Environmental Geochemistry and Health, 1991 Vol. 13, page 3

Fluoride in drinking water: a survey of expert opinions

R. Rajagopal 1 and Graham Tobin 2 1 Department of Geography, 316 Jessup Hall, The University of low& Iowa City, Iowa 52242, USA 2 Department of Geography, University of Minnesota, Dulth, USA

Abstract In recent years, public debate over the standard setting process related to fluoride in drinking water and the fluoridation of water supplies has been steeped in much controversy. Discussion of such issues has been con strained by the limited consideration of options relevant to particular problems. To examine the responses to specific issues, we presented an analysis of the problem of excessive fluoride in drinking water to a group of 120 experts. Ninety-seven of the 120 responded to a detailed mail questionnaire distributed as part of a larger exploratory survey. Definite patterns in preferences were noted with certain aspects of the problem, although in some cases significant differences were found due to such factors as the institutional affiliation, residential status, and the length of professional experience of the participants. In general, our experts preferred immediate corrective action over extensive further research into the reduction of,scientific uncertainties; were willing to take personal action to obtain fluoride-free water rather than wait for official action; preferred the supplier to fluoridate the supplies, if needed; and favoured a strong local control of such issues with consumers of public water systems and private well owners shouldering much of the financial responsibility. Preliminary results from such exploratory surveys can lead to insightful research hypotheses for further testing; Verification of such hypotheses by consumers, from areas with excessive fluoride in drinking water, is a valuable area for future research.

Introduction The removal of excess fluoride from drinking water, and the addition of small amounts in the case of its absence, are issues of common concern to the general public as well as the professionals. Some of the questions that are often _raised in the analyses of such issues include: - Where in the state and at what concentrations are fluoride found in groundwater? - What is the nature of its health effects? - How many people are exposed to it at its different concentrations? - What are the available measures to correct such problems? - How much will they cost and who should pay for them? - Who should participate in making such decisions? For some of these issues, there are no ready-made or instantaneous analyses. The issues are complex and the perspectives vary (Marshall, 1990). Rather than going deeper and raising pertinent questions related to the issues, decision-makers often find it convenient to abide by existing legislation and mandated water quality standards and thus maintain the status quo. In many instances, state-level organisations leave it to the federal government to intervene on such issues and expect the problems to be resolved to everyone's satisfaction.

The case study presented in this paper dealt with such issues faced by a group of 40 to 60 communities that have violated prevailing drinking water quality standards of 2.0-2.2 mg L -1 for fluoride in the state of Iowa. The case study and the follow-up survey were intended to capture the reactions of a group of knowledgeable and experienced individuals to selected economic and policy questions r e l a t e d to the p r e s e n c e o f e x c e s s i v e f l u o r i d e in ground-water supplies. The survey was carried out in the context of ground-water quality problems faced by real communities in Iowa, but the questions raised are generic enough to be applicable elsewhere. Consumers, agency staff, and expert witnesses are often called upon to participate in the regulatory s t a n d a r d - s e t t i n g process (Ground Water Monitor, November 12, 1985; and January 7, 1986). There is very little information on how consumers or experts perceive technical assessments of risk from constituents such as fluoride in drinking water. In a recent survey, it was found that technical information on the occurrence of radon in the home environment made elderly people anxious and confused (Environews Inc., 1987). The analysis of participant responses to perceptual, participatory, policy and economic questions within a structured context forms the backbone of this research. As far as we know, no such highly focused analysis on key

4

Fluoride in drinking water

ground-water issues based on expert opinions is available at this time. With careful interpretations, certain general conclusions can be drawn from the results of a survey of such a limited group of participants (Cormer et al., 1984).

The Survey and the Participants The approach To obtain thoughtful responses from a select group of individuals to the case study, a comprehensive mail questionnaire, based on closed- and open-ended questions was prepared. Included were questions related to tradeoffs between economic and health issues and conflicting values over ground-water resources. Many of the questions were of interdisciplinary nature, some were provocative, and others were posed in a world of incomplete and uncertain information. For this research we surveyed a sample of only those who are, or have been, actively involved in ground-water protection issues, either by professional practice, occupation, teaching, research, consulting, or community service. In addition, we wanted our respondents to have experienced life in the Midwest, in particular Iowa. Thus, our survey sample could be classified as groundwater experts who were (presumably) familiar with fluoride problems. Based on our earlier efforts, we identified about 150 individuals who we thought would make excellent survey participants and serve as knowledgeable advisors. We contacted these 150 individuals and explored their willingness to participate in the survey. One hundred and twenty out of the 150 individuals agreed to participate in the survey. The participants were required to read four s i n g l e - s p a c e d pages of narrative and numerical information related to the presence of fluoride in Iowa's ground water and then thoughtfully respond to the questionnaire. In the final tally, we obtained 97 completed forms, resulting in an 81% response rate. Survey participant profile We postulated that respondents' attitudes towards groundwater problems and their perception of protection strategies would vary as a function of certain educational, experiential, institutional, and residency characteristics. Therefore, such characteristics were elicited from personal questions directed at: level of formal education and subjects studied; length of general and groundwater related professional experience; professional position (legislator, researcher, farmer, agronomist, etc.); institutional affiliation (government, private, or education); and residential status in Iowa. These data were then used to verify the postulated hypotheses. As shown in Table 1, many participants have formally studied subjects related to the field of ground water. They are predominantly people in decisionmaking, research, teaching, engineering, and farming practice, with a small number from public interest groups, sales and marketing organisations, and enforcement agencies. Over 75% are from government and academic institutions.

