POLLUTION IN DENTISTRY – A CRITICAL REVIEW

POLLUTION IN DENTISTRY - A CRITICAL REVIEW

J. Kavitha ^{* 1}, S. Sivakrishnan ¹, S. Lakshmisree ² and S. Srinivasan ³

Department of Periodontia ^{1, 2, 3}, RMDCH Department of Pharmacy ¹, FEAT Annamalai University, Annamalai Nagar, Chidambaram - 608002, Tamil Nadu, India.

ABSTRACT: Health may be defined as the capability to adapt and manage physical, mental, and social concerns throughout life. Oral health is a key indicator of overall health, wellbeing, and quality of life. WHO defines oral health as “a state of being free from chronic mouth and facial pain, oral and throat cancer, oral infection and sores, periodontal (gum) disease, tooth decay, tooth loss and other diseases and disorders that limit an individual’s capacity in biting, chewing, smiling, speaking and psychosocial wellbeing. Oral diseases are the most frequent non-communicable diseases (NCDs) and affecting humans lifelong, resulting in pain, malaise, malformation, and till death. Environmental pollution is now recognized as a global threat, and the actions of mankind are largely accountable for this. Various oral diseases like dental caries, fluorosis are influenced by the food and water quality in a particular topographic area. Chemicals in water can be both naturally occurring or introduced by human interference and can have a huge impact on teeth and oral mucosa. High concentrations of arsenic in water can have an adverse effect on health particularly skin and other tissues of the body, including tongue, gingiva, and buccal mucosa. Without access to clean water, people living in developing and underdeveloped countries may suffer oral health deterioration well into their adulthood. This results in tooth loss, periodontitis, and even mouth cancer. Air pollution influences the development of cleft palate in some kinds of animals. There is evidence from the epidemiologic data on the relation of prenatal air pollution exposure and the risk of oral clefts. Oral precancer and cancer are complex multi-factorial diseases arising from the interplay between the genetic components and the environmental determinants. Environmental exposures in farmers can be explained by solar exposure. This study mainly focuses that air and water pollution produces serious effects in oral health for living organisms, especially in humans.

Oral health, Periodontal, Air Pollution, Fluorosis, Water pollution

INTRODUCTION: Health, as defined by the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity ¹. This definition has been subject to controversy, as it may have limited value for implementation ². Currently, three kinds of descriptions of health seem to be possible and are used.

The first is that health is the absence of any disease or impairment. The second is that health is a state that allows the individual to cope with all demands of daily life adequately. The third shows that health is a state of balancing, an equilibrium that an individual has created within himself and between himself and his social and physical environment.

Oral health is integral to general health and is essential to the overall health and wellbeing of all individuals. Oral health means more than healthy teeth. The word “oral” refers to the mouth, which includes not only the teeth, gums, and supporting tissue but also the hard and soft palate, the mucosal lining of the mouth and throat, the tongue, the lips, the salivary glands, the chewing muscles and the jaw. The salivary glands are a model of other exocrine glands, and an analysis of saliva can provide clues of overall health or disease. Oral health is multi-faceted and includes the ability to speak, smile, smell, taste, touch, chew, swallow and convey a range of emotions through facial expressions with confidence and without pain, discomfort, and disease of the craniofacial complex. Stress, physical and mental abuse, nutrition and diet, exposure to toxins, pathogens, radiation, and chemicals as environmental factors and determinants of growth and body composition can contribute to the risk of some human cancers such as oral cancer. Oral health is considered a determinant of quality of life.

Oral health is a fundamental component of general health as poor oral health affects growth, development, and learning knowledge for a child, communication, nourishment, self-esteem, and several systemic conditions because of its effects on day-to-day-life. The impact of environmental change on the lives of natives of a particular geographical region influences the overall health status of an individual. The contamination of water by harmful or undesirable substances making it unfit for use. Chemical substances in water can be both occurring naturally or introducing by individual interference produces significant health problems. Without access to clean water, people living in developing and underdeveloped countries may suffer oral health deterioration well into their adulthood.

This may lead to loss of tooth, periodontitis and oral cancer. Poor, inadequate and polluted air quality is linked to sudden or early death, carcinoma, and chronic damage to cardiovascular and respiratory systems.  Exposure to solvents and possibly pesticides, fertilizers, engine exhaust, textile dust, and leather dust also increase the risk of oral cancer. Climate change-induced oxidative stress, dietary transition ^4-8 contamination, impacts on food chain ecosystem and food security have increased the vulnerability to oral cancer. Exposure to solvents and possibly pesticides, fertilizers, engine exhaust, textile dust, and leather dust also increase the risk of oral cancer. Indoor air pollution contributes to oral cancer, with other significant inflammatory respiratory diseases and infections. Estimated exposure to wood smoke and biomass smoke released from cooking in households in developing countries has led to an increased risk of oral cancer, particularly in women and children. In India, environmental pollution-related disorders may further weaken the existing inadequate public health infrastructure. Research should be targeted to understand the complex interplay of environment interactions and oxidant mediated oral diseases. Epidemiological assessment and willingness to tackle health burden arising due to the impact of environmental factors need to be strengthened. This would facilitate a harmonious balance to enable the sustainable development of optimum oral and in turn, overall health.

