Dr. Kavita Yadav is a dentist and a public health professional.she has been part of many research projects and has represented India in many international forums. She has many journal articles to her credit and has presented papers in national and international conferences. She has been heading the national campaign “Mercury Free Dentistry”. Here’s excerpt from an interaction.
What is Mercury?
Dr. Kavita: Mercury is a naturally occurring liquid metal and exists in various forms: elemental (or metallic) and inorganic and organic .WHO considers mercury to be one of the top ten chemicals of public health concern as it causes significant damage to the environment and to the human health.
How does mercury affect the environment?
Dr. Kavita: Once the mercury is in the environment, it doesn’t remain limited to its source but travels, at times even thousands of kilometers away from the source. Mercury can also get transformed by bacteria into methylmercury which is even more toxic as it enters the food chain and then undergoes biomagnifications (eg. large predatory fish are more likely to have high levels of mercury as a result of eating many smaller fish). Exposure to this methymercury can cause impaired neurological development. Cognitive thinking, memory, attention, language and fine motor and visual spatial skills are highly compromised in children who were exposed to methylmercury as fetuses.
How are we exposed to mercury?
Dr. Kavita: Mercury exists in various forms, and people may be exposed to its different forms under different circumstances. The most common way is by eating fish /shellfish containing methylmercury. Other exposures may result from using or breaking products containing mercury. Dental amalgam is also well known source of continuous mercury exposure for the general population who happen to have amalgam filling in their teeth.
What is dental amalgam and how does it affect us?
Dr. Kavita: Dental amalgam is a type of dental filling which is black in colour and contains 50% mercury by weight. A major portion of the mercury vapor that is released from the amalgam filling gets absorbed into the blood and gets distributed to other organs of the body. As metallic mercury is lipophilic (fat loving), it can enter the brain and the womb of mother where it gets oxidized to inorganic form. Once in the inorganic form, mercury cannot move and hence gets accumulated in the brain and fetal tissues. The inorganic salts of mercury are corrosive to the skin, eyes and gastrointestinal tract. In this way, the level of mercury can increases in the urine, feces, blood, saliva, exhaled air, kidney, pituitary gland, liver and even breast milk. Studies have shown that the average uptake of mercury from amalgam filling can be as high as 19 micrograms/day. Apart from damaging the internal organs, mercury also shows effects in mouth like white patches, burning-mouth sensation and ulcers. These health risks of mercury exposure from dental amalgam are not just limited to the patient with amalgam fillings. Dentists are also exposed to high concentra¬tions of mercury not only while doing an amalgam filling but while removing amalgam fillings as well.
Are there any safer options?
Dr. Kavita: The best way to avoid mercury is by opting for the mercury free fillings instead of amalgam.GIC and Composites are the currently available options which are not only tooth colour but also provide the strength needed for a filling material to withstand the chewing forces. So next time when you visit your dentist, don’t forget to ask for a mercury free filling.
What is being done at global level?
Dr. Kavita: To address the issues of mercury toxicity and to protect human health and the environment from hazardous and toxic mercury, in January, 2013, 140 countries in Geneva adopted a ground-breaking, world’s first legally binding treaty on mercury, now called “Minamata Convention on Mercury,” limiting the use and emission of health-hazardous mercury. To-date, the convention has already been signed by 128 countries and ratified by 98countries. India is also a signatory to Minamata convention and took a decision to ratify the convention on 18th June 2018.