Limitations The survey participants are a select group (purposive sample) of ground water experts and not a random sample from the universe of available experts. A majority have lived in the Midwest, in particular Iowa, and in some way influence the processes governing ground water protection in the state, Obviously, the results obtained from such a survey will have serious limitations in generalisability. On the other hand, findings from such an exploratory survey could provide insights for the generation of new hypotheses for further testing. Most of our survey participants are not from Iowa communities with fluoride problems. Their responses, in general, are inferior to those from communities with fluoride problems. This is so because the responses of participants from affected communities do not have the possibility for unstated assumptions. Hence, tt is essential that results on preferences reported in this paper be validated with comparable data from participants of affected communities. Glossary of selected terms PWS Systems: Systems that provide piped water for human consumption and have at least 15 service connections or regularly serve an average of at least 25 individuals daily at least 60 days of the year are called Public Water Supply (PWS) Systems. All other systems are referred to as non-PWS Systems. PWS systems used by year-round residents are called community PWS systems and all other PWS systems are called non--community PWS systems. MCL: The Maximum Contaminant Level is the maximum permissible level of a contaminant in water which is delivered to any user of a public water supply. There are two types of MCLs, primary and secondary. Primary MCLs are based on potential adverse health effects on humans and are usually enforced. Secondary MCLs are based on levels required to protect public welfare (odour, appearance, etc.) and are usually not enforced. Until 1987, the primary MCL for fluoride varied (between 1A and 2.4 mg L -1) as a function of the average air temperature of the location of the PWS system. As of October 2, 1987, the primary MCL has been changed to a single value of 4.0 nag L--12-and a secondary MCL of 2 mg L - ' h a s also been introduced (US EPA, 1986). Case Study: Fluoride in Drinking Water Many research studies have reported that fluoride in drinking water at about 1 mg L -1 reduces dental cavities in children. However, some children exposed to levels of fluoride greater than about 2.0 mg L-t may develop dental fluorosis. Dental fluorosis, in its moderate and severe forms, is a brown staining and/or pitting of the permanent teeth. Research studies have also shown that the ambient air temperature influences the concentration ievel at which the health effects of fluoride become significant. For this reason, the national interim ~rimary drinking water standard varies (1.4 to 2.4 mg L- ) according to the annual average maximum daily air temperature for the location m which the community water system is situated. This standard, after much debate and discussion, has been

8.

7.

6.

5.

4.

1,

Survey Partidpant

lkoffle

High School

24

Bachelor's

28

Master's

27

Ph.D. 12

Other (such as D.Ed., J.D,, etc.)

Hydrology/Water Resources Geology Env. S c i e n c e s (Botany/Zoology, Ecology, Others) Planning/Policy

19 15 14 13 13

E n g i n e e r i n g ( E n v . / C h e m . , Others) Business Management Chemistry Agronomy Economics

11 10 9 3 2

Public/Env. Health Geography Law Statistics/Biometry Toxicology/Epidemiology

Admlnistration/Management Research Teaching Engineering ii

12 I1

Policy A n a l y s i s E l e c t e d Official (Representatives o r S e n a t o r s ) Farming

Govemment(Total)

51

19

6 2 1 I 9

0 - 2 years

2

2 - 5 years

15

26

25 5

0 - 2 years

26

2 - 5 years

Yes

36

No

22

94

Yes

5

No

I0

Enforcement Public I n t e r e s t G r o u p Reps. Sales/Marketing

4 2 0 13

Legal P r a c t i c e Well Drilling Medical P r a c t i c e Others

Soft S c i e n c e Computer Science Physics Others

10 - 15 y~ars

10 - 15 y e a r s

29

56

Public I n t e r e s t G r o u p s

16 or m o r e y e a r s

16 or m o r e y e a r s

Universities/Colleges/ExtensionServices

4

5 5

2 2 2 13

midwesterrl states: iowa, Illinois, I n d i a n a , Michigan, Ohio, W i s c o n s i n ,

5 - 10 years

Pa~ you or have b e e n a r e s i d e n t o f one o r m o r e of t h e following Minnesota, N e b r a s k a , Missouri, a n d K a n s a s . (Check one.)

