Organochlorines and breast cancer:

Social Science & Medicine 52 (2001) 1589–1605

Organochlorines and breast cancer: the uses of scientific evidence in claimsmaking S. Michelle Driedger*, John Eyles McMaster Institute of Environmental Health, School of Geography and Geology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada, L8S 4K1

Abstract This paper explores the role and utilization of scientific evidence concerning one of the potential adverse health impacts (breast cancer) of the use of chlorine through examining the aims of an environmental group, Greenpeace, and its opponents. Specifically, the paper identifies the claims of Greenpeace and the scientific evidence used to justify those claims in its (Thornton, 1993) report Chlorine, Human Health and the Environment: The Breast Cancer Warning. A media analysis was conducted over a ten year period to assess what counter-claims were generated. The claimsmaking activities of breast cancer advocacy groups, scientists, pro-chlorine groups, and environmentalists were monitored. To counter the Greenpeace claims, pro-chlorine supporters argued for the responsible use of science, and redefined the chlorine issue as one of public health and economic security. The counter-claims between the supporters and the opponents of the chlorine issue stemmed from differences in their agendas, values, and solutions proffered in the environmental health policy domain. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Claimsmaking; Organochlorines; Breast cancer; Greenpeace; Environmental health policy; Canada

Introduction This paper explores the role and utilization of scientific evidence concerning one of the potential adverse health impacts (breast cancer) of the use of chlorine through examining the aims of an environmental group, Greenpeace, and its opponents. breast cancer, itself, is targeted for two reasons. First, the causes of breast cancer are not fully understood, and some of what is known remains contentious (Davidson & Yager, 1997). Second, breast cancer incidence rates have been increasing rapidly (Parkin, Pisani, & Ferlay, 1985), prompting breast cancer activists to politicize the disease and generate great public concern (see Waller & Batt, 1995; Hoy, 1995; Mallet, 1996; Robson, 1996). Specifically, the paper examines the role of Greenpeace and the scientific evidence used to justify its claims in the *Corresponding author. Tel.: +1-905-525-9140 x24081; fax: +1-905-546-0463. E-mail address: [email protected] (S.M. Driedger).

report: Chlorine, Human Health and the Environment: The Breast Cancer Warning (Thornton, 1993). This report, while itself emerging because of key events, helped to shape the agendas and campaigns of other interested parties such as the chlorine industry, international organizations, and breast cancer advocacy groups. The paper emphasizes the scientific evidence on the issue, charting those human epidemiological research studies up to the present, to comment on the basis of the various claims. Chlorine is a pervasive chemical. It is used everyday in the production of other chemicals, plastics, solvents, pulp and paper, pharmaceuticals, and waste and water purification. Chlorine is credited with being responsible for the largest single leap in public health in the 20th century (Mills et al., 1998). Used as a water disinfectant, chlorine reduces the threat of waterborne illnesses such as typhoid, cholera, hepatitis, and dysentery. It is used to disinfect more than 90% of North America’s drinking water (Rodden, 1994). However, the benefits of chlorine are not without costs. It is an active component in

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compounds perceived and identified as being toxic, implicated in environmental damage and adverse human health effects (Leiss & Chociolko, 1994). As such, chlorine provides a useful case study to understand how scientific information is used to further specific agendas in the environmental health policy domain (for other examples, see Garvin & Eyles, 1997; Harrison, 1991). The public is frequently influenced by media headlines (e.g. ‘‘Studies link DDT to breast cancer’’) where a threat to human health is being utilized as a powerful justification for advocating changes in environmental legislation, regulation and practices (Burger, 1990, Iannantuono, & Eyles, 2000). Organochlorines } synthetic chemicals produced by using chlorine as a base (Baarschers, 1996) } have especially raised public interest, as evidenced by debates within the pulp and paper industry on the use of chlorine bleach over the last decade in its processing plants, as well as the role organochlorines has played in the development of the environmental movement since the 1960’ s (e.g. threat to health from DDT, PCBs, dioxins). Environmental groups, too, have used human health to advance their agenda. Such groups arose particularly in the 1960s with a fusing together of mutual interests between civil rights and peace movements with environmental activism (Bailey, 1993). This activism stemmed from concerns about nuclear war, and later, concerns about what effects chemicals and other environmental hazards may be having on the health of the ecosystem. Starting in the 1980s, we have witnessed the growing number and prominence of environmental non-governmental organizations (NGOs), networks, and coalitions (Princen & Finger, 1994). Most of their actions are directed towards environmental and ecosystem improvement, and they are largely immune to the political and economic agendas of governments and market forces respectively (Korten, 1990). Funded largely by membership and non-corporate donations (Ehrlich & Ehrlich, 1996), NGOs are pivotal as agents of social change because they research, expose and monitor environmental trends without fear of offending constituencies (e.g. voters) or losing customers (Princen & Finger, 1994). Success is achieved when current environmental issues are framed in such a way as to achieve the greatest resonance with the public (Hannigan, 1995; Sandbach, 1980), and when the issue of interest is taken up by other parties (Sabatier & Jenkins-Smith, 1993). Specifically, the Greenpeace agenda is geared to the protection of the environment. It is wholly independent of government control, political parties and organizations, commercial groups, or other environmental groups (www.greenpeace.org/report97/how.html). It has been partly responsible for policy changes among governments ranging from France’s shift on nuclear testing, to Sweden’s position in favour of phasing out polyvinyl chlorides (PVCs), stemming from successful

Greenpeace campaigns (www.greenpeace.org/
jess/ test/gpworks/textworks.html). While Greenpeace has directed their campaign on the ‘‘chlorinated killers’’ for many years, it was not until 1995 that they started seeing results through many different resolutions, such as the United Nations global treaty on phasing out persistent organic pollutants (POPs) (www.greenpeace.org/
jess/chlorine/textchl.html). In fact, Greenpeace was at the forefront globally of framing the chlorine controversy as a health issue. According to the US Chemical Manufacturers Association and the Chlorine Institute, Greenpeace, working locally, strongly encouraged the International Joint Commission (IJC) } the binational (Canada/US) commission on Great Lakes water quality issues } to argue for an eventual phaseout of chlorinated compounds at both its 6th (1991) and 7th (1993) Biennial meetings (Draper, 1993). At the very least, the Greenpeace report coincided with and supported the concerns expressed in the IJC’s scientific documents about the effects of PCBs, in particular, on the environment and wildlife (see Health Canada, 1997; Tremblay & Gilman, 1995). We thus isolate and utilize the Greenpeace report as a ‘fateful moment’ (Giddens, 1991) in the chlorine controversy that pointed to what appears to be a substantial risk for the world’s population, although the report itself has a North American focus. Given its scientific nature, we examine the scientific claims regarding the role of environmental causes on breast cancer as argued in the report (Thornton, 1993). Further, we place these claims in the context of the broader scientific debates surrounding the use of chlorine. We begin articulating the framework and data sources of the paper before turning to the Greenpeace claims.

