MERCURY IN OUR LIVES

Mercury is an element to which we are no strangers. From sphygmomanometers for measuring our blood pressure to the thermometer for measuring our body temperature; this metal is surprisingly so remarkably liquid that by the virtue of this magic anomaly it has occupied a place in our minds which no other element can.

However, the tide of public opinion, with solid scientific evidence to back it up in several instances is slowly turning against this element’s place in our lives. Mercury is a bioacccumulative toxicant and is easily absorbed through the skin, respiratory as well as gastrointestinal tissues. It attacks the central nervous system and endocrine system and badly affects the mouth, teeth and gums. It has been implicated in brain damage, and researchers have evidence to link this element with autism and even Alzheimer’s disease. Mercury exposure in very young children can have severe neurological consequences: - Mercury has been shown to have an inhibitory effect on myelin, the building block protein that forms nerve sheaths.

In much of the developed world, mercury is being replaced with safer alternatives. Thus:-

• Several states in the US have banned the use of mercury thermometers. Also, with the exception of some Influenza (flu) vaccines, none of the vaccines used in the U.S. to protect preschool children against 12 infectious diseases contain thiomersal, an organo-mercury compound as a preservative.

• Sweden has banned import, manufacture and sale of mercury thermometers since 1992. And in 1994, announced a phased ban of dental amalgam.

• EU has announced a phase-out of mercury thermometers this year. In fact, the EU strategy aims at minimising mercury emissions by phasing out European exports of the chemical by 2011 as well as reducing European demand

• Germany has issued warnings against amalgam in children, pregnant women and people with kidney problems.

Today, India is the world’s largest consumer of Mercury. The Hazardous Waste Management and Handling Rules 1989 of the Government of India which cover a few mercury compounds as ‘‘waste’’ does not include mercury from healthcare products. After 1992, mercury came under the Open General License meaning, any trader is free to import mercury as much as he wants. Also, there is no inventory of where this mercury is going. India’s imports of this metal have more than doubled in six years—from 254 tonnes in 1996-97 to 531 tonnes in 2002-3—displacing US as the largest consumer of mercury in the world.

The large unregulated market involving mercury remains that of thermometer manufacturers and those which make thermostats, button cells and tube lights. Mercury is used by Chloralkali plants which remain the major consumers, 13% of our mercury imports are for Choralkali plants. Other consumers of this metal are from a range of industries such as: - ayurveda, paints and pesticides, temple and gurudwara builders, bangles and cosmetic industry and, of course, parad shivling manufacturers. Incidentally, each parad shivling has mercury to the extent of 30% by weight making it one of the most serious examples of uncontrolled mercury use in the country.

The use of mercury in dentistry for tooth fillings in the form of amalgams has its supporters as well as detractors. The critics argue that that Critics argue that long-term exposure to the low levels of mercury vapor causes neurodegenerative diseases, birth defects, and mental disorders. Supporters claim and with evidence that “Mercury has been a major ingredient of dental amalgam (35-42 percent) for more than 150 years. No other filling material has been proven to be safer, more durable and more cost-effective. The National Institutes of Health reports only about 100 documented cases of allergy to mercury mentioned in the scientific literature since 1906 - despite billions of uses of mercury amalgam and tens of millions more of thimerosal-containing vaccines. Fillings containing mercury typically emit about 1-3 millionths of a gram (micrograms) per day. An individual might be unavoidably exposed to another 5-6 micrograms of mercury through food, water and air. Such exposures are well below the World Health Organization’s "acceptable daily intake" for mercury, about 30 micrograms per day”.

According to the Handbook of Pharmaceutical Excipients, 2005 published by the American Pharmacists Association the following is the regulatory data for organomercury based preservatives:-

• Phenylmercuric acetate is no longer permitted to be used as a pesticide in the USA. It is, however, included in the FDA Inactive Ingredients Guide (ophthalmic preparations), and is also included in nonparenteral medicines licensed in the UK. In France, a maximum concentration of 0.01% is permitted for use in pharmaceuticals. The use of phenylmercuric acetate in cosmetics is restricted in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients (however, there must be no other suitable preservatives available).

