|
|
|
|
|
|
|
|
|
|
Are workers in the transportation industry, who are continuously exposed to diesel emission fumes, at an increased risk of developing adverse health conditions, such as lung cancer, ischemic heart conditions, asthma, and other respiratory conditions? A coalition of state regulatory agencies and environmental activists groups think so and have lobbied strenuously for stronger regulations and restrictions on the transportation industry to enforce the conventional belief that exposure to diesel emissions is a public health crisis.
The concerns over this public health issue are in large part an intuitive (and illogical) response based on the presumption that diesel smoke or soot, like cigarette smoke, is harmful when inhaled and that the darker, more heavy black carbon particulate in diesel fumes makes it a more potent carcinogen. The net effect has been the designation of diesel emissions as a "probable human carcinogen" and a "chemical known to the state of California to cause cancer."
While no one disagrees that diesel fume emission is a contributor to air pollution and potentially global warming, there is little to no compelling epidemiological evidence upon which to conclude to a reasonable degree of scientific or medical certainty that long-term exposure to diesel emissions at average or anticipated concentrations causes lung cancer, ischemic heart conditions, or other upper respiratory diseases, let alone that it can be "known" with any confidence to cause cancer.
In the current regulatory environment, the true cost of diesel fuel may be significantly more than its cost per gallon. The federal EPA, state governments, environmental organizations, private citizens, and class action attorneys may target the transportation industry for causing cancer and other health conditions. While the long-term liability of the transportation industry for diesel fume exposure remains unclear, companies may implement policies now to mitigate against any potential liability for claims by employees and the public.
Exposure and Emissions from Diesel Engines
The diesel engine's lower fuel cost has made it the most attractive choice for commercial transportation. Despite its many advantages, the diesel engine is inherently dirty. When diesel fuel burns in an engine, the resulting exhaust is made up of soot and gases that may contain thousands of different chemical substances, some of which are either known, suspected, or probable carcinogens by themselves at sufficient concentrations.
The exact composition of diesel exhaust depends upon operational conditions, such as engine and fuel type, fuel composition, speed, motor load, ambient air temperature, and relative humidity. Estimating ambient concentrations of diesel exhaust is difficult because there are many other sources of the most common compounds in diesel exhaust. Nauss, Diesel Exhaust: A Critical Analysis of Emissions, Exposure, and Health Effects (summary of a Health Effects Institute (HEI) Special Report, HEI Diesel Working Group: Cambridge, Mass., 1997). Black carbon (a.k.a. soot) is commonly used to estimate diesel particulate matter because it constitutes a relatively high fraction of the visible emission. Zaebst, "Quantitative Determination of Trucking Industry Workers' Exposures to Diesel Particles," 52 Am.Ind.Hyg.Assoc.J. 529-41 (1991).
To determine human health consequences of diesel exhaust exposure, ambient concentrations must be related to human exposure. Since a typical person is indoors approximately 87 percent of the time, compared with approximately five percent outdoors and seven percent in vehicles, indoor concentrations must be accounted for in an exposure assessment. Studies of indoor diesel concentrations have generally focused on occupational settings (e.g., warehouses and garages) rather than in homes, offices, or schools. Klepies, Analysis of the National Human Activity Pattern Survey (NHAPS) Respondents from a Standpoint of Exposure Assessment (68-01-7325, U.S. Environmental Protection Agency, National Exposure Research Laboratory. Las Vegas, 1996). Most houses, public buildings, and offices without internal sources of diesel exhaust are expected to have lower diesel particulate concentrations than outdoor air. However, residents in communities surrounding truck terminals or distribution centers may claim that they are exposed to harmful diesel particulate concentrations.
In a diesel particulate exposure assessment conducted in California, the average indoor diesel particulate concentration estimates were 2.0 ± 0.7 µg/m³, assuming no indoor diesel particulate sources, compared with an outdoor diesel particulate concentration estimated at 3.0 ± 1.1 µg/m³. Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant, Appendix III. Part A: Exposure Assessment (California Air Resources Board: Sacramento, 1998). Actual measurements at sidewalks in New York City reported soot concentrations that varied with truck traffic volumes from 1.5 to 6 µg/m³. Kinney, "Airborne Concentrations of PM 2.5 and Diesel Exhaust Particles on Harlem Sidewalks: A Community-Based Pilot Study," 108 Environ.Health Perspect. 213-16 (2000).