Water Pollution in Oral Health: Many of the major problems that humanity is facing in the twenty-first century are related to water quantity and/or water quality issues ^{9, 10}. These problems are going to be more aggravated in the future by climate change, resulting in higher water temperatures, melting of glaciers and an intense-fication of the water cycle, with potentially more floods and droughts. With respect to the individual health, the most direct and most serious impact is the deficit of better sanitation and related to it is the inadequate and insufficiency of secure drinking water, which currently affects more than a third of the people in the world.

Additional threats include, for example, exposure to pathogens or to chemical toxicants via the food chain (e.g., the result of irrigating plants with contaminated water and of bioaccumulation of toxic chemicals by aquatic organisms, including seafood and fish) or during recreation (e.g., swimming in polluted surface water). Surface and groundwater quality concerns apply to both drinking water and recreational waters. Polluted by infective agents or chemicals substances can cause mild to serious complications. Quality of the water has been seen to directly influence oral health based on several studies. The case study proved that without access to clean and safe drinking water, almost all of the children aged 5-7 years who were involved in the study had some level of tooth decay ¹¹. The water in their area was found to have no fluoride, high levels of manganese, and high acidity level, which all contributed to the poor oral health of the residents. Long-term effects of poor water quality ^12-14 are, without access to clean water, people living in developing and underdeveloped countries may suffer oral health deterioration well into their adulthood. This leads to tooth loss, gum disease, oral cancer ^15-17. Several oral diseases like dental caries, fluorosis are influenced by the food and quality of the water in a specific topographic region. Chemicals in water can be both naturally occurring or introduced by human interference and can have a huge impact on teeth and oral mucosa. Arsenic occurs naturally or by phosphorus from fertilizers. High concentrations of arsenic in water can have an adverse effect on health particularly skin and other tissues of the body including tongue, gingiva and buccal mucosa.

Dental Caries: It affects the majority of populations in many developing countries. It is characterized by the dissolution of the dental enamel and dentine. This eventually destroys the affected tooth or tooth surface. The immediate cause is an organic acid produced by micro-organisms present on the tooth. Dental plaque ¹⁸ consists of bacteria and a matrix of extracellular poly-saccharine produced from sucrose ^19-26 by the bacteria. Tooth plaque, specific bacteria, diet, fluoride, and saliva are all involved in the dental caries process. In recent decades, preventive measures have helped to dramatically lower levels of dental caries in industrialized populations. The most important of these measures is exposure to an appropriate level of fluoride, from various sources, including water, food, and toothpaste.

Dental Fluorosis: Dental fluorosis ^27-31 is a specific disturbance of tooth formation caused by excessive fluoride ³² intakes during the development of teeth. It is characterized by opaque white patches in the dental enamel. These patches may become stained yellow to a darker color, and in more severe cases normal tooth structure may be destroyed. The degree of fluorosis, plasma, and bone fluoride levels ^33-34, is directly related to the concentration of fluoride in drinking water. In drinking water, fluoride is tasteless, odorless, colorless and totally soluble and its detection requires laboratory equipment and specially trained personnel. Methods for removing excess fluoride are well established, although the prevention of fluorosis through the treatment of drinking water requires favorable socio-economic conditions. The provision of a safe low level of fluoride in water from alternative sources should be investigated as a first option. Defluoridation of water may be the only option to prevent fluorosis if alternative supplies are either not available or too expensive. The methods for defluoridation depend on the specific local circumstances in the community and the level of fluoride concentration in the drinking water. In developing countries ³⁵, whose initiative ³⁶ has emphasized the effective and less expensive methods that are suitable for individual households, or community defluoridation of water for drinking and cooking.

Heavy Metals: These may be waterborne, or maybe found in air, food, or other sources of exposure ^37-38. These can also cause damage to your teeth. Metal amalgam is a common source of heavy metal exposure ³⁹. Although the heavy metals in amalgams are not damaging to teeth, they can damage the body if they are mobilized through vigorous chewing, tooth grinding, or with time. People in areas with high levels of heavy metal pollution have significant damage to their teeth as a result ^{40, 41}. The metals result in roughening of the tooth surface, which makes them more susceptible to decay from bacteria. Arsenic occurs naturally or by phosphorus from fertilizers. High concentrations of arsenic in water can have an adverse effect on health, particularly skin. Pipes and hoses, fixtures, soldering, and the power supply lines of several household pipeline systems containing lead that pollutes the source of drinking water. Petroleum products pollute the ground-water from under-ground fuel storage reservoir.