Methodology: framework, method and data sources Primarily we present a study of scientific claimsmaking. In issue framing (Gamson, 1992) and claimsmaking (Hannigan, 1995; Best, 1995) the way in which an issue is presented provides a critical feature of how it is being defined and played out (Kingdon, 1995). Gieryn (1999) argues that the epistemic authority of science } the power to define, describe, and explain reality } grants science special features not typically ascribed to other domains. Science stands ‘‘metonymically for credibility, for legitimate knowledge, for reliable and useful predictions, for a trustable reality: it commands assent in public debate’’ (Gieryn, 1999, p. 1). When particular knowledge claims are made in science and brought into the public and policy domains through science, they have tended to be accepted without contest. Yet, this is not an unproblematic process. In ambivalent, equivocal or controversial situations, claims are contested, in that

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more than one claim likely exists in a particular policy domain (Stone, 1997). These competing claims find their audience in courtrooms, legislatures, boardrooms, and living rooms. It is here where ‘battle lines’ are drawn in efforts to lend credibility to the interpretation of some knowledge claims over others (Gieryn, 1999), and where attempts are made to criticize the scientific basis of the claims of others (Sabatier, 1987). Thus, just as the construction of claims is an important feature in claimsmaking activities, so too is the role of counter-claims. Counter-claims are those statements or messages which run contrary to the dominant claims (Best, 1995). They provide a different frame on the issue and can be instrumental in the (re)construction of the issue. Similarly, analyzing the role of the claimsmaker can help assess issues of credibility. The source of the message or claim can play a pivotal role in gaining an audience’s acceptance (Hannigan, 1995). Identifying which groups are making the claims, their affiliations, and their connections, help pinpoint the rhetoric used. These also lend authority to the claim (Ibarra & Kitsuse, 1993; Best, 1995). Toulmin (1958) examines the pattern of an argument through the construction of claims. The claim or conclusion is established on the foundation of the facts or data that are presented. An example drawn from Toulmin is: Harry was born in Bermuda (data), therefore Harry is a British subject (conclusion). Such an argument can be challenged, and simply offering additional facts may not persuade the challenger. Hence, warrants are utilized to provide justification or supporting statements which allow individuals to accept the data both as starting points and as a legitimate step towards the claim or conclusion. To extend Toulmin’s original example, a warrant to justify the claim that ‘Harry is a British subject’ would be that ‘A person born in Bermuda will be a British subject’. The distinction Toulmin draws between data and warrants is that data are explicit statements, whereas warrants are made implicitly. Warrants cannot provide justification to the acceptance of claims if the facts themselves are not defendable. Our intention here is not to examine all aspects of Toulmin’s argument construction (see Toulmin, 1958), but rather to provide the basis of the analytic framework that has been adopted and modified by others to analyze knowledge claims. Building on Toulmin’s argument, Best (1995, p. 350) outlines three central questions for analyzing the nature of claims: ‘What is being said about the problem?’, ‘How is the problem being typified?’, and ‘What rhetoric is being used in terms of persuading the audience to accept the situation as it is being defined?’. It is this last question which is often not given sufficient attention. It is primarily through rhetoric or language that we can understand the construction of knowledge claims. There are three aspects to analyzing the rhetoric of claims

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(Best, 1987). The first, grounds, provide the data, the facts, or the examples which frame the issue in a particular light. The second, warrants, provide the justification for demanding certain actions be taken. The last, conclusions, spell out the action that is required to solve a particular problem. These terms or labels are related to the three original questions identified by Best (1995) in analyzing claims. ‘What is being said about the problem’ identifies the problem according to an existing set of grounds or facts. ‘How is the problem being typified’ serves to reveal the warrants. In this context, the justification (or warrants) provides additional support for the interpretation of the ‘facts’ (or grounds) by the claimsmaker. Thus, we use ‘warrants’ to identify explicitly the values that underlie the use of particular grounds or facts in particular ways. Last, ‘What rhetoric is being used to persuade the audience to accept the situation as it is being defined’ identifies which actions (or conclusions) flow from the justification or warrants provided to solve the problem. It is primarily in the warrants where the greatest challenge lies to any claim. Further, it is here that the values and assumptions of the claimsmaker can be revealed (Stone, 1997; Sabatier, 1987). These values will also shape the type of conclusion or actions recommended to solve a particular problem. Within the context of the case study on organochlorines and breast cancer as presented here, the interpretation of the facts in defining the problem and the actions suggested differ according to the values of the claimsmakers. The way in which this is presented within the arguments is dependent upon the values and assumptions attached to the interpretation of the scientific knowledge claims. Thus, the interpretation of the scientific claims forwarded by Greenpeace } the scientific authority they possess } are judged against the claims of other interested parties. To derive these elements of claims, we undertook a careful textual analysis of the Greenpeace report on organochlorines and breast cancer to isolate: (1) those elements deriving from science and the claims of scientists (i.e. the facts or grounds), (2) those used to justify problem definition, and, as the basis of actions (i.e. the warrants) to help reveal the values and assumptions, and (3) the actions suggested (i.e. conclusions). Text analysis is utilized in the reconstruction of narratives (Roe, 1994), Lakoff and Johnson (1980) and Stone (1997) for understanding the treatment of metaphors, and Best (1995) in unraveling the construction of claims. Manning (1987) provides a framework for deriving these elements from language (i.e. texts and its meaning in specific contexts). Indeed, the focus on language and meaning is utilized to reveal and examine the underlying social context of an issue (Yanow, 1996). Implicit within these approaches is a recognition that the construction of claims does not occur in a vacuum.

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Claims are shaped and defined by the actors involved (Stone, 1997), and often take the form of written texts (e.g. policy documents, reports, regulations, legislation). These written texts or claims assert their authority on issues through language, particularly scientific argument, not so much in what they say, but in what they represent (Yanow, 1993). The use of language serves to make visible ‘symbolic representations’ (Stone, 1997) or ‘signs’ (Manning, 1987). However, the meaning attached to symbols or signs are not intrinsic properties. They gain meaning through their construction and reconstruction (Berger & Luckmann, 1966) in terms of their interpretation and use (Stone, 1997). Yet, There are often multiple meanings involved. Yanow (1993, p. 47) writes: ‘‘meaning is not universal or determinate; it depends on the context and on the perception and interpretation of the participants’’. This becomes critical within environmental health policy debates because the key elements are issues of interpretation, not facts (Dunn, 1981), that is, the grounds seen in relation to the warrants. Hence, revealing the claims through their construction, (scientific) narratives or arguments, is the fundamental characteristic of our approach. In addition to analyzing the salience of the Greenpeace report in Canada, a media analysis was conducted over a ten year period to assess what counter-claims were generated on this issue. The activities and claims of breast cancer advocacy groups, scientists, pro-chlorine groups, and environmentalists were monitored. Databases consulted for the media analysis include the Canadian Periodical Index, the Canadian Business and Current Affairs Index, and the Canadian News Index. Moreover, to assess the contest of scientific claims and evidence, review articles published in peer-reviewed journals, and Health Canada’s (1997) scientific review of the evidence concerning cancer issues in the Great Lakes region were utilized along with MEDLINE (a health database) searches.