One study measured soot inside vehicles and found 0-10 µg/m³ in Sacramento and 3-40 µg/m³ in Los Angeles over two-hour sample durations. Rodes, Measuring Concentrations of Selected Air Pollutants inside California Vehicles (93U-6786-000; prepared for California Air Resources Board and South Coast Air Quality Management District by Research Triangle Institute, N.C., 1998). As one might expect, soot concentrations were higher when following diesel vehicles. Another study found average soot concentrations in Los Angeles of: approximately 5 µg/m³ with no vehicle in front; 15 µg/m³ when following a diesel powered truck with a high vertical exhaust pipe (i.e., a tractor trailer); 50 µg/m³ when following a diesel-powered truck with a low exhaust location; and 130 µg/m³ when following an urban transit bus making frequent stops. Fruin, "Fine Particle and Black Carbon Concentrations Inside Vehicles" (Conference of International Society of Exposure Analysis, 2000). All tests were performed with the windows closed.
Occupational diesel particulate exposures may be relatively high, particularly in the transportation industry. In one trucking industry study, average personal black carbon exposures were 27 µg/m³ for mechanics and 5.2 µg/m³ for truckers. Fruin, supra. These levels far exceeded the measured highway soot concentration of 3.4 µg/m³ and residential background concentrations of 1.1 µg/m³. Id. However, most occupational exposure studies are relatively recent, and epidemiological exposure studies have been hindered by the lack of good historical exposure estimates. Lipsett, "Occupational Exposure to Diesel Exhaust and Lung Cancer: A Meta-Analysis," 89 Am.J.Pub.Health 1009-17 (1999).
Public Regulation of Diesel Emissions
Based in large part on an outdated and/or incomplete body of scientific research, numerous regulatory actions have been proposed in the United States and around the world to regulate exposure to diesel emissions. In 1988, the National Institute for Occupational Safety and Health (NIOSH) classified diesel exhaust as a potential occupational carcinogen. Shortly thereafter, in 1990, the State of California, pursuant to the Proposition 65 that was enacted by the voters, designated diesel exhaust as a "chemical known to the state to cause cancer." (emphasis added.) In the mid-1990s, the American Conference and Governmental Industrial Hygienists (ACGIH) designated diesel emissions as a suspected human carcinogen. California's Air Resources Board determined that diesel particulant matter (DPM) was a toxic air pollutant.
The federal EPA considers diesel exhaust to be "likely to be carcinogenic to humans" and an air toxin. However, it has not yet assigned a numeric value to the risk posed by diesel emissions exposure. Health Assessment Document for Diesel Exhaust - SAB Review Draft, EPA/600/8-90/057E; see http://www.epa.gov/ncea/pdfs/diesel/frmatterfinal.pdf. The International Agency for Research and Cancer (IARC) classifies diesel emissions exposure as "probably carcinogenic to humans." See the IARC's monograph, Diesel and Gasoline Engine Exhaust, in The Evaluation of Carcinogenic Risks to Humans, Vol. 46 (1989). The U.S. Department of Health and Human Services has found that diesel exhaust is reasonably anticipated to be a carcinogen. Ninth Report on Carcinogens, National Toxicology Program (Research Triangle Park, N.C., 2000).
Assuming these classifications were founded in good science, why is it then that even the most recent meta-analysis finds only minimal, statistically non-significant increased risk for lung cancer, and even less association of other health conditions, such as ischemic heart conditions and acute leukemia? The answer appears to be simple: regulators respond to perceived public health concerns. The regulators, reacting to mounting activism, perceive a relationship (better known as a hypothesis) between diesel emissions as a significant source of air pollution and short-term respiratory difficulties. Regulators extrapolate that longer-term exposure must be the cause of the occurrence of various human health conditions in people employed in the transportation industry. The fallacy is that the hypothesis lacks a sound scientific basis to conclude that long-term exposure to diesel emissions as a whole causes these conditions, irrespective of exposure duration and/or occupational conditions.
The Result of Diesel Emissions Regulations
There can be little debate that the regulatory emphasis on removing less efficient diesel engines from service and the introduction of cleaner diesel fuel, such as low sulfur content or biodiesel, may result in significant reductions of emissions, and therefore, present the potential for improved health conditions due to cleaner air. The near term result, however, has been increased litigation and costs to the industry. Weinhold, "Fuel for the Long Haul? Diesel in America," 110 Environ.Health Perspect. 458-64 (2002); Chow, "Diesel Engines: Environmental Impact and Control," 51 J.Air & Waste Mgmt.Assn. 1258-70 (2001).