These pollutants come from mines waste and tailings, landfill sites, or hazardous garbage dumps, chlorine-containing solvents, metals, and thermo-plastic effluents, fabric scrubbing, electrical, electronic and aircraft construction are often discharged and polluted groundwater.

Oral Manifestations:

• Arsenic: Intense inflammation of oral mucosa, severe periodontitis, and tissue become painful, local contact with arsenic trioxide produces ulceration and general poisoning will cause excessive spit.
• Inorganic Copper, Iron, Nickel, Chromium Coal: Staining of teeth, pigmentation of gum, generalized abrasion, calculus, gum inflammation and hemorrhage ^{42, 43}.
• Lead: Blue-black pigmentation of gum and cause gingivostomatitis.
• Mercury: Gingivostomatitis, osteitis, pyta-lism, gingivitis/gingival gums and ulcers of oral cavity ^{44, 45}.
• Phosphorus: Gingivostomatitis, ulceration of oral tissues, and osteomyelitis.
• Organic Sugar:
• Bismuth: Oral mucosa, gingivostomatitis, bismuth line: a thin blue-black line within the marginal gingiva typically confined to gingival papillae, also seen in buccal mucosa and ventral surface of tongue, Pigmentation shows precipitated granules of bismuth sulfide produced by action of hydrogen sulfide on bismuth, hydrogen sulfide is produced by microorganism degradation of organic material or food debris, burning sensation and metallic taste.

Agrochemicals: In the developing nation, deaths by accidental poisoning may be closely associated with improper usage and poor environmental governance of toxic and harmful chemical products including pesticides. Chronic pesticide exposure is most often a problem in the occupational setting, particularly among poor rural populations where men, women, and children all work and live in close proximity to fields and orchards where chemicals are applied and stored.

Chronic exposure to pesticides enhances the risk of developmental disorders and sexual problems, immune-system and hormonal disturbances, impaired nervous system function, and development of certain carcinomas. Pesticides, as well as fertilizers, can infiltrate water sources contaminating drinking water and animal species, e.g., fish, upon which humans rely on nutrition. Such contamination leads to a range of secondary public health issues.

A study of pesticides sales different parts of Brazil and cancer mortality rates a decade later finds pesticide sales show a statistically significant correlation with the mortality rates for several cancers, including cancer of the lip. A Swedish study based on a cancer registry of agricultural workers finds an increased risk of cancer of the lip by a factor of greater than 2.51.

Oral Hygiene and Safe Water Supplies: Good oral health requires a clean, safe and pure water supply ^46-48, adequate for brushing and cleaning teeth frequently from an early age. Poor oral hygiene may also result in periodical problems since dental plaque may induce gingival inflammation and deep pockets. While fluoride intake from drinking water and a balanced, low sugar diet are almost the main factors for reducing tooth decay, deficiency of clean and pure water for basic oral health may tip the balance towards earlier and more severe patterns of caries. Where fluoride concentrations in water or the diet are known to be low, community water fluoridation ⁴⁹ is safe and cost-effective. In the agriculture field, control the use of chemical contained fertilizers and pesticides. Agriculture peoples are switch over to natural-based fertilizers and pesticides to prevent the contamination of water.

Air Pollution in Oral Health: Air pollution is a worldwide issue, particularly in rural areas. In particular, particulate matter (PM) has been evaluated intensively as regards its impact on human health ^{50, 51}. PM ⁵² consists of breathable particles to which several compounds, such as heavy metals ⁵³, polycyclic aromatic hydrocarbons (PAHs), and some volatile compounds, may adhere. Epidemiological studies have found a consistent association between exposure to airborne PM and incidence and mortality for cardiovascular disease⁵⁴ and lung cancer and natural-cause mortality. Recently, also diabetes and other chronic diseases have been associated with PM exposure, possibly through oxidative stress and inflammation. Poor quality of air is connected to premature death, carcinoma, and chronic damage to cardiovascular and respiratory systems ⁵⁵.

Exposure to solvents and possibly pesticides, fertilizers, engine exhaust, textile dust, and leather dust ⁵⁶ also increases the risk of oral cancer. Indoor air pollution contributes to oral cancer, with other significant inflammatory respiratory diseases and infections. Estimated exposure to wood smoke and biomass smoke ⁵⁷ released from cooking in households in developing countries has led to an increased risk of oral cancer, particularly in women and children. There is evidence from the epidemiologic data on the relation of prenatal air pollution exposure and the risk of oral clefts ^58-62.

Ozone: Exposure to outdoor air ozone during the first and second months of pregnancy may increase the risk of CL/P ^63-66. Similar levels of O₃ encountered globally by a large number of pregnant women.