The Greenpeace report: the claims Table 1 provides a summary of the major claims and supporting evidence as grounds, warrants and conclusions, used in the Greenpeace report to define the issue of breast cancer and organochlorines as ‘facts’ from a distinctive perspective or value position. Frequently, the report states that we have a ‘moral responsibility to act now’ for the good of all women and the environment. This moral stance (Stone, 1997) is employed when claimsmakers wish to convince an audience that unless action is taken, dire consequences will follow } namely that breast cancer rates will continue to rise due to organochlorines, causing many more women to die unnecessarily and prematurely.

In establishing its argument, the Greenpeace report draws on ‘third-party’ credibility by incorporating at its outset a ‘Scientists’ Endorsement’. This is signed by 21 scientists in a variety of fields including health, medicine (physicians), environment and policy. Sixteen of these individuals are affiliated with a university department or school, while the remaining are affiliated with environment and health organizations as well as consulting firms. With three exceptions, all of the scientists have either a Ph.D. or an MD. The arguments and statements made in the Scientists’ Endorsement all serve to reinforce the report’s main claim. The report’s very first sentence, located in the endorsement, reads: The Greenpeace report, ‘‘Chlorine, Human Health and the Environment: The Breast Cancer Warning’’, provides an excellent public presentation of a growing body of evidence that links low-level organochlorine contamination of the environment to the risk of breast cancer in women (Thornton, 1993, p. 6). Nonetheless, while the scientists listed in the endorsement recognize the scientific credibility of the report, as well as the fact that the evidence still remains inconclusive and requires further investigation, they are unequivocal in their conclusion. They write: ‘‘the need for more detailed scientific study need not preclude or delay action in the field of public policy and environmental regulation’’ (Thornton, 1993, 7). This Scientists’ Endorsement also serves to provide a clear line of attack against a potential critic of the report: The Chlorine Institute. It establishes that the Greenpeace report is based on credible science, while ‘‘the Chlorine Institute’s position, is itself based on a process of selective analysis, simplistic assessment of data, and wholesale dismissal of a legitimate body of experimental and epidemiological evidence’’ (Thornton, 1993, 6). This form of methodological attack is common for issues of great uncertainty (Leiss & Chociolko, 1994; Sabatier & Jenkins-Smith, 1993). Further, Greenpeace is trying to pre-empt and counter the scientific arguments of the opposing coalition. Table 2 outlines the human experimental science used within the Greenpeace report to ground its claims as ‘fact’. Within the table, all of the studies leading up to Wolff, Toniolo, Lee, Rivera, and Dubin (1993) } the year of the Greenpeace report release } with the exception of Davies, Barquet, Morgade, and Raffonelli (1976), are included in the Greenpeace report. Despite earlier negative findings (see Davies et al., 1976; Unger, Kiaser, Blichert-Toft, Olsen, & Clausen, 1984), later studies have showed some positive relationships. Falck, Ricci, Wolff, Godbold, and Deckers (1992) argued that their data suggest a 10 parts per billion

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Table 1 Summary of Greenpeace claims and supporting evidencea The claims Grounds The incidence of breast cancer is rising at ‘epidemic’ proportions

The evidence Worldwide, since 1930, breast cancer incidence rates have been rising by 1–2% annually, and is the leading cause of cancer death among premenopausal and postmenopausal women. By year 2000, the number of deaths due to breast cancer is expected to exceed 1 million.

Several risk factors (genetic inheritance, reproductive and hormonal factors, diet, alcohol consumption, exposure to radiation) all play a role, but the majority of breast cancer remains unexplained. Warrants The buildup of higher concentrations of organochlorines within our global environment may be harmful to health (the ecosystem, the food chain, and the bodies of wildlife and humans, are seen as being under threat).

According to many researchers, including the Canadian and American Cancer Societies, these risk factors account for only approximately 30% of breast cancer rates.

Biological Mechanisms: Many organochlorines interfere with the endocrine system, suppress the immune system, and disrupts the body’s control of cell growth and replication. Experimental Evidence: At least 16 organochlorines, of the 117 that have been shown to cause cancer, affect breast cancer in laboratory animals despite the fact that only a few have been tested for this effect.

While not conclusive, evidence suggests that organochlorines contribute to breast cancer, and if we do not act to reduce such compounds, women are exposed to higher mortality risk. If we do not act, their problems are undervalued.

Exposure Studies: women exposed to higher than normal levels of synthetic chemicals in the community and workplace have been found to have significantly elevated risks of breast cancer. Tissue Studies: some studies have found a relationship between the levels of certain organochlorines in a woman’s blood, fat, or breast tissues and risk of breast cancer. Case of Israel } following a phaseout of DDT, lindane, and BHC (in 1976), breast cancer mortality fell rapidly (8% between 1976 and 1986), and breast cancer rates fell by approximately 20%.

Conclusions A new standard for proof, the Precautionary Principle, should be adopted to measure environmental health impacts.

Should not dismiss scientific evidence that links pollution to human health effects simply because it does not reach the level of formal scientific proof.

The evidence compels us to phaseout chlorine and related chemicals, and public health policies should prohibit the environmental discharge of disease-causing chemicals, particularly organochlorines. a

Source: after Greenpeace Report (Thornton, 1993).

(ppb) increase in tissue levels of PCBs and DDE corresponded to a 1% increase in breast cancer rates. Greenpeace argued that tissue levels of PCBs and DDE in the general population are 300 and 1000 ppb, respectively. Consequently, these two compounds alone could explain a major portion of total breast cancer rates, although Greenpeace emphasizes that it still cannot be proven. Similarly, Wolff et al. (1993) found statistically significant levels of DDE (a DDT metabolite) in adipose tissue of women with breast cancer compared to controls. This study controlled for known potential confounders: differences in body mass index,

age at menarche, age at first full-term pregnancy, lifetime months of lactation, family history of breast cancer, and history of smoking and drinking alcohol. In addition, Greenpeace argued that while the traditional risk factors (e.g. age of menarche, number of children, age of first and last childbirth, use of contraceptives, hormone (estrogen) replacement therapy) contribute to breast cancer risk, they do not account for all of the shifts in breast cancer rates. Exposure to industrial chemicals could explain some of these rising rates, as evidenced by community occupational exposure studies (see Walrath et al., 1985;

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Table 2 The Science Used by Greenpeace: Human Case Control Studies on Organochlorines and Breast Cancera Study

Location

Chemical studied

Key findings

Davies et al (1976)b

}

DDT

Did not observe significant differences in DDT levels in adipose tissue among cases (N ¼ 29) or controls (N ¼ 29).

