May 1994 (vol. 10, #4) 1601 N Tucson Blvd #9, Tucson AZ 85716 c 1994 Physicians for Civil Defense


In assessing environmental risks, the standard method of the Environmental Protection Agency (EPA) leads to the startling conclusion that greater can be less, and less can be greater.

If used as the basis for determining a utilitarian Good the greatest good for the greatest number the method can dictate a governmental policy that actually renders the greatest harm to the greatest number.

It has often been noted that in searching for ``safety,'' the EPA magnifies risks to individuals. Its so-called conservative assumption is the One Molecule Hypothesis. This states that a single molecule of a carcinogen is capable of inducing a cancer and that there is no ``threshold,'' no concentration of a carcinogen that can be considered safe. The dose-response curve for compounds that are carcinogenic to rats in near-lethal doses, or carcinogenic to humans in industrial exposures, are extrapolated to the (0,0) origin. (This assumption is not made for compounds that are merely poisonous rather than carcinogenic; for toxic effects, its falsity is obvious.)

This step leads to exaggeration of all risks. It is the next step that leads to the paradox: if one is prioritizing or ranking risks, one is quite likely to get them in the wrong order.

The EPA's next step is to take the risk to an individual and multiply it by the population exposed to the risk. In other words, to submerge the individual in the collective. The formula is:

Cancer Incidence = CPF x dose x exposed population,

where CPF is the Cancer Potency Factor from the slope of the extrapolated dose-response curve (``Assessment of Environmental Risks to Human Health,'' draft presented to Human Health Technical Subcommittee of the Arizona Comparative Environmental Risk Assessment Project, ACERP 1994.) (ACERP is one of a number of state projects designed to bring ``participatory democracy'' into risk assessment.)

Let us consider a hypothetical carcinogen, trichloronastystuff (TCNS), which in the concentration found in a certain well hypothetically increases cancer risk by 1 in 1,000.

(Let us digress to note that this increase must be hypothetical as it could not possibly be detected in an epidemiologic study. The natural cancer incidence is one in four. In a population of 1,000, 250 cancers are expected, with a standard deviation of about 14, which is much larger than the one extra cancer supposedly caused by TCNS.)

Let us further suppose that 1,000 people drink from the well for 70 years. Extra cancer incidence: one.

Now suppose that TCNS has diffused through the water table and contaminated the water in a heavily populated region. If the dose is reduced by a factor of 1,000, but the population is 10,000 times as large (10,000,000), the extra cancer incidence is ten. The individual risk is 1,000 times less, but the population risk is ten times more.

By the standard method of risk assessment, the higher individual risk is the one assigned the lower priority.

The implications are even more startling if the excess hypothetical lifetime risk of cancer is juxtaposed with the known risks of various ``abatement'' activities. The annual risk of death to construction workers is 25.6 in 100,000 or 256 in one million (MMWR 4/15/94). The lifetime risk of death due to occupational injury for a man who works in construction for 50 years is 1,280 per 100,000 or 12,800 per million. These are real, traumatic, premature deaths, not hypothetical ones.

Yet the EPA may force industry to undertake otherwise useless heavy excavations to prevent at most a one per million excess cancer risk due to events such as leakage from an underground fuel tank.

Such requirements have caused at least one actual death in Tucson. A man was killed by a rock crusher while engaged in ``environmental cleanup.'' The site of a leaky underground tank was excavated to a depth such that a nine-story building could be buried in the pit. Rocks from the excavation were crushed so that the material could be loaded into an incinerator to remove ``contaminants.'' Eventually, the soil, now piled in huge mounds, will be used to fill the hole.

It is not clear whether the petroleum derivatives found in a well came from this site, as there were other possible sources. In addition, the materials would have had to flow up a concentration gradient (in effect, uphill). Nevertheless, this site was selected for cleanup.

The owner, of course, is bankrupt.

If you ever drive, you will probably see a number of craters along the road, where gas stations used to be. The craters are not caused by meteor impacts.

In addition to the excavation hazards, there is danger in the substitutes for underground tanks. Above-ground fuel tanks can explode and burn. At an ACERP meeting in Phoenix, I asked for comparative data.

``That would be getting into the area of risk management,'' said the visiting EPA resource person. ``We keep risk assessment separate.''

One example of schizophrenic EPA policy was the inferno in Malibu, California, that resulted when avoiding disturbance to the habitat of kangaroo rats was given a higher priority than firebreaks and controlled burns.

Another example, from an EPA handout to ACERP committee members: ``The director of a drinking water system in a Midwestern city [said] that ``the EPA is going to make him spend almost $1 million per year to remove a tiny bit of lead from the drinking water. He wanted to protect kids from lead poisoning, too, but he knew he could buy more protection by spending the same money on lead in public housing. `But I would go to jail,' he said'' (A Practitioner's Guide to Comparative Risk Assessment -- and How We Got There 2/16/94).

Author Richard Minard, Jr., continues: ``Although the stridency of some of the rhetoric coming from cities often gives their message an anti-environment, anti-regulatory flavor, they have a point.'' Nevertheless, ``letting the cities off the hook on the radon expenditures, for example, may do nothing to ensure that they invest the savings in neighborhood clinics, wetlands protection, or lead-paint abatement.''

When it comes to TCNS, the EPA knows best.