32(1) 1999
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International Society for Fluoride Research | Table of Contents 32(1) 1999 |
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Guest Editorial
THE XXIIND CONFERENCE OF THE ISFR
AN APPRECIATION
Richard G Foulkes B.A., M.D.*
Abbotsford, BC, Canada
Reading maketh a full man, conference a ready man, and writing an exact man.
Francis Bacon1
The XXIInd Conference of the International Society for Fluoride Research (ISFR) was held in Bellingham, Washington, USA, August 24 - 27, 1998. There were 34 platform presentations and 29 posters on display. Abstracts were published as a supplement in Fluoride 31 (3), August 1998.
PARTICIPANTS WORLD-WIDE
The participants/delegates, as listed in the Program and Abstracts Book, were from: Japan (29); USA (19); China (13); Poland (8); India (7); United Kingdom (6); Moldova (3); Germany (3); Canada (2); New Zealand (2), and Hungary (1). They came from many universities, government institutes, hospitals and non-governmental organizations. The wide geographic area origins of the participants is further illustrated by naming some of the universities and major teaching hospitals represented: Binghamton University, Children's Hospital (Boston), Cornell University, and Dartmouth College in the US; Iwate Medical University, Osaka Medical College, and Shiga University of Medical Science in Japan; China Medical University (Shenyang) and Tianjin Medical University in China; Medical University of Gdansk and Pomeranian School of Medicine in Poland; Gujaret University, Post Graduate Institute of Medical Education and Research in India; Dunedin School of Medicine in New Zealand; and the University of Surrey in the United Kingdom.
There were a number of things that made this conference fulfill its objective of "making the ready man", to quote Francis Bacon. First, there was the opportunity to meet international colleagues. Some of these were acquaintances from previous conferences. Others were those whose work and writings were familiar and with whom one could interact, face-to-face. Second, a number of persons attended to hear about the concerns of "basic science" so that they could contribute to their special interests. They included environmentalists, legal professionals representing major industrial unions as well as union representatives of workers at risk in the smelting industry and phosphate fertilizer manufacturing, and, members of organizations interested in health matters in general.
COMPREHENSIVE SUBJECT MATTER
The subject matter of the platform and poster presentations was comprehensive. Although there were presentations of studies carried out by individuals, most represented the work of multiple researchers from different organizations in the same country, or the joint efforts of several. For example, there were presentations of the joint efforts of China and Japan, and the USA and Moldova.
The presentations may be grouped in a number of ways to serve this brief discussion: environmental aspects, health effects; biological effects; special consideration of bone response; and, fluoridation of public water supplies. The country (countries in joint efforts) of origin of the research is presented in parentheses. Inevitably, there will be some overlap, omissions, and misclassifications, for which the author apologizes in advance.
ENVIRONMENTAL ASPECTS
Studies were presented on fluoride concentrations in food and air from coal burning (China); and, airborne fluoride in Vog (volcanic fog) (USA). Fluoride in soil and the susceptibility of plants (wheat and corn) (USA & Moldova) were reported on, as well as fluoride in water and soil and the effects on animals (European deer) (Moldova; Poland).
HEALTH EFFECTS
The extensive problems of dental and skeletal fluorosis in China secondary to exposure to high concentrations of fluoride in the atmosphere (coal burning) and drinking water supplies were considered in a number of platform and poster presentations (China & Japan). Efforts to develop improved diagnoses include analyses of fluoride in hair and urine and the use of bone mineral density (BMD) (China; Poland). The prevention of iodine deficiency in endemic fluorosis areas with iodized salt was discussed (China) along with nutritional factors contributing to dental fluorosis (low calorie, low calcium) and the incidence of cardiovascular abnormalities in skeletal fluorosis (India).