As one example, a coalition of environmental protection groups and the California Attorney General sued four large supermarket chains, charging them with illegally exposing thousands of neighbors of their distribution centers and workers to diesel exhaust and unlawfully failing to warn these individuals about their exposure, as required by Proposition 65. The environmental groups performed air monitoring in the communities near the distribution centers where diesel truck traffic was heaviest and claimed that the facilities were exposing local communities to diesel exhaust concentrations far above the average of outdoor air. The lawsuit demanded that the supermarket chains make a transition to trucks and other vehicles that use less polluting fuel and pay damages to neighbors and workers who have been harmed by breathing the diesel exhaust.
In April 2000, the parties in the California action entered into a consent judgment that resolved the claims. It required the supermarket chains to: provide warnings at all entrances to the distribution centers and on all buildings that face the street; mail warnings to residents near the distribution centers following a risk assessment performed by the Attorney General's Office; limit idling of diesel trucks at their facilities to no more than three minutes; implement alternative fuel vehicles as a replacement for diesel vehicles, contingent upon government funding; and, pay $895,000 in attorneys' fees and costs to the private plaintiffs. Ultimately, the monetary loss to the supermarket chains, while significant, pales in comparison to the potential loss of hard-earned goodwill of customers and potential clients.
In Massachusetts, residents near the Plainville Truck Stop are looking to the town's Zoning Board of Appeals to uphold a limit on where tractor-trailers may park. Kocian, "Truck-fume Dispute Spurs Appeal," Boston Globe, July 3, 2003. Plainville residents had complained for years that as many as 200 parked tractor-trailers were spewing harmful diesel fumes into their yards and houses. A Plainville building inspector intervened on behalf of the residents and issued a cease-and-desist order requiring the truck stop to limit parking to about one quarter of its lot. The truck stop owner appealed that order to the zoning board, and a decision is pending.
Not surprisingly, companies in the transportation industry have also been subject to suits filed by their employees as a result of diesel exposure. See Wilson v. CSX Transportation, Inc., 2003 Tenn.App.LEXIS 221; Dunn v. Metro Area Transit, 2002 Neb.App.LEXIS 327; Gortney v. Norfolk & Western Railway Co., 216 Mich.App. 535, 549 N.W.2d 612 (1996). Moreover, even in light of the controversial nature of health effects of occupational exposure to diesel emissions, courts have allowed experts to testify that exposure to diesel exhaust can cause cancer and other chronic diseases. See Wilson v. CSX, supra; Dunn v. Metro, supra (release of claims against railroad in exchange for early retirement enforceable to preclude claim of cancer caused by diesel exposure); Gortney v. Norfolk & Western, supra.
Health Effects of Exposure to Diesel Exhaust
Whether diesel emission is a source of adverse human health conditions continues to be open to debate, despite five decades of research and a large volume of studies. That the debate continues at all is largely due to inherent flaws in the body of research, difficulties in studying exposure, significant confounding variables in the study population (truck drivers and train crews typically on the road), inadequate controls, and the limitations of animal exposure studies. Many researchers have recognized these inherent limitations, and in fact, one recognized the difficulties when he recently called for additional research on the issue of the health effects of diesel emissions. Mauderly, "Diesel Emissions: Is More Health Research Still Needed?" 62 Tox.Sciences 6-9 (2001). Mr. Mauderly noted that studies to date failed to assess numerous factors, including the adjuvant effect of sub-acute and chronic inhalation of diesel emissions. His research also revealed that there is still only a nominal understanding of the effect of diesel emissions at realistic doses.
Many studies have been unable to control for occupation or dose, other than by gross time calculations. Other research is based on animal overexposure studies, which has questionable application to human exposure, either because of the unique expression of tumors in laboratory animals, or unrealistic exposure levels when compared to both ambient air and general occupational conditions of workers in the transportation industry. Moreover, there is an inherent disconnect between occupational exposure to diesel emissions and ambient air bystander exposure, which may also contain co-pollutants.
Much of the research on the health effects of diesel emissions has been conducted in animals; questions remain concerning the relevance of exposure levels in findings, and whether they can be extrapolated into humans. Sydbom, "Health Effects of Diesel Exhaust Emissions," 17 Eur.Respir.J. 733-46 (2001). Other researchers report that inhalation of diesel emissions particles depressed lung functioning and the ability to suppress antimicrobial activity, suggesting an increase of susceptibility to pulmonary infection. Castranova, "Effect of Exposure to Diesel Exhaust Particles and the Susceptibility of Lung to Infection," 109 Environ.Health Perspect. 609-12 (2001). However, the study was based on rat overexposure studies of the production of interferon, which is not necessarily extrapolated to human interferon production. Moreover, this research oversimplifies the susceptibility and defenses unique to the human body to resist pulmonary infection.
