SOUTHERN CALIFORNIA’S ENVIRONMENT At the Crossroads : HEALTH: PINPOINTING THE RISKS : The Pollutant Factor

These are key health effects of some of the major pollutants in the Southern California environment.

AIR POLLUTANTS

* Ozone: This colorless, irritant form of oxygen is the most pervasive air pollutant. At high altitudes, it protects the earth from harmful ultraviolet radiation, but it can be formed in excess when sunlight interacts with hydrocarbons and nitrogen oxides emitted by cars and industry. Short-term effects of exposures include headaches, eye irritation, sore throat, coughing, wheezing, and chest discomfort. Chronic exposures to high levels of ozone appear to accelerate the aging process of the lung and people who live in highly polluted areas are likely to have a greater risk of developing chronic lung diseases. The effect is independent of the effects of tobacco smoking. Scientists have not been able to prove that chronic ozone exposure increases the risk of developing lung and other cancers.

* Nitrogen oxides: Like ozone, nitrogen oxides are harmful lung irritants. They are produced when fossil fuels such as gasoline and oil are burned. The brown gas may increase susceptibility to bronchitis and other respiratory infections.

* Particulates: These are microscopic liquid droplets or solids less than the width of a human hair that are suspended in the atmosphere. They include soil, metals, sulfates, nitrates and organic chemicals. The smallest particles, those less than 10 microns in diameter, or PM-10, are the greatest health hazard because they can be breathed deeply into the lungs. They may increase susceptibility to respiratory infections. The average Los Angeles Basin resident has a risk of death in any year of 1 in 10,000 greater than would be the case if federal PM-10 standards were met, according to a study prepared for the South Coast Air Quality Management District. Riverside and San Bernardino County residents have risks that are about twice the basin average; Orange County residents are below the average. By contrast, the yearly risk of dying in a motor vehicle accident in California is two in 10,000.

* Carbon monoxide: This colorless, odorless gas is produced by incomplete combustion of gasoline and other carbon-containing fuels. More than 90% of the carbon monoxide in the basin is emitted directly from motor vehicles. Carbon monoxide interferes with the oxygen-carrying capability of the blood. Symptoms include headaches and breathing difficulties. Individuals with heart disease may have increased vulnerability to angina, a chest pain caused by oxygen deprivation of the heart, or irregular heart beats during exercise.

* Sulfur compounds: Sulfur dioxide is a colorless gas with a sharp odor that is emitted by power plants, petroleum refineries and chemical plants. It can be converted to the more irritant sulfuric acid, which contributes to acid rain, and a variety of sulfur-containing particles. Exposures can cause asthmatic reactions as well as nose, throat and eye irritation. Sulfur compounds are one of the few significant pollutants that are not abundant in Southern California air.

* Toxic chemicals. There are hundreds of cancer-causing chemicals in Southern California air, but only about 10, including benzene, chromium, and ethylene dibromide, are specifically regulated, according to Dr. John Froines, director of the UCLA Occupational Health Center. These compounds may be emitted through industrial combustion or when fuels, solvents and paints evaporate. Researchers lack good estimates of the number of cancers or birth defects that may be caused by air-borne toxics.

DRINKING WATER

Federal law requires that all water be disinfected to prevent the transmission of infectious diseases.

In general, when a drinking water source, such as a well, is found to contain excess pollutants, health guidelines are met by either closing the well or blending the well water with water from other cleaner supplies. But there may be health risks from the low concentrations of regulated chemicals that are permitted in drinking water, high concentrations of regulated chemicals that escape detection, and unregulated contaminants.

* Nitrates: Nitrates are California’s major ground water pollutant. They enter through nitrogen-based fertilizers, animal wastes, sewage spills and septic tanks. The maximum contaminant level is 45 parts per million. Nitrates are primarily a hazard to infants. Nitrite, a nitrate conversion product, can cause methemoglobinemia, or “blue baby syndrome,” a potentially fatal interference with the oxygen-carrying capacity of the blood.

* Organic chemicals: Surface water and ground water may be contaminated by hundreds of chemicals, including pesticides, such as dibromochloropropane (DBCP), and industrial solvents, such as trichloroethane, trichloroethylene (TCE) and perchloroethylene. While the health effects of specific organic chemicals vary, the general concerns relate to cancer, birth defects, and, in the case of DBCP, sterility in highly exposed men.

* Disinfection byproducts: These are formed when chemicals added to water to prevent infectious diseases react with organic materials that are present in the water. One example is trihalomethanes (THMs), which are produced when chlorine reacts with organic materials. “Trihalomethanes in treated water represent a higher cancer risk than most toxic pollutants at the levels that the latter have been measured in drinking water,” according to an article by California Department of Health Services officials. The maximum contaminant level of 100 parts per billion would be expected to cause 200 additional cancer cases in 1 million people over a 70-year lifetime. Public health officials justify this risk by pointing to the even greater benefits of preventing water-borne infectious diseases, caused by bacteria and other germs.

OCEAN WATER

The Southern California ocean has been contaminated by millions of gallons of pesticides, gasoline industrial wastes, storm drain runoff and untreated and partly treated sewage. These contaminants may pose health risks to swimmers, boaters and individuals who eat contaminated seafood. In general, many of these health risks can be minimized by following the recommendations of health officials. Do not, for example, swim near storm drain outfalls or at beaches that are closed because of sewage contamination or fish or collect mussels and other shellfish in known hazardous areas.

* Swimming: When unapproved areas are avoided, state health officials say it is unlikely that ocean swimmers will contract bacterial diarrhea and other water-borne ailments.

* Seafood consumption: The safety of seafood from Southern California coastal waters is variable, according to state health officials. Specific warnings have been issued for certain fish from certain areas. For example, white croaker from much of Santa Monica Bay may be contaminated by DDT and polychlorinated biphenyls, or PCBs. Health officials are only now in the process of analyzing recently collected fish samples from up and down the coast that may help to pinpoint the potential risk from other areas and for other fish. Until more data is available, a general guideline is to not eat the same fish caught in the same spot all the time. It is also prudent to cook mussels, oysters and other shellfish.

SOIL POLLUTANTS

Soil pollutants include pesticides, solvents, metals, acids, and petroleum wastes. These pollutants are most likely to be found near dumps that accept toxic wastes and near industrial sites. Thousands of sites have been identified in Southern California where industry and, in some cases, local governments have dumped or spilled hazardous materials that could represent some risk to the public health.

Soil pollutants may pose a general health risk if they contaminate ground water supplies. In addition, extremely toxic pollutants may be produced when organic chemicals are burned.