hormesis and environmental policy: an ethical analysis

North American Philosophical Publications

Hormesis and Environmental Policy: An Ethical AnalysisAuthor(s): Kevin ElliottSource: Public Affairs Quarterly, Vol. 20, No. 1 (Jan., 2006), pp. 31-53Published by: University of Illinois Press on behalf of North American Philosophical PublicationsStable URL: http://www.jstor.org/stable/40441426 .

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Public Affairs Quarterly Volume 20, Number 1, January 2006

HORMESIS AND ENVIRONMENTAL POLICY: AN ETHICAL ANALYSIS

Kevin Elliott

Introduction

low-dose effects of toxic and carcinogenic chemicals are currently a hot topic of discussion in environmental research and public policy. Because

the costs for cleaning up and regulating toxic chemicals increase dramatically as their concentrations decrease, significant amounts of money are at stake in scientific and policy debates about these effects. It is difficult to get statistically significant data to settle these disputes, however, because it would require studies with enormous numbers of experimental animals. The result is an ongoing conflict between representatives from the medical, environmental, industrial, and military communities concerning the most appropriate models to use for extrapolating data on the high-dose effects of toxins down to lower dose levels. On one hand, some research indicates that a number of chemicals may "mimic" hormones such as estrogen or otherwise interfere with the endocrine system and therefore produce surprisingly harmful effects on humans and wildlife at very low doses (see, e.g., Colborn, Dumanoski, and Myers 1997; Krimsky 2000). On the other hand, some scientific researchers and industry groups are appealing to an alleged biological phenomenon called hormesis to support the notion that current governmental regulatory standards overestimate the harm caused by low-dose exposure to toxins (Calabrese and Baldwin 2003).

The phenomenon of hormesis involves beneficial or stimulatory effects caused by very low doses of toxic chemicals that are harmful or inhibitory at higher doses (see Figure 1, p. 32). A familiar example of this sort of dose-response curve is that of alcohol. Low levels of alcohol decrease human mortality rates below control levels. Nevertheless, high levels of alcohol consumption increase human mortality rates above control levels. Other alleged examples of hormesis are more counter-intuitive than that of alcohol and more realistic for illustrating the environmental policy ramifications considered throughout the rest of this paper. For example, some evidence seems to indicate that, at particularly low

31



32 PUBLIC AFFAIRS QUARTERLY

Figure 1. Examples of the general form of hormetic dose-response relationships. The bottom curve could represent the relationship between alcohol and human mortality, whereas the top curve could represent the hormetic effects of growth inhibitors on plant growth.

dose levels, toxins such as lead may actually increase plant growth, and potent carcinogens, such as dioxin, may decrease tumor development (Calabrese and Baldwin 2003, Kaiser 2003).

In recent years, the prominent toxicologist Edward Calabrese has performed at least three extensive literature searches designed to uncover evidence for hormesis in previous toxicology studies (see Calabrese and Baldwin 1997, 2001; Calabrese 2001). Although these literature searches may have methodological weaknesses (see Crump 2001, Elliott 2000a, Jonas 2001, Menzie 2001, Rodricks 2003), Calabrese and Baldwin claim that they have enough evidence to suggest that hormetic effects are widely generalizable across different species, biological endpoints, and toxins (1998, 2003). Other researchers have agreed that "[t]here can be no doubt about the reality of hormesis" (Gerber, Williams, and Gray 1999, p. 278). Calabrese and Baldwin's recent discussion of the hormesis hypothesis in the journal Nature (2003) and a review of their work in Science (Kaiser 2003) appear likely to promote and legitimate even more discussion of the phenomenon in the future.

To the extent that the hormesis phenomenon is generalizable, it could have a variety of ramifications for individual scientific disciplines such as toxicology, pharmacology, medicine, and agriculture. For example, Calabrese and Baldwin (2002a) have suggested that hormesis might require more careful analyses of the pharmacological effects of medicines at varying dose levels. It might also encourage more careful use of agricultural herbicides and pesticides, which could



HORMESIS AND ENVIRONMENTAL POLICY 33

stimulate weed or pest outbreaks if administered at doses that are too low ( Appleby 1998, Morse 1998). Perhaps the most dramatic potential ramifications of hormesis lie in the areas of environmental policy and risk assessment (see, e.g., Calabrese, Baldwin, and Holland 1999; Barnes 2000; Lave 2001; Calabrese and Baldwin 2003; Conolly and Lutz 2004). For example, Calabrese and Baldwin claim that the hormesis phenomenon "is counter to the cancer risk assessment practices by U.S. regulatory agencies . . . which assume that cancer risk is linear in the low- dose area" (Calabrese and Baldwin 1998, VIII- 1; see also Calabrese, Baldwin, and Holland 1999). In fact, they go so far as to state that a hormetic dose-response curve could be used as the default dose-response model for the risk assessment of both carcinogenic and non-carcinogenic toxins (Calabrese and Baldwin 2003). And, although Lester Lave (2000, 2001) insists that the phenomenon must be studied in greater detail, he also suggests that hormesis could provide the basis for a new phase in U.S. regulatory policy. The resulting policy would seemingly involve less stringent regulation of toxic chemicals and possibly even encouraging the public to obtain low-dose chemical exposures.

