Hot Spots for Cancer Risk From Toxic Air Identified

Cancer risks from breathing toxic air pollution are excessive throughout the Southland, but residents of southeastern and central Los Angeles County face the worst threat, according to a report to be released today by the South Coast Air Quality Management District.

The two-year, $1-million study shows that people in the congested core of Los Angeles County--especially in communities such as Huntington Park and Pico Rivera with a large number of low-income, minority residents--face the greatest odds in the region of contracting cancer linked to polluted air.

The report points to one source for the vast bulk of the problem: diesel vehicles, mostly big trucks, that spew tiny pieces of carbon soot that health experts have linked to lung disease.

Although air pollution carries a cancer risk, health experts stress that people face a much greater danger from other well-known causes--mostly food and cigarettes.

In general, one of every four Americans contracts cancer. The AQMD data show that air pollution can be blamed for only about 0.5% of those cases. Still, that risk is considered high for an environmental cause. Cancer caused by environmental factors is viewed as an involuntary risk because people cannot personally control it.

The AQMD study showed that the risk generally “follows the freeways,” said the agency’s deputy executive officer, Mel Zeldin.

Diesel engines account for 71% of that risk, with cars and other mobile sources responsible for about 20% and plants such as refineries and aerospace factories blamed for about 10%.

AQMD Executive Officer Barry Wallerstein said the threat from breathing toxic air in the Southland is probably comparable to--and perhaps lower than--that in other major urban U.S. areas because of the region’s strong emissions controls.

The AQMD concluded that people living in an area that generally follows the Long Beach Freeway, as well as the Santa Ana Freeway from downtown Los Angeles to north Orange County, face the highest threat in the region: As many as 1,700 people would be likely to contract cancer for every 1 million exposed for a lifetime to the pollutants in that area.

On average in the basin--Los Angeles, Orange, Riverside and San Bernardino counties--1,200 to 1,400 people would be at risk of cancer from air pollution out of every 1 million exposed, the AQMD says.

Of 10 sites that the AQMD monitored in the four counties, Huntington Park and Pico Rivera--flanked by freeways heavily traveled by trucks--have the unhealthiest levels of carcinogenic air pollutants.

“I am appalled and devastated by the results,” said Huntington Park Mayor Rosario Marin. “Clearly this is unacceptable. We’ve long believed we were the victims of environmental injustices. We’re an overcrowded community, a poor community. So many of these things are beyond our control.”

The AQMD board ordered the study to determine whether minority and poor areas are disproportionally harmed by toxic air pollution. It was one of 10 environmental justice initiatives authorized by the board at Chairman William Burke’s request.

The study is groundbreaking, because it tries, for the first time in the nation, to quantify the risk posed by 31 common carcinogenic air pollutants, from dry cleaners’ solvents to benzene in car exhaust.

The good news, Wallerstein said, is that the cancer risk is about a third its level of a decade ago, largely due to regulations aimed at another air problem--smog. Toxic gases from vehicles, benzene in gasoline and compounds such as chromium released by factories have been cut.

The findings will be reported to the AQMD board today, but a strategy for reducing the threat won’t come until January, when the board considers a sweeping anti-toxics plan designed to cut such emissions from vehicles and industries.

The AQMD expects to develop measures aimed at forcing or promoting conversion of some diesel vehicles to cleaner fuels. The state Air Resources Board and U.S. Environmental Protection Agency, however, are the dominant forces in cleaning up diesel vehicles and fuel, and they are planning tighter standards for new vehicles.

The California Trucking Assn., representing truck company owners, and diesel engine makers have long disputed the link between diesel exhaust and lung cancer, saying there are too many scientific uncertainties. Also, they say the AQMD statistics could be inaccurate because they do not include direct measurements of diesel exhaust, only of a carbon compound that could come from other sources too.

Environmentalists worry that the diesel findings will weaken the AQMD’s focus on cleaning up industrial plants, especially in Wilmington. But Wallerstein said the agency still intends to adopt new regulations early next year that target toxic pollutants from industries.

Zeldin said that even though no toxic hot spots were found around industries, they probably exist. He said they are just hard to detect, because they probably occur right at the fence lines of the plants.

No federal or state laws limit the cancer risk that is allowable from air pollutants. But, in general, some regulators have considered an acceptable rate to be one cancer case out of every 1 million people exposed. Compared with that goal, people in most of the Los Angeles Basin face a risk 1,200 times higher.

The study showed that toxic pollutants are seasonal--they peak in November and December, when coastal breezes weaken, trapping soot and gases near the ground. The pattern is the opposite of that for smog, which peaks in summer because sunshine is a critical component.

The AQMD study measured cancer risk. Whether people in southeast and central L.A. County are actually contracting cancer at higher rates than elsewhere in the region is unknown. People move around too often and are exposed to too many variables and causes of cancer to do any meaningful comparisons, epidemiologists say.

The findings were based on a year of monitoring at 10 fixed spots, as well as mobile monitors that sampled the air for about a month at 14 other sites near industrial plants. Then the AQMD applied a cancer risk figure for each pollutant set by state health officials. To check the accuracy of its data, the AQMD ran computer models that factored in regional traffic patterns, weather and emissions. The models confirmed risk levels strikingly close to the spot checks in the 10 cities, Zeldin said.

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Cancer Risk

The AQMD measured toxic air pollutants at selected sites and found communities along major freeways, especially the 710 and parts of the 5, carried the highest risk of cancer. About 250,000 of every 1 million Americans contract cancer in their lifetime, mostly because of smoking and diet. Here are estimates of additional cancer cases that could result over a lifetime from pollution at 1998 levels.

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Source: South Coast Air Quality Management District