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Effects of exposure to mercury on health of dentists - Sunil Nair Health Informatics Dalhousie University

Effects of exposure to mercury on health of dentists - Sunil Nair Health Informatics Dalhousie University



A pilot study of the effects of exposure to mercury on health of dentists

A pilot study of the effects of exposure to mercury on health of dentists



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    Effects of exposure to mercury on health of dentists - Sunil Nair Health Informatics Dalhousie University Effects of exposure to mercury on health of dentists - Sunil Nair Health Informatics Dalhousie University Document Transcript

    • A PILOT STUDY TO DETERMINE THE EFFECTS OF EXPOSURE TO MERCURY ON THE HEALTH OF DENTISTS HINF6030 – RESEARCH METHODS – FINAL Master of Health Informatics Sunil Nair B00492855 sunil@cs.dal.ca Sunil Nair Page 1 14/04/2008
    • 1. INTRODUCTION The effects of mercury poisoning on adverse human behavior is legendary and is said to be responsible for the origin of the phrase “mad as a hatter” [1, 11]. Occupational and environmental hazards of exposure to mercury are well documented [2, 3, 4, 5]. The presence of metallic mercury in amalgam, used as a tooth restorative material, exposes dental personnel to the dangers of mercury poisoning [6]. A simple search on PubMed with key words “mercury poisoning” dental profession” resulted in more than 500 results [7]. Dental Amalgam has been used as a tooth filling restorative for over 100 years [8]. It is an alloy made by combining mercury with amalgam powder which contains silver, tin, copper and zinc in specific proportions. This mixing procedure is done in the dental office in room temperature and is handled by dental personnel including dentists. Although studies have proved that the end product of this mixture is proven to be a stable and safe material for teeth restoration [9, 10], minute amounts of mercury vapors are released while the dental amalgam is being prepared. Mercury is understood to be the most potent non-radioactive heavy metal toxin to humans [11]. Long-term exposure to mercury may lead to several medical conditions including renal damage, behavioral changes, Alzheimer’s disease, sexual dysfunction, autism in children, stress and cognitive dysfunctions to name a few [12, 13, 14]. 2. OBJECTIVE There have been a number studies done in the recent past that tries to link health and behavioral problems with the higher suicide rates among dentists [15, 16]. Stress, burnout, substance abuse are thought to be precursors to the increased number of suicides among dentists [17]. Is this phenomenon related to long-term exposure to toxic mercury? Although the adverse health effects of using dental amalgam in dental procedures is well researched and evaluated in much of Europe and North America, conclusive studies have not been done in populous developing countries like India. Due to high costs of alternative tooth restorative choices, a large number of dental amalgam fillings are being done in dental practices in most parts of India. Increasing awareness about the toxic effects of dental amalgam may have reduced the number of amalgam fillings in India. In this pilot study, I will be studying the adverse health effects of prolonged exposure to mercury vapors among dental practitioners in India. Sunil Nair Page 2 14/04/2008
    • 2.1 Hypothesis Null hypothesis, Ho: There is no significant in change in health status to practicing dentists due to prolonged exposure to mercury. Alternate hypothesis, Ha: There is a significant change in health status to practicing dentist due to prolonged exposure to mercury. It is possible to study the threshold effects of mercury in a Dentist population because they are more homogenous than other groups in relation to education level, skill of work and ability to take part in testing. Therefore it is possible to detect any effect of mercury poisoning on long-term exposure in a specific occupational group. Independent variable is the effect of mercury exposure to health status. Dependent variables are the level of mercury in urine, the behavior test score and the cognitive function test score. 3. METHODS This experiment will use a cross-sectional sample of dentists with over 10 years of practice in a particular state or province in India. 3.1 The Study population and test procedure A contact list of registered practicing dentists can be availed from the Indian Dental Association (IDA). It would be important to pre-select the subjects who are having more than 10 years of practice as the goal of the experiment is to establish the effects of prolonged mercury poisoning in causing deterioration of health status among dentists most likely the presence of a chronic condition. We would consider health status as deteriorated if there are significant behavioural changes and cognitive dysfunction issues. Both of which can result in cases of increased stress levels and likelihood of practitioner burnout. In the event of mercury poisoning, the element lodges itself in brain and attacks the Central Nervous System. Mercury is excreted via the urine. Therefore, we can evaluate the mental attributes by measuring the behavioural changes and cognitive function in the subjects and also measure the level of mercury in their urine sample. Provided we establish proper control we would be able to draw a direct correlation between the higher levels of mercury in the body and a declining health status. Sunil Nair Page 3 14/04/2008