A literature research review found that the animal and in vivo studies, do "not indicate that there is a unifying mechanism of action which can explain different alleged public health effects of particulate air pollution," and that a shortcoming in many of the studies is the inability to establish the relevance of studied exposure level to background or actual peak exposures in the workplace. Sydbom, "Particles in Ambient Air," 26 Scand.J.Work Environ.& Health 28-38 (2000). Another researcher found that "the role of various diesel exhaust in causing ill health is not clear" and that reduction in exposure to diesel emissions should be accompanied by a suitable and thorough risk assessment, including assessment of all mechanical systems in the workplace. Groves, "A Survey of Exposure to Diesel Engine Exhaust Emissions in the Workplace," 44 Ann.Occup.Hyg. 435-47 (2000).
Tumors that were observed in rats, hamsters, and mice following chronic diesel exhaust exposure have not been reproducible in humans, and have now been shown to be induced by other compounds, such as carbon black and titanium dioxide. Stober, "Revisiting Epidemiological Key Studies on Occupational Diesel Exhaust Exposure and Lung Cancer in Truck Drivers," 10 Inhal.Tox. 1045-78 (1998); McClellan, "Lung Cancer in Rats from Prolonged Exposure to High Concentrations of Carbonaceous Particles: Implications for Human Risk Assessment," 8 Inhal.Tox. 193-226 (1996). One study similarly reported that the IARC classification of diesel emissions as a probable human carcinogen relies on animal exposure data, and that the studies of lung cancer are largely based on the study of a population with unique lifestyle factors. Steenland, "Diesel Emissions and Lung Cancer in the Trucking Industry: Exposure-Response Analysis and Risk Assessment," 34 Am.J.Ind.Med. 220-28 (1998). The authors themselves characterized the findings of an increased trend of lung cancer based on duration of exposure to only be exploratory.
Causation and unique lifestyle issues have also been significant confounders in the research. According to one research team, many of the studies to date had been flawed for failing to adequately account for multiple confounding factors. Morgan, "Health Effects of Diesel Emissions," 41 Ann.Occup.Hygeine. 643-58 (1997). Many of the studies purporting to find an increased incidence of lung cancer in the exposed population failed to control at all, or inadequately, for smoking history. Id. Well documented studies show that United States truck drivers smoked in excess of the American average, and work under conditions that require unusual lifestyles in between long hauls, making these individuals ill-suited for comparison to the general population as a control group. Stober, supra; Edling, "Risk Factors of Coronary Heart Disease Among Personnel in a Bus Company," 54 Int.Arch.Occup.Environ.Health 181 (1984). Still other studies failed to correct for race, sex, socioeconomics, and exposure history, or use superficial information gathering techniques that fail to elicit the totality of a person's work and exposure history. Other studies, particularly on garage and railroad workers, failed to control for asbestos exposure. Stober, supra, at 1057.
The "inadequate historical exposure data in diesel exhaust studies remains a major limitation in evaluating the epidemiology to date." Steenland, "Exposure to Diesel Exhaust in the Trucking Industry and Possible Relationships with Lung Cancer," 21 Am.J.Ind.Med. 887 (1992). See also, Stober, supra. Even the EPA concedes that evidence for non-cancerous human health effects resulting from exposure to ambient diesel exhaust was not as consistent or as strong as that for lung cancer. Lloyd,"Diesel Engines: Environmental Impact and Control," 51 J.Air & Waste Manag. Assn. 809-18 (2001). Finally, using measurements of elemental carbon as a means of calculating exposure is inherently inaccurate because studies show that only 50 percent of estimated elemental carbon is attributable to highway diesel emissions. Steenland, supra. Overall, flaws in controls and gaps in exposure data had led to publishing of poorly controlled studies replete with inaccurate data and spurious conclusions. Morgan, supra.