63

Are you o r have y o u b e e n a r e s i d e n t of Iowa?

12

How m a n y y e a r s of y o u r p r o l e s s l o n a l e x p e r i e n c e h a v e b e e n related to g r o u n d w a t e r ?

0

5 - I0 years

P r i v a t e Sector{Total)

Farming Well Drilling I n d u s t r y Dealers/Distributors Chemical Industry Other

How m a n y y e a r s of p r o f e s s i o n a l e x p e r i e n c e do you h a v e ?

State Federal Local Other

28 16 5 2

W h a t is y o u r c u r r e n t i n s t i t u t i o n a l affiliation? (Check one.)

28 23 21 14

W h a t is t h e field o f y o u r c u r r e n t professional practice or o c c u p a t i o n ? (Check u p to a m a x i m u m of two.)

20

29 25 23

What are the formal subjects that you have studied? (Check up to a maximum of three subjects in which you believe you have a strong background.)

9

W h a t is the h i g h e s t level of e d u c a t i o n you have a t t a i n e d ?

A t o t a l of n i n e t y - s e v e n i n d i v i d u a l s p a r t i c i p a t e d i n t h e s u r v e y . All r e s p o n s e f r e q u e n c i e s a r e e x p r e s s e d i n p e r c e n t a g e s .

T a b l e Io

~t

o~

6

Fluoride in drinking water

changed to a single level of 4.0 mg L -1. This revised primary MCL took effect as of October 2, 1987 (EPA, 1986). It is an enforceable standard that has been established to protect public health. Exposure to drinking water levels above 4.0 mg L -I for many years may result in some cases of crippling skeletal fluorosis, which is a serious bone disorder. A secondary MCL of 2.0 mg L -1 has also been put into place as of May 2, 1986 (EPA, 1986). Federal law also requires that public water supplies notify their consumers when monitoring indicates that fluoride in their drinking water exceeds 2.0 mg L "1. This is intended to alert families about dental problems that might affect children under nine years of age. Occurrence in Water Resources Natural water in most places has less than 1 mg L -i of fluoride. Higher concentrations of fluoride in ground water can be found in a variety of geological settings. In general, the fluoride content in ground water increases with depth, Higher values may be due to contributions from minerals containing fluoride such as volcanic ash or coal with high pyrite content (Sonneborn, 1983). An extensive survey of more than 2,600 c o m m u n i t i e s in the US showed concentrations of 0.7 mg L -1 or more of naturally occurring f l u o r i d e in water supplies. About 20% of these communities had concentrations of 2.0 mg L-1 or more of fluoride. Many of these communities are in Arizona, Colorado, Illinois, Iowa, New Mexico, Ohio, Oklahoma, South Dakota, and Texas. Due to differences in annual average air temperature, the primary fluoride MCL for southern Iowa was set at 2.0 mg L -1 and 2.2 mg L -1 for northern Iowa. As mentioned before, the new primary MCL is 4.0 mg L -1 for the whole state starting in October, 1987. The former fluoride standards of 2.0 and 2.2 mg L-1 were exceeded at a higher rate (%) in southern Iowa than

in northern iowa. Some communities add a small amount of fluoride (less than 1 mg L -1) to their water supplies for the suppression of dental cavities in children. About 50% of PWS systems in Iowa have fluoride in concentrations below 0.43 mg L -1, 75% below 0.95 mg L-1, 90% below 1.70 rn~ L-1, 95% below 2.40 mg L-1, and 99% below 4.0 mg L (Rajagopal, 1987). In general, large fluoride concentrations are found in ground-water supplies drawing water from the Cambro-Ordovician and Pennsylvanian rock aquifers (Rajagopal, 1984). A total of 69 PWS systems serving over 41,000 people have violated the earlier MCL at some time during the period March 1978 and December 1986. Of the 69 violators, 91% were community PWS systems and 9% were non-community PWS systems. A maximum of 53 systems were in violation during January 1985, and the latest monthly violation report for December 1986 listed 45 violations. Fifty-two percent of the dominant wells (wells pumping at the highest rate) of systems violating the f l u o r i d e MCL w e r e d r a w i n g w a t e r from the Cambro-Ordovician aquifer and 41% of the violating systems were in south central Iowa (Waters el al.. 1987). All the dominant wells from PWS systems violating the earlier fluoride MCL were deeper than 156 feet. None of the dominant wells of violating systems were drawing water from the shallower Quaternary or Cretaceous formations (Waters et at, 1987). Health Effects Two primary health effects of high intake of fluoride over long periods are dental and skeletal fluorosis. Dental fluorosis may occur in the range of fluoride concentrations from 0.7 to 1.3 mg L -l. Skeletal fluorosis, hardening or abnormal bone density, has developed in persons drinking water with more than 3 mg L -t of fluoride. Increased bone

Table 2 A two-way stratO%ation (population size by concentration class) of 69 ground-water-based PWS systems that have violated the fluoride MCL of 2.0 to 2.2 mg L-1 sometime during the period March 1978 and December 1986 in Iowa.