Wasserman et al. (1976)

}

p,p0 -DDT, PCBs

Statistically significant increase in levels of p,p0 -DDT and PCBs in malignant breast tissue compared with normal tissue of women with malignant breast cancer (BC) (N ¼ 9). Similar PCB levels were found in non-cancerous tissues of the cases and controls (accidental deaths, N ¼ 5). Total DDT was almost twice as high in the tissues of the controls than in the non-cancerous tissues of the cases. Body mass not controlled for and patients were at a fairly advanced stage of disease.

Unger et al. (1984)

Denmark

DDE, PCBs

Adipose breast tissue samples from living BC patients (N ¼ 14) and from deceased BC patients (N ¼ 14) were compared to samples from patients with other breast diseases (N ¼ 21), and from deceased patients without BC (N ¼ 35). There was no association between BC and the levels of PCBs and DDE in adipose breast tissue. Non-significantly increased PCB levels were observed in deceased cancer patients compared with living patients who had received early diagnoses. PCB levels may have been influenced by illness.

MussaloRauhamaa et al. (1990)

Finland

Organochlorines, PAHsc

Only -HCH residues were significantly higher in the BC cases; significant odds ratio of 10.5 for BC for breast adipose tissue levels of -HCH > 0.1 ppm adipose. However, differences in OC levels between cases and controls may be attributable to differences in parity and diet. The results remained significant after controlling for age and number of children born. No statistically significant difference in PAH levels in adipose breast tissue were observed between women with BC (N ¼ 44) and without BC (accident fatalities, N ¼ 33).

Falck et al. (1992)

Connecticut

p,p0 -DDT p,p0 -DDE PCBs

Mean levels of PCBs and p,p0 DDE were 50–60% higher in adipose breast tissue (wet weight) of women with malignant BC (N ¼ 20) when compared with patients with non-malignant BC (N ¼ 20); p,p  -DDT levels were also elevated among cases. Only PCBs remained significantly elevated when results were expressed on a lipid weight basis.

Wolff et al. (1993) (prospective cohort study)

New York

DDE, PCBs

Known BC risk factors were not controlled for in this study. Mean serum levels of DDE and of PCBs were higher for cases (N ¼ 58 BC patients) than for matched controls (N ¼ 171), but were statistically significant only for DDE (four-fold greater risk of BC for elevation of serum DDE level from 2.0 to 19.1 ppb).

a Source: Compiled from Greenpeace (1993) and the following review articles/documents: Laden and Hunter (1998); Health Canada (1997); Wolff et al. (1996); Adami et al. (1995); and Ahlborg et al. (1995). b This study is not included in the Greenpeace Report. c not an OC.

MacCubbin, Herzfeld, & Theriault, 1986; Griffith et al., 1989; Manz et al., 1991; Hall & Rosenman, 1991). Furthermore, studies have linked organochlorines to infertility, reproductive failure, developmental impairment, immune suppression, and possibly testicular cancer among marine mammals, fish and wildlife species, as well as some humans, to suggest that sufficiently high organochlorine levels can also contri-

bute to breast cancer rates (see Moss, Osmond, Bacchetti, Torti, & Gurgin, 1986; Science Advisory Board, 1989, 1991; Canada gov. 1991; Gray, 1992; Colborn et al., 1990, 1992; Carlsen, Giwercman, Keiding, & Skakkebek, 1992). Greenpeace critics argue that many of the human based experimental studies are flawed. Many confounders, such as the role of dietary fat, are ignored. Breast

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cancer rates are typically higher in industrialized nations where diets higher in fat are common. Greenpeace counterposes this argument by claiming that while fat consumption is associated with a higher degree of industrialization, such industrialization is accompanied by higher pollution levels. Consequently, ‘‘correlations of national fat intake and breast cancer rates may indicate an underlying cause other than the fat itself’’ (Thornton, 1993, p. 8). So prudence dictates that chlorine use is reduced and eventually eliminated. In sum, on the basis of these studies, Greenpeace posits a relationship between the presence of organochlorines within the environment and elevated risks of breast cancer, emphasizing that organochlorine pollution is a major contributing factor to breast cancer incidence rates. More compelling in terms of needed action, organochlorines in the environment are both preventable, and rank highly on official lists of priority pollutants recommending phaseouts of their use. While Greenpeace clearly states that the studies themselves are inconclusive, the conclusion to be reached is: based on the weight of evidence, action is still required. Thus, an underlying value of Greenpeace suggested by its warrants is the Precautionary Principle (which is itself a battlefield of claims and counterclaims not to be expanded on here). The Precautionary Principle asks that the burden of proof should be placed on those to prove that a particular chemical (as an example) does not have any harmful health effects, as opposed to the current standard where environmentalists must prove that a chemical does cause harm (Yearly, 1996; Hannigan, 1995). Hence, by adopting the Precautionary Principle, the Greenpeace warrants could be summarized as: we value health more than the products of chlorine use, we must thus conclude } ban all organochlorines.

The chlorine controversy: the context of the Greenpeace claims The historical context concerning chlorine and chlorinated compounds grew out of a number of events. The 1960s and 1970s marked a period where the public was just becoming aware of the adverse effects of some of the modern technological advances facilitated by the use of chemicals. The ‘cranberry scare’ of 1959 in the United States, growing out of concerns that a weed killer, aminotriazole (3-AT), may cause cancer in rodents and possibly humans, marked one of the first appearances of ‘‘the concept of hidden dangers with long lead times’’ (Wildavsky, 1995, p. 15). On the heels of this event was the publication of Rachel Carson’s Silent Spring (1962) which served as a major impetus for the environmental movement, especially concerning public exposure to chemical additives in food production through pesticides

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and insecticides. Carson was concerned about the impact of organochlorines (e.g. DDT, dieldrin) on birds and other animals in the natural environment, and by extension on humans. Another chemical in the organochlorine series to add to these concerns was polychlorinated biphenyl (PCB) residue in food, soil and water stemming from its presence in a host of products (e.g. fire-resistant insulators in electrical transformers, capacitors, industrial machinery, paints, pesticides). Accidents (e.g. Yusho (Japan) incident via rice oil poisoning; St.-Basile-le-Grand (Quebec) fire of about 1500 barrels of PCBs containing oil) and documented cases of improper industrial disposal of PCBs (e.g. General Electric and the Hudson River), heightened concerns. PCBs have a long break-down period (Wildavsky, 1995), are bioaccumulative through the food chain, and are stored in fat tissues (Milly & Leiss, 1997; Ehrlich & Ehrlich, 1996; Bullard, 1994). Similarly, the exposure to dioxins (see Harrison & Hoberg, 1991), Agent Orange, and other pesticides led to assessments of their hazards to human health and pressure to restrict or ban their use to protect the public against risk (Wildavsky, 1995). Since then, concern over environment and health aspects of chlorine has been high. Certain chlorinated compounds have been banned (e.g. DDT), market demand for some products yielding chlorinated byproducts has dropped (e.g. chlorine bleached pulp), and there has been a phasedown in the production of ozonedepleting CFCs (e.g. chlorinated compounds containing chemicals that deplete atmospheric ozone can no longer be produced after January 1, 1996 as per the Montreal Protocol on Substances that Deplete the Ozone Layer). However, none of these events would have had the same impact if it had not been for the efforts of environmental and other interest groups in raising the profile of these issues in the public arena (Reich, 1991). One of the key events in raising the profile of the chlorine issue in this case study is that in 1991, the International Joint Commission (IJC) recommended the phasing out of chlorine and chlorinated industrial products as part of its efforts to revive the Great Lakes ecosystem. The language used by the IJC did not suggest a complete ban or an immediate cessation of chlorine by edict. Rather, it was to be a gradual process, negotiated and implemented over time. However, the way in which this recommendation had been framed by both prochlorine supporters and environmentalists alike does not reflect this gradual process. Instead, both sides had viewed the IJC recommendation as supporting, at least in the North American context, an all-out ban. In their claimsmaking activities, environmental groups, like Greenpeace, initially extended this chlorine ‘ban’ to include all chlorine-uses (Isaacs, 1993). Given some negative public reaction, this view was modified to provide exemptions for chlorine as a drinking-water

