Teeth as Bio-indicators: an Aid in Identification of Silent Killers

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Environment eventually receives all what is generated by us Human Beings this has disturbed the ecosystem. Ultimately the environment has lost its recreational capacity, since it is a cycle what goes in to the ecosystem is now coming back.(Skenderovic etal., 2015) River Yamuna being the largest tributary of river Ganga also serves as the main lifeline of water supply to Delhi and NCR.Now as we are approaching the next decade we are facing huge scarcity of water as per UN consensus 2014.(Malik etal., 2014) Since Treated surface water and groundwater was distributed to consumers as tap water, bottled drinking water and bottled mineral water which were used as drinking water. Due to its immeasurable abuse it is degenerating very fast. And ended up becoming a sewage drain so much so that its water has become un-potable, harmful and toxic in nature. (Upadhyay et al., 2011)

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The condition has now become a life threatening issue due to large number of unsupervised and unmodulated expulsion in to the river from various sources like untreated sewage, industrial effluents, emersion of idols, dumping of garbage and dead bodies. Important industries like pulp and paper mills, sugar mills, distilleries, tanneries, fertilizers and petrochemical units produce enormous amount of liquid wastes. These are rich in suspended particles, heavy metals, alcohols, carbonates, detergents, soaps, metals and other organic and inorganic substances. All these chemicals in excess are found to be lethal. (Singh et al., 2012) With the financial assistance of 17.7 billion yen from Japan government Yamuna action Plan was executed by the Ministry of Environment and Forests, National River Conservation Directorate and the Government of India. The cleaning of polluted Yamuna was carried out in line with the level of the biological oxygen demand of Yamuna. 286 schemes, which also included 39 sewage treatment plants (STPs), were completed in 21 towns of Delhi, Uttar Pradesh, and Haryana at a cost of Rs 1,453.17 crore and sewage treatment capacity of 767.25 million litres per day has been created. A recent report by Energy and resource institute (Teri) stated that addition of fresh water is required on a daily basis but there are no reports on addition of fresh water. From recent reports it is very clear that there exist a huge difference in sewage production and its treatment.(Sato et al., 2006)

To solve these life threatening issues we should start first by understanding the course of the river. It starts at Saptrishi Kund and passes through different states of India like Uttaranchal, Himachal Pradesh, Uttar Pradesh, Haryana and Delhi various centers for pilgrimage are based on the banks of the river which are considered holy places, because of which the river serve as a boon for various sectors like agriculture on which majority of the people of India are dependant, Industrial sector and the Urban sector. There are 5 major parts in the tributary i) Himalayan part which still remains untouched, ii) Upper part, iii) Delhi part, iv) mixed part, vi) diluted part. Among these the Delhi part is the most polluted. The pollutants could not get diluted as the river has very little or no flow in non monsoon season. The difference in sewage production and its treatment has severely affected the water carrying capacity of the river. (Sehgal et al., 2012)

The ever increasing contamination of the river because of above mentioned reasons makes everyone of us helpless against the rising supply of Heavy metals in Human Body. Assessment of these metals should be the next important step in execution of Preventive and corrective measures. Numerous studies have been conducted to find out the presence of heavy metals in river by checking the levels in fish species it was noted that the levels were higher than the range of maximum acceptable limits as given by WHO, in vegetables grown on the river banks as well as on people dependant on river water similar results were reported. Heavy metals are bioaccumulative, Toxic, stable, dangerous, and potent carcinogenic therefore requires close monitoring. Since these metals can enter the food chain via various routes like food , water, or by consumption of soil and through skin.(Chaudhary et al.,2016)

Hence we have conducted this research work so as to evaluate the presence of these lethal metals like Lead, Chromium, Cadmium, Manganese, in the Okhla region of South Delhi in human body with the help of Teeth, as a Biomonitor. Since elemental composition of teeth can very well act as indicator of Environmental Pollution, Pollutant clearance in teeth takes place on a very slow rate as compared to other Biomonitors like Hair ,Urine, Bone and Blood and the most important reason is their easy availability.

Aims and Objective: The aim of the present study is to evaluate the levels of Heavy metals in Different layers of tooth that is enamel and dentin, Further to analyze the concentration of each heavy metals in water from Okhla region ,South Delhi.

Materials and Methods: The research included 300 healthy living subjects of various age and sex residing in Okhla region of South Delhi. This area is highly polluted due to large scale industrialization. All the subjects included in the study were informed about the course of the study and participation in the study was voluntary and subjects who gave consent were included in the research, they were given the right to withdraw from the study at any stage. Subjects working in Tea and Tobacco factories were not included similarly subjects on Vitamin supplements were also not included. Ethical approval was taken from the Faculty of Dentistry; Jamia Millia Islamia University. Each subject underwent painless tooth extraction. The extraction procedure was performed under Local Anesthesia.

Analysis of Tooth:

The tooth intended for analysis was removed completely and immediately cleaned by soaking in H2O2 to remove connective tissue, washed with deionised water and dried overnight. The teeth were individually ground and weighed and then digested in 10 ml of HNO3 using a microwave digestion system. From the prepared teeth, samples of enamel and dentin were prepared with diamond drill bits under microscope. After mechanical division of a tested tooth, enamel and dentin samples were left for 24 hours in 30% solution of H2O2 to remove organic contaminants, then washed with distilled water and high purity HPLC-grade water, dried at 80degree C, and finally ground. The obtained material was analyzed for the content of lead, cadmium, manganese, and chromium, separately for enamel and dentin of the assessed teeth by using Graphite Furnace Atomic Absorption Spectrometry (GFAAS).