Fluoride in mg L-1 Population served by the PWS < 200

2.0-3.0

3.1-4.0

4.t-5.0

9 (1,003)

9 (708)

1 (155) -

>5.0

Total

3 (198)

22 (2,064)

2 (564)

34 (18,584)

201-999

!9 (10,413)

13 (7,607)

_> 1,000

8 (10,767)

3 (5,502)

1 (1,924)

1 (2,846)

13 (21,039)

Total

36 (22,183)

25 (13,817)

2 (2,079)

6 (3,608)

69 (41,687)

Numbers in parentheses represent total populations served by the PWS systems in the corresponding concentration classes.

R. Rajagopal and G. Tobin

density may be beneficial to a certain extent. However, crippling skeletal fluorosis may result from chronic intake of fluoride in excess of 20-40 mg/day (NRC, 1977). Also, the health effects due to excessive intake of fluoride are not uniform among all individuals or groups. Some are affected more than others depending on the amounts of fluids and the types of foods consumed, and the composition of the daily diet (Underwood, 1977). In Chile, a 104% rise in mortality in undernourished children has been attributed to poisoning from or sensitivity to fluorine (Sonneborn, 1983). In certain parts of Southern India, dental mottling is accompanied by serious skeletal defo~wnities such as stiffness of the spine and other bone disorders (Underwood, 1977). Such manifestations are seen only among the poor whose staple diet is sorghum with very little daily intake of calcium. To test the hypothesis that fluoride intake of greater than I m g L -1 in drinking water may protect women from osteoporosis, Sowers et al. (1986), undertook a study of over 800 women in three rural communities of Iowa. The three communities were classified as: high fluoride: 4 mg L -1 fluoride and 16 mg L -1 calcium in drinking water; high calcium: 1 mg L -1 fluoride and 375 mg L-I calcium in drinking water; and low calcium: 1 mg L -1 fluoride and 65 mg L -1 calcium in drinking water. Their observations and conclusions are stated below: "... We observed no protective effect of fluoride for women in the high fluoride community. Bone mass was lower in the high fluoride community among women aged 55-80 years, though the difference was not statistically significant. There were significantly more fractures, by history, in women of the high fluoride community as compared to the two other communities. There was no observed difference in bone mass or fracture history of women aged 20-35 years, irrespective of community. Women in the high fluoride community, aged 20-35 years, who consumed calcium and vitamin D in excess of daily Recommended Dietary Allowances had significantly better bone mass than peers who reportedly failed to consume sufficient calcium and vitamin D." "... In summary, greater fluoride intake generated by access to communal water with a naturally-occurring level of 4 mg L -1 was not associated with greater bone mass or fewer fractures. Additionally, substantial fluoride intake may magnify the need for adequate dietary calcium and vitamin D intake, particularly in premenopausal women." Available evidence does not suggest increased or decreased cancer mortality rotes from fluoride (NRC, I977). A recent study by Lynch (1984) in Iowa evaluated 9 e fluoride-cancer association for cancer at different sites. The results of this study failed to support a clear fluoride-cancer association. High fluoride levels can also be toxic to aquatic life. Substantial data are available on the freshwater toxicity of fluoride for a variety of aquatic life. Based on such information, the North Carolina Department of Natural Resources and Community Development (1986)

7

recently recommended that no change in the states' freshwater quality standard of 1.8 mg L -1 for fluoride b e made until more chronic and selected acute data become available.

Population Exposure About 32% of PWS systems exceeding the fluoride MCL (2.0 or 2.2 mg L -1) serve populations of 200 people or less, 49% serve populations in the range of 201 to 999, and the rest of 19% serve populations greater than or equal to 1,000 people (Table 2). Only eight systems serving about 5,700 people exceed the proposed future standard of 4.0 mg L -1. All but one of these systems are located in south-central Iowa and draw water from wells deeper than 200 feet. Very little information is available regarding fluoride exposure through private (individual) wells. Since higher concentrations of fluoride occur in the deeper rock aquifers and many individual families cannot afford to drill deep wells, we seldom find private well owners requesting fluoride analyses of their drinking water supplies. As mentioned earlier, the US EPA has recently revised the primary fluoride MCL to consist of a single primary (4.0 mg L -1) as well as a single secondary MCL (2.0 mg L-l). The primary MCLs are based on levels considered potentially harmful to the health of people and secondary MCLs are based on aesthetics relating to the public acceptance of drinking water. The secondary MCLs are not federally enforceable but are intended as guidelines for the states.