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disinfectant and chlorine uses in the pharmaceutical industry (Hileman, Long, & Kirschner, 1994). For the pro-chlorine supporters, it too was in their best interest to frame the issue as a complete ‘ban’ of all chlorine uses (Hileman, 1993). They could more easily rally support from labour unions and industry-dependent communities fearing plant closures and job losses, pharmaceutical companies (which rely heavily on chlorine use in its products) fearing a dramatic change in the way they operate, and the support of scientists who believe that policy should be supported by conclusive evidence. The warrants here are job protection, community survival, safe drugs and good science, based on strict epidemiologic and clinical criteria for evidence. These values support a certain interpretation of facts leading to a ‘wait and see’ approach and continued use of chlorine, as opposed to the promotion of the Precautionary Principle advocated by proenvironmental groups. The IJC was not alone in its call for a chlorine phaseout. International groups also encouraged the phase out of halogenated organics like organochlorines. The Paris Commission for the Prevention of Marine Pollution (1992), the Barcelona Convention of the Mediterranean Sea (1993), the International Whaling Commission (1993), and the World Wilderness Conference (1993) were among those making similar recommendations (Graff, 1995). Moreover, provincial governments within Canada took limited preventative measures on the chlorine issue. The provinces of British Columbia (1994), Quebec (1994) and Ontario (1993) all took measures to reduce chlorine effluent discharge emissions from pulp and paper mills. For example, in Ontario, Environment Minister Grier (New Democratic Party } a left leaning political party) announced organochlorine cuts from pulp and paper mills of 40% by 1996, 70% by 2000, to a complete removal of free chlorine use for pulp bleaching by 2002 (Mittelstaedt & Mahood, 1993). In a similar vein, the US Environmental Protection Agency (EPA) unveiled a plan as part of President Clinton’s reauthorization of the Clean Water Act, in 1994, which would begin to treat chlorine more holistically, with potential restrictions in the use, or phasing out of chlorinated compounds (Graff, 1995; Hileman & Hanson, 1994). In addition to these policy suggestions, other groups began questioning the potential effect of chlorinated compounds, especially organochlorines, on people’s health. In 1993, the American Public Health Association recommended a reverse onus of proof regarding organochlorines: rather than individuals or groups having to prove that organochlorines pose a health risk, industries and chemical manufacturers have to prove that organochlorines are safe (this resolution was later withdrawn in 1994, see below). Similarly, breast cancer advocacy groups were instrumental in raising public

awareness of breast cancer and its relation to the environment. In every year from 1993 to 1999 there was a different conference1 held to examine the link between potential estrogen mimics in the environment (e.g. organochlorines) and breast cancer rates. In fact, the 1993 Greenpeace report on organochlorines and breast cancer coincided with debates at the public level through the activities of these different organizations. The report was therefore successful in Greenpeace’s terms as it helped raise public awareness and debate about an issue of concern to the NGO. They could now move to other elements of the chlorine issue with emphasis being placed on soft-chlorinated compounds (e.g. PVCs and non-chlorine-containing phthalates used in the production of flexible PVC) found in children’s toys and hospital IV drip bags (Greenpeace, 1996), to name but two applications. And, in spite of the many issues examined at these breast cancer conferences, such as preventive measures, life-style, diet, heredity, and genetic predisposition, the media focused almost exclusively on the role of the environment in rising breast cancer rates (Friesen, 1997).

The counter-claims: alternative values and warrants The chlorine industry, as suggested in the last section, has not been silent. Surprised by the anti-chlorine sentiment, the chemical industry through the US Chlorine Chemistry Council developed counter-claims with two main thrusts: the role of science and issue redefinition. Pro-chlorine groups ground their claims in the responsible use of science; where the role of science is to help inform decisions based on evidence from proven, reliable and replicable studies, even in situations of uncertainty. The facts surrounding an issue must be unequivocal to lead to changes in policy. In 1992, the Chlorine Institute (a special interest group affiliated with the Chemical Manufacturers Association) initiated an outreach program to address criticisms against the industry and to allay any fears. This outreach program was credited by the Chlorine Institute, in 1994, as being instrumental in encouraging the American Public Health 1

Includes: National Breast Cancer Forum (1993); National Institute of Health Conference on Breast Cancer and Environmental Pollutants (1994); Fourth International Conference on the Protection of the North Sea (1995) (discusses relationship between organochlorines and estrogen mimics); first ever Canada/US Women’s Health Forum (1996); International Breast Cancer Conference (1996); first ever World Conference on Breast Cancer (1997); Second World Conference on Breast Cancer (July 1999). In 1998 and 1999 there were also two United Nations conferences on Persistent Organic Pollutants (POPs) which dealt with organochlorines: UN Environmental Program Conference on POPs (1998) and UN Treaty Negotiations on POPs (1999).

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Association to withdraw its resolution which called for a reverse onus for organochlorines. The Chlorine Institute in its 1992 annual report stated that their ‘‘efforts concentrated on conveying the essential, scientifically supportable role of chlorine chemistry in society and the latest credible information pertaining to health and environmental issues’’ (Rodden, 1994, p. 20). Moreover, to protest the EPA’s proposal } to phase out or restrict chlorine } the Chemical Manufacturers Association attacked the EPA position as not being grounded in ‘‘good science’’ (Hileman et al., 1994, p. 16). Similarly, the American Chemical Society (ACS) rejected the EPA Administration’s recommendation for a far-reaching chlorine and chlorinated compound review. The ACS preferred that instead of focusing on chlorinated compounds as a whole class, which in effect treats all chlorine chemicals equally, the EPA should ‘‘continue and accelerate, as appropriate, its study and strategy development for persistent bioaccumulative toxic chemicals } including those chlorine compounds of greatest concern’’ (Ibid.). With such warrants, the pro-chlorine group attracted support, especially for its interpretation of the science. Thus, the Society of Toxicology, in its third position statement in its history, argued that not all chlorinecontaining compounds were equally hazardous. They argued that treating chlorinated compounds as a class was ‘‘irresponsible and unscientific’’ and ignored ‘‘the basic principles of toxicology that [governed] risk assessment’’ (Hileman, 1994, p. 6). The Society’s position was echoed by the American Medical Association (AMA) which urged the EPA to evaluate ‘‘the environmental risks of chlorine on the basis of reliable data specific to each chlorinated compound’’ (Hileman, 1994, p.6). In effect, science was (and still is) being used to urge caution and responsible decisions. Treating chlorine as a whole class, ignoring the lack of scientific evidence to substantiate such a treatment, was presented by these groups as an action based on fiction, not fact. The facts did not warrant any changes in policy or action among these groups which regard unequivocal evidence as the only justification for policy change. The warrant of good science was thus shared by many groups, hence supporting the counter-claims of the chlorine industry. In addition, the Chlorine Chemistry Council initiated a review of approximately 150,000 scientific studies on the effects of chlorine and published an abridged version of their report in a supplementary issue of the 1994 Journal of Regulatory Toxicology and Pharmacology entitled: Interpretive Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health and the Environment. The main conclusion stemming from this 1056 page report (prepared by CanTox Inc., a consulting firm in Mississauga, Ontario) was: ‘‘most chlorinated organic chemicals can now, and

