Indian Rare Earths mining area at Vellanathu Thuruth in Kollam. file | Photo Credit: C. Sureshkumar
In a pan-India study conducted by scientists at the Bhabha Atomic Research Center (BARC), in parts of Kerala, the level of background radiation, or that emitted from natural sources such as rocks, sand or mountains, was nearly three times higher than estimated Is. found. However this does not translate into a higher health risk.
The radiation originates from the decaying nucleus of an unstable element and can come from anywhere, including from inside our bodies to the constituents of matter. Gamma rays are a type of radiation that can pass through matter unimpeded. Although highly energetic, they are harmless unless present in large enough concentrated doses. It is similar to the heat from a fire that feels pleasant until a sustained, focused burst can start or worsen the fire.
Especially around nuclear plants, gamma radiation levels are monitored as well as the average amount of radiation that plant workers are exposed to. The International Atomic Energy Agency (IAEA) specifies maximum radiation exposure levels and this has also been adopted by the Atomic Energy Establishment of India. Public exposure should not exceed 1 milli-Sievert per year, people who work in plants or at the base of their occupation should not exceed 30 milli-Sievert per year.
The present study found that the average natural background level of gamma radiation in India was 94 nGy/hr (nano gray per hour) (or roughly 0.8 millisievert/year). The last such study, carried out in 1986, calculated such radiation at 89 nGy/hr. 1 gray is equal to 1 sievert, although one unit refers to emitted radiation and the other to biological risk.
However, a 1986 study measured the highest radiation exposure at Chavara, Kerala, at 3,002 nGy/year. The current study found that the level in Kollam district (where Chavara is located) was 9,562 nGy/hr, or nearly three times higher. This calculates to about 70 mg per year, or slightly more than a worker at a nuclear plant would be exposed to. “This does not mean that Kollam is being exposed to high, dangerous levels of radiation. There have been extensive studies in the past that have examined high rates of cancer or mortality and found nothing unusual, told Dinesh Aswal, senior scientist at BARC and one of the authors of the study. Hindu, “It only shows that the body is accustomed to high doses of radiation. The limits set by the IAEA are extremely conservative and reflect only an abundance of caution.”
The high radiation levels in Kollam are attributed to monazite sand, which has a high concentration of thorium, and has been part of India’s long-term plan for sustainable production of nuclear fuel for many years. Southern India, due to the presence of granite and basaltic, volcanic rock has high levels of radiation from uranium deposits.
“We have found a slight reasonable relationship between soil classes and absorbed dose rate. Low values of absorbed dose rate in air (about 67 nGy/h) were recorded for mixed red and black soils of Maharashtra and Gujarat, while high values (about 170 nGy/h) were recorded in the west-coastal plains of Kerala that included coastal and derived delta alluvial soils,” the authors note in the study, which is published this month in peer-reviewed Journal of Environmental Radioactivity,
Dr Aswal said that India’s plans to increase dependence on nuclear power meant that the time had come to update estimates on natural background radiation.
The current study measured radiation levels from nearly 100,000 locations across the country, in contrast to a 1986 survey that mapped only 214 locations.