Cost of Fluoride Removal from Water Supplies Fluoride removal from water supplies can be accomplished using granular activated alumina as a reversible absorption medium. The quality of raw water (pH, alkalinity, and fluoride concentration) will have a major impact on the cost of fluoride removal (Gumerman et al., 1983). Estimated cost of installing and operating a fluoride removal plant of 100,000 gals/day can range anywhere from $0.50/1000 gals to $0.80/1000 gals depending on the fluoride concentration of raw water (which in turn affects the regeneration frequency and the total volume of activated alumina, and thus the operation and maintenance cost of running the plant). As the size of the plant increases, economies of scale will reduce the cost of treatment per 1,000 gallons. For example, the above costs for a 500,000 gals/day plant are estimated to fall in the range of $0.15/1000 gals to $0.25/1000 gals (extrapolated from Gumerman et al., 1983). D e p e n d i n g on c o m m u n i t y size and the concentration of fluoride in the raw water, the consumer should expect to pay anywhere from $0.15/1000 gals to $0.80/1000 gals in 1986 dollars. In short, a family of three consuming 10,000 gals/month of water would incur a bill of $1.50 to $8.00/month for fluoride removal in 1986 dollars.

Concluding Remarks Many communities in the US fluoridate or raise the fluoride content of their water supplies to about 1.0 mg L -1 with the

8

Fluoride in drinking water

objective of reducing dental cavities in children. The process of fluoridation and its benefits have been the subjects of many controversies, discussions, debates, and public referenda. In a recent commentary published in Nature (a British scientific journal), Diesendorf (1986) states: "... Large temporal reductions in tooth decay, which cannot be attributed to fluoridation, have been o b s e r v e d in both u n f l u o r i d a t e d and fluoridated areas of at least eight developed countries over the past thirty years. It is now time for a scientific re-examination of the alleged enormous benefits of fluoridation." As discussed earlier, dental and skeletal fluorosis may result due to high intake, greater than 2 mg L -1, of fluoride over long periods. Also, such health effects are not uniform among all individuals or groups. The presence of very little fluoride, less than 0.5 mg L -1, in drinking water prompts some communities to fluoridate their water supplies. In the presence of 2.0 to 4.0 mg L -1 of fluoride in drinking water, the federal government requires the supplier to notify the consumers, especially to alert families about dental problems that might affect children under nine years of age. Finally, federal r e g u l a t i o n s require that fluoride concentration not exceed 4.0 mg L-1 in drinking water, which is an enforceable standard. About 75% of public water supplies in Iowa have fluoride concentrations below 1.0 mg L -1, between five and ten percent have concentrations in the range of 2.0 to 4.0 mg L -1, and less than one percent of the supplies exceed 4.0 mg L-I. What action plans are appropriate and cost-effective for these different communities? Who should initiate and implement such plans? How do we make decisions related to risk under such cases of scientific uncertainty? What role should the general public have in the deliberation and resolution of such issues? How can communities with similar problems learn from each others' experiences? We hope such case studies and your reactions to them will provide some valuable insights in dealing with such issues. ................. End of Case Study ...............

Analysis and Discussion of Survey Results A summary of participant responses to the survey questions are presented in Table 3. The responses to the questions were, as expected, quite mixed. The responses were further analyzed based on the differences in four selected participant profiles: educational qualification, institutional affiliation, professional ground water experience, and residency status. To simultaneously test for the significance of these profile variables on observed responses, standard multivariate modelling methods (analysis of variance using the General Linear and Categorical Models) for the study of cross--classified data were employed. Only responses and interactions found to be significant at the 0.05 probability level are discussed in this paper. Definition of the four profile variables used to categorise survey participants are as follows:

Educational qualification: Participants were classified into one of two groups based on the highest level of education attained: Bachelor's degree or less and Master's degree or higher. Institutional affiliation: Participants were classified into one of three groups based on their institutional affiliation: governmental institutions, U n i v e r s i t i e s / Colleges/ Extension Services, and all other institutions (private sector, non-profit interest groups and others). Professional ground water experience: Participants were classified into one of two groups based on the length of their groundwater related professional experience: ten or less years of ground water experience and more than 10 years of ground water experience. Residency status: Participants were classified into one of two groups based on their residential status: those who are or have been a resident of the state of Iowa and those who are not or have not been a resident of the state of Iowa. The length of a participant's ground water related experience and the residency status were the two most often identified variables that explained much of the observed difference in responses to some of the questions. In a few occasions, educational qualification and institutional affiliation explained the significant difference in responses to questions. Only once, the interaction effect between variables was found to be significant and even in that case reliable inference could not be made due to small sample sizes in intersecting cells.