Analysis of Water:

Water sample were collected in pre-cleaned plastic containers from 6 different locations Abu Fazal I & II, Shaheen Bagh, Okhla Head, Batla House and Zakir Nagar. 5ml of Nitric Acid (HNO3) was added into it so as to preserve the sample. Using measuring cylinder 100ml of water was taken and 5ml of Hydrochloric acid was added into it. This was taken into a conical flask and heated to 25ml on a hot plate. Later this water sample is taken in a volumetric flask,into this 25ml water, 100ml of distilled water was added so as to fill up to the mark were it was filtered and transferred into pre-cleaned sample bottles and further taken for atomic absorption spectrometry.

Heavy Metal determination using Atomic Absorption Spectrometry Method:

Main principle of AAS is that the ground state atoms are capable of absorbing radiant energy of their own specific resonance wavelength when passed through a solution containing the atoms in question, then part of the light will be absorbed. The extent of absorption is proportional to the number of ground state atoms present in the flame. Black model 200A flame Atomic Absorption Spectrometer was used in the metal analysis of the sample.

Levels of Heavy Metals in Groundwater, Local supply, Municipal water, RO :

In the present study we have collected sample of water from Ground, Local water supplier, Municipal water, RO water. It was reported that the concentration of Heavy Metals were very much higher than the maximum permissible limit given by WHO and Central Pollution control Board (CPCB).It was also reported that level were raised in all the samples but highest was found amongst the groundwater 1.5 μg/ml and lowest was found in the RO water which was 1.2 μg/ml. It was reported that the level of Lead in the Dentin & Enamel was highest in the Groundwater, followed by Manganese, Chromium and Cadmium.

Metals are found naturally in abundance in the environment. They are used widely in all areas of life. Although required in small amounts they are vital in maintaining optimum health because many of these elements are required for maintaining various functions, metabolic activities in the Human body since these are part of enzymes, hormones, and cells in the body. Deficiency or imbalance, whether occurring naturally or from human activities, has been shown to present significant problems for the health of man. Excessive levels, a level higher than needed for biological functions, of these elements can be toxic for the body health. Therefore, it has been found that the imbalances in the optimum levels of trace elements may adversely affect biological processes and are associated with many fatal diseases, such as cancers. (Falah S. Al-Fartusie et al., 2017).

The Levels of all the metals were significantly higher in the present study. The dentin and enamel lead level in this cohort of subjects were found to be higher as similar to the literature reported it could be through food and other exposures like alcoholism and occupational exposure, although there is no proof to rule out or confirm this possibility. Potential transfer of pollutants from metal-accumulating macrophytes to herbivores may occur. This may be a significant food chain transfer pathway which could possibly reach the human population. (Akan .J.C. et al 2014).

The Chromium levels in both the layers of tooth i.e enamel and dentin was reported higher which was similar to other researches. Higher values of Chromium could be because of stainless-steel, welding, chromium-plating, chrome-pigment, leather tanning, textile production, coal and oil combustion, chemical factories and waste incineration, etc. (Khandoker Asaduzzaman et al., 2017). Similarly the Cadmium concentration in Enamel & Dentine of Tooth were reported to be higher which is in accordance with other researches, which indicated that Environmental Pollution is the main reason for elevated levels of Heavy Metals in layers of Tooth. (M. Prodana et al .,2010A), (J. Bayo et al.,2001), (M. J. Maah et al,2001).

Manganese is considered an important Trace element for various neuronal functions but in excess causes renal failure, Hepatic and Pancreatic disorders. Manganese concentration was found to be raised could be due to Industrial effluents in this area similar results were reported in other studies also. (M. Roger., 2011).

The results of the present study indicate that hard tissues of evaluated teeth contained significantly more Heavy Metals. And also demonstrates considerable influence of the place of living on the Metal content in human teeth which is similar to other reported studies.(Alomary .A., et al 2006). Heavy metals concentration in water samples are presented in Figure 10 and Figure 11.The Heavy Metal load in water was found to be raised as compared to WHO permissible limits in water which is in accordance with other studies (Upadhyay.R et al .,2011)

None of the studies in available literature describe the concentration of trace elements in enamel and dentin of the Indian population. Available literature from other parts of the world contains reports confirming the above observation.

Trace elements play a pivotal role in maintaining optimum Health by regulating various biochemical functions in Human Body like enzymes reactions, redox reactions etc. It is also important to understand the role of these elements in causing deadly diseases like cancer, Hepatic and Renal Neural disease because these disease are on a rise recently following ever increasing Environmental Pollution. The increased levels of heavy metals in the water lead to accumulation of heavy metals in the agricultural soils and plants grown on these contaminated soils, leading to great harm to humans. Hence, it is very much important to rectify the various heavy metals resources which lead to addition of these metals into the river bodies. In addition, water should be tested regularly to keep an eye on the heavy metal pollutant into the water and purify the water.

The data obtained in this study is a significant contribution, since very few studies are conducted in India using Teeth as biomonitors. Also teeth prove to be an important resource of Knowledge regarding heavy metal levels and there co-relation to environmental pollution due to many reasons like Teeth provide a permanent cumulative and relatively stable record when compared to Blood, Hair ,Bone. Easy availability, ease in handling, analyzing the samples. However, it is proposed that further study with large sample size (representative) is desirable.

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