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in the future, be used without adverse effects’’ (Expert Panel, 1994, p. xxix). The second main basis of the counter-claims, issue redefinition, was employed at two different levels. First, as evidenced in our ten-year media analysis, when confronted by anti-chlorine sentiment which generated pressure for change, pro-chlorine groups redefined the issue as one of public health, suggesting that no action is warranted as it would threaten the underlying value of no compromise to healthy populations through negligent action; in this case the reduction in the potability of drinking water, one of the bases of human life itself. Prochlorine groups pointed to the number of deaths from waterborne diseases that have been prevented since the use of chlorine as a drinking water disinfectant. In this manner, they tried to show how the issue affects every single individual. What is not mentioned is that the use of chlorine as a water disinfectant accounts for only 1– 2% (estimates vary) of total chlorine use (Thornton, 1993; Anderson, 1993). Further, supporters demonstrated how vital chlorine is in drug manufacture, arguing that its removal is not warranted as doctors would not prescribe unsafe drugs, thereby violating the Hippocratic Oath. Thus, pro-chlorine groups pointed to the beneficial contributions of chlorine to the pharmaceutical industry. While this represents a greater portion of chlorine use (85% of its products depend on chlorine } Anderson, 1993), it serves as a powerful redefinition or re-warranting of the chlorine debate: personal and family health will suffer without chlorine. Second, the issue was also redefined in terms of individual economic loss and hardship. If governments were to proceed with a shift in policy, resource industry-dependent communities may be faced with serious job losses and plant closures (Anderson, 1993). This generated strong chlorine allies among those workers and communities most affected. Politicians, concerned with a re-election imperative, and with demonstrating fairness to rural, resource-based communities seen as disadvantaged in many ways in urbanized society, would be more reluctant to proceed with such an action.

Discussion and conclusion: how is science used in grounds? A main thread in both the claims and the counterclaims is the role and use of scientific facts interpreted through warrants to support the actions suggested. Yet the science available at the time of the Greenpeace report (Thornton, 1993), as well as the science which was used in the Chlorine Chemistry Council’s Expert Panel review (1994), while inconclusive, is relatively exhaustive of that available at the time. However, surprisingly, while the Expert Panel’s 1056 page supplementary review included an examination of approximately 150,000 scientific studies on chlorine, it did not include

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the various human case-control studies included in the Greenpeace report, with the exception of Unger et al. (1984) (see Table 2). In fact, while many studies are available on the effect of particular chlorinated chemicals on specific organs within laboratory animals, relatively few are available for humans. Tables 3 and 4 outline the case-control and nested case-control studies (i.e. in prospective cohort studies) dealing with human subjects that have been conducted since the release of the Greenpeace report. Contrary to the evidence provided by the Greenpeace report, studies published between 1994 and 1997 (Table 3) show different trends. The Krieger et al. (1994) study is in direct contradiction to the findings of Wolff et al. (1993). (It is worth noting that Wolff was also an author of the Krieger study which contradicts Wolff’s earlier findings.) The Krieger study did not find higher serum levels of DDE among cases compared with controls. In fact, the Krieger study was a much larger prospective cohort study from which to develop its nested casecontrol study than Wolff’s, where serum levels of women from different racial groups were compared. Dewailly et al. (1994) found that women with positive estrogenreceptors had a significant higher body burden of DDE than women with benign breast disease. But other studies did not reach the same conclusion (see Hunter et al., 1997; Moysich et al., 1997). In fact, the van’t Veer et al. (1997) study found a significant inverse trend between levels of adipose DDE and risk of breast cancer after controlling for known risk factors. Lopez-Carillo et al. (1997) analyzed DDT levels in Mexican women, and Schechter, Toniolo, Dai, Thuy, and Wolff (1997) analyzed DDT levels in Vietnamese women. DDT is still in use in both Mexico and Vietnam. The results from both studies were not consistent with an increased risk of breast cancer due to DDT exposure. Moreover, the conclusions reached by review articles (see Laden & Hunter, 1998; Health Canada, 1997; Wolff, Collman, Barrett, and Huff, 1996; Adami et al., 1995; Ahlborg et al., 1995) suggest that results from exposure studies on organochlorines with breast cancer are inconclusive. Laden and Hunter (1998, p. 117) write: ‘‘the most recent evidence in prospective analyses does not support an association [of the environment] with breast cancer risk’’. Studies that have been released on the issue since the publication of review articles are summarized in Table 4. Overall, these studies also do not support an association between environmental exposure to organochlorines and breast cancer while controlling for various confounders (see Table 4) with two exceptions. While Hoyer, Grandjean, Jorgensen, Brock, and Hartvig (1998, p. 1816) could not demonstrate an association between total DDE, total DDT and total PCB concentrations and development of cancer, they were able to show that there was enough evidence to ‘‘support the hypothesis that exposure to xeno-estrogens may

