Municipal Public Relations
CITATION: Michaels, RA.
Health risk assessment:
WTE [waste-to-energy] vs. peanut butter. Solid Waste and Power, 2(5):22-7, October 1988.
Health Risk Assessment: WTE vs. Peanut Butter
The hazard of living by a waste-to-energy plant is much less than the hazard of eating peanut butter, but residents often worry more about WTE. The author compares risks, and examines why the public demands that some activities be safer than others.
By Robert A. Michaels
| Be degree to which society will come to accept potential health risks associated with municipal waste-toenergy plants depends on three factors: the reliability with which exposure and adverse health effects associated with facility emissions can be described, quantified, and gradually reduced; the relative magnitude of the risks compared with those of other waste management options, especially landfilling and recycling; and the relative magnitude of the risks compared with those of more familiar activities, such as driving, flying, smoking, and eating peanut butter sandwiches.
Progress in risk assessment has already improved quantification of human exposure to emissions through the food chain, as well as through other pathways within the general categories of inhalation, ingestion, and dermal contact. Where does this progress leave municipal refuse incineration relative to other risks? This article explores that issue.
WIE Facility Risk Assessments
Several health risk assessments have been conducted in the past five years which have analyzed indirect exposure, including exposure through the food chain where appropriate, to
Robert A. Michaels is president of RAM TRAC Corporation.
22 SOLID WASTE & POWER/OCTOBER 1988
yield a complete accounting of potential health risks arising from facility emissions. These detailed assessments were undertaken for facilities in Brooklyn, N.Y.; San Marcos, Calif.; Stanislaus County, Calif.; Huntington, N.Y.; and St. Lawrence County, N.Y. Total worst-case incremental cancer risks (per million 70-year lifetimes of individuals continuously exposed to the worst-case scenario) associated with these facilities have been estimated to be in the range of 5.9 for Brooklyn, 519 for San Marcos, 47.2 for Stanislaus County, and between 4 and 15 for
“Voluntary risks are typically less tightly controlled by regulators.”
laus County, and about 4 to 5 for Huntington and St. Lawrence County. These assessments indicate that worst-case risks are significantly lower in non-agricultural areas, such as Brooklyn and Huntington. Comparing San Marcos with St. Lawrence County, it is likely that San Marcos’ risks are significantly higher _ principally because of the large size of the facility (4,500 tons per day, or TPD) and the relatively old age of the emission data (from an older facility with less-ad-
vanced emission controls) forming the basis for the risk assessment. As author of the St. Lawrence
County document, I can state with confidence that even a risk level of 5 per million is a cautious estimate. However, to be extremely conservative in comparing municipal refuse incinerators to other risks, it is appropriate to consider the maximum baseline risk in the range of 10 per million.
Comparison With Other Waste Management Options
I cannot presently quantify typical differences between the risks of landfilling and the risks of incinerating municipal. refuse. However, speaking only qualitatively, there are several reasons to believe that incineration poses the lesser public health risk. If this is so, then municipal refuse incineration would be relatively desirable. Incinerator ash volume represents only a small percentage of initial waste volume, and the ash is relatively stable when compared with municipal refuse, which may contain metabolizable pesticides, volatile solvents, acid-mobilized metals, and other hazardous materials.
Further, municipal landfills tend to be located close to population centers, where refuse is generated. They tend to be unlined, and tend to accept untreated mixed waste materials which
may participate in unpredicted and undesirable-even explosive-chemical interactions, in contrast to incinerator ash monofills. Landfills may pollute groundwater in the vicinity of drinking water wells, and the volatile emissions of landfills occur at nose level rather than at stack elevations determined by Good Engineering Practice.
One form of legitimate waste management is absolutely essential if incineration is to gain acceptance-recycling. However, even this highly popular, relatively non-technological form of waste management may pose significant risks to participating individuals. In particular, recycling plans frequently call for in-home storage of hazardous materials separated from
household wastes. _ In-home storage increases the po-
tential amount of time residents may come into contact with these materials. At the same time, the materials may become concentrated as they accumulate in designated places, such as garages. These places may be relatively accessible to children, who cannot read labels or adhere to their warning messages. A suggestion that the risks are of great magnitude comes from the fact that poison control centers receive most of their emergency calls from household residents accidentally contacting the materials in question.