Unfortunately, despite the significant potential ramifications of hormesis for chemical risk assessment and environmental policy in general, few studies have provided "second-order" ethical evaluations of other researchers' claims concerning the policy ramifications of hormesis.1 Furthermore, the few works that do provide some secondary analysis are fairly brief and focus primarily on the technical and legal difficulties of applying hormesis to public policy. This paper attempts to provide a more explicitly ethical analysis of the ramifications of the hormesis phenomenon. In particular, it analyzes the notion that it would be acceptable to allow public exposure to chemicals that produce hormetic effects. Whether or not it is justifiable to allow such exposures seems to be a particularly important regulatory issue for at least two reasons. First, allowing public exposure to hormetic toxins appears to be a dramatic reversal of former regulatory policies, which focused on lowering public exposure to toxic chemicals to the greatest feasible extent (see, e.g., Foran 1998). Second, other proposed regulatory policies, such as altering the reference doses (RfD) that set limits for safe human exposure to toxic chemicals, seem to presuppose that it is justifiable to allow human exposure to hormetic toxins at low levels (see, e.g., Calabrese and Baldwin 1999, Barnes 2000).

The first main section of this paper clarifies a number of different potential versions of the claim that it is justifiable to allow public exposure to hormetic chemicals. It then suggests a maximally defensible formulation of this claim. The second section then suggests four necessary conditions for applying this approach to public policy in an ethically satisfactory manner. It also identifies some of the major challenges to meeting those conditions. By clarifying this claim and some major ethical conditions for employing it, the article aims to provide a foundational ethical "road map" for applying hormesis to regulatory policy.




Clarification of a Policy Claim

As a starting point for clarifying the notion that hormesis supports allowing public exposure to at least some toxic chemicals, let us consider quotations from three recent articles that propose altering current regulatory policies in response to hormesis.

[CBH] The implications of the hormesis concept for cancer risk assessment is [sic] that it provides a biologically based foundation supporting the concept of thresholds for many, if not most, carcinogenic responses. It also suggests that the regulatory "goal" of exposure to carcinogenic agents should not be zero as has been the case (e.g., carcinogens in drinking water), but a "goal" aimed at achieving an optimized health-based response." (Calabrese, Baldwin, and Holland 1999, p. 276, italics added)

[L] [H]ormesis suggests that . . . lower exposure [to toxicants] is likely to worsen health or, at best, to have no beneficial effect.

Hormesis squarely challenges the standard risk analysis model and thus the basis for regulation of toxicants at low concentrations. Rather than protecting people from low-level exposure to toxicants, hormesis suggests that public health officials should be encouraging or even mandating some toxicant discharges. (Lave 2001, p. 64)

[P] [T]hroughout the 20th century and in particular during the past 30 years, . . . studies . . . have repeatedly identified the hormesis effect, i.e., health benefits as- sociated with exposure to low doses of toxic substances. . . . Should hormesis be borne out, the usual philosophy of continually minimizing exposure, which is costly for industry (and, it can be argued, for society as a whole) is reversed; hormesis implies that some exposure and intake of low-doses of toxic substance is not only acceptable but ought to be sought after given its potentially positive impact upon public health. (Poumadere 2002, pp. 33-34)

Although a number of other articles are making similar claims to those in these three quotations (e.g., Foran 1998, Gerber, Williams, and Gray 1999, Paperiello 2000), it is not essential for the purposes of this paper that the quotations be representative of a general scholarly consensus on the regulatory ramifications of hormesis. The purpose of these quotations is not to determine the proportion of thinkers who defend the notion that hormesis supports allowing public exposure to toxins. Rather, these quotations illustrate how at least some important thinkers have expressed this notion so that this section can develop a more careful formulation of it.

These quotations all appear to express the ethical claim that, if the public is exposed to a toxin that produces a hormetic effect, and if particular additional conditions are met, then government should allow public exposure to that toxin. The general form of this ethical claim, which the paper will subsequently call




"R," appears to be a conditional of the form, "If (A&B), then C." "A" stands for the claim that the public is exposed to low-dose levels, L{ . . . Ln, of one or more toxins, Xj . . . Xn, that produce a hormetic effect on one or more human biological endpoints. "C" stands for a claim about appropriate government regulatory action in response to the hormetic effect produced by toxins Xj . . . Xn (e.g., that government regulators should allow public exposure to levels hx . . . Ln of the toxins). "B" stands for a statement of additional sufficient (and perhaps necessary) conditions for the effect mentioned in claim A to warrant the regulatory actions described in claim C.

Nevertheless, the three quotations (and the articles from which they are taken) appear to be designed primarily to offer general regulatory suggestions rather than to state a detailed version of claim R. Thus, there are at least six issues related to claims "A," "B," and "C" that this section attempts to elucidate. The first, "toxin- scale," issue addresses claim A:

(TI) Does claim A refer only to an individual toxin that produces a hormetic effect or also to groups of toxins that produce a hormetic effect in con- cert!

The second, "endpoint," issue is a question about claim B:

(El) In order to warrant the regulatory actions specified in claim C, is it sufficient for an individual to experience a beneficial effect on at least one endpoint, or must an individual's entire exposure to a hormetic toxin result in a net health benefit?

Statement (El) provides an important distinction between the beneficial effect described in claim A, on one hand, and a net benefit from an individual's entire exposure to a hormetic toxin, on the other hand. An individual could experience one or more beneficial hormetic effects from a chemical, but the individual's exposure to the toxin could result in a net harmful health effect (because, for instance, of harmful side effects produced by the toxin). For example, Calabrese and Baldwin themselves note that "stimulation of detoxifying enzyme levels observed in the larval form of a species would be evaluated for its hormetic potential even though this increased metabolic activity, while beneficial in the short-term, may have a detrimental effect on other endpoints" (1998, II-5).

The third, "condition," issue also addresses claim B:

(CI) In order to warrant the regulatory actions specified in claim C, precisely what additional conditions (including factors such as (1) scale of effects over time and groups of people,2 (2) side effects, (3) practical feasibil- ity of implementing a new regulatory policy, and (4) consent of those who experience hormetic effects) are required to justify the proposed regulatory changes?