The Findings The survey questions were framed so as to elicit responses along the following major themes of inquiry: 1 Seriousness of the problem? 2 Preference among corrective actions under incomplete information? 3 Who should pay for the cost of actions, including corrective actions? 4 The role of groups and institutions in decision-making and planning processes?

Seriousness of the problem A majority of respondents felt that fluoride in Iowa's drinking water was a localised supply-specific problem and that some corrective action was desirable but did not warrant immediate action (questions 1 and 2 in Table 3). The mean score for question 1, which dealt with the seriousness of the problem, was 2.2 on a scale of 1 to 5, while the importance of corrective action posed under question 2 was rated higher at 2:7. Six participants commented that debates still go on regarding the benefits of fluoridation and that research on topics such as food as a source of this contaminant should be further explored. One participant stated that the drinking water standard for fluoride should be lowered to a level below 2 mg L "1. Four respondents stated that fluoride was not a problem of serious concern in Iowa, that risks from fluoridation are manageable, that benefits of fluoridation far outweigh hazards, and that this case study has overemphasised the health risks Of fluoride compared to that of nitrates in Iowa ground water.

R. Rajagopal and G. Tobin Correclive actions under incomplete information When asked to rank selected corrective actions (question 3) for dealing with fluoride problems, the respondents r a n k e d (mean r a n k 3.9) the option of b l e n d i n g contaminated supplies with other sources as the most preferred. This was followed by the options of installing fluoride-removal measures (mean rank 3.2), providing fluoride-free water to sensitive populations such as children younger than nine years of age (mean rank 3.1), abandoning contaminated supplies and utilising alternative sources (mean rank 2.7), and finally postponing corrective action until clear confirmation of health effects become available through further scientific research (mean rank 2.0). Formal statistical tests (paired comparisons) of responses indicated that the survey participants preferred some form of action under uncertainty (items 3a to 3d) over postponement of all actions due to a lack of scientific certainty (item 3e). If their PWS system consistently violated the fluoride standard, a sizeable majority of 68% declared that they would make independent plans to seek fluoride-free water and not wait for action by the community water supply authorities (question 7). This reinforces the earlier observation noted for question 3 regarding action under uncertainty. Whenever there are potential health effects concerns, participants preferred some form of immediate action and in this case were willing to make their own independent plans rather than wait for action by the local government, It was interesting to note the responses to question 9 which dealt with the absence of fluoride in drinking water. If their water supply was free of fluoride, 68% stated that the supplier should fluoridate the supply, while 32% took the opposite stand of suggesting that families with children should take their own preventive actions such as providing fluoride tablets to their children. Expression of preferences by our participants may not n e c e s s a r i l y r e f l e c t what goes on in real world circumstances. An important and interesting area for further research would be to examine the proportion of population adopting different corrective measures in communities with serious fluoride problems, especially after the extensive media attention given to the recent National Toxicology Program's study on fluoride and cancer in rats (Begley, 1990 and Marshall, 1990). A respondent suggested that communities should be informed of existing levels of fluoride in their drinking water before adding any more to their supplies, another commented that we should not be spending any monies for either adding or removing fluoride from drinking water and yet another commented that sensitive populations should seek corrective actions by themselves. Finally, two participants claimed that any stand on corrective actions would have to be based on the knowledge of the level of fluoride in drinking water supplies. Who should pay for the cost of corrective action? Question 4, pertaining to who should pay for what share of the cost of corrective action, elicited a range of responses. Since the fluoride problem in Iowa is of natural origin, the suggested average share of the cost to be borne by the PWS consumers was 47%, which is more than twice the share

