Diesel engine exhaust earns ‘carcinogenic’ label

Introduction

Diesel engine exhaust is “carcinogenic to humans,” an international health body declared Tuesday, bolstering the findings of a controversial study published recently in the United States.

After a weeklong meeting of experts in Lyon, France, the International Agency for Research on Cancer (IARC), part of the World Health Organization, said there is “sufficient evidence that exposure [to diesel exhaust] is associated with an increased risk for lung cancer.” IARC also found “limited evidence” that diesel is linked to a heightened risk of bladder cancer.

IARC previously had classified the fumes — emitted from trucks, trains, ships, buses, mining equipment and other sources — as “probably carcinogenic to humans.”

The IARC finding is consistent with a study of 12,000 U.S. miners published earlier this year by the National Cancer Institute and the National Institute for Occupational Safety and Health. That study, publication of which was held up for years by mining industry litigation, found that the lung cancer risk for non-smoking, heavily exposed miners was seven times higher than it was for those exposed to low doses. Some industry-funded scientists have questioned the study’s conclusions.

Both the IARC and the U.S. studies have implications for the general public — especially people who live near ports, highways and rail yards — as well as workers.

In a statement Tuesday, the Diesel Technology Forum, an industry group, said that emissions of two contaminants in diesel exhaust — nitrogen oxides and particulates — from trucks and buses in the U.S. have been reduced by 99 percent as a result of new technologies and cleaner fuels.

“Air pollution is a critically important health issue and the diesel industry takes clean air concerns very seriously,” the group said. “Diesel engine and equipment makers, fuel refiners and emission control technology manufacturers have invested billions of dollars in research in an ongoing effort to develop and deploy technologies and strategies that reduce emissions to meet the increasingly diverse and stringent clean air standards in all nations throughout the world.”

In its own press release, IARC said the experts who considered the latest science on diesel have given regulators “a valuable evidence-base on which to consider environmental standards for diesel exhaust emissions.”

IARC acknowledged the new technologies and stricter diesel standards adopted in Europe and North America over the past two decades. “However,” it said, “while the amount of particulates and chemicals are reduced with these changes, it is not yet clear how the quantitative and qualitative changes may translate into altered health effects…”

Andrea Hricko, a professor of preventive medicine at the University of Southern California who has warned for years of diesel’s hazards, said in an email that the IARC decision is “a call to action” for the U.S. Occupational Safety and Health Administration and Environmental Protection Agency “to regulate diesel exposures of workers and environmental exposures for the public.

“We need to further reduce diesel emissions from ships, locomotives, trucks, construction and yard equipment to protect public health,” Hricko said. “And it is time for the involved industry sectors to accept the unanimous IARC decision that diesel engine exhaust causes cancer and spend their energies on reducing exposures instead of fighting the scientific evidence as they have been doing for decades.”