Statement (CI) lists four sorts of conditions, in addition to the condition of producing a net benefit on human health (which was already mentioned under the




endpoint issue), that play a role in determining whether it is justifiable to allow public exposure to a hormetic chemical. This article does not maintain that the conditions mentioned in statement (CI) provide an exhaustive list of the factors that one would need to consider in order to determine whether public exposure to a hormetic toxin is justifiable; rather, these conditions are merely important examples of those that one might need to consider.

The fourth, "status" issue is also a question about claim B:

(STI) What is the status of the conditions for regulatory action mentioned under the endpoint and condition issues (e.g., are the conditions necessary for warranting the regulatory actions specified in claim C, or are they sufficient for warranting those regulatory actions, and precisely which conditions are jointly sufficient)?

A fifth, "satisfaction," issue relates to claim B as well:

(SAI) Does claim B state that all hormetic effects do satisfy the conditions that it specifies, or does claim B state only that some hormetic effects may satisfy its specified conditions?3

Finally, the sixth, "action," issue addresses claim C:

(AI) Exactly what sort of regulatory action does claim C recommend?

For example, claim C might recommend that government ought to allow public exposure only to low levels of hormetic chemicals, or it might recommend that

government ought to allow public exposure to low levels of toxic chemicals in

general (based on the assumption that a large number of toxic chemicals are hormetic). Claim C might also recommend that government should not only allow public exposure to hormetic chemicals but that government ought to actively promote such exposures.

Depending on the stance that one takes on these six issues, one could formulate different versions of claim R. The remainder of this section suggests a maximally defensible version of it that can serve as a starting point for further work. Recall that the "toxin-scale" issue concerns the question of whether, in claim A, a hormetic effect must be produced by an individual chemical or a group of chemicals. With regard to this issue, it does not appear that one position is significantly more defensible than others. As long as claim B includes appropriate additional conditions, it does not seem to matter whether individual chemicals or groups of chemicals cause hormetic effects. One might object that allowing hormetic effects caused by a single toxin appears to be more controversial than allowing hormetic effects caused by groups of toxins, because people are exposed to multiple chemicals at once under real- world conditions. Nevertheless, it seems just as defensible to allow public exposure to a single toxin that produces hormetic effects as long as claim B requires that the hormetic effects produced by an individual chemical must occur under the conditions to which people are actually exposed in the real world (including the presence of other toxins).




The second, "endpoint," and third, "condition" issues concern the additional criteria provided in claim B for hormetic effects to justify the regulatory actions stated in claim C. Most recent articles, including those quoted earlier in this section, emphasize that hormetic chemicals should produce "beneficial" or "healthy" effects in order to warrant public exposure to them. The notions of "beneficiality" or of "health" can be ambiguous, however, because chemicals could produce a beneficial or healthy effect on one endpoint (e.g., increasing levels of a beneficial enzyme) while producing a harmful or unhealthy effect on other endpoints (e.g., increasing metabolic stress). Therefore, the most defensible position on the endpoint issue is probably that exposure to a hormetic chemical should produce a net benefit on human health as a whole rather than merely a beneficial effect on one or more particular endpoints. It is more difficult to identify a maximally defensible version of the condition issue, because this article has not tried to specify all the different conditions that might be necessary. Thus, it seems wise to include a general caveat that identifies at least some of the important sorts of conditions that should ultimately be specified.

The fourth, "status," issue concerns whether the conditions described in claim B are necessary or sufficient for regulatory action (and precisely which conditions are jointly sufficient). The most defensible position on the status issue can be determined on the basis of the preceding analysis of the conditions issue. Given that other conditions not explicitly mentioned in this paper might be necessary in order to justify regulatory action, it appears most defensible to claim that the production of a net health benefit is sufficient for regulatory action only in conjunction with other conditions that remain currently unspecified. For example, the production of a net health benefit might be sufficient to justify regulatory action only if the benefit occurs over an extended period of time and on a large proportion of the population. Moreover, it seems most defensible to claim that the conditions described in claim R (e.g., the production of a net health benefit) are not necessary conditions for regulatory action, because one might insist that under some very special conditions it would be justifiable to allow hormetic exposures even if they do not meet these particular conditions.

The satisfaction issue addresses the question of whether all or only some hormetic exposures meet the conditions stated in claim B. This question is an empirical one that will require further investigation. Therefore, for the time being, it seems most ethically defensible to assume that only some hormetic exposures may meet the conditions. In other words, the most ethically justifiable position for the purposes of developing new regulations is that some hormetic exposures may result not only in a beneficial effect on one particular endpoint but may also produce a net benefit on human health as a whole and meet the other conditions that the articles currently leave unspecified.

Finally, the sixth, action, issue concerns what regulatory actions claim C should recommend in response to hormetic exposures. The three quotations presented ear-




lier in this section suggest that government should take an active role in promoting hormetic exposures that are beneficial. Nevertheless, it seems more defensible to claim that regulatory agencies merely ought to allow these exposures.4 Further- more, although the articles do not clearly state whether government regulation should adjust current standards for all toxic chemicals or merely for hormetic chemicals, it seems easier to justify the claim that regulations should be altered only for hormetic chemicals that meet the conditions mentioned in claim B.

Based on this analysis of the six issues, a plausible, highly defensible recon- struction of ethical claim R is the following:

Claim R: IF one or more toxic chemicals, Xj . . . Xn, produce a hormetic effect on humans that are exposed to low doses (L1 . . . Ln) of Xl . . . Xn, AND IF human exposure to Xj . . . Xn meets the following conditions (as some hormetic exposures may do):

(1) the exposure results in a net benefit to human health, and

(2) the exposure meets additional conditions, Cl . . . Cn (perhaps including conditions that specify specific scales over which the hormetic effects must occur across time and on groups of people, particular allowable side effects, specific criteria for implementing new regulatory policies, and particular standards for obtaining consent to hormetic exposures),

THEN government regulators ought to allow public exposure to low doses L1 . . .