increase the risk of breast cancer.’’ An extension of this earlier study, also conducted by Hoyer, Jorgensen, Grandjean, and Hartvig (2000), did find higher concentrations of DDT associated with a statistically significant three-fold risk of breast cancer, for which a dose-response relationship was apparent. These two nested case studies are part of the same prospective cohort study on heart health which collected serum blood levels along with complete histories on lifestyle factors, reproductive histories, socioeconomic conditions and physical examinations. The researchers were able to track all the study participants completely as facilitated by Denmark’s 10-digit ID number issued to every resident in Denmark by the Civil Registration System. Similarly, Aronson et al. (2000) found a clear association between breast cancer risk and exposure to some PCBs measured in adipose tissue. In fact, Aronson et al. (2000, p. 55) argue that while results of studies examining blood serum levels have been inconsistent, it is important to look at adipose tissue as a biomarker. They write: ‘‘levels [of environmental exposure to organochlorines] in breast adipose tissue are higher and represent cumulative internal exposure at the target site for breast cancer’’. Only two (Aronson et al., 2000; Guttes et al., 1998) of the seven epidemiological studies since 1998 have examined adipose tissue as opposed to blood serum levels. Nonetheless, the overall evidence regarding environmental exposure and increased risk of breast cancer remains equivocal. Yet, despite the inconclusive nature of the science, each side within the debate uses and interprets the data to suit its claims. Studies that show that specific organochlorines could be responsible for increased breast cancer risk are discredited by pro-chlorine groups on the basis of study design. For example, they may argue the sample size is too small to be representative of the population, or that certain key confounders (e.g. dietary fat) were not controlled. While these are valid criticisms of any scientific study, these same criticisms are not raised when the data support the scientific claims made by pro-chlorine groups. Greenpeace works in a similar way. In other words, criticisms are raised against evidence which weakens particular claims and evidence is ignored when the data supports the other claim. If the facts remain debated and thus the grounds equivocal, they can support different values and hence justify different actions. Consequently these differences can be used to manipulate the issue on or off the policy or political agenda (Kingdon, 1995). And the evidence produced since the Greenpeace report (Tables 3 and 4) suggest that there is unlikely to be scientific agreement and closure in the near future. While seemingly self-evident, this finding is important because of the role and authority of science (see Gieryn, 1999). Thus, for Greenpeace, its claims were firmly grounded within a scientific rationality in order to try to

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Table 3 Human case-control studies on organochlorines and breast cancer, 1994 to 1997 (as covered by review articles) Study

Location

Chemical studied

Key findings

Krieger et al. (1994)a

San Francisco

DDE

Women (African American, Caucasian, Asian, N ¼ 50 both cases/ controls respectively) at the highest tertile of serum DDE levels (54.1– 149.5 ppb) had a non-significant four-fold greater risk of BC than those at the lowest tertile (13.8–32.9 ppb).

Dewailly et al. (1994)

Quebec City

Organochlorines

Following determination of estrogen receptor (ER) status of primary BC tumors, the study found that: Most adipose tissue and blood plasma organochlorine (OC) levels were higher in BC cases (N ¼ 20) than in controls (N ¼ 17) with benign breast disease, although a statistically significant difference was observed only for HCB in plasma. In the ER-negative cases, mean OC levels in adipose tissue were generally lower than in controls, with statistically significant differences for mirex and PCB 118 levels. In ER-positive cases, there was a statistically significant increase in levels of DDE in adipose and blood plasma. Results suggest that women with ER-positive BC, but not those with ER-negative BC, had a higher DDE body burden than women with benign breast disease.

Henderson et al (1995)a

Michigan

PBBs (polybrominated biphenyls)

Serum PBB levels in 20 breast cancer cases were elevated compared to 290 matched controls. The odds ratio for women with PBB levels  to 2 ppb compared with women with lower PBB serum levels was 3.3 (95%CI=0.9–11.4); however, there was no evidence of a doseresponse relationship.

Hardell, Lindstrom, Liljegren, Dahl, and Magnuson (1996)

}

OCDD

Contrary to expectations, levels of octachlorinated dibenzo-p-dioxin were slightly elevated in the cases.

Hunter et al. (1997)a

Data from 11 States

DDE, PCBs

Measured plasma levels of DDE and PCBs among 236 cases and matched controls from blood collected in 1989 and 1990. Found no evidence of a positive association of breast cancer with either DDE or PCBs.

van’t Veer et al. (1997)

Europe

DDE

Significant inverse trend between levels of adipose DDE and risk of BC after controlling for known BC risk factors. PCBs not evaluated, but no difference was found between cases and controls (N ¼ 265 cases) for most isomers of the dioxins, PCDDs and PCDFs.

Moysich et al. (1997)

New York

DDE, HCB, Mirex, total PCBs

Research still ongoing, but among 154 incident BC cases and 192 community controls there is no evidence of a positive association between any of these compounds and BC risk with the possible exception of lower chlorinated PCBs (OR=1.66, 95% CI=0.99–2.88). However, among women who have never breast fed, data suggest an increased risk of BC with higher serum levels of total PCBs (OR=2.92, 95% CI=0.95–11.35).

Lopez-Carillo et al. (1997)

Mexico

DDT

Analyzed DDT (which is still in use in Mexico) serum levels in women (N ¼ 141 cases; N ¼ 141 controls). Results not consistent with an increased risk of BC due to DDT exposure. The odds ratio comparing the first tertile with the third was 0.97 (95% CI=0.55–1.70).

Schechter et al. (1997)

Vietnam

DDT

Matched 21 cases and controls respectively. Analyzed DDT (which is still in use in Vietnam) serum levels in women. Found no evidence of significantly higher levels of DDE in cases. Adjusted for age at menarche, parity, history of lactation and body weight.

a

Indicates nested case-control studies in prospective cohort analyses Source: Compiled from the following review articles/documents: Laden and Hunter (1998); Health Canada (1997); Wolff et al. (1996); Adami et al. (1995); and Ahlborg et al. (1995).

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Table 4 Human case-control studies on organochlorines and breast cancer, 1998 to 2000 (as of May) Study

Location

Chemical studied

Key findings

Hoyer et al. (1998)

Denmark

Organochlorines, DDT and PCBs

Measured concentrations of organochlorine compounds in serum blood samples obtained in 1976 from 240 women who developed breast cancer by 1995 against 477 matched controls. Found no association between total DDE, total DDT or total PCB concentrations and development of cancer; though their findings did support a hypothesis that exposure to xeno-estrogens may increase breast cancer risk. Found interaction between parity and serum organochlorine concentrations.

Guttes et al. (1998)

Hesse, Germany

Pesticides and PCBs

Analyzed chloroganic pesticides and PCBs in breast tissue of women with malignant and benign breast disease (N ¼ 45 cases; N ¼ 20 controls). After statistical age adjustments were made, they found, on average, 62% higher concentration of p,p0 -DDE and 25% higher concentration of PCB No.118 in cancer tissues. Data concerning weight, height, occupational/living conditions, diet, number of children, breast-feeding record, menopause, use of oral contraceptives, and congenital history of heart disease not available.

Dorgan et al. (1999)a

Columbia, Missouri

Organochlorine pesticides and PCBs

Analyzed serum blood levels of 105 women donors (cases), and for every case, 2 controls matched on age and date of blood collection were selected. Five DDT, 13 organochlorine pesticides, and 27 PCBs were measured in serum. Found no evidence for a dose-response relationship and found no increased risk for BC overall. Obtained self-reported and medical review data on age, height, weight, menstrual and reproductive histories, smoking, medication (including hormone use), and family history of breast cancer.

Helzlsouer et al. (1999)a

Maryland

DDE, DDT, PCBs

Examined serum blood levels of women who donated blood in 1974, 1989 or both (N ¼ 346 cases and controls respectively) to prospectively examine exposure to DDE and PCBs and the development of BC through 1994. Results after 20 years of follow up and exposure to high concentrations of DDE or PCBs, showed no evidence of contributing to an increased BC risk.

