| Abstract|| |
Aim: The present study aimed to measure the concentration of lead in various indigenous preparations of tooth powders available and used locally in and around Udaipur, Rajasthan, India.
Materials and Methods: Seven different brands of tooth powders manufactured and/or marketed locally were obtained from stores all over Udaipur city. Some home-made powders commonly used for cleaning teeth were also collected. The tooth powders were analyzed for lead content by atomic absorption spectrophotometry.
Results: All tooth powders tested were found to contain high levels of lead ranging from 21 ppm to 82 ppm, above the maximum permissible level of 20 ppm prescribed by the Bureau of Indian Standards.
Conclusion: Indigenous tooth powders contain high levels of lead and thus may be a source of lead poisoning that is often overlooked.
Keywords: Covert lead poisoning, indigenous tooth powders, lead in tooth powders
|How to cite this article:|
Hegde S, Shubha A B, Rao B D. Indigenous tooth powders = Covert lead poisoning?. Indian J Dent Res 2013;24:678-80
The knowledge of the importance of oral hygiene is not recent for the Indian people. However, almost 70% of the Indian population resides in rural areas  and a majority of this rural Indian population remains deeply rooted in tradition and culture and depends largely on traditional systems for the maintenance of oral hygiene. ,
Indigenous materials commonly used by the Indian rural folk for cleaning the teeth include those derived from plants or their parts such as leaves (mango, cashew, coconut), twigs and stems (babul/Acasia arabica, neem/Azadirachita indica), fruits or their parts (coconut), bark (walnut), charcoal from rice husk, walnut/almond shell, coconut shell and its sheath, wood, coal and other powders (sand, common salt-powder and crystalline, brick and tile powder, tobacco, areca nut).  In addition, a variety of indigenous tooth powders are marketed which are very popular with the local people. Many of these age-old formulations of tooth powders may contain harmful ingredients and one of them is lead. This is because lead is naturally-occurring, is present in the environment and can make its way in trace quantities into raw materials. 
The toxicity of lead is well-established and this heavy metal is known to affect several organ systems including the nervous, hemopoietic, renal, endocrine and skeletal systems. Pediatric lead poisoning is associated with an increased risk of undesirable effects, by virtue of children being in the growth phase and because of their increased capacity for absorption and retention. , Adult humans absorb 10-15% of ingested lead; however, children absorb up to 50% of ingested lead. ,
In adults, 94% of absorbed lead is deposited in the bones and teeth, but children store only 70% in this manner, a fact which may partially account for the more serious health impacts on children.  The half-life of lead in the blood in adults is about 40 days, but it may be longer in children whose bones are undergoing remodeling,  which allows the lead to be continuously re-introduced into the bloodstream. 
Although the Indian legislation states that the concentration of impurities such as lead should be no more than 20 ppm,  there are no centralized laws governing the manufacture of cosmetics (which include tooth pastes and tooth powders) in India. Hence a number of local brands flood the market. The use of tooth powders that may contain lead poses a potential health risk, which is increased further in young children who may ingest the tooth powder while cleaning their teeth with it. Therefore, our study aimed at measuring the concentration of lead in various indigenous preparations of tooth powders available and used locally in and around Udaipur, Rajasthan, India.
| Materials and Methods|| |
Seven different brands-Vardhaman Dant Manjan (Shri Vardhman Jivdaya Kendra, Mumbai, Maharashtra), Lip-pink (Vikram Bahuddeshiya Anusandhan Kendra, Ajmer, Rajasthan), Kasturi Dant Manjan (Kasturi Udyog, Bundi, Rajasthan), Gurukul Dant Manjan (Gurukul Udyog, Udaipur, Rajasthan), Dant Prabhakar Churn (Krishna Gopal Ayurvedic Bhavan, Ajmer, Rajasthan), Bajaj Kala Dant Manjan (Vilas Udyog, Udaipur, Rajasthan), Payokill Churn (Gurukul Kangri Pharmacy, Haridwar, Uttarkhand)-of tooth powders that are manufactured and/or marketed locally were obtained from stores all over Udaipur city. In addition, some of the home-made powders (powdered charcoal from burnt wood or coconut shell etc.,) commonly used for cleaning the teeth were collected.