These comments are intended to introduce realism into the public’s consideration of comparative risks. They are not intended as a criticism of recycling, any more than the presence of incinerator risks should constitute a basis for criticizing incineration. Criticism of any waste management option is properly based upon the presence of unnecessary risks, not risks per se.
Comparison of Risks Associated With Familiar Activities
Inasmuch as it is presently difficult if not impossible to quantitatively compare incineration risks with risks associated with generically defined alternative waste management options, it is at least useful to compare them with carefully measured risks associated with activities familiar to most people. A sampling of familiar risks has, therefore, been provided (Table 1). The lifetime (70-year) risk values tabulated in the right-hand column are expressed in three significant digits. Thus, the lifetime risk of dying in a
tornado can be interpreted mathematically as 42.0 per million.
To place incineration risks in the context of risks reported in Table 1, it is important to note that some of the tabulated risks have been actuarially measured. Thus, they are actual estimated probabilities of dying from each listed mortality factor over a 70-year period, assuming risks have not changed significantly. It should be apparent that this assumption may be incorrect. Air travel may have become more dangerous because of air traffic congestion, a shortage of experienced air traffic controllers and pilots, and
terrorism. It may, however, have grown safer as a result of technological advancement and airworthiness directives. The net result is unknown and probably unknowable.
In contrast, incineration risks are typically estimated under a constellation of deliberately pessimistic assumptions about the unknown values of risk parameters. The result is almost certainly a significant overestimation of cancer mortality risk. Such overestimates are assumed to be correct only to protect the public when policy decisions must be made relating to whether and under what conditions
SOLID WASTE & POWER/OCTOBER 1988 23
Table 1: Lifetime Risks of Familiar Activities
Peril
Lifetime (70-year) Risk per Million Population
Cigarette smoking All cancers
Mining and quarrying Construction Mountain climbing
Agriculture
Police killed in line of duty
Air pollution (Eastern U.S.)
Motor vehicle accident (traveling) Police killed in line of duty by felons
Home accidents
Service and government Manufacturing
Frequent airline traveler Pedestrian hit by motor vehicle
Alcohol, light drinker
Background radiation at sea level (excluding radon)
Peanut butter, four tablespoons per day Electrocution Tornado
Drinking water containing chloroform at maximum allowable EPA level Lightning
Living near a WTE plant (typical worst-case)
Earthquake (Southern California)
Smoking 1.4 cigarettes Drinking 0.5 liters of wine Traveling by canoe six minutes Traveling by bicycle 10 miles Traveling by car 30 miles
Traveling by jet plane 1,000 miles (air crash)
Traveling by jet plane 6,000 miles (cancer from cosmic rays)
252,000 196,000 66,500 42,700 42,000
42,000 15,400 14,000 13,900
9,100
7,700 7,000 5,740 3,500 2,940
1,400 1,400 560 371 42.0
Drinking water containing trichloroethylene at
maximum allowable EPA limit
0.140
Adapted from Health Risk Assessment for Air Emissions of Metals and Organic Compounds from the PERC Municipal Waste To Energy Facility, Charles T. Main, inc., December 1985; and from Risk Assessment and Comparisons: An Introduction, by R. Wilson and E.A.C. Crouch, Science, April 17, 1987.
risk-posing facilities may be permitted. One might speculate that an approximation of actual incremental cancer mortality risk associated with an incinerator estimated to pose a worstcase risk of 15 per million might be 0.15 to 1.5 per million, although for any particular risk assessment, this range clearly depends upon the degree of conservativeness (protectiveness) of the input assumptions.