LofX^.X.

Even though the goal of this paper is to propose this maximally defensible version of claim R, however, one could also develop alternative forms of R that have more ambitious regulatory consequences but that are somewhat more difficult to defend. First, with regard to the endpoint issue (El), one might claim that hormetic chemicals need not produce net benefits but only beneficial effects on at least one endpoint in order to justify public exposure to them. Second, with regard to the status issue (STI), one could suggest that the production of a benefit (either a net benefit to health or a benefit on at least one endpoint) is, in and of itself, a sufficient condition for altering current government regulations. Third, with regard to the action issue (AI), one might affirm that government ought to promote (rather than merely allow) public exposure to hormetic chemicals. One might even claim that government should promote or allow public exposure to all or most toxins (not just to specific chemicals that have been identified as hormetic). The rest of this paper focuses only on the version of claim R that is easiest to defend, but it might eventually be valuable to examine variants of the claim that have even stronger regulatory ramifications.

Four Ethical Conditions for Employing Claim R

The maximally defensible formulation of claim R in the previous section of this paper included the acknowledgment that a series of conditions (Cl . . . Cn)




must be met in order to justify allowing public exposure to hormetic chemicals. Thus, the extent to which one can justify changes to current environmental policy based on the phenomenon of hormesis depends on how difficult it will be to meet these conditions. This section argues for four of these necessary conditions, but it does not claim that this is an exhaustive list. It also discusses some of the main challenges to meeting these conditions and suggests that these challenges will be difficult to surmount in the near future.

Concept Condition Elliott (2000b) has argued that current researchers are employing a variety

of different concepts of hormesis and that confusion over these concepts may be exacerbating scientific controversy about the evidence for the phenomenon. For example, he claims that some researchers define the phenomenon primarily operationally, in terms of either U-shaped dose-response curves or low-dose stimulatory effects and high-dose inhibitory effects (see, e.g., Davis and Svendsgaard 1990, Calabrese and Baldwin 2002b). Others add a normative component to their concept of hormesis, describing it as the production of beneficial effects at low doses and harmful effects at higher doses (e.g., Paperiello 2000; Gerber, Williams, and Gray 1999; Teeguarden, Dragan, and Pitot 2000). Still other researchers emphasize mechanistic concepts that characterize hormesis in terms of a particular causal process, such as overcompensation or the production of multiple effects at different dose levels (e.g., Stebbing 1982, 2003; Calabrese 1999).

If one cannot specify precisely what sorts of effects qualify as hormetic, however, then one cannot effectively determine which effects meet the antecedent clause of claim R. Thus, a first necessary condition for employing claim R in an ethically justifiable fashion is the following:

Concept Condition: Any ethical use of claim R to justify exposing people to hormetic chemicals must include sufficient specification of the concept of hormesis to identify (a) the effects that qualify as instances of "hormesis" and (b) the ethical consequences of allowing hormetic effects.5

For the purposes of this paper, one can define the "concept" of hormesis in terms of the behavior of essential variables. For example, the independent variable for virtually any concept of hormesis is likely to be the dose level of a toxic chemical to which an organism is exposed, but the dependent variable may vary from one concept to another. For instance, the dependent variable could be defined as a "benefit," a "net benefit," or a "stimulation" of a biological endpoint, or it could be any effect on which an "opposite" response is measured at low versus at high doses.

Given Elliott's (2000b) argument that researchers are currently employing multiple concepts of hormesis, however, it may be difficult to meet either part (a) or part (b) of the concept condition. According to part (a), for example, the concept of hormesis must be sufficiently precise to identify the effects that qualify




as instances of hormesis. Unfortunately, different effects qualify as hormetic depending on which concept one employs. For instance, a harmful low-dose

stimulatory effect of a toxin would qualify as an instance of hormesis if one defines the phenomenon operationally (as an instance of low-dose stimulatory effects of a toxin) but not if one defines it normatively (as the production of beneficial effects at low doses).

According to part (b) of the concept condition, the concept of hormesis must be sufficiently precise to determine the ethical consequences of allowing public exposure to hormetic chemicals. This part of the condition may also be difficult to meet given the current conceptual confusion about hormesis, because hormetic effects have different ethical ramifications depending on which concept one uses. For example, all else being equal, it seems more ethically justifiable to allow

public exposure to chemicals that meet a normative definition of hormesis (such as the production of net beneficial effects on an organism) than to chemicals that meet only an operational definition (e.g., the stimulation of one or more biological endpoints, which would be compatible with a net harm for the organism as a whole).

One might object that it actually should not be very difficult to satisfy the

concept condition, because the maximally defensible formulation of claim R

developed in this paper already encourages the use of a normative concept of hormesis. Specifically, it specifies that public exposure to hormetic chemicals is

justified only if they result in net health benefits. Thus, one could plausibly suggest, in response to the concept condition, that hormesis should be defined (at least for the purposes of regulatory policy) as a net beneficial effect produced by low-dose

exposure to a substance that produces net harmful effects at higher doses. This

stipulation might be a reasonable solution, but for it to be workable in practice it will also plausibly require criteria for determining which exposures qualify as producing net benefits. For example, one must stipulate: (i) which endpoints must be affected (e.g., longevity, quality of life, or disease incidence) in order for an effect to be a net benefit, and (ii) how to balance "tradeoffs" between effects on different endpoints. Without this specification of criteria for identifying net beneficial exposures, even a normative concept of hormesis cannot be employed in practice.