Aronson et al. (2000)

Ontario

Organochlorine and PCBs

Analyzed adipose breast tissue (N ¼ 217 cases; N ¼ 213 benign controls). Results found ORs above 1.0 for almost all organochlorines except 5 pesticide residues, and ORs 52.0 (PCB congeners 105 and 118) and increased linearly across categories (Ps for trend  0.01). Found clear association with BC risk for some PCBs in adipose tissue. Controlled for: age, ever-pregnant, lactation, age last breast fed, present use of hormone replacement therapy, ethnicity, family history, body mass index, fat and alcohol intake, present smoking, cumulative smoking, and menopausal status.

Zheng et al. (2000)

Connecticut

DDE, PCBs

Analyzed blood serum levels of 457 cases and 502 controls in 1995–1997. Found no significant association with serum levels of DDE (OR=.96, 95% CI=0.67– 1.36) and PCBs (OR=.95, 95% CI=0.68–1.32) encountered through environmental exposure and increased risk of BC. Controlled for: menstrual and reproductive history, lactation history, medical history, family cancer history, occupation, diet and demographic factors.

a

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1601

Table 4 (continued) Study

Location

Chemical studied

Key findings

Hoyer et al. (2000)a

Denmark

DDT, PCBs

Looked at blood serum levels of 155 cases and 274 matched controls among women who had given blood in both 1976–78 and 1981–83 examination periods. Found higher concentrations of DDT associated with more than a 3 fold statistically significant risk of BC and a dose-response relationship was apparent. Controlled for: parity, body weight, hormone replacement therapy, and change in body weight between 2 different examinations.

a

Indicates nested case-control in prospective cohort studies.

ensure the greatest credibility. Authorship and authority are important (Bourdieu, 1991). Greenpeace is an organization which is not always viewed as being credible and reliable in its claims. The violent protests of some of its members, actions which run against the Greenpeace principle of non-violence, have sometimes left the general public and critics labeling the activities of Greenpeace as ‘radical’ and ‘extreme’. Consequently, only by grounding their claims within a scientific framework was Greenpeace able to present its messages with apparent responsibility and balance. Similarly, pro-chlorine groups also adopted a scientific basis for their claims in order to prevent any perception that their actions were merely self-serving. Thus, science was used to legitimize a situation even where conclusive proof was not present. In our case study then the differences in the values and warrants of the two claims clearly emerge, yet there are no obvious major shifts in policy or regulation with respect to chlorine use in Canada in general and the Great Lakes area in particular. To effect change on policy issues, the solutions or amendments to regulations must be congruent with the over-arching values of the policymakers, specifically, or the larger society, generally (see Stone, 1997; Yanow, 1996; Sabatier & Jenkins-Smith, 1993; Rein, 1983; Weiss, 1983). Environmental groups like Greenpeace have a particular perspective about how the world should work, and this runs contrary to what chemical industry representatives may prefer. These different values are evident in the nature of the claims that are made by each side, and it seems Greenpeace’s claims had some success in influencing public opinion on policy until it was challenged. In this case, the challenge came not only from the chlorine counter-claims but also from continued uncertainty in science, the realization of scale of changes that would have to be made for a chlorine-free world, and changes, in some jurisdictions, in the political environment. For example, Ontario instituted policy changes on the effluents from pulp and paper mills using chlorinebleaching; an ideological preference of the left-leaning New Democratic Party (NDP) which supports environmental protection, as well as government involvement in business and the economy. With the change in Ontario’s

provincial government from the NDP to the Conservatives in 1995, there was a further policy shift. In 1997, the government } now more business friendly } announced that it would revisit the requirement for reduced chlorine emissions in the pulp and paper industry (Paape, 1997). Thus the scientific evidence is no longer seen as sufficiently conclusive to justify any kind of change in policy which would favor environmental protection: in terms of scientific evidence, the Conservatives seemed to demand irrefutable proof and will not usually act on the basis of prudence for environmental concerns. They accepted different grounds and warrants than the NDP. In our case then, the changes in the political environment and the strength of the counter-claims (and its warrants of sound science, job protection and community survival) resulted in no significant policy shifts or diminution in the uses of chlorine with some exceptions. For example, those provinces that did introduce policies to phase out the use of chlorine bleaching in pulp and paper industries found that many operations substituted chlorine bleach for chlorine dioxide. This eliminated potential dioxin formation in effluents, at the costs of millions of dollars. Identifying the warrants and actions in issue definition and the use of science point to how the agendas and the claims of the competing groups were shaped. The role of environmental groups, like Greenpeace, is to raise the awareness of a particular issue. Once accomplished, environmental groups tend to move their attention to another issue. Their activities on one topic are relatively short-lived. From the 10-year media analysis, there is considerable activity stemming from the International Joint Commission recommendation for a phase-out of chlorine. This activity lasted until the mid-1990s; around 4–5 years. After that, the issue seems to disappear. Chlorine supporters no longer appear as vocal on the issue because groups like Greenpeace, having already placed chlorine on the public agenda, switch their focus from organochlorines to PVCs, nuclear testing, disposal of nuclear waste and so on. Consequently, the issue falls off the public agenda, in spite of the fact that groups, such as the Science Advisory Board of the IJC and other international organizations, still advocate for

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chlorinated compounds to be treated as a class of chemicals, and breast cancer advocacy groups still organize meetings, media releases and campaigns that emphasize the role of the environment. For example, one of the primary objectives of the Workshop On Primary Cancer Prevention (1999, emphasis in original), Everyday Carcinogens: Stopping Cancer Before it Starts, was to examine the impact of environmental pollutants on cancer. In conclusion, we assert that this case-study of claimsmaking has shown how different groups use, in a political way, the authority of scientific evidence to ensure their own credibility in the public domain. While similar grounds (e.g. facts, studies) are often used, the warrants and conclusions differ with different solutions being advocated. These claims then have to be presented in the ‘court’ of policy making and public opinion unless or until there is some resolution } in this case, no major new changes occurred in legislation to control the uses of chlorine, an important environmental health policy outcome. Although the actions of Greenpeace could not prompt further changes to government regulations and legislation, it nonetheless served to help breast cancer advocacy groups politicize the disease, and raise awareness among the public in general, and women in particular. Given the nature of environmental groups, they are likely to move on to other issues once the identified problem has engaged the public. They recognize, perhaps more than most, that public attention is a scarce resource (see Hilgartner & Bosk, 1988). And if a decision-making body through evidence and public interest (pressure) is not motivated to act, or if the political environment becomes less conducive to their claims, they have additional reasons to move on and pursue claims in other arenas. It is sufficient that the link between breast cancer and the environment is asserted and others activated. The claim remains salient if it becomes the claims of others. If this happens, it is also likely that the demand for scientific research will remain to help settle the issue. But as this case study shows, evidence may be used in partial ways and will, only in a few cases, make a claim (i.e. its values) untenable.

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