Whether society will accept incinerator risks, or will require their further reduction, depends only partially upon how the absolute risk values compare with familiar risks which are found to be acceptable, such as those given in Table 1. Another determinant is how the distribution of risk compares with the distribution of benefit. Although it is fair to say that municipal refuse incinerators pose significant health risks to the general public, it is also fair to say that, in exchange, the general public derives great benefit from incineration. This
24 SOLID WASTE & POWER/OCTOBER 1988
benefit, as indicated earlier, includes benefit in kind: reduction of health risk by reducing reliance upon waste management options which pose even greater risks. It also includes economic benefits of reduced waste disposal costs, and possibly recovery of valuable materials and energy.
This contrasts sharply with some commercial situations in which society may bear most of the costs of pollution associated with product manufacture, while an entrepreneur and_ his/her customers may derive the lion’s share of the benefits. In cases of this type, society’s acceptable risk standards may be quite different, as reflected by policies of such regulatory agencies as the Consumer Product Safety Commission, the Food and Drug Administration, and the Environmental Protection Agency (EPA).
Thus, placing incinerator risks in the context of, say, the 25.2-percent risk of dying as a result of cigarette smoking (Table 1) might require not
only a comparison of the absolute risks, but of the distribution of risks and benefits. Such a comparison is often deceptively complicated. In the case of cigarette smoking, it may at first seem that all of the benefits and all of the risks go to the smoker. It has been recently shown, however, that some of the risks are borne by passive smokers who, in the presence of smokers, become secondary smokers, and face an elevated probability of dying of cigarette-induced lung cancer. Society’s standards for risk acceptability are frequently said to vary depending on whether the individual(s) facing the risk(s) do so voluntarily or involuntarily. Two principles apply. First, voluntary risks are typically less tightly controlled by regulators: it is legal to participate in downhill skiing, even if there is a significant chance it will kill you. (Ironically, however, you may not go downhill skiing in order to kill yourself-suicide attempts are illegal; fortunately for those who succeed, it carries no punishment.) The second principle applying to voluntary vs. involuntary risks is that it is exceedingly difficult to distinguish between them. For example, although it is obvious that infants become passive smokers involuntarily, it is not so obvious that the non-smoking spouse of a smoker does so involuntarily. It is also unclear whether an individual secondarily exposed to cigarette smoke at work does so voluntarily (other jobs are available that do not involve such exposure), or involuntarily (most people cannot afford to be out of work long enough to find such a job). Even the risks taken by a primary smoker may be regarded as a voluntary (he or she has been warned and does not have to smoke), or involuntary (cigarettes are intensively advertized and highly addictive). Despite the caveats discussed above, it is appropriate to compare incinerator risk estimates with estimates risks associated with familiar activities. The lowest tabulated risk is 0.14 per million, associated with drinking water containing the chemical trichloroethylene (TCE) at the maximum allowable EPA limit. This risk is clearly lower than incineration risks, and it may be instructive to inquire why the EPA does not similarly limit incineration risks. Part of the answer lies in the distribution of benefit theory, wherein
society derives little if any benefit from contaminating its drinking water with TCE, but society bears the risks associated with others’ commercial or industrial activities. This is, however, only an incomplete explanation, not least because citizens derive significant benefit from living in an industrial society.
The fact is, TCE and other drinking water contaminants are controlled at
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relatively low risk levels, perhaps the one-per-million level, simply as an expression of our cultural attitude about the water we drink. Individuals may breathe grossly contaminated air in urban industrial centers. Nevertheless, they want to drink crystal clear, pristine water which is also fit for fishing and swimming, a sentiment the U.S. Congress has embodied in the Safe Drinking Water Act. Despite the
sentiment, a risk of 42 per million is reported in Table 1 to be associated with drinking water containing chloroform (CHCI,) at the maximum allowable EPA limit.
Of greater relevance to comparing the TCE risk from drinking water with incineration risks is the fact that the EPA standard for TCE applies to only a single substance. In contrast, incinerators produce numerous classes of risk-posing chemical compounds, probably amounting to thousands of individual substances. With regard to most if not all of these individual substances, facility-associated risks probably are controlled within the one-permillion risk level. The one probable exception (or numerous exceptions, depending upon one’s viewpoint) seem(s) to be the 75 chlorinated dibenzo-p-dioxins and 130 dibenzofurans which, combined, may predominate among incinerator emissions in posing incremental cancer risks to the general public, particularly in agricultural areas.