• Phenylmercuric nitrate is included in the FDA Inactive Ingredients Guide (IM and ophthalmic preparations). Included in nonparenteral medicines licensed in the UK. In the UK, the use of phenylmercuric salts in cosmetics is limited to 0.003% (calculated as mercury, equivalent to approximately 0.0047% of phenylmercuric nitrate) as a preservative in shampoos and hair creams, which contain nonionic emulsifiers that would render other preservatives ineffective. Total permitted concentration, as mercury, when mixed with other mercury compounds is 0.007% (equivalent up to approximately 0.011% of phenylmercuric nitrate). This preservative is also included in the Canadian List of Acceptable Non-medicinal Ingredients (ophthalmic, nasal and otic preparations only; there must be no other suitable alternative preservative).

• Phenylmercuric borate is included in nonparenteral medicines licensed in Europe. In France, a maximum concentration of up to 0.01% is permitted for use in pharmaceutical formulations. In the UK, the use of phenylmercuric borate in cosmetics is restricted. Included in the Canadian List of Acceptable Non-medicinal Ingredients (ophthalmic, nasal and otic preparations; there must be no other suitable alternative preservative).

• Thiomersal is included in the FDA Inactive Ingredients Guide (IM, IV, and SC injections; ophthalmic, otic, and topical preparations). Included in nonparenteral and parenteral medicines licensed in the UK. In the UK, the use of thiomersal in cosmetics is limited to 0.003% w/w (calculated as mercury) as a preservative in shampoos and hair-creams, which contain nonionic emulsifiers that would render other preservatives ineffective. The total permitted concentration (calculated as mercury) when mixed with other mercury compounds is 0.007% w/w. Included in the Canadian List of Acceptable Non-medicinal Ingredients.

The following mercury based agrochemicals are mentioned in the list of insecticides given in the recent SCHEDULE, GAZETTE OF INDIA, EXTRAORDINARY:-

• ethyl mercury phosphate
• ethyl mercury chloride
• mercury (I) chloride
• methoxy ethyl mercury chloride
• methyl mercury chloride
• phenylmercury acetate
• phenyl mercury chloride
• phenyl mercury urea
• tolyl mercury acetate

The Charaka Samhita contains medications using minerals and metals and mercury is involved in some of this recipes. Thus, in a sense mercury is an active pharmaceutical ingredient of Ayurveda. This is further reinforced by an Ayurvedic patent from US patent office issued in 2005. The patent abstracts an ayurvedic mercury based preparation for the treatment of leukemia. The abstract is as follows: -

“The present invention relates to a process on ayurvedic preparation comprising in the steps of subjecting silver, mercury, sulphur and arsenic trisulphide to the steps of detoxification, grinding the detoxified mercury and silver in the presence of a citrus juice and then adding detoxified sulphur and again subjecting to the step of grinding to obtain a greyish black powder, adding detoxified arsenic trisulphide thereto and subjecting to the step of grinding, imparting a shape such as a ball thereto, coating the ball with detoxified sulphur in the presence of a citrus juice and subjecting the coated ball to the step of slow firing, adding detoxified arsenic trisulphide and firing, repeating said step of addition and firing ground in a citrus juice such that the weight of the ball is reduced by at least 10% to obtain an intermediate, adding serpentive and delphenium root thereto.”

CONCLUSION:-

The use of mercury and mercury based compounds in our lives ranges from agrochemicals to preservatives, from dental amalgams to instruments for monitoring our blood pressure and body temperature, from various gauges in industries to chloralkali plants to religious icons such as silver amalgam based shivlings and traditional Ayurvedic formulations.

While there is no doubt about the toxicity of mercury, a benefit to risk examination by various concerned authorities, of its use in the areas of dentistry in the form of amalgam fillers and as various organo-mercury preservatives for pharmaceutical and cosmeceutical formulations shows that the benefits actually outweigh the risks by quite some margin. Incidentally, mercury was and remains an active ingredient of certain mineral based Ayurvedic formulations. –Dr. V.R. Shenoy

REFERENCES

• CDC document on thiomersal safety.
• Lorscheider and Syed, How Mercury Causes Brain Neuron Degeneration, University of Calgary.
• Bernard et al, Medical Hypotheses, 56(4)(2001)462–471
• Mercury in health care, WHO Policy Paper, August 2005
• Oken et al, Environmental Health Perspectives, 113(10) October 2005,1376-1380.
• Sonu Jain, Rest of world phases out mercury, India unchecked Consumer No. 1, Indian Express, 22^nd June, 2006
• Steven Milloy, Mercury Ban Promotes Lawsuits, Not Health, Fox News, Friday, May 10, 2002
• Handbook of Pharmaceutical Excipients, 2005, APhA.
• United States Patent 6,939,567