In addition to associations with lung cancer and ischemic heart conditions, several researchers have reported an increased incidence of acute leukemia among truck drivers. A study of leukemia patients in Sweden reported an increased etiological relationship between development of acute leukemia and exposure to petroleum products, including diesel exhaust, among occupation-exposed individuals. Lindquist, "Acute Leukemia in Professional Drivers Exposed to Gasoline and Diesel," 47 Eur.J.Haemtol. 98-103 (1991). The researchers interviewed 125 adult patients with acute leukemia that had previously been participating in treatment studies organized by the Leukemia Group of Middle Sweden between 1980 and 1983, and compared them to a control group of 125 individuals. Occupational and exposure histories were based on a simple questionnaire. They stated that their opinions of an increased risk for acute leukemia among professional drivers is consistent with earlier studies by Brandt, "Occupational Exposure to Petroleum Products in Men with Acute Non-Lymphocytic Leukemia," Br.Med.J. 553 (1978).
The conclusory opinion of the Swedish leukemia study that it is reasonable to deter children and adolescents from having regular hobby activities that include the handling of fuel-driven motors, however, is not supported by their research. Id. Moreover, the significance of the research is questionable as the authors acknowledge potential problems with both selection and reporter bias. The questionnaire did not permit distinctions between diesel and gasoline exhaust fumes. The study also failed to adequately control for exposure to organic and inorganic petroleum products, such as solvents, normally used in garages and most closely associated with an increased risk of developing acute leukemia. Finally, the study conducted in 1991 was of acute leukemia patients in the early 1980s with presumably significantly earlier exposure, prior to the institution of improved indoor air quality and cleaner operating emissions technology. Rewalter, "A Further Study of Air Pollution in Diesel Bus Garages," 42 Br.J.Ind.Med. 824-30 (1985) (noting improved conditions with improved technologies).
The demonstrable lack of consensus on the quality and divergence of conclusions to be drawn from the research, however, has not been sufficient to stem a rush to judgment by governmental agencies, environmentalists, and plaintiff's attorneys. The State of California believes that a consistent causal relationship between occupational diesel exhaust exposure and lung cancer was found in more than 30 human epidemiological studies. Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant. Appendix III, Part B: Health Risk Assessment for Diesel Exhaust (California Environmental Protection Agency: Sacramento 1998). On average, long-term occupational exposures to diesel exhaust were associated with an increase of approximately 40 percent in the relative risk of lung cancer. Lipsett, supra.
Population-based case-control studies that were adjusted for smoking have identified statistically significant increases in lung cancer risk for truck drivers. Hayes, "Lung Cancer in Motor Exhaust-Related Occupations," 16 Am.J.Indus.Med. 685-98 (1989). See also, Hansen, "A Follow-Up Study on the Mortality of Truck Drivers," 23 Am.J.Indus.Med. 811-21 (1993); and Steenland, "Diesel Exhaust and Lung Cancer in the Trucking Industry: Exposure-Response Analyses and Risk Assessment," 34 Am.J.Indus.Med. 220-28 (1998). Industry-specific studies, both case-control and cohort design, have identified statistically elevated lung cancer risks for truck drivers, although not all studies were not adjusted for smoking. Gustavsson, "Lung Cancer and Exposure to Diesel Exhaust among Bus Garage Workers," 16 Scan.J.Work Environ. & Health 348-54 (1990). See also, Rafnsson,"Mortality Among Professional Drivers; 17 Scan.J.Work Environ. & Health 312-17 (1991); and Guberan, "Increased Risk for Lung Cancer and for Cancer of the Gastrointestinal Tract among Geneva Professional Drivers, 49 Br.J.Ind.Med. 337-44 (1992).
In a study of more than 3,400 men with and without lung cancer, Swedish researchers found that those with the highest on-the-job exposure to diesel fumes were 63 percent more likely than men not exposed to exhaust to develop lung cancer. Gustavsson, "Occupational Exposure and Lung Cancer Risk: A Population-based Case-Referent Study in Sweden," 152 Am.J.Epid. 32-40 (2000). This increased risk was comparable to the 68 percent higher risk found for on-the-job asbestos exposure, a well-established risk factor for lung cancer.
The U.S. EPA reviewed 22 epidemiologic studies of workers exposed to diesel exhaust in various occupations and found increased lung cancer risk in 8 of 10 cohort studies and 10 of 12 case-control studies for several industries, including truck drivers. Health Assessment Document for Diesel Exhaust - SAB Review Draft, EPA/600/8-90/057E (U.S. Environmental Protection Agency 2000), http://www.epa.gov/ncea/pdfs/diesel/frmatterfinal.pdf. As a result, the EPA proposed identifying diesel exhaust as a probable human carcinogen and further stated that diesel exhaust is likely to be carcinogenic to humans by inhalation at any exposure condition. Id. While the EPA did not attempt to quantify the cancer risk from exposure to diesel emissions, it noted that the risk is likely to be higher for people who regularly work with or around diesel engines.
