Air Pollution, and Cancer Risk: A Link to Scrutinize

A recent report from the staff of the South Coast Air Quality Management District indicates that some residents of the South Coast Air Basin--the urban areas of Los Angeles, Orange, Riverside and San Bernardino counties--may be subjected to highly elevated risks of cancer from toxic contaminants in the air they breathe.

The report focuses on 20 toxic pollutants, including such key human carcinogens as benzene and chromium and applies theoretical but commonly used risk-assessment techniques. It shows that the cancer risk over a lifetime could range as high as 1 in 200 in areas such as the South Bay community of Rancho Dominguez, located near major oil refineries. This represents a cancer risk 5,000 times higher than the maximum allowed by state and federal authorities from any single pollutant in the water supply.

According to a report by district staff issued in June, 1987, much of the rest of the basin is also subjected to considerable risk. Most residents of metropolitan Los Angeles, for example, have a theoretical cancer risk from airborne benzene alone of about 1 in 1,000, or 1,000 times the maximum risk allowed by California health authorities from benzene in drinking water. In a city of 3 million people, this elevated level of risk could translate into 3,000 cancer cases.

At a press conference called to discuss the most recent report, district officials--while acknowledging the existence of some so-called toxic “hot spots”--attempted to downplay the hazards from the air we breathe, saying that since approximately 1 out of 4 residents of the basin will contract cancer anyway, the additional cases caused by air pollution add little to the total rate of incidence. And in his haste to allay public alarm, Riverside County Supervisor Norton Younglove, the district board chairman, issued a statement to the news media that erroneously understated the elevated cancer risk in the hot-spot areas by a factor of at least 1,000. Younglove went on to say that “even higher risks occur as a result of other common activities, such as driving on our freeways.”

The science of assessing cancer risk from environmental pollutants is difficult and controversial. While most environmentalists and many outspoken scientists regard any cancer risk as too high, representatives of industry and a number of equally vocal scientists argue that life in modern society creates many risks and that policies regulating toxic pollutants must take into account the high costs that can be involved. Nevertheless, the theoretical cancer risk to which most residents of the basin are exposed from toxins in the air is far higher than what both sides of this controversy generally consider acceptable.

In fact, under almost all other circumstances, a cancer risk of 1 in 1,000 from an identifiable source, is considered a public-health emergency. Under state and federal water-pollution guidelines, for example, a contaminated drinking-water well would be shut down long before it was allowed to reach this level of risk. The theoretical cancer risk in Rancho Dominguez is only slightly lower than that which forced the evacuation of Times Beach, Mo., due to dioxin contamination; it is also just slightly lower than the risk that prompted Environmental Protection Agency administrator Lee M. Thomas to urge all homeowners in the United States to test their residences for radon gas.

Why, then, are South Coast district officials attempting to play down the results of their own risk-assessment studies? A partial answer may lie in the fact that the district is on the verge of proposing new regulations governing the emissions of toxic air pollutants, and that the regulations as currently drafted will do little to alleviate the risk. In fact, the new rules represent--as one district official put it privately--an attempt to balance the concerns of industry and environmentalists and “come up with something that will fly politically.” The proposed regulations governing toxic air emissions would be considerably more lax than the district’s earlier stated policy. The proposed rules would tolerate cancer risks as much as 10 times greater than previously allowed in new industries if they can show that this is the best they can do. Moreover, the regulations apply only to new sources of pollution--controls on existing sources are only in the discussion stage. Thus the new rules will at most slow the rate of increase--and do nothing to decrease--the current high cancer risk levels.

Under even the most lenient risk-assessment guidelines, air pollution in Southern California is a public-health emergency. Yet regulators have long avoided taking truly drastic measures against Southern California polluters, fearing the high economic and political costs.

Although district officials have lately been more aggressive against polluters, especially under the leadership of new executive officer James M. Lents, they do a grave disservice by attempting to downplay the risks from toxic air pollution. If anything, they need a concerned and outraged public behind them if they are to institute the kind of serious controls needed to protect the public health.