ShareThisTrucking company workers who have been regularly exposed to diesel exhaust from vehicles on highways, city streets and loading docks have a higher risk of lung cancer than other workers, according to a new national study.
The study, based on 31,135 worker records, found that drivers who do short-haul pickups and deliveries, including loading and unloading containers at ports and working at freight-delivery companies, had the highest rate of deaths and disease.
Dockworkers were also at a higher risk, according to the report by researchers at University of California Berkeley and Harvard.
California's Air Resources Board will consider the study's findings when it meets Friday to vote on a landmark regulation to reduce risk to the general public from 1 million diesel trucks in the state.
If the rule is adopted, California would be the first state in the nation to require a retrofit or replacement of every privately owned older, heavy-duty diesel truck on the road -- even vehicles registered in other states and nations. The phaseout would begin in 2010.
"This study confirms that truck drivers exposed to diesel have higher lung cancer rates," said Dr. John Balmes, a member of the state air board and a professor at University of California San Francisco and UC Berkeley's School of Public Health.
Long-haul drivers were at lower risk. The study's authors believe these drivers are protected because they shut their windows. In contrast, short-haul drivers who often leave their windows open are exposed to the exhaust. The study noted that fresh, newly released particles have a greater potential to cause mutations of DNA.
In the last decade, scientists have linked diesel exhaust to higher rates of lung cancer in workers in construction, trucking and railroads who inhale the toxic stew of about 400 chemicals, including benzene, formaldehyde, arsenic, cyanide and lead.
This new study compared eight jobs within the trucking industry, including clerks, and found a higher rate of lung cancer among these certain categories. A 2007 study by the same authors compared all jobs within the trucking industry to the general population, and also found higher lung cancer rates in the industry, Balmes said.
The research from Harvard University Medical School and UC Berkeley School of Public Health was published in the journal Environmental Health Perspectives in October.
The study analyzes workers' exposure histories up to the year 2000 and health outcomes between 1985 and 2000. There were 4,306 deaths and 779 cases of lung cancer, including 734 deaths where lung cancer was the underlying cause.
Workers in the study averaged 22 years on the job and were predominantly Caucasian and lived in the South or Midwest.
Most of them worked at four large companies, which weren't named in the study. They were hired after long-haul trucks changed from gas to diesel during the 1950s and '60s but before or during the transition of pickup and delivery trucks from gasoline to diesel during the 1970s and '80s. Diesel forklifts were also used by dockworkers on some loading docks during the 1980s.
California, which listed diesel exhaust as a known carcinogen in 1990, considers more than 40 chemicals in the exhaust to be toxic air contaminants, a designation that warrants the toughest regulation.
The fine particles in the exhaust enter lung tissue, where they can accumulate in the lungs and lymph nodes. High concentrations can cause respiratory diseases, and people with asthma, heart disease and emphysema can worsen if exposed to the exhaust. Long-term exposure leads to chronic obstructive lung disease as well as lung cancer.
California gradually has tightened restrictions on fleets of diesel buses, off-road equipment, boats and some trucks. There is no worker standard for diesel exhaust.
"This is the biggest regulation in cleaning up the state's diesel emissions," said air board spokesman Leo Kay.
Bob Ramorino, president of family-owned Roadstar Trucking Inc. in Hayward, Calif. said the trucking industry supports the need to clean up emissions in California. But it has asked the air board for exemptions as a way to deal with the cost.
Ramorino, who is also president of the California Trucking Association, said he owns 30 large diesel cabs and 60 trailers and employs 60 workers. Retrofitting costs about $20,000 per truck, and a new vehicle runs about $100,000.
He also questioned the study, saying it includes exposures from the 1960s through the 1980s. "Trucks manufactured after 1994 are much cleaner than the earlier trucks," Ramorino said.
E-mail Jane Kay at jkay(at)sfchronicle.com.
(Distributed by Scripps Howard News Service, www.scrippsnews.com.)
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