Some other consumable items also present a cancer risk. Table 1 indicates that eating four tablespoons of peanut butter per day may pose a risk of 560 per million-far higher than risks associated with incineration. The peanut butter risk arises from aflatoxins produced by fungus growth on peanuts which have been improperly stored, for example, in top-loading bins from which peanuts on the bottom may be selected by customers only rarely.
Peanuts stored in humid places may lose their healthy appearance, and preferentially be selected for use in peanut butter, just as imperfect tuna fish and oranges are preferentially selected for canning and juicing, respectively. Nevertheless, some people will extol the virtues of natural foods regardless of risk, while deploring incinerator technology, also regardless of risk. Perhaps such people distrust technology, or wish to return to a simpler agrarian form of life. Whatever the explanation, it is apparent that predicting public acceptance of incineration risks based upon the risk comparison approach may yield surprises, as illustrated by the case of the aflatoxins.
Aflatoxins in peanut butter have been shown to be potent carcinogens. It may be instructive, therefore, to inquire why regulators find it acceptable for peanut butter to be marketed,
despite the high risk associated with its ingestion.
Aflatoxin levels are controlled, but the level at which they are controlled is inconsistent with another cultural peculiarity of U.S. citizens. That is, they do not like carcinogens to be added to their food, even in minuscule amounts, a sentiment embodied by the U.S. Congress in the Delaney Clause of the Food and Drug Law. Peanut butter may be marketed, despite its cancer risk, simply because aflatoxins grow in food; they are not added to it, and are (curiously) exempt from Delaney Clause restrictions. Other notable exceptions are pesticides: when they are applied to crops, their appearance in produce is regarded as ecosystem contamination rather than deliberate addition.
Yet another risk associated with a consumable is posed by alcohol. A light drinker is reported to face a 1,400 per million incremental mortality risk. The precise source of the excess mortality is unspecified; mixed causes may be in action, such as adverse health effects and accidents. Nevertheless, many individuals will choose to face such risks while objecting to the much lower risks associated with municipal refuse incineration. I can only speculate about the explanation for this apparent inconsistency in some people’s relative concern about risks.
It is tempting, but unjustified, to suppose that, in contrast to incinerators, alcohol consumption will exert no negative effects upon the market value of real estate in communities proposed as incinerator sites. Speculating further, it is possible that apparent concern about risks arising from incinerators may serve some individuals as a surrogate for an actual but unstated concern about property values or other issues which neither motivate widespread support nor justify litigation. Extensive documentation of self-serving motivations behind righteous statements of concern for the environment was presented in the form of case studies in The Environmental Protection Hustle by Bernard J. Frieden of the Massachusetts Institute of Technology.
To conclude, it appears to me that inclusion in health risk assessments of comparative risks associated with familiar activities is desirable if not essential as one means of risk communication. However, this form of
communication should not be overrated, in that the message one transmits to the public may differ from the one some members of the public receive. Most particularly, it should not be assumed that public acceptance will be motivated by a simple, favorable comparison of risk values. Rather it is apparent that other dynamics may influence public opinion; indeed, the visible dynamics forming public opinion may be like the tip of the iceberg, underlain by far more massive invisible dynamics.
The bottom line is that to assure that the message transmitted to the public is identical to the message received, it is essential to communicate effectively in technical documents, and advisable to vigorously follow up such communications with public relations initiatives. oO
Robert A. Michaels can be reached at RAM TRAC Corporation; 21-41 34th Avenue, Suite 11C; Long Island City, NY 11106; (718) 626-4947.
SOLID WASTE & POWER/OCTOBER 1988 27
Publication citation
Michaels, RA. Health risk assessment: WTE (waste-to-energy) vs. peanut butter. Solid Waste and Power, 2:5, 1988;