Control of Air Pollution: Air pollution can be better controlled by (a) reducing the emission of pollutants and (b) by using non-polluting materials. Some of the major steps for reducing air pollution are as follows: controlling particulate pollutants by using scrubbers, filters, cyclone separators, and electrostatic precipitators in the industries. Change from high-sulfur coal to low-sulfur coal, especially for the thermal power plants, to check the emission of sulfur dioxide. It is locating industries far from human settlements. Check automobile pollution by the use of unleaded petrol, better engines with low emissions, and proper maintenance of vehicles. Installation of catalytic converters in the vehicles. Conducting regular pollution control checks on the vehicles and adopting less polluting fuels like Compressed Natural Gas (CNG) and Liquefied Petroleum Gas (LPG) and adopting more non-conventional energy sources that are non-polluting, such as solar energy, wind energy, etc. Using mass transport systems and switching over to non-polluting modes of transport like bicycles. To check deforestation and encourage plantation especially around the polluting Industries.

Occupational Hazards: An occupational hazard is a risk faced in the place of work. Workplace hazards include several kinds of hazards, including chemical hazards. Chemical hazards are a subtype of occupational risks that contain dangerous chemicals. Chemical exposure in the workplace may occur in acute or chronic health illnesses.

A polychlorinated Biphenyls PCBs: ^{67, 68} is an organochlorine compound. PCBs were once commonly used as dielectric and cooling fluids in electric appliances, carbonless copy paper, and in heat transfer fluids. In general, people are exposed to PCBs overwhelmingly through food, much less so by breathing contaminated air and least by skin contact. Once exposed, some PCBs may change to other chemicals inside the body. These chemicals or unchanged PCBs can be excreted in feces or may remain in a person's body for years, with half-lives estimated at 10-15 years. PCBs ⁶⁹ collect in body fat and milk fat. PCBs biomagnify up the food web and are present in fish and waterfowl of contaminated aquifers. Human infants are exposed to PCBs through breast milk or by intrauterine exposure through transplacental transfer of PCBs and are at the top of the food chain.

Polychlorinated dibenzofurans PCDFs: ⁷⁰ is a group of organic substances with single or more of the hydrogens in the dibenzofuran ⁷¹ structure replaced by chlorines. It is also known as persistent organic pollutants (POP), classified among the dirty dozen in the Stockholm Convention on persistent organic pollutants ^72-74.

Dibenzofuran exposure may occur through inhalation and contact with body skin, specifically at areas where coal tar, coal tar derived products and creosote are generated or used. Seafood like fish and milk and dairy products consumption also had been explored in relation to the body burden of dibenzofuran in women who are pregnant. Consumption of contaminated water and food is the primary source of exposure. PCDFs are eliminated 22% of the regular consumption of dioxins from meals is discharged from stools and 29% from sebaceous matter.

Food, Water and Air: Generally, levels of PCBs, PCDDs, and PCDFs in the air are very low, except in the vicinity of inefficient incinerators. Concentrations of these compounds in drinking water and surface water are also very low because they are poorly soluble in water. Air releases from insufficient incineration and releases from waste disposal sites pollute the land and aquatic sediments, leading to bioconcentration and bioaccumulation through the food web.

The higher chlorinated components and compounds with specific positions of chlorination persist longer in the environment and show greater bioaccumulation. The substances have high-fat solubility, which may lead to higher concentrations in fatty foods, such as dairy products, some fish, meat, and shellfish. Most human exposure is through ingestion of contaminated food. These components remain in adipose tissue, with typical half-lives in individuals in excess of seven years. Severe developmental effects were ascertained in infants and kids born to mothers who had been exposed to polychlorinated dibenzofurans/ biphenyls (PCDFs/PCBs). A variety of dental and oral changes were additionally reportable in children exposed to PCB/PCDF are Birth-natal teeth oral pigmentation, childhood-missing permanent teeth delayed eruption of permanent teeth, disturbed root development, and  Adulthood - the periodontal disease was common.

Waste Disposal: Any other source of organic substances in the presence of chlorine or other halogens will generate dioxins and furans during combustion. PCDDs and PCDFs are produced through the incineration of waste (domestic, industrial, and hospital) at lower to medium temperatures; guidance had been designed to determine and quantify releases from various incineration processes. The use of modern incineration technology destroys dioxins and furans, whereas inadequate incineration creates them ^75-78. Disposal of electrical equipment may release PCBs (and PCDF contaminants); guidance is available on equipment likely to contain PCBs^79-85. Stockpiles of old industrial lubricants containing PCBs are also a potential source of emissions.

CONCLUSION: There is a huge burden of oral diseases that afflict humankind, which require population-wide prevention and access to appropriate care. The many links between general and oral health, particularly in terms of shared risk factors and other determinants like air and water pollution provide the basis for closer integration of oral and general health for the benefit of overall human health and wellbeing. Without access to clean water, people living in developing and underdeveloped countries may suffer oral health deterioration well into their adulthood. This leads to tooth loss, periodontitis, and even oral cancer. Contaminated air influences the progression of cleft palate in animals. Synthetic and natural trace contaminants that are present in natural water and air. Most of these micropollutants may exert toxicological effects even at such low levels, specifically when present as mixtures. The wide range and great structural variety of micropollutants make it, however, usually very difficult to assess such side effects, which often are not acute but are subtle, long term effects. This contrasts with the common, acute health effects of the rather small number of well-known pathogens that may be present in polluted water and air. Therefore, considering the problems of evaluating the effects of micropollutants on aquatic life and individuals health and that suitable, affordable water treatment methods for their effective elimination are not available in many parts of the world, major efforts (such as restricted use, substitution or oxidative treatment) have to be undertaken to prevent these chemicals from reaching natural water.