The search for easier and more specific methods for the diagnosis of occupational exposure to fluoride was the subject of several presentations. In a study of aluminum plant workers, effects on the respiratory system were examined, and a significant correlation was reported between ventilatory function tests and exposure period. Radial BMD was tested and found to be of no significance in the diagnosis of skeletal fluorosis (Japan & China). A study of residents in fluorite mine areas led to the conclusion that levels of alkaline phosphatase (ALP), lactic dehydrogenase (LDH) and hydroxybutyrate dehydrogenase (HBDA) were valid indicators for the early diagnosis of endemic fluorosis. They are easier to measure than fluoride in urine, saliva and serum (China).
Other presentations covered such aspects as safe dietary fluoride levels (India) and fluoride accumulation in human bones (UK). Studies also dealt with the influence of fluoride on periprosthetic bone loss (Poland); the impact of water borne fluoride on bone mineral density (BMD) (Poland); and, the lack of association of BMD of the proximal phalanx in fluorosis (Japan). BMD of the lumbar vertebrae was thus favored as the most sensitive indicator of disease.
BIOLOGICAL EFFECTS
A number of presentations reported the results of laboratory animal studies using sodium fluoride. Several of these described neurological effects. One showed behavioral effects (USA); another, neuropathology (Poland). Experiments involving sodium fluoride and aluminum fluoride alone or in combination revealed increased aluminum levels and lesions resembling those found in Alzheimer's disease patients (USA). An experiment using the Mongolian gerbil demonstrated high concentrations of fluoride in the pineal gland. This led to speculation that since the pineal is responsible for the production of melatonin, the inhibition of synthesis by fluoride may be associated with accelerated onset of puberty – a new risk to consider in the prophylactic use of fluoride (UK).
Studies were presented showing the dose-response relationship of intravenous sodium fluoride and acute renal damage in rats (Japan). The methods used to monitor kidney damage to ascertain the effect on a number of biochemical indicators may have applications for use in industrial workers to detect acute renal failure resulting from damage to the proximal tubule (Japan).
Evidence for weakening of the oxidation system in rats was reported along with data suggesting that beta-carotene and superoxide dismutase (SOD) may counteract these effects (China). Findings on the role of free radicals in liver and kidney toxicity in mice were presented, together with conclusions that vitamins E and D may be useful preventives in endemic areas (India). The influence of fluoride on biological free radical reaction in mouse ovaries and the reversal of fluoride effects on fertility in male mice and on the ovary and uterus of mice by vitamin C and calcium were considered in a number of presentations (India). The production of pulmonary edema in mice by inhaled fluorides was demonstrated (Japan) as well as the toxic effect of fluoride on hematopoietic cells in human cord blood (Poland).
One presentation showed that current US tolerances for fluoride in commercial animal feed are so high that toxicity results in diminished milk production (USA).
JOINT AND BONE EFFECTS
Further details of the complex damage to joints in experimental osteo- and arthrofluorosis using the rat model were presented (Hungary). This work was complemented by discussions of current views on the treatment of osteoporosis by hormones and bisphosphonates (USA); and, further, by use of fluoride and the "fast response" as seen in osteoporosis therapy and industrial exposure. Using BMD for diagnosis and follow-up (Germany) was also discussed.
FLUORIDATION
Most presentations on this topic dealt either with adverse effects on humans and animals of fluoride found in nature and because of industrial pollution in water, soil or air. Some reported on animal experimentation, principally with the use of sodium fluoride. Other presentations included studies and opinions relating to the use of fluoride in dentistry such as the effect of fluoride containing glass ionomer cement on fluoride concentration in surface enamel (Japan) or, the alleged cariostatic effect of fluoride. Some researchers dealt with the deliberate supplementation of low-fluoride water supplies with the fluoride ion provided, in most cases, from the dissociation of silicofluorides. This is a practice found in a minority of countries represented at the conference: USA, Canada, New Zealand and the United Kingdom.