The tooth powder samples (1 g each) were digested in aqua regia  (nitrohydrochloric acid), a mixture formed by freshly mixing concentrated nitric acid and concentrated hydrochloric acid, usually in a volumetric ratio of 1:3 respectively. After digestion, the samples were dried and transferred to test tubes. 0.5 ml of Ammonium Pyrrolidine Dithio Carbamate solution was added to each tube and the tube was capped and inverted 15 times, then allowed to stand for 5 min, after which 3 ml of n-butyl acetate was added. The tube was capped again and shaken for a minimum 3 min at a rate sufficient to ensure adequate mixing. The tube was then centrifuged at 3000 revolutions/min for 2 min. The contents of the tube were aspirated into the flame of the Atomic Absorption Spectrophotometer with electrothermal atomization (Varian Inc., Palo Alto, CA, USA) and absorbance was recorded. The specifications of the instrument were: Lamp current 9.0 mA, wavelength 217.0 nm, band pass 0.5-1.0 nm, ash temperature 800°C and atomization 2300°C without temperature control. ,,
| Results|| |
The present study was conducted to determine the levels of lead in seven locally manufactured and two home-made preparations of tooth powders widely used in and around Udaipur, Rajasthan, India.
All the tooth powders tested were found to contain high levels of lead ranging from 21 ppm to 82 ppm [Table 1], all above the maximum permissible level of 20 ppm prescribed by the Bureau of Indian Standards. 
| Discussion|| |
Uncommon sources of lead exposure include water boiled in leaded pots and pans, cosmetics (kohl, hair dyes, sindoor, lipstick) ,, and folk medicines  (lead acetate). Indigenous preparations of tooth powders could very well be sources of lead that have been ignored or overlooked.
Acceptable limits for heavy metals like lead vary according to the subpopulation of interest (e.g., children are more susceptible to heavy metal toxicity than adults; have greater exposure potential due to hand-to-mouth activity), the amount of product used and the site of application (e.g., arms vs. lips). 
Health Canada has determined that lead concentrations in cosmetic products are seen to be technically avoidable when they exceed 10 ppm.  The German Federal Government conducted tests to determine background levels of heavy metal contents in tooth pastes and other cosmetic products. Based on their studies, it was determined that lead levels in cosmetic products above 20 ppm are considered technically avoidable.  In addition, following a survey of its member companies, the German Industrial Association for Personal Care and Detergents Inc. confirmed that heavy metal contents in tooth pastes are at least a decimal power lower than for other cosmetic products.  Therefore, the Commission for Cosmetic Products at the Federal Ministry of Health in Germany concluded that 1 ppm is the maximum acceptable concentration of lead for tooth pastes. 
The Bureau of Indian Standards limits the concentration of lead in cosmetics including tooth pastes and tooth powders (IS code no. 5383:1978) to not more than 20 ppm when tested by the methods prescribed in the Indian Standards.  In the present study, we found that all the tooth powders tested contained levels of lead higher than this maximum permissible level.
It is the manufacturer's responsibility to ensure that the finished product contains as few heavy metal impurities as possible so that it does not exceed the limits. By law, manufacturers must ensure that their products and the ingredients used in the manufacture of their products are of high quality and safe and do not pose a health risk to consumers.
However, there are no centralized standards for ingredient purity and while it seems likely that some companies purchase or manufacture refined, purified ingredients, it is equally likely that many do not. Consumers and government health officials have no way to know. Because the purity of cosmetic ingredients is not regulated by law, product purity has become a business decision. Companies can weigh the cost of purchasing purified or certified ingredients against the potential liability of selling products that may contain impurities. Liabilities are low: It could be years before a disease is manifested and a doctor can rarely trace a disease back to particular exposures.
It is acknowledged that heavy metal impurities in cosmetic products are unavoidable due to the ubiquitous nature of these elements, but should be removed wherever technically feasible.  In the present study it was observed that most of the indigenous preparations of tooth powders available locally had concentrations of lead above the permissible level. These findings call for an immediate mandatory regular testing program to check the presence of lead and other toxic metals in all tooth powders manufactured locally in villages and cities in order to curtail their excess and safeguard consumer health. Simultaneously, programs to instill and increase public awareness of the less known sources of lead and the consequences of long-term chronic exposure to lead are recommended. Regulatory authorities need to give more attention to ensure that all tooth powders are free from lead and other impurities.
| Acknowledgments|| |
Dr. Anand Mohan Mahawar, MD, Chief Medical Officer, Rajpur Dariba Hospital, Dariba, for assistance in processing of samples and analysis of lead content.
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Department of Paediatric Dentistry, Pacific Dental College and Hospital, Udaipur, Rajasthan
Source of Support: None, Conflict of Interest: None