On the other hand, increasing the sensitivity of people to air pollution concerns and promote the local authorities’ involvement in efforts to reduce urban air pollutants. In this review, we conclude that good oral health depends on safe water and clean air supply. Good management, use, and disposal of agrochemicals, particularly pesticides, is an important health and environmental issue in developing countries, where economies may be heavily reliant on agriculture. The use of modern incineration technology destroys dioxins and furans, whereas inadequate incineration creates them. In this review, we conclude that good oral health depends on safe environmental conditions.

ACKNOWLEDGEMENT: Nil

CONFLICTS OF INTEREST: No conflicts of interest.

REFERENCES:

1. World Health Organization: The preamble of the constitution of the World Health Organization Constitution of the World Health Organization. Bulletin of the World Health Organization 2002; 80: 982.
2. Callahan D: The WHO definition of health. The Hastings Center Studies 1973; 1: 77-87.
3. Taylor S and Marandi A: How should health is defined. BMJ 2008; 337: 290.
4. Burt BA and Pai S: Sugar consumption and dental caries. Journal of Dental Education 2001; 65: 1017-23.
5. Duggal MS, Toumba KJ, Amaechi BT, Kowash MB and Hingam SM: Enamel demineralization in-situ with various frequencies of carbohydrate consumption with and without fluoride toothpaste. J of Dental Res 2001; 80: 1721-24.
6. Gibson S and Williams S: Dental caries in preschool children: associations with social class, tooth brushing habit and consumption of sugars and sugar-containing foods. Caries Research 1999; 33: 101-13.
7. König KG: Diet and oral health. International Dental Journal 2000; 50: 162-74.
8. Touger-Decker R and Loveren VC: Sugars and dental caries. American Journal of Clinical Nutrition 2003; 78: 881-88.
9. Haseena M, Malik MF, Javed A, Arshad S, Asif N, Zulfiqar S and Hanif J: Water pollution and human health. Environ Risk Assess Remediat 2017; 1(3): 16-19.
10. Chowdhury S, Annabelle K and Klaus FZ: Arsenic contamination of drinking water and mental health. IZA Discussion 2015; 1-28.
11. Khanal S, Acharya J, Gautam S and Malla M: Pattern of distribution of oral diseases among children in jorpati, kathmandu. J of Dental Association 2013; 13: 33-39.
12. Alrumman SA, El-kott AF and Kehsk MA: Water pollution: source and treatment. American Journal of Environmental Engineering 2016; 6: 88-98.
13. Pawari MJ and Gawande S: Ground water pollution and its consequence. International Journal of Engineering Research and General Science 2015; 3: 773-76.
14. Kumar S AND Meena MH: Water Pollution in India: Its impacts on the Human Health Causes and Remedies 2017; 12(2): 275-79.
15. Sturgis EM: A review of social and behavioural efforts at oral cancer preventions in India. Head and Neck 2004; 26: 937-44.
16. Sherry LP and Aleksejuniene J: Oral cancer and cultural factors in Asia. Canadian Journal of Dental Hygiene 2008; 42: 291-95.
17. Khanna S: Climate change and oral health: current challenges and future scope. International Journal of Environmental Science and Development 2010; 1: 190-92.
18. Yadav K and Prakas S: Dental caries: a review. Asian Journal of Biomedical and Pharmaceutical Sciences 2016; 6: 01-07.
19. Jayadevan A, Chakravarthy D, Padmaraj SN, VijayaRaja S, Bal L and Dimple N: Dental caries and sugar substitutes: a review. IOSR Journal of Dental and Medical Sciences IOSR-JDMS 2019; 18(5): 13-23.
20. Sharma VK, Ingle NA, Kaur N, Yadav P, Ingle E and Charania Z: Sugar substitutes and health : a review. Journal of Advanced Oral Research 2015; 6: 1-5.
21. Nayak PA, Nayak UA and Khandelwal V: The effect of xylitol on dental caries and oral flora. Clinical Cosmetic and Investigational Dentistry 2014; 6: 89.
22. Gupta P, Gupta N, Pawar AP, Birajdar SS, Natt AS and Singh HP: Role of sugar and sugar substitutes in dental caries: A review. ISRN Dentistry 2013; 1(2): 421-19.
23. Zafar T, Naik QAB and Shrivastava VK: Aspartame: effects and awareness. Med Crave Online Journal of Toxicology 2017; 3: 23-26.
24. Bobde J: Artificial sweeteners. Journal of Conservative Dentistry 2016; 3: 6-10.
25. Sheet BS, Artik N, Ayed MA and Abdulaziz OF: Some alternative sweeteners (xylitol, sorbitol, sucralose and stevia): review. Karaelmas Fen ve Mühendislik Derg/ Karaelmas Sci Eng J 2014; 4(1): 63-70.