    • The experiment package, preferably online, can be sent to the dentists registered with IDA on or before January 1998. The package would contain • A consent form • Medical Questionnaire • Dental practice Questionnaire The questionnaires would be some close-ended and mostly open-ended questions. The close-ended questions would have modified Likert scale of rating. 3.1.2 Medical questionnaire A medical questionnaire to evaluate the medical condition of the participants is essential to control any factors that may influence the test performance or results. Questions would be focused on variables like age, race, and gender, history of any neurological disorder and medication history. The questionnaire would also be lifestyle or habits related which would include history of any alcohol abuse, substance abuse and any other addictions. Lifestyle questions could include dietary information for example the amount of fish or seafood intake because excessive sea food in the diet could have increased levels of mercury in the urine sample. 3.1.3 Dental practice questionnaire This questionnaire would help in controlling some factors like the years of practice. Questions would be to find out the type of practice setting, urban or rural, whether they use amalgam in regular practice or not and so on. A sample of the questionnaire is listed in Appendix 4.1. 3.1.4 Control Using the above pre-test questionnaires, we should be able to control for the following: • The years of practice, minimum 10 years • The type of practice o Urban or rural o High-tech or not automated o Amalgam free practice or not • Confounding factors like o Sea food intake o Living/working near a mine or polluted area which are Environmental factors. Sunil Nair Page 4 14/04/2008
    • o Pre-existing medical condition o Number of dental amalgam fillings in the mouth. 3.2 Measures Reliability The survey questionnaire would have a high inter consistency reliability, as to improve the reliability all the points on the Likert rating scale and are labelled with words. The questionnaire would have controls for different response patterns of the respondent, controls for the effects of an issue’s position in survey, to measure the variability of each question and even able to detect collusion. Validity Threats to Internal validity o As the questionnaire is administered online there could be a possibility that the respondents might have difficulty in understanding the questions or they may interpret it differently that the researcher intended. o There could be ambiguity in the statements. o Since there are some close-ended questions the subjects tend to answer the choices offered in the survey and do not volunteer to give a response. o Subjects realize that they are chosen for a study and they respond differently than they would do normally. o We do not know how many subjects will take the survey seriously. As the subjects are chosen based on convenience there could be confounding variables in the study o Some could have more work experience than the others. o Those who volunteered for the study were different in terms of motivation from those who did not participate. o Age– There is possibility that some of the senior dentists have been practicing for many years. o Possibility that men are more practicing dentistry than women or vice versa. o Possibility that the dentists in the urban practice were all young using the latest technologies and newer restorative materials. o There could be a possibility that a dentist from a rural practice has decided to shift to the urban setting. Sunil Nair Page 5 14/04/2008
    • Threats to external validity o Since this study is done only in a particular area we are not sure how the dentists in other areas are practicing. o As we are taking only limited number of dentists from each setting we cannot confirm that it’s a good sample to represent the whole population. o We are discussing only about dentists and their opinion but do not refer to dental hygienists, dental nurses (who would maximum utilize/ prepare dental amalgam, as they have a heavy workload). o The time of the year could also affect the external validity. Threats to construct validity o There could be evaluation apprehension as some may be over anxious (not due to the survey questions) and this might lead to their poor performance or some subjects may want to “look good” and might give a good response. o The researcher can bias the outcome of the study. The survey questions could be manipulated to encourage the subjects to answer in a desirable manner what we want. Threat to Statistical Validity o A possibility that the survey questions used to assess the impact of chronic exposure to mercury on health and cognitive functioning are undependable. o We as researchers could make changes to the statistical tests to get desirable results as per the hypothesis. 3.3 Experimental design As this is a pilot study a small number of participants could be chosen for both groups. o Urine samples could be taken to measure the mercury levels. o A set of behavioural test covering a broad range of functions could be administered. o For cognitive function test a Cognitive Drug Research Computerized Assessment system could be used. [18] Sunil Nair Page 6 14/04/2008
    • This would be a descriptive cross sectional study. There is only one component which is the assessment of health status by administering validated questionnaires to document demographic data, medical history and lifestyle and habit information. A complete medical exam and urine sample can also be collected then measured for mercury levels. The behavioural and cognitive tests can be administered. 3.4 Comparisons to be made A cross-sectional analysis can be done with the results. Comparisons will be made between the mercury levels in dentist practicing in urban and rural setting, those who do not use amalgam and those who use amalgam in their practice. 4. APPENDICES 4.1 Sample Dental Practice Questionnaire SAMPLE PRE-TEST DENTAL PRACTICE QUESTIONNAIRE 1. Years in dental practice. a. 0-10 b. 11-20 c. 21-30 d. More than 30 years. [With this question we can filter those dentists who have been in practice for more than 10 years.] 2. What type of dental practice do you have? a. General practice, I do all the work. b. Specialist practice, I do the fillings c. Consultant, I visit other dentist. d. General practice for more than 10 years but now specialist practice. e. Other _______________ [With this question we can determine the financial status of the practice, the stress level of dentist as well, the dental surgeon at the more than 10 years old general practice where the dentist does all the work could be more stressed, burnout, than a specialist or consultant who chooses the time and number of patients to see.] Sunil Nair Page 7 14/04/2008
