Commuters’ Cars Pose Cancer Peril, New Study Warns

Commuters who travel the Los Angeles Basin’s congested roadways are exposed in their cars to between two and four times the levels of cancer-causing toxic chemicals found outdoors, according to a new study to be released today.

Added to this disturbing finding, the two-year study by researchers for the South Coast Air Quality Management District concluded that it makes little difference whether drivers roll their windows up in an effort to block fumes; commuters are only slightly better off with windows closed. And, perhaps surprising to some, the study found that motorists are better off with car vents open rather than closed.

Not surprisingly, however, the study also concluded that motorists caught in traffic of less than 25 m.p.h. have greater exposure to toxic gases than when traffic is moving at more than 30 m.p.h., and that older vehicles--those made from 1973 to 1983--allow “significantly higher” levels of carbon monoxide, benzene and toluene to seep in.

“Even assuming a constant level of inspection and maintenance, older vehicles’ emission controls and other parts continue to deteriorate, causing more emissions of exhaust pollutants” into the car and the atmosphere, the study said.

Researchers cautioned that higher exposures do not necessarily translate into equally heightened health risks. But there is general agreement that as exposures increase, so do health risks.

The study, funded by the U.S. Environmental Protection Agency, is expected to add new urgency to the AQMD’s drive to tighten vehicle emission standards and step up ride-sharing efforts. The study, a copy of which was obtained by The Times, is to be released at an AQMD board meeting in El Monte.

The report called for stepped-up ride-sharing, traffic signal synchronization and staggered work hours--all proposed in the AQMD’s sweeping clean air blueprint approved by the district in March.

Measures Suggested

“These measures, in combination with more stringent vehicle emission limits, can reduce exposures to air pollutants in vehicles as well as in other environments,” the study said.

Scientists have long recognized that outdoor exposures account for only a portion of an individual’s total exposure to various pollutants. Over the last several years, researchers have found that concentrations of some toxic, cancer-causing and mutagenic pollutants found indoors, while still relatively low, are nonetheless often at least 10 times greater than outdoors and far exceed limits placed on the same pollutants in outdoor air by the federal Clean Air Act.

While there have been previous studies dealing with carbon monoxide exposures in cars and hundreds of studies dealing with toxic pollutants in buildings, the AQMD research is believed to be one of the first “substantive” examinations of a wide range of air toxics found in cars, according to an AQMD source who asked to remain anonymous.

Benzene, a known human carcinogen associated with leukemia, poses the greatest health risk to the Basin’s commuters of all the 16 toxics studied, researchers said. They found benzene concentrations in cars were about four times higher than those outdoors.

It is estimated that, among the Basin’s total population, there is a one in 10,000 chance of getting cancer from benzene exposure. Based on the study, researchers concluded that 15% of those cases--or 15 out of a million-- would be due to exposure during commuting to and from work.

Higher Risk

But the total cancer risk from benzene exposures while driving is probably much higher than that, researchers said. They cautioned that their study looked only at exposures during round-trip commutes to work, which averaged 1 1/2 hours each weekday. The study did not survey trips to the store or other errands.

“This risk from total in-vehicle exposure would be greater if all non-work commute trips were considered,” the study warned.

The study noted that others have estimated that each weekday there are 3.35 million round trips from home to office, 13.5 million non-work round trips, and 3.15 million one-way work related trips.

Lead concentrations measured in vehicles were roughly 60% higher than outdoor levels.

A total of 140 commuter cars were sampled for in-vehicle concentrations of 16 air pollutants while commuting to and from work. The participants, who were randomly selected, lived throughout the four-county South Coast Air Basin, but all commute to Flair Business Park in South El Monte.

Monitoring Devices

Special monitoring devices were installed in the cars and drivers kept a log of their mileage.

Researchers called for support of the state Air Resource Board’s proposal to limit benzene content of gasoline beginning in 1993.

The new limits would cut the cancer risks estimated in the study by 20%, researchers said.

“Benzene contributes the great risk to the Basin’s commuters,” the study said.

The study was conducted by Ditas C. Shikiya, Chung S. Liu, Michael I. Kahn, Jesse Juarros and Wayne Barcikowski of the AQMD’s Office of Planning and Rules.

The 16 pollutants studied were: carbon monoxide; benzene; toluene; xylene; ethylene dibromide; ethylene dichloride; lead; formaldehyde; acetaldehyde; carbon tetrachloride; chloroform; perchloroethylene; 1,1,1-Trichloroethylene; cadmium; chromium and nickel.

COMMUTERS AND TOXIC POLLUTANTS A new study by the South Coast Air Quality Management District shows that people driving in cars are exposed to higher concentrations of most toxic air contaminants than are found in generally in the Los Angeles Basin. Researchers placed special monitors inside vehicles and asked drivers to keep a log of their commuting habits. Gas levels are in parts per billion; metals levels are in micro-grams per cubic meter

ORGANIC GASES

In-vehicle Background Level Formaldehyde 12.5 6.8 Acetaldehyde 7.6 5.4 Carbon Monoxide 3.661 8.599 Benzen 13.3 5.3 Toluene 36.3 14.7 Xylene 32.9 15.3 1,1,1-Trichloroethane 5.5 4.5 Carbon Tetrachloride 0.15 0.15 Perchloroethylene 4.5 4.7

METALS

In-vehicle Background Level Chromium 0.012 .023 Lead .218

Background levels during peak commuting hours for gases measured at checkpoints in Long Beach, Los Angeles and for metals measured at a checkpoint in El Monte.