9

recommended for the local (20%), state (16%), or federal government (12%). In the case of private wells with fluoride problems, a significant majority took a stand that well owner's action in seeking fluoride-free water should not be subsidised by the local (75%) or the federal government (70%), whereas, only 57% took such a stand for the private owner receiving state subsidies (question 8). Since high fluoride concentrations in pocket locations of towa ground water are from natural sources, 85% ruled out the idea of chemical industry subsidising the cost of any corrective action. Significant differences in responses in a few cases were observed based on the length of professional experience and the residency status of participants. For example, participants with longer ground-water related experience compared to those with lesser experience consistently down-played the need for subsidies from the Iocal government and recommended a higher share of the cost to be borne by PWS consumers (questions 4c and 4d), whereas, non-resident Iowans compared to Iowa residents down-played the need for federal subsidies (question 4a). Three respondents rightly pointed out that since fluoride in Iowa drinking water is from natural geologic sources, questions related to subsidies from the private sector for corrective actions were inapplicable. Again, one respondent went further and stated that if a local industry was tbund to be the source of contamination, then such an industry should be made to pay a major share of the cost of corrective action. A couple of respondents also pointed that their answers to questions related to subsidies for corrective measures were dependent on the severity of the problem (level of contamination) and the ability of the community or the individual to bear the cost of such measures. One respondent stated that public funds should be spent on urgent problems first and then on fluoride problems if funds permit. Finally, a respondent wrote to say that the cost of corrective measures borne by the local government is eventually passed on to the consumers, so it is the consumers who ultimately pay for such corrective actions. Regarding the question of willingness to pay for fluoride-free water (question 5), 17% stated that they would not be willing to pay anything, 76% would be willing to pay $1 to $10/month, and 7% would be willing to pay $10 to $20/month. Again, such willingness to pay statements are only indications of the extent to which people will go to obtain fluoride-free water and do not necessarily reflect what they will actually pay in real world circumstances. An important area for further research is to verify such statements of willingness with actual expenditures of residents in areas with known fluoride problems. The role of groups and institutions in the decision-making process Answers to question 6 revealed that the survey respondents had identified the local and state governments and experts and consultants who are thoroughly familiar with the problem to play a major role in dealing with it (mean scores of 4.3, 3.7, and 3.4 respectively for questions 6a, 6c, and 6b). A moderate to a minor role was assigned for the

5o

4.

16.3 19.7 47.0 4.8 0.1 100,0

93 93 93 93 93 Total Percent:

b. State g o v e r n m e n t

c. Local g o v e r n m e n t

d. PWS C o n s u m e r s

e. Local polluting I n d u s t r i e s

t: Others

a. b. c. d. e.

None $ 1 to $ 10 to $ 20 to $ 30 to

$ $ $ $

10/month 20/month 30/month 50/month

If your water s u p p l y exceeded the fluoride s t a n d a r d , how m u c h more(in addition to y o u r c u n m n t w a t e r bill) would y o u be willing to p a y to obtain fluoride-free water ? (Circle o n e . )

Federal g o v e r n m e n t

12.0

a

93

If corrective actions are taken, who should p a y for it? (Enter a percent figure for each source, with the total equalling 100 percent.)

2.0

3.1

95

d. Provide fluoride-free w a t e r to sensitive populations, (such as families with children u n d e r nine years of age) 95

3.2

95

c, Install fluoride-removal m e a s u r e s at the s o u r c e of s u p p l y

e. Postpone corrective action until clear confirmation of h e a l t h effects become available t h r o u g h further scientific r e s e a r c h

2.7

95

b. A b a n d o n c o n t a m i n a t e d source(s) and utilize alternative source(s)

2.7

3.9

If corrective a c t i o n s are contemplated, w h a t are y o u r preferences? (Rank all the five alternatives: least preferred=l ...... m o s t preferred=5.)

3.

96

2.2

95

How important is it to take action to alleviate the fluoride problem in supplies exceeding the s t a n d a r d ? (Score on a scale of 1 to 5, action not necessary to immediate action warranted.)

2.

96

Mean

a. Blend water from c o n t a m i n a t e d well(s) with w a t e r from o t h e r s o u r c e s

How serious is the fluoride problem (for s y s t e m s exceeding the m a x i m u m c o n t a m i n a n t level of 2.0 to 2.2 mg/l) in drinking water supplies of Iowa? (Score on a scale of 1 to 5, not a problem to a very serious problem.)

I.

N

1 1

1.1 1.2

0 0 0 0 0

16.0 23.0 36.3 15.9 1.0

i0

100

100

100

50

100

5

5

5

5

5

5.0

4.0

17 76 7 0 0

F Percent r e q u ~ s p o n s e

0

19.6

l

1

1.4

1.4

1

1.0

1.0

Max.

A total of

Min.

1.3

0.8

0.7

S.D.

Response frequencies in this table, whereever applicable, are expressed in p e r c e n t a g e s i n s t e a d of n u m e r i c a l counts. ninety-seven individuals participated in the survey. N refers to the n u m b e r r e s p o n d i n g to the specific question. ee

0~

2.

r

95 96 96

d. Federal agencies (such as EPA)

e. Civic organizations

f. General public

Make m y own i n d e p e n d e n t p l a n s to seek fluoride-free water

32

68

30 15

c. the federal g o v e r n m e n t ?

d. the chemical i n d u s t r y

32

b. the supplier s h o u l d n o t fluoridate the supply, families with children s h o u l d take their own preventive actions, s u c h a s providing fluoride tablets to their children, ff n e c e s s a r y

5

5

5

5

5

5

Percent with n o c o m m e n t s = 68

68

the supplier s h o u l d fluoridate the supply, so that families with children m a y benefit from prevented dental cavities

Percent c o m m e n t i n g = 32

85

70

57

75

N__fi

P e r c e n t Freqy~n~v R e s p o n s e s

43

Ye.._.~s

b. the state g o v e r n m e n t ?

a

1

I

1

I

1

2

P_.e~cent Freq.u__ency ResP0nses

25

If y o u r w a t e r s u p p l y was free of fluoride, (Choose one.)