Although the totality of evidence demonstrating the carcinogenic effects from exposure to diesel exhaust appears persuasive, many uncertainties remain due to data and knowledge gaps about human exposures to diesel exhaust and the mechanics by which the diesel exhaust causes cancer in humans. Lloyd, supra. It is unclear how the physical and chemical nature of past exposures to diesel exhaust compare to present-day exposures. Extrapolation of high occupational exposures to lower environmental exposures is unproven. Nevertheless, the EPA found that the weight of evidence for a causal relationship between lung cancer and diesel exposure was strong even though inferences were involved in the assessment. Id.
Limiting Diesel Exposure
* Engine Technology and Regulatory Requirements
In 2001, the EPA issued new national standards that will eventually make bus and truck diesel engines dramatically cleaner. When the standards take full effect in 2007, they are expected to reduce emissions from trucks and buses by more than 90 percent, the equivalent of taking 13 million of the nation's 14 million trucks and buses off the roads.
Diesel engine emissions are primarily controlled through improvements to the engine, rather than through the use of aftermarket devices. Electronic control modules on diesel engines have helped improve emissions. However, in some cases, these controls use special air and fuel management parameters to pass emissions tests, but then revert to more polluting settings during on-road operations.
While these new standards and technological developments may prevent future exposure, they will not eliminate potential liability for years of past exposure. Companies in the transportation industry may implement policies now to reduce exposure to harmful diesel emissions. Such policies may mitigate the potential liability for diesel exposure.
* Fuels
Diesel fuel improvements have resulted in significant reductions in harmful emissions. Lee, "Fuel Quality Impact on Heavy-Duty Diesel Emissions - A Literature Review" (Paper No. 98-2649, Society of Automotive Engineers, 1998). Low sulfur fuels may be used to minimize harmful emissions. However, such fuels are more expensive than higher sulfur fuels. Unfortunately, the high sulfur content of diesel fuel today limits the use of advanced clean-up technologies.
* Idling
Diesel vehicles parked indoors or at loading docks should not be allowed to idle unnecessarily. Generally, prolonged idling of the engine should be avoided. Nor should a driver be inside the vehicle when it is idling for a long period. New technologies are being developed that allow trucks to use battery power to run utilities rather than requiring power from the engine. Such technologies may significantly reduce the need to allow engines to idle.
* Indoor Ventilation
Garages, warehouses, or other enclosed areas that house diesel trucks should be ventilated. Local exhaust ventilation is the best way to reduce potential exhaust hazards. A good ventilation system should include both intake and exhaust fans that remove fumes at their source. Tailpipe or stack exhaust hoses should be provided for any vehicles being run in a maintenance shop. General ventilation uses roof vents, open doors and windows, roof fans, or floor fans to move air through the work area. This is not as effective as local exhaust ventilation, and may simply spread the fumes around the work area. General ventilation may be helpful, however, when used to supplement local exhaust ventilation.
Trucks should have air-conditioned cabs to isolate the driver from fumes, and windows should be rolled up so that fumes do not seep inside.
* Maintenance
All diesel equipment should have regular maintenance and frequent tune-ups. This practice reduces exhaust particulates. The exhaust system should be checked for leaking fumes. Any cracks in the vehicle should be fitted with weather stripping to prevent fumes from seeping in. The floor of the vehicle should not have any holes.
* Protective Gear
Prevent skin contact with diesel exhaust by requiring employees to wear protective clothing (gloves, long pants, long-sleeved shirts, and face and eye protection).
Conclusion
At worst for the transportation industry, an association between diesel emissions and adverse health conditions is suggested, but is not yet proven. At best, properly controlled studies reveal no statistically significant increased incidence of adverse health conditions beyond short-term upper airway respiratory conditions. While scientists are calling for additional research, the debate goes on, the lawsuits keep coming, the legislation moves forward, and the transportation industry pays the economic penalty.
While the evidence relating diesel exposure to cancer and other adverse health conditions is uncertain, pressure on the transportation industry is mounting. It has been targeted as a primary source of diesel emissions and the regulatory or litigation climate is unlikely to improve. The low, short-term cost of diesel fuel has made it the most attractive choice for the transportation industry, yet we are now finding the long-term cost may be significant. Given the potential liability for diesel exposure to employees and the public, transportation companies should be encouraged to implement policies that reduce diesel emissions.
CauseOfCancer.pdf
|
|
|
|
|