Scale Condition In order to employ claim R, one must not only be able to determine whether

a toxic chemical is producing a hormetic effect or not; one must also decide how to specify the additional conditions (i.e., C{ . . . Cn) mentioned in the antecedent clause of claim R. One proposed set of conditions in claim R involves the scale of hormetic effects, which suggests a second necessary condition for justifiably employing claim R:




Scale Condition: Any ethical use of claim R to justify exposing people to hormetic chemicals must include both (a) a specification of the scale (i.e., range of people and temporal period) on which hormetic effects must occur in order to justify public exposure to those chemicals, and (b) enough empirical information to determine with a satisfactory degree of accuracy whether particular hormetic effects actually occur on that necessary scale.

There are two "scales" that are mentioned in part (a) of this condition. One scale is the range of people on which hormetic effects occur, and the other scale is the period of time during which those effects occur. First, the range of people who experience hormetic effects is important, because it seems much more justifiable to allow public exposure to those effects if they occur on the vast majority of the population rather than if they benefit only a limited group of people (see, e.g., Lave 2001).6 Thus, researchers plausibly need to gain some information about the extent to which people vary in their likelihood to experience hormetic effects, depending on factors such as their age, health, diet, behavior, stress level, genetics, and other chemical exposures. Second, the period of time during which hormetic effects occur is important, because it seems more justifiable to allow public exposure to toxic chemicals if they produce hormetic effects that last an extended period of time than if they produce effects that are very short-lived (and possibly followed by detrimental effects) (see Davis and Farland 1998, Elliott 2000a). Part (b) of the condition states that one must achieve a "satisfactory" degree of accuracy when estimating the scales of hormetic effects, but it leaves open the ethical question of what a "satisfactory" degree of accuracy might be. It is not practicable in this paper to identify particular scales (of people or time) on which public exposure to hormetic effects would be justifiable. Rather, the proposal of the scale condition serves as a reminder that claim R can justifiably be employed only after one answers this question and then goes on to provide adequate information to determine if those scales are met. In order to promote public acceptance of regulatory decisions involving hormesis, it might be valuable to incorporate some form of broad-based public deliberation for deciding on the scales for justifying hormetic exposures and the standards of accuracy for evaluating empirical information about those scales (see, e.g., Fiorino 1990, NRC 1996).

Admittedly, proponents of hormesis do appear to be at least implicitly aware of the scale condition and are seeking information to help meet it. For example, Calabrese and Baldwin (2002a) appeal to evidence that (i) hormesis can occur with mixtures of toxins, and that (ii) hormesis appears to be a temporary phenomenon in some cases but perhaps not always.1 The data provided by Calabrese and Baldwin seem fairly unlikely to pass the requirement in part (b) for a "satisfactory" degree of accuracy in estimating the scale of hormetic effects, however. Currently, they have provided very little information about the ways in which common variations in background chemical exposures, nutritional intake, activity levels, and illnesses




would affect the production of hormetic effects in typical members of the human population. And, even though they claim that hormetic effects can be produced by mixtures of toxic chemicals, they provide only a limited degree of evidence for their claim. Namely, they appeal to four studies that revealed hormetic effects produced by petroleum mixtures, four studies of wastewater effluent, and two other studies that yielded hormetic effects as a result of multiple chemical

exposures (see Calabrese and Baldwin 2002a, 333). Although these studies do

suggest that chemical mixtures can produce hormetic effects in some cases, they do not provide sufficient information to determine whether typical members of the public are likely to experience hormetic effects in response to the mixtures of chemicals to which they are frequently exposed.

Implementation Condition The concept and scale conditions address largely conceptual and empirical

issues, respectively, surrounding hormetic effects. Another plausible necessary condition for allowing public exposure to hormetic chemicals is that there be no insurmountable practical problems that arise from the social, cultural, and political context in which the proposals in claim R are implemented. Without trying to give an exhaustive list, some of these problems might potentially include: (1) the potential for vested interest groups to abuse the new regulations; (2) lack of

funding and technology for identifying hormetic chemicals, their scales of effects, and the levels of chemicals to which the public is actually exposed with reasonable accuracy; (3) difficulty regulating multiple sources of chemicals in a coordinated way so that the sum total of public exposure to chemicals remains in the hormetic zone; (4) complications assigning responsibility for harms caused by toxic chemicals, if each individual polluter releases chemicals at hormetic dose levels;8 (5) overwhelming public distrust and opposition to new regulations; and (6) the potential for a "slippery slope" toward unjustified weakening of current

regulatory policies for toxic chemicals. Some of these practical difficulties (e.g., public distrust) might arise after the concept and scale of hormesis have already been determined, while other difficulties (e.g., lack of funding) might prevent researchers from effectively determining the concept and scale of hormetic effects in the first place.9

The following definition of the "implementation condition" states that these sorts of practical issues must be addressed in order to justify public exposure to hormetic chemicals, but it does not attempt to provide an exhaustive list of these issues:

Implementation Condition: Any ethical use of claim R to justify exposing people to hormetic chemicals must include a reasonable level of assurance that it is possible to implement the policy of allowing hormetic exposures, given actual social, cultural, and environmental conditions (including current knowledge, potential for




human error, vested interests, and available financial resources), without causing an unreasonable amount of harm to the public.

This paper does not suggest precisely how much assurance one must offer in order to be "reasonably" sure that a policy of allowing public exposure to hormetic chemicals (in conjunction with current social, cultural and environmental conditions) will not result in unforeseen harm to the public. As in the case of determining appropriate standards of evidence for the scales on which hormetic effects occur, broad-based deliberation may provide the most effective means for obtaining public agreement that adequate assurance has been given.