26. Shrivastav JP, Verma AK, Walia R and Parveen R: Pharmaceutical jaggery : A revolution in the field of natural sweeteners. European Journal of Pharmaceutical and Medical Research 2016; 3: 198-02.
27. Das K and Mondal NK: Dental fluorosis and urinary fluoride concentration as a reflection of fluoride exposure and its impact on IQ level and BMI of children of Laxmisagar, Simlapal Block of Bankura District, W. B, India. Environmental Monitoring and Assessment 2016; 188(4): 21-28.
28. Bashash M, Thomas D, Hu H, Angeles Martinez-Mier E and Sanchez BN: Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6-12 years of age in Mexico. Environmental Health Perspectives 2017; 125(9): 097017.
29. Mohanta A and Mohanty PK: Dental fluorosis - revisited. Biomedical Journal of Scientific and Techinical Research 2018; 2: 2243-47.
30. Selwitz RH, Nowjack-Raymer RE, Kingman A and Driscoll WS: Prevalence of dental caries and dental fluorosis in areas with optimal and above-optimal water fluoride concentrations: a 10-year follow-up survey. Journal of Public Health Dentistry 1995; 55: 85-93.
31. Selwitz RH, Nowjack-Raymer RE, Kingman A and Driscoll WS: Dental caries and dental fluorosis among school children who were lifelong residents of communities having either low or optimal levels of fluoride in drinking water. Journal of Public Health Dentistry 1998; 58: 28-33.
32. Seraj B, Shahrabi M, Shadfar M, Ahmadi R and Fallahzadeh M: Effect of high water fluoride concentration on the intellectual development of children in Makoo/Iran. Journal of Dentistry, Tehran University of Medical Sciences 2012; 9: 221-29.
33. S. Environmental Protection Agency: (2011). Basic information about fluoride in drinking water -Review of fluoride drinking water standard. Available at http:// water. epa.gov/ drink/contaminants/basicinformation/ fluoride
34. CFM, Szpunar SM and Burt BA: Dental caries, fluorosis, and fluoride exposure in michigan schoolchildren. Journal of Dental Research 1988; 67: 802-06.
35. Alhobeira HA, Siddiqui AA and Mian RI: Prevalence and severity of dental fluorosis in hail, saudi arabia. Journal of International Oral Health 2015; 7: 1-4.
36. Petersen PE: The World Oral Health Report Continuous improvement of oral health in the 21^st century the approach of the WHO Global Oral Health Programme. Community Dentistry and Oral Epidemiol 2003; 31: 3-24.
37. Su CC, Yang HF, Huang SJ and Lian IB: Distinctive features of oral cancer in Changhua County: high incidence, buccal mucosa preponderance, and a close relation to betel quid chewing habit. Journal of Formosan Medical Association 2007; 106: 225-33.
38. Su CC, Tsai KY, Hsu YY, Lin YY and Lian IB: Chronic exposure to heavy metals and risk of oral cancer in Taiwanese Males Oral Oncology 2010; 46: 586-90.
39. Yuan TH, Lian IB, Tsai KY, Chang TK, Chiang CT, Su CC and Hwang YH: Possible association between nickel and chromium and oral cancer: a case control study in central Taiwan. Science of the Total Environment 2011; 409(6): 1046-52.
40. Tsai KY, Su CC, Chiang CT, Tseng YT and Lian IB: Environmental heavy metal as a potential risk factor for the progression of oral potentially malignant disorders in central Taiwan. Cancer Epidemiology 2017; 47: 118-24.
41. Kumar S, Debnath N, Ismail MB, Kumar A and Kumar A: Prevalence and risk factors for oral potentially malignant disorders in Indian population Adv. Preventi Med 2015; 7.
42. Su C, Lin Y, Chang T, Chiang C, Chung J, Hsu Y and Lian L: Incidence of oral cancer in relation to nickel and arsenic concentrations in farm soils of patients’ residential areas in Taiwan. BMC Public Health 2010; 10: 1-10.
43. Kasprzak KS, Sunderman FW and Salnikow K: Nickel carcinogenesis. Mutatation Research Fundamental Mole-cular Mechanisms of Mutagenesis 2003; 533: 67-97.
44. Zefferino R, Piccoli C, Ricciardi N, Scrima R and Capitanio N: Possible mechanisms of mercury toxicity and cancer promotion: involvement of gap junction intercellular communications and inflammatory cytokines. Oxidative Medicine and Cellular Longevity 2017; 1-6.
45. SyversenT and Kaur P: The toxicology of mercury and its compounds. Journal of Trace Elements in Medicine and Biology 2012; 26: 215-26.
46. Ullah S, Javed MW and Shafique M: An integrated approach for quality assessment of drinking water using GIS: a case study of lower dir. Journal of Himalayan Earth Sciences 2014; 47: 163-74.
