have the appropriate information to make a decision. Occasionally, I pose an ethical dilemma to my young daughter. I am almost always surprised by the maturity, thought, and accuracy of her responses.

The author David Clutterbuck has written in detail about corporate ethical mentorship. I propose that we take Clutterbuck’s idea one step further and engage in professional ethical mentorship. Professional ethical mentors are people who help you think through ethical dilemmas. They need to be trustworthy and good listeners. They may help you develop your ability to anticipate, avoid, and resolve ethical dilemmas. Resolution may not be easy, and an ethical mentor can help guide you through potential pitfalls.

Ethical mentors should have deep insight into human behavior and life experience. They should pose insightful questions and help others reflect upon their values, judgments, and actions. They must be capable of processing complex, emotionally charged dilemmas without becoming emotional. They can’t be judgmental. The outcome of ethical mentoring is counsel that improves the ability of the mentee to make sound and reasoned decisions.

As you read the hypothetical case studies below, consider how an ethical mentor might have helped the characters address their ethical dilemmas.

The Missing Aspergillus Species

A 60-year-old individual was diagnosed with Aspergilloma. The individual claimed that the disease was due to exposure to indoor mold in a recreational vehicle. Three industrial hygiene consultants investigated this claim, and each contributed a report and professional opinion. All agreed that the cause of disease was mold from inside the RV.

The first consultant conducted culturable surface sampling that presented sampling data dominated by Penicillium species. Although fungi classified as “other” were identified in the samples, the laboratory did not identify the species. Additional culturable surface samples identified 10 species of fungi, which were dominated (greater than 50 percent) by three species of Penicillium. No species of Aspergillus were identified.

The second consultant took non-culturable surface samples from the RV that were dominated byCladosporium species and Aspergillus/Penicillium-like fungi. 

Both the first and second consultants took non-culturable air samples that were dominated by Asp/Pen-like fungi, and no individual species of Aspergillus was identified. The laboratory report clearly stated that there could be no interpretation as to whether the fungi identified in the RV was definitively Aspergillusor Penicillium species because this type of sampling does not differentiate between spores of the two types.

The third consultant, who had a doctorate in toxicology and was a former director of an IH laboratory, based his opinions on the findings of the first two consultants and concluded that the Aspergilloma was caused by mold from within the RV. 

The ethical issue here is that although none of the causative agents of Aspergilloma were identified, these consultants were attributing causation to exposure to an Aspergilloma-causing fungus within an RV. All three consultants either failed to recognize or ignored the fact that they did not find Aspergillus species within the RV, which would be necessary (among other things) to opine that exposure to Aspergillus species caused a disease. Here, the first two consultants did not have much experience and simply may not have known better. But the third consultant was aware of the differences in sampling and analytical techniques and limitations of the different sampling types.

Questions to consider: 

  • How might the first two consultants have resolved these ethical lapses? How might their resolution differ from that of the third consultant?

  • Because the first two consultants were inexperienced, is their lapse in judgment less severe than that of the more senior consultant?

  • How could an ethical mentor have helped the inexperienced consultants respond to this dilemma? 

The Not-So-Drunken Yankee

Jake was a very tall young man who weighed approximately 340 pounds. One summer, shortly after moving to south Texas, he started working in the oil field. At the end of his first week on site, the foreman reported to the safety supervisor that Jake was drunk. The company had a strict alcohol and drug-use policy, and Jake was taken to the safety supervisor’s trailer and questioned about whether he had been drinking. He acted erratically and did not provide direct answers, so the safety supervisor drove him approximately one hour to the company’s regional headquarters to submit to a drug test.

The drug screen was negative for alcohol and drugs. The safety supervisor then drove Jake back to the job site and sent him home. On Jake’s way home, a fellow motorist reported him as a drunk driver. He was pulled over and became erratic with the officer, who jailed him on suspicion of drunk driving. Two days later, jailers noticed that Jake had become severely lethargic. He was transported to the emergency room where he was diagnosed with and treated for heat stroke.

Questions to consider: 

  • What ethical lapses did the company make in its treatment of Jake?

  • Was it incumbent upon the safety supervisor and other personnel in the home office to consider other reasons for Jake’s strange behavior?

  • Would there have been an opportunity for an ethical mentor to play a role in this situation? 

  • How could the company have acted as an ethical mentor?

  • How can industrial hygienists use this case as an example to mentor young professionals?

The Self-Reference

A young industrial hygienist named Jill is hoping to take the CIH exam. Her supervisor is very busy and has not yet filled out her reference form despite multiple requests.

Jill approaches her supervisor again, reference form in hand, as the deadline for applications is looming. She asks him to take a moment to complete it so that it can be mailed off by the deadline. He signs the form, hands it back to her, and instructs her to fill in the blank reference information and mail the form.

Jill fills in the reference form and mails it. A few months later, she passes the CIH exam.

Questions to consider: 

  • What ethical lapses occurred here?

  • Was it inappropriate of the supervisor to require Jill to fill in the reference form?

  • Should the supervisor have reviewed the information contained in the reference before he signed the form?

  • Is Jill’s supervisor someone who should be considered an ethical mentor?

Everyone Makes Mistakes

Everyone occasionally has lapses in ethical judgment. None of us learn ethical behavior by ourselves: we must receive feedback, learn cultural and professional norms, and agree to subscribe to those norms. The important aspect of our behavior, then, is not necessarily that we had a lapse in ethical judgment but that we recognized the lapse and responded to it. We are the proverbial guinea-pigs of our ethical being because we all make mistakes and must resolve them in our own way. Resolving ethical lapses may not be easy, and a multitude of resolutions may exist. In these cases, the counsel of an ethical mentor can prove very helpful. 

MICHAEL D. LARRAÑAGA, CIH, CSP, PE, PhD, is principal consultant for ENVIRON, a member of the NIOSH Board of Scientific Counselors, and a director of the American Board of Industrial Hygiene. He can be reached at .

Resources

  • Clutterbuck, David: “Step Forward the Ethical Mentor,” http://bit.ly/clutterbuck-ethics (October 2013).

  • Head, George: “Where Our Ethics Come From,” http://bit.ly/head-ethics (March 2006). 

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