Unfortunately, there appear to be at least two factors that, considered to-

gether, might make it difficult to achieve a "reasonable" level of assurance. First, it seems challenging to distinguish (given the level of funding available in our society) between chemicals that do and that do not produce hormetic effects under "real-life" conditions. The chief reason is that very expensive and time-consuming studies would be required to provide convincing evidence that a

particular chemical produces hormetic effects under most people's actual living conditions (taking into account age, diet, behavior, genetics, health, and other chemical exposures). It is possible, in fact, that the variety of toxic chemicals to which humans are currently exposed might be interacting in such a way that most humans would already have to be exposed to less rather than more chemicals in order to experience hormetic effects. Calabrese and Baldwin have appealed to many studies that provide evidence for hormetic effects in particular organ- isms, with particular chemicals, under particular conditions, but it is not clear that the same chemicals would produce hormetic effects on human beings under the typical array of real-life conditions to which the public is typically exposed. For example, Vichi and Tritton (1989) observed hormetic effects caused by the

cytotoxic agent Adriamycin when cells were exposed to sub-optimal nutrient levels. Further research would be needed to verify that those hormetic effects could occur under the wider range of environmental and nutritional conditions found in human societies.

Given that it is likely to be difficult to obtain reliable information about hormetic effects, a second factor increases the possibility that a policy of allowing public exposure to hormetic chemicals could result in harm to the public under current social conditions. This second consideration is that powerful interest

groups would be very likely to try to use claim R to justify public exposures to toxic chemicals even if there were not adequate information to determine whether those chemicals actually produced hormetic effects under real-life conditions. Numerous authors have documented how industry groups have withheld information, produced and appealed to biased (and even fraudulent) scientific results, and used powerful public relations strategies in order to weaken regulatory policy for toxic chemicals without adequate scientific justification, (see Beder 2000, Fagin et al. 1999, Markowitz and Rosner 2002, Wargo 1996). Therefore, despite inad-




equate evidence about the number of toxins that would actually provide beneficial health effects for the public, the representatives of powerful interest groups are likely to call for public exposure to low levels of most toxic chemicals. Kaiser has reported that the Texas Institute for the Advancement of Chemical Technol- ogy has already put out a flyer citing examples of hormesis and suggesting that it could allow "society to enjoy the benefits of many chemicals that have been banned" (2003, 377).

One might argue, of course, that the mere possibility that vested interests could abuse the system is not an adequate reason to prevent the use of claim R to allow hormetic exposures. After all, steps can be taken to limit such abuses. For example, one could require strict conflict-of-interest disclosures for research related to hormetic effects (see, e.g., Campbell 2001, Krimsky 2002). One could also demand careful federal oversight of laboratory studies (perhaps including government choice of the labs that perform the studies) and place the burden of

proof on industry to show that particular toxic chemicals are beneficial at some dose levels (Fagin et al. 1999). The implementation condition serves as a reminder, however, that one must have a reasonable level of assurances such as these in order to justify using claim R to allow public exposures to hormetic chemicals.

Consent Condition A fourth necessary condition for ethically justifying public exposure to hor-

metic chemicals under claim R is that the public must provide some form of free, informed consent to this policy:

Consent Condition: Any ethical use of claim R to justify exposing people to hormetic chemicals must ensure that reasonable steps are taken to obtain some form of free, informed consent from the public.

The consent condition is plausibly necessary for at least two reasons. One reason is that, at least in the near future, there is likely to be at least some uncertainty about the extent to which most allegedly hormetic chemicals actually produce beneficial effects under real-life conditions. Thus, assuming that the members of the public have rights to provide consent to risks that are imposed on them (see, e.g., Shrader-Frechette 1991), they arguably have rights to provide consent to chemical exposures that could be beneficial but that could also turn out to be harmful. A second reason to think that the consent condition is ethically necessary is that at least some thinkers (most notably libertarians) would claim that one has a right to provide consent to interference in one's affairs even if that interference is beneficial. According to this perspective, people would have a right to reject exposure to hormetic chemicals even if those exposures were clearly beneficial.

Few people are likely to object to the notion that some form of free, informed consent to regulatory policies about hormesis must be obtained from the public, but many thinkers might regard the fulfillment of this condition as a fairly trivial




matter in western societies such as the United States. One might argue, for example, that the people of western societies provide adequate indirect consent for any regulatory policies concerning toxic chemicals through the election of the members of government who develop policies and laws concerning these issues. There are several reasons, however, that it is probably unwise to assume that the current policymaking process in countries such as the U.S. would guarantee adequate informed consent from the public to new regulatory policies such as those suggested by claim R. First, the members of U.S. administrative agencies (such as the EPA) are not directly elected by the public (Fiorino 1995). Second, U.S. administrative agencies have, or at least are suspected by large numbers of the population as having, social and financial ties to vested interest groups that may prevent them from acting as faithful representatives of all citizens' interests (see, e.g., Beder 2000, Fagin et al. 1999, Shrader-Frechette 1991). Third, administrative agencies and lawmakers in the United States have such large numbers of constituents (many of whom have extremely different values and priorities) that it might seem unreasonable to think that they can actually provide informed consent to policy decisions on behalf of those that they represent (Dietz 1995).

A fourth reason not to regard meeting the consent condition as a trivial matter is that at least some scientists appear to be providing questionable evaluations of the evidence for hormesis in influential publications. For example, in a recent commentary piece in the journal Nature, Calabrese and Baldwin (2003) made the following claims:

The hormesis model is not an exception to the rule - it is the rule. . . . Now, we not only know that it [i.e., hormesis] exists but accept its dominance over other models As both types of biological response [i.e., the biological responses to non-carcinogens and carcinogens] follow the hormetic paradigm and display similar quantitative features of the dose response, the EPA could use the hormetic model as default to assess risk in both non-carcinogens and carcinogens. (691-692)

Although Calabrese and Baldwin presumably offered their opinions about hormesis in good faith, they did not acknowledge the views of those who question both the evidence for hormesis and its relevance for risk-assessment policy (see, e.g., Elliott 2000a, Jonas 2001, Rodricks 2003, Kitchin and Drane 2005). If powerful interest groups overemphasize the claims made by scientists such as Calabrese and Baldwin, it could contribute to ill-informed decisions by policymakers. Under such circumstances, those decisions would not meet typical standards of informed consent, which requires reasonable disclosure and understanding of all information that is material to the decision (see, e.g., Beauchamp and Childress 2001).