47. Huntington TG: Evidence for intensification of the global water cycle: review and synthesis. Journal of Hydrology 2006; 319: 83-95.
48. Schwarzenbach RP, Egli T, Hofstetter TB, Von Gunten U and Wehrli B: Global water pollution and human health. Annual Review of Environment and Resources 2010; 35: 109-36.
49. Riley JC, Lennon MA and Ellwood RP: The effect of water fluoridation and social inequalities on dental caries in 5-year old children. International Journal of Epi-demiology 1999; 28: 300-05.
50. Anderson JO, Thundiyil JG and Stolbach A: Clearing the air: A review of the effects of particulate matter air pollution on human health. Journal of Medical Toxicology 2012; 8: 166-75.
51. WHO: Review of evidence on health aspects of air pollution-revihaap project. First results. WHO Regional Office for Europe World Health Organisation 2013; 1-309.
52. Martinez M, Santos J and Mejía G: Source apportionment of PM 2.5 for supporting control strategies in the monterrey metropolitan area, Mexico. Journal of the Air and Waste Management Association 2016; 66: 631-42.
53. Sanders AP, Desrosiers TA, Warren JL,  Herring AH, Enright D,  Olshan AF,  Meyer RE and Fry RC: Asso-ciation between arsenic, cadmium, manganese and lead levels in private wells and birth defects prevalence in North Carolina: a semi-ecologic study. BMC Public Health 2014; 14: 1-12.
54. Kuehl K and Loffredo C: Clustering of left heart obstructive congenital cardiovascular malformations: ISEE-210. Epidemiology 2003; 14: 42.
55. Liu CB, Hong XR, Shi M, Chen XQ, Huang HJ, Chen JH, Yang K, Chen SQ, Chen HQ and Kan HD: Effects of prenatal pm 10 exposure on fetal cardio vascular malformations in fuzhou, china: a retrospective case–control study. Environmen Health Perspectives 2017; 15.
56. Csavina J, Taylor MP, Felix O, Rine KP, Sáez AD and Betterton EA: Size-resolved dust and aerosol contaminants associated with copper and lead smelting emissions: implications for emission management and human health. Science of the Total Environment 2014; 493: 750-56.
57. Liu Y, Wang B, Li Z, Zhang L, Liu J and Ren A: Indoor air pollution and the risk of or facial clefts in a rural population in shanxi province, China. Birth Defects Res Part A Clinical and Mol Teratology 2016; 106; 708-15.
58. Elizondo R, Lagravere MO, Flores E and Letechipia N: Presurgical preparation of infants with unilateral cleft lip and palate: the sac-pp-mr innovative technique. Cleft Palate-Craniofacial Journal 2019; 56: 408-14.
59. Alfwaress FS, Khwaileh FA, Rawashdeh MA, Alomari MA, Nazzal MS, Lip C and Palate: Demographic patterns and the associated communication disorders. Journal of Craniofacial Surgery 2017; 28: 2117-21.
60. Zhou Y, Gilboa SM, Herdt ML, Lupo PJ, Flanders WD, Liu Y, Shing M, Canfield MA and Kirby RS: Maternal exposure to ozone and PM 2.5 and the prevalence of orofacial clefts in four U. S. states. Environmental Research 2017; 153: 35-40.
61. Deshpande AS and Goudy SL: Cellular and molecular mechanisms of cleft palate development. Laryngoscope Investigate Otolaryngology 2018; 4: 160-64.
62. Gasca-Sanchez FM, Santos-Guzman J, Elizondo-Dueñaz R, Mejia-Velazquez GM and Ruiz-Pacheco C: Spatial clusters of children with cleft lip and palate and their association with polluted zones in the monterrey metropolitan area. International Journal of Environmental Research and Public Health 2019; 16: 2488.
63. Spinder N, Bergman JE, Marike H, Vermeulen RC, Kromhout H and De-Walle EK: Maternal occupational exposure and oral clefts in offspring. Environmental Health 2017; 16: 1-11.
64. Angulo C, Acosta LF, Guadron AM, Canizales A, Gonzalez F, Osuna I and Murillo J: Maternal risk factors associated with the development of cleft lip and cleft palate in Mexico: a case-control study. Iranian Journal of Otorhinolaryngology 2017; 29: 189-95.
65. Barrera C and Mezarobba N: Maternal risk factors associated with cleft lip with or without cleft palate: A review. International Journal of Odontostomatology 2016; 10; 359-68.
66. Setó-Salvia N and Stanier P: Genetics of cleft lip and/or cleft palate: association with other common anomalies. European Journal of Medical Genetics 2014; 57: 381-93.
67. Bohannon MEB and Ottinger MA: Polychlorinated biphenyls: sources, fate, effects on birds and mammals, and mechanisms of action. Encyclopedia of the Anthropocene 2018; 207-13.