1.2

1.0

1.3

0.9

1.0

0.9

Percent F r e q u e n c y R e s p o n s e s

3.0

2.6

2.9

3.7

3.4

4.3

the local g o v e r n m e n t ?

a

S h o u l d individual private well owners' actions in seeking fluoride-free d r i n k i n g water be subsidized by

b. Wait for action b y the c o m m u n i t y PWS system

a

If you were served by a PWS s y s t e m that consistently violated the fluoride MCL, w h i c h one the following would closely resemble y o u r action ? (Circle one.)

96

c. State agencies (such as DNR)

96 96

The local c o m m u n i t y (government)

b. Experts and c o n s u l t a n t s

a

In dealing with fluoride problems, w h a t level of i n p u t into the d e c i s i o n - m a k i n g p r o c e s s should the following parties have ? (Score on a scale of 1 to 5 : least involvement = 1 ....... m o s t involvement = 5.) N Mean S.D. Min. Max.

10. Do y o u have a n y c o m m e n t s on this case ?

9.

8.

7.

6.

~o

12

F l u o r i d e in d r i n k i n g w a t e r

participation of the general public, federal agencies, and civic organisations (mean scores of 3.0, 2.9, and 2.6 respectively for questions 6f, 6d, and 6e). In g e n e r a l , m o r e e x p e r i e n c e d p a r t i c i p a n t s significantly down-played the State's role in resolving fluoride issues in comparison to their less experienced colleagues (questions 6c). On the other hand, participants with higher educational qualifications or those affiliated with educational or governmental institutions rated the State's role significantly higher than their lesser qualified or private sector colleagues (question 6c). Similarly, non-resident Iowans down-played the role of federal government in resolving such local issues compared to their resident counterparts (question 6d).

A few participants emphasised the need for further education and public awareness programs so as to apprise the consumers of the relative risks and benefits of exposure to fluoride from drinking water and food. Finally, several participants noted that if detailed facts and figures were to have been available on factors such as health effects, exposures from multiple sources, and level of income in the community, their responses would have been much more precise. Unfortunately, we live m an imperfect world with limited resources and will never be able to fully meet the demand for such complete information. Therefore, this case study should be viewed as a search for significant patterns in perceptions based on the responses of a select group of participants to incomplete and uncertain information.

Conclusions and Recommendations

Acknowledgement

This case study was intended to capture the reactions of a select group of participants to problems faced by a class of communities experiencing groundwater contamination by fluoride. In the case of supplies with high fluoride problems, the participants showed a clear preference for immediate corrective action in a world of incomplete information over extensive further research into the reduction of scientific uncertainties. The general consensus of the participants was that fluoride in Iowa's drinking water was a supply-specific problem in pocket locations that needed some attention but did not warrant immediate state-wide action. Since, children under nine years of age were identified as a sensitive population at risk in this case study (similar to infants and pregnant women in the case of nitrates), p r o v i d i n g f l u o r i d e - f r e e water to such a population was one of the modestly preferred alternatives. If personally faced with a problem of excessive fluoride in drinking water, a significant majority said that they would make their own independent plans to seek fluoride-free water rather than wait for local authorities to make such provisions. In addition, over 80% were willing to pay some amount in the range of $1 to $20/month for securing fluoride-free water. On the other hand, in the absence of fluoride in drinking water, a majority preferred the supplier to fluoridate the supply so that families with children may benefit from prevented dental cavities. These findings very much reflect the view that whenever there are health effect concerns, an informed population (such as the one surveyed for this study) would prefer some form of immediate action. In dealing with fluoride problems, at the local level, the survey participants favoured an approach of active local involvement in decision making. They also suggested that PWS consumers and individual private well owners should share a bulk of the financial responsibility for corrective actions. In the case of governmental subsidies for corrective actions, it was suggested that community PWS systems receive a larger share of their cost compared to individual private well owners. While such were the consensus, significant differences did emerge between the various profile groups for responses to questions related to decision making and cost sharing (questions 4a, 4c, 4d, 6c, and 6d).

The preparation of this paper was made possible by a grant from the Joyce Foundation of Chicago, Illinois, to the Department of Geography at the University of Iowa. The views expressed in this paper are those of the authors and do not necessarily reflect the views or policies of the sponsoring organisations. We thank Ping-Chi Li, Ramana Kuchibhatla and Usha Natarajan of the Department of Geography at the University of Iowa tbr providing valuable assistance in the conduct of the survey and subsequent data compilation and statistical analysis,

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