    • 3. How would you describe your practice setting? a. Urban – high-tech [this would mean that the practice is located in an urban setting and follows all safety standards and infection control, uses modern equipments and automated] b. Urban [practice is in urban area, safety followed, the clinic is modern, but not automated] c. Rural – high tech [ rural-safety standards followed-automated] d. Rural – rural area-no safety standards are followed, not automated] [With this question, other than separating urban and rural practice setting, we can differentiate between a clinic where safety standards are maintained and not maintained. This would mean that in a rural clinic with no safety standards and no automation, every amalgam filling done would induce more mercury in to the air and in turn increases the probability of the dentist to be exposed to the vapours.] 4. Do you use dental Amalgam in your practice, if yes, how many fillings per week are done? a. No, mine is amalgam free clinic b. Yes, 1-25 fillings per week. c. Yes, 26-50 fillings per week d. Yes, 51-100 fillings per week e. More than hundred fillings per week. 5. Where is your lab located? a. In the office/clinic premises b. Within office but separate room c. Away from main clinic area d. At a distant location. e. Not applicable [This question would help differentiate he level of exposure. Though amalgam is almost always mixed at chair side, some dentists insist on the trituration process at a distant location thereby reducing the exposure] 6. What type of flooring do you have in your clinic? a. Carpet through out b. Ceramic c. Vinyl d. Carpet in the lab; ceramic or vinyl in the clinic area e. Hardwood throughout. [This question would help assess the kind of cleaning that can be maintained. A carpeted clinic or lab would lodge spilled mercury and be difficult o clean even with vacuum.] 7. What is your opinion/knowledge about hazards of mercury usage in dental office? a. Very toxic, will not use. b. Toxicity depends on safety methods followed. c. Research is not substantial d. Don’t care [An urban practice where amalgam is done and safety is practiced and if the dentist doesn’t care about the ill effects of mercury, then there are chances of careless handling] Sunil Nair Page 8 14/04/2008
    • REFERENCES [1] http://www.worldwidewords.org/qa/qa-mad2.htm (Internet, accessed April 2008) [2] Clouse, Rebecca MS, RN. Mercury Use in Health Care: An occupational and public health hazard. ANA: Health & Safety. Volume 105(9), September 2005, p 104 [3] Toyoto Iwata et al., Effects of mercury vapor exposure on neuromotor function in Chinese miners and smelters. International Archives of Occupational and Environmental Health. volume 80, Number 5 / April, 2007 [4] ALENKA FRANKO1, METKA V. BUDIHNA and METODA DODIC-FIKFAK. Long-Term Effects of Elemental Mercury on Renal Function in Miners of the Idrija Mercury Mine. Annals of Occupational Hygiene 2005 49(6):521-527; doi:10.1093/annhyg/mei022 [5] Nelia P.C. Maramba et al., Environmental and human exposure assessment monitoring of communities near an abandoned mercury mine in the Philippines: A toxic legacy. Journal of Environmental Management Volume 81, Issue 2, October 2006 [6] S. Langworth e al., Exposure to Mercury Vapor and Impact on Health in the Dental Profession in Sweden. J Dent Res 76(7): 1397-1404, July, 1997 [7] PubMed http://www.ncbi.nlm.nih.gov.ezproxy.library.dal.ca/sites/entrez?cmd=Link&db=pubmed&dbFrom=PubMed&fro m_uid=9207773 [8] About Amalgam on American Dental Association website: www.ada.org/public/topics/fillings.asp#amalgam [9] The Safety of Dental Amalgam. Health Canada report. Minister of Supply and Services Canada, 1996 Cat. H49- 105/1996E ISBN 0-662-24873-2 [10] Timothy A. DeRouen, PhD. et al., Neurobehavioral Effects of Dental Amalgam in Children: A Randomized Clinical Trial. JAMA. 2006;295:1784-1792. [11] Mercury Properties and Health Effects. U.S. Department of Labor. Occupational Safety & Health Administration. http://www.osha.gov/SLTC/mercury/properties_health.html [12] Pamela Levin, RN. From mad hatters to dental amalgams: heavy metals toxicity and testing. MLO December 2007 MLO www.mlo-online.com [13] AJ Spencer. Dental amalgam and mercury in dentistry. Australian Dental Journal 2000;45:(4):224-234 [14] Health Effects of Mercury. The Canadian Centre for Occupational Health and Safety (CCOHS). http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/mercury/health_mercury.html. Document last updated on December 21, 1998 [15] Petersen MR, Burnett CA. The suicide mortality of working physicians and dentists. Division of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health. Occup Med (Lond). 2008 Jan;58(1):25-9. Epub 2007 Oct 27 [16] Mathias S, Koerber A, Fadavi S, Punwani I. College of Dentistry, University of Illinois. Specialty and sex as predictors of depression in dentists. J Am Dent Assoc. 2005 Oct;136(10):1388-95. [17] Arnetz BB, Hörte LG, Hedberg A, Malker H. Harvard School of Public Health, Occupational Health Program, Boston. “Suicide among Swedish dentists. A ten-year follow-up study”. Scand J Soc Med. 1987;15(4):243-6. [18] Cognitive Drug research Computerized Assessment System (CDR System) www.cognitivedrugresearch.com/newcdr/index.php?cat=5 Sunil Nair Page 9 14/04/2008