One might respond to these four suggestions about the difficulty of meeting the consent condition in two very different ways. On one hand, some thinkers might suggest that one should abandon altogether the attempt to obtain consent from the public as a whole to government policies that allow hormetic chemical exposures. They might argue that it is more ethically appropriate to allow indi-




viduals to choose their own exposure to chemicals that are allegedly hormetic. For example, if some individuals believed that they were not receiving enough exposure to toxic chemicals, they could supplement their diet with pills that contain these chemicals (much like taking vitamins). The government could then maintain its current regulatory policies, which would allow other individuals who were skeptical of the evidence for hormesis to maintain relatively low exposures to toxic chemicals. On the other hand, a very different response to the difficulties with obtaining public informed consent to allowing public exposure to hormetic chemicals would be to dismiss these difficulties as insufficient reasons to abandon efforts at obtaining public consent. For example, one might argue that concerns about biases among members of regulatory agencies or among scientists are not

unique to the hormesis case but rather afflict all regulatory decisions. One could also argue that, even if some scientists and policymakers provide questionable interpretations of current evidence about hormesis, the adversarial nature of the U.S. regulatory process (coupled with likely pressure from the public not to relax current standards) will ensure that an adequate variety of perspectives are

incorporated in regulatory decisions about hormesis. Although a full evaluation of the extent to which the consent condition can

be met is beyond the scope of this paper, one promising way to address it is

arguably to use the hormesis case as an opportunity to explore new deliberative

approaches to science policy that facilitate more explicit consent from the public as a whole (e.g., Kleinman 2000). It is probably unrealistic to leave the consent decision entirely up to individuals (allowing people to take toxic "vitamin" pills, for instance), because the costs of government regulation of toxic chemicals are extremely high. If one could obtain convincing evidence that a number of chemicals are actually beneficial at low doses, it would be difficult to argue that industries should be forced to enact extremely expensive pollution prevention and remediation efforts that leave citizens less well off than they otherwise would have been! It seems arguable that people's rights to provide individual consent to these beneficial effects could be overridden for the sake of significant economic consid- erations, just as current regulatory policy allows public exposure to low levels of toxic chemicals as long as those levels do not seem likely to cause much harm.10 Nevertheless, rather than allowing policy decisions about hormesis to involve the same questionable level of public consent that other regulatory decisions involve, one could obtain consent to policy decisions about hormesis by experimenting with new approaches such as consensus conferences (Sclove 2000) and citizen advisory committees (Lynn and Kartez 1995). Moreover, it seems reasonable to maintain attention to the consent condition in the course of these deliberations because, even though it may seem plausible that all scientific perspectives will be heard and emphasized in the process of regulatory deliberations about hormesis, this paper has emphasized that powerful interest groups have the resources and the motivation to try to emphasize only scientific opinions about hormesis that




further their interests. Thus, it seems to wise to emphasize the consent condition as a reminder to policymakers to ensure that all major, plausible scientific perspectives (not merely those of powerful interest groups) are given adequate attention in policy discussions concerning hormesis.

Conclusions

This article aimed to accomplish two main tasks. First, it attempted to clarify the claim that the hormesis phenomenon supports allowing public exposure to at least some toxic chemicals. It suggested six issues that must be elucidated when formulating this claim and then proposed a maximally defensible version of it. Second, the paper identified four necessary conditions (concerning concepts, scale, implementation, and consent) for ethically using this claim to justify public exposure to hormetic chemicals. It also analyzed some of the main challenges to meeting those four conditions. Based on this study, there appear to be several important avenues for further ethical, scientific, and policy analysis regarding the environmental policy ramifications of hormesis. First, further ethical analyses should determine whether the four necessary conditions developed in this paper are sufficient for justifying public exposure to hormetic chemicals or whether additional conditions are required. Second, scientists should develop a clear concept for hormesis (at least for policy purposes), together with operationaliz- able criteria for determining whether specific chemicals fit that concept. They should also develop more detailed information concerning the scales of hormetic effects (across people and time). Finally, it would be valuable for policymakers to explore, on one hand, the extent to which new regulatory policies (based on hormesis) can actually be implemented without causing unreasonable harm to the public and, on the other hand, effective means of obtaining public informed consent to these new policies.

Louisiana State University

NOTES

I would like to thank Kristin Shrader-Frechette and an anonymous referee for very helpful comments on earlier versions of this paper.

1 . For previous efforts to provide "second-order" analyses of others ' claims concerning the policy ramifications of hormesis, see Elliott 2000a, van der Schalie and Gentile 2000, Joslyn 2000, Morris 2000, Weis 2000, Applegate 2001, Cross 2001, Menzie 2001, Chris- tiani and Zhou 2002, Marchant 2002, Rodricks 2003, and Kitchin and Drane 2005.

2. For the purposes of this paper, there are two scales that are particularly important for determining the regulatory ramifications of hormetic effects. The first scale is the range




of people on which hormetic effects occur. It might depend on factors such as people's age, health, diet, behavior, stress level, genetics, and other chemical exposures. The other scale is the period of time during which hormetic effects occur. For example, these effects might occur for a short period of time and then be followed by adverse effects.

3. The satisfaction issue addresses an empirical or possibly a conceptual question, not an ethical question. Namely, it considers whether the authors accept the claim that all hormetic effects meet the necessary conditions that they specify for ethically allowing public exposure to hormetic chemicals. The question appears to be empirical, because further research is needed to determine whether all hormetic effects do actually meet the conditions that the authors specify. It could also be a conceptual question, however, if researchers define 'hormesis' in such a way that effects count as hormetic only if they meet the authors' conditions.