68. Kodavanti PRS: Polychlorinated biphenyls (pcbs). Reference module in neuroscience and biobehavioral psychology. Encyclopedia of the Neurological Sciences 2014; 917-21.
69. Liu C, Wang C, Yan M, Quan C, Zhou J and Yang K: PCB153 disrupts thyroid hormone homeostasis by affecting its biosynthesis, biotransformation, feedback regulation, and metabolism. Hormone and Metabolic Research 2012; 44: 662-69.
70. Safe S: Polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and related compounds: Environmental and mechanistic consi-derations which support the development of toxic equivalency factors (Tefs). Critical Review of Toxicology 1990; 21: 51-88.
71. Rappe C and Kjeller LO: Dioxin, patterns and source identification. Freseniu J of Analy Chem 1994; 348: 63-75.
72. Wevers M: Concentrations of PCDDs and PCDFs in ambient air at selected locations in flanders in fielder h. dioxin 93: 13^th international symposium on chlorinated dioxins and related compounds vienna. Vienna Austrian Federal Environment Agency 1993; 123-26.
73. König J, Theisen J, Gunther WJ, Liebl KH and Buchen M: Ambient air levels of polychlorinated dibenzofurans and dibenzo (p) dioxins at different sites in Hessen. Chemosphere 1993; 26: 851-61.
74. Broman D, Naf C and Zebuhr Y: Long-term high- and low-volume air sampling of polychlorinated dibenzo-p-dioxins and dibenzofurans and polycyclic aromatic hydrocarbons along a transect from urban to remote areas on the Swedish Baltic coast. Environmental Science and Technology 1991; 25: 1841-49.
75. UNEP (2002): PCB transformers and capacitors: From management to reclassification and disposal. Geneva, United Nations Environment Programme UNEP Chemicals (http:// chem. unep.ch/Pops/pdf/ PCB transcap. pdf).
76. UNEP (1999): Guidelines for the identification of PCBs and materials containing PCBs. Geneva, United Nations Environment Programme, UNEP Chemicals (http:// www.chem.unep.ch/pops/pdf/PCBident/pcbid1.pdf).
77. Berg VDM, Birnbaum LS, Denison M, De-vito M, Farland W and Feeley M: The 2005 World Health Organization reevaluation of human and mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxico-logical Sciences 2006; 93: 223-41.
78. WHO (2000): Assessment of the health risk of dioxins: re-evaluation of the tolerable daily intake (TDI). IT’S Consultation Geneva 1998. Geneva World Health Organization (http:// who.int/ ipcs/publications/ en/ exe-sum-final.pdf).
79. WHO (2000): Polychlorinated biphenyls (PCBs). in: air quality guidelines for Europe, 2^nd Copenhagen, World Health Organization Regional Office for Europe (http:// www.euro.who.int/__data/assets/pdf_file/0005/74732/E71922.pdf).
80. Summaries IARC and Evaluations: Polychlorinated dibenzo-para-dioxins. Lyon, International Agency for Research on Cancer. (IARC Monographs on the Evaluation of Carcinogenic Risks to Huma 1997; (69): 33.
81. IARC (in preparation): A review of human carcinogens. F. chemical agents and related occupations. lyon, international agency for research on cancer (iarc monographs on the evaluation of carcinogenic risks to humans, vol. 100) summary in baan r. a review of human carcinogens-part f: chemical agents and related occupations. The Lancet Oncology 2009; 10: 1143-44.
82. Summaries IARC and Evaluations: Polychlorinated biphenyls (group 2a). lyon international agency for research on cancer. (IARC Monographs on the Evaluation of Carcinogenic Risks to Human 1987; 7: 322.
83. UNEP (1999): Dioxin and furan inventories: National and regional emissions of PCDD/PCDF. Geneva, United Nations Environment Programme, UNEP Chemicals (http://portalserver.unepchemicals.ch/Publications/DioxinFuranInvMay99.pdf).
84. WHO (2004): Health-care waste management. Geneva, World Health Organization (Fact Sheet No. 281; http://www.who.int/mediacentre/factsheets/fs281).
85. WHO (2010): Global Environment Monitoring System – Food Contamination Monitoring and Assessment Programme (GEMS/Food). Geneva, World Health Organization (http://www.who.int/foodsafety/chem/gems).
    

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    Kavitha J, Sivakrishnan S, Lakshmisree S and Srinivasan S: Pollution in dentistry - a critical review. Int J Pharm Sci & Res 2020; 11(7): 3069-77. doi: 10.13040/IJPSR.0975-8232.11(7).3069-77.

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