The ISFR takes no "official" stand on the fluoridation issue. In those countries in which fluoridation is sanctioned by government policy, it remains highly controversial. In several presentations, incidental comments indicated that the author(s) consider fluoride to be essential for sound teeth. However, other presentations cast a serious negative outlook on this belief. A study was presented which illustrated the lack of "beneficial" effects of fluoridation in terms of caries reduction and dental care costs in California (USA). Another pointed out that the possible long-term effects of life-long ingestion (by age 70) are still unknown (UK). A positive correlation between water fluoride content and BMD (bone mineral density) was shown and may be interpreted as either a "benefit" or a sign of pre-clinical skeletal fluorosis (Poland).
Researchers of one presentation compared present fluoridation "goals" and the true value of a public health goal (PHG) for ingested fluoride based on ref-erence doses (RfD). Animal experiments and human studies reported in peer-reviewed literature were used to calculate a Maximum Contaminant Level (MCL) of 1.0x10-4 mg/kg/day for humans, or an appropriate PHG of zero (USA). Another dramatic presentation revealed multiple and serious adverse effects of water fluoridation on crocodilians and rodents in captivity (USA).
A number of the laboratory studies of biological effects on experimental animals recording damage to the nervous system could have significance for humans exposed to current levels of total fluoride ingested, especially in fluoridated areas. These include studies showing adverse behavioral outcome related to low levels of fluoride and to fluorinated (vs non-fluorinated) steroids (USA); studies of neuropathology (Poland); and those showing aluminum levels elevated in both those animals given aluminum fluoride (AlF3) and sodium fluoride (NaF) and those given NaF alone compared to controls (USA).
An epidemiological study of the IQ of 7 and 9 year old children living in a fluoridated (1 ppm F) and a non-fluoridated area (0.1 ppm F) in New Zealand that showed no statistical difference was compared to Chinese studies (Zhao et al) done on children living in areas of 4.2 ppm F and 0.91 ppm F. A question was thereby framed concerning whether or not statistically significant impairment occurs only at water fluoride levels above 1 ppm (NZ).
Much interest was generated by a presentation that silicofluorides (hydrofluosilicic acid and sodium silicofluoride) used in water fluoridation are associated with high lead levels in children and the more frequent occurrence of behavior disorders, including criminal behavior and cocaine addiction. The behavioral changes may be attributed to lead neurotoxicity (USA). Several US cities have noted a drop in lead levels at the tap consequent to the temporary cessation of fluoridation. However, the increase in lead levels associated with neurotoxic effects are postulated by these presenters to be due to the action of silicofluorides that are ingested in an incompletely dissociated state.
Animal experiments providing toxicity data are invariably carried out with sodium fluoride. The authors of the report discussed above stated they were unable to find studies that test, on animals or humans, the effects of water treated with silicofluorides. The need for research using silicofluorides was emphasized.
CONCLUSION
This XXIInd conference of the ISFR, like its predecessors, has served to make ready men and women of its participants, delegates, and guests from countries around the world. The findings of the comprehensive presentations are of benefit to those interested in understanding the nature and effects of fluoride and in applying these findings in the service of the environment and its inhabitants, including mankind.
REFERENCE
ANNOUNCEMENTS
Pan-Asia-Pacific Conference on Fluoride and Arsenic Research
August 16-20, 1999, Shenyang, China
Sponsored by the: Fluoride and Arsenic Society of China
This is the first conference on both fluoride and arsenic to be held in the Asia Pacific Region. Sponsored by the Fluoride and Arsenic Society of China FASC), the conference will offer the latest research on fluoride and arsenic. Main themes are:
Further information and registration forms can be obtained from:
Professor Sun Guifan
School of Public Health, China Medical University
92 Beier Road, Shenyang, 110001, China
Tel: 86-24-23871744 Fax: 86-24-23871744
Email: sungf@iris.cmu.edu.cn
Call for Abstracts
Prospective authors are requested to submit abstracts (
300 words on A4 paper). Abstracts should include Title, Authors and Affiliations, and Content.
Deadline Dates:
Abstracts, May 15, 1999; Registration and Payment, July 1, 1999; Hotel Confirmation, July 15, 1999; Conference, August 16-20, 1999.
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