4. There are at least two reasons that it is more controversial to claim that government should promote, rather than merely allow, public exposure to hormetic chemicals. First, given that there is a risk that allegedly hormetic chemicals will produce some form of unexpected harm to those exposed to them, some ethicists would appeal to a distinction between acts and omissions in order to argue that government officials would be less morally culpable for those harms if they merely failed to regulate the chemicals rather than if they actively encouraged chemical exposures. In other words, if government officials actually promoted public exposure to hormetic chemicals, they would be taking actions that contributed to public harms, whereas allowing public exposures to those chemicals would merely involve omitting actions that could have prevented the harms (see, e.g., Foot 1967 and Thomson 1986 for discussions of this distinction). A second reason that it is more controversial to claim that government should promote, rather than allow, public exposure to hormetic chemicals is that it appears to presuppose that people have welfare rights. In other words, it assumes that citizens have a positive claim on the government to provide them with various goods (e.g., healthcare, food, and shelter). This presupposition of welfare rights may be problematic, however, because most proponents of weakened government regulations concerning toxins hold a relatively "libertarian" political philosophy, according to which government should interfere with citizen affairs as little as possible and thus should not be held responsible for providing its citizens with services like health benefits.

5. The ethical consequences of hormetic effects could be very diverse, including such things as: ( 1) a new public mindset for thinking about pollution (namely, that small quanti- ties of pollutants are not bad), (2) new cost-benefit calculations employed in regulatory policy, and (3) new models for calculating the biological effects of toxins. In the context of the concept condition, however, this article is concerned primarily with one potential ethical consequence of hormetic effects, namely, the question whether it is justifiable to allow public exposure to low levels of toxins.

6. As Calabrese and Cook (2005) suggest, it is also possible that all people experience hormetic effects, but more sensitive individuals experience those effects at lower dose levels than less sensitive individuals. This possibility would alter the details that need to be considered for meeting the scale condition, but it would not eliminate the condition's ethical importance. If hormetic effects were to occur on all people but at different dose levels, then meeting the scale condition would arguably require: (a) an ethical decision concerning the particular group of people (i.e., less sensitive, intermediate, or more sensitive individuals) that should have their hormetic effects maximized (and/or their harmful




effects minimized), and (b) enough empirical information to determine with a satisfactory degree of accuracy that the chosen group of people actually experience maximal hormetic effects at the doses recommended by government regulators.

7. As noted in note 6, Calabrese and Cook (2005) also address the scale condition by suggesting that hormetic effects may occur on all people but at different dose levels. As in the case of the other arguments that Calabrese and Cook make in response to the scale condition, however, they do not provide extensive empirical evidence to support their suggestion.

8. The possibility that each individual polluter could release levels of chemicals that are beneficial to the public but that the aggregate of these chemical releases could be harmful to the public may raise not only practical issues for assigning culpability but also very interesting theoretical issues. For example, Derek Parfit (1984) has argued that it is an error in moral mathematics to claim that actions that produce imperceptible harms are not morally blameworthy (if those harms affect a great number of people or if a number of people all cause imperceptible harms that together create perceptible harms). Although something like Parfit's position appears to be reasonable, his arguments in defense of his position have weaknesses (see, e.g., Gruzalski 1986, Parfit 1986, Shrader-Frechette 1987). The hormesis phenomenon appears to raise further problems for Parfit's arguments, insofar as it involves the potential for individual polluters to cause imperceptible benefits that could together aggregate into perceptible harms or benefits, depending on the number of polluters and the amount that they pollute. If individual chemical releases produce imperceptible benefits rather than harms, for example, Parfit would not be able to explain the blameworthiness of releasing small amounts of toxic chemicals (which together aggregate into significant harmful effects) by appealing to imperceptible harms that they cause. Although there is not space in the present paper to explore this issue, the hormesis phenomenon could provide support for Shrader-Frechette's (1987) suggestion that it is better to evaluate actions based on the risks of harm that they produce rather than the actual, imperceptible harms or benefits that they produce.

9. One might suggest that the factors that prevent researchers from effectively determining the concept or scale of hormetic effects should be included under the concept or scale conditions rather than a separate implementation condition. Nevertheless, the paper's definition of the implementation condition appears to be reasonable, because it groups similar issues under similar conditions. The concept and scale problems currently address largely conceptual and empirical issues, respectively, about the characteristics of hormesis. In contrast, the factors that prevent researchers from effectively elucidating the concept and scale of hormetic effects are practical problems related to the social, cultural, and political characteristics of society. For example, society may not have adequate resources for studying the scale of hormetic effects, or vested interests may design studies in such a way that they provide misleading information about the scale of effects. Therefore, it seems reasonable to group all these practical issues together under one "implementation" problem, whether they occur after the concept and scale of hormesis have been determined or during the determination process.

10. One might argue, for instance, that it would be even more justifiable to allow public exposure to hormetic chemicals than it is to fluoridate public drinking water, which is already an accepted practice. In the fluoride case, as in the hormesis case, there are at least some worries that public policies allowing these chemical exposures could cause harm to some individuals. Nevertheless, the government deliberately promotes fluoride exposure




because of the benefits that they provide to most members of the population. One might argue that allowing polluters to release toxic chemicals at hormetic doses would be even more justifiable, both because it would save large amounts of money and because the government would merely be allowing the exposures (as opposed to actively promoting them). A potential objection is that fluoride exposure is easier for concerned individuals to avoid (by drinking bottled water, for example) than exposure to hormetic chemicals. Nevertheless, one could probably also affect one's exposure to hormetic chemicals by moving either toward or away from polluting sources, like industrial plants.

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