Secrecy Over Radioactivity in Goa - I

Why is everyone silent on this critical issue? One fear is that the radiation bogey may drive away tourists. Another fear is that it may change the way we look at diet, public health and diagnose certain diseases - like the kidney ailments in Canacona, a location that has radioactive granite rocks.

If knowledge is power then hiding it from public is to make them powerless and vulnerable. People have the right know about the concentration of radio elements in soil, water, and food, and concentration of radon in local and imported building materials like granite tiles

By Nandkumar M Kamat

 

t is a dirty secret, which the government is not willing to disclose. It is a shame that Goa doesn’t have a comprehensive natural radioactivity map in public domain. The central government is promoting the sale of iodized salt even in areas where people have a lot of iodine-rich sea food, not because it is worried about iodine deficiency disorders (there are other serious issues like Vitamin A, iron deficiency to be tackled), but because it is anxious to build a natural iodine reserve among population exposed to radioactivity - natural - from atmospheric fallout. It is also an undisclosed part of India’s nuclear expansion programme doctrine - a preventive build-up of iodine in population if a nuclear accident takes place. Goa is such an area in the shadow of Kaiga nuclear power station.

Why is everyone silent on this critical issue? One fear is that the radiation bogey may drive away tourists. Another fear is that it may change the way we look at diet, public health and diagnose certain diseases - like the kidney ailments in Canacona, a location that has radioactive granite rocks. If knowledge is power then hiding it from public is to make them powerless and vulnerable. People have the right know about the concentration of radio elements in soil, water, and food, and concentration of radon in local and imported building materials like granite tiles.  

Studies carried out 30 years ago by Bhabha Atomic Research Centre (BARC) were not comprehensive. Actually these had been done under a very closed and draconian regime. To what extent are natural radioactive elements and radon responsible for kidney diseases in Canacona, rising breast cancers, tumours and fibroids among Goan women?

To search for this answer we can’t go to DSTE, FDA, GSPCB, and Goa Medical College, Goa University or NIO. They are tight lipped over such sensitive issues. But there is one saviour of Goa, who is not afraid of calling a spade a spade. His name is D N Avadhani.

Dr Avadhani is an experienced radiation physicist and   heads the department of physics at R V College of Engineering, Bengaluru. He has mapped natural radioactivity in Goa. His first paper with five co-authors published in 2001 was about radioactivity in beach sands of Goa to be followed by another one in 2005 namely ‘Distribution and Behaviour of Natural Radionuclides in Soil Samples of Goa.’ This was followed in 2006 by studies on natural radioactivity in Vegetation Samples of Goa Environment with two co-authors.

He surprised the nuclear world when he presented a paper on the radioactive element polonium-210 in the total environment of Goa at the DAE-BRNS symposium on Nuclear and Radiochemistry at M S University of Baroda in 2007. He estimated the concentration of radioactive radium (226), thorium (232) and potassium (40) in soil samples of Canacona, Balli, Margao, Cortalim, Vasco, Panaji, Mapusa, Sanquelim, Valpoi, Dharbandora, Quepem, Netravalim, Ponda, Keri and the mining area. Radioactivity was expressed in bequerel (Bq) units per kilogram of sampled soil. Margao had the lowest concentration of radium (3.8) and Sanquelim the highest (49.1). Thorium was lowest in Margao soils (2.8) and highest in Canacona soils (78). Radioactive potassium was lowest at Keri (30) and unsually high in Canacona soil (680).

When radioactive elements are present in the soil the gamma rays emitted by these into the air are estimated as gamma absorbed dose rate in air, also known as total ionizing dose (TID). It is estimated in nGy per hour units (G for gray and nG for nanogray).

The world average is 56 nGy per hour. But in Goa it was found to be higher at Canacona (96), Panaji (61) and Sanquelim (63) although not alarming.  In the whole of Goa the dose ranged from 36 to 110 and is claimed to be within the global range (28 to 160).

They investigated some of the food samples like vegetables and rice, marine food samples like fish and prawn and diet samples such as composite vegetarian and non-vegetarian meals, breakfast, etc, were collected and analysed for their natural radionuclides concentration. They reported activity of radium-226  in ridge gourd, spinach and rice samples which varied from 0.11 to 0.17 Bq per kg, 0.08 to 0.17 Bq per kg and 0.10 to 0.25 Bq per kg with corresponding mean values of 0.14 Bq, 0.12 Bq  and 0.15 Bq per kg respectively.

As for seafood that is popular among Goans the amount of radioactive radium (226) in fish was found to vary in the range 0.25 to 0.27 Bq per kg with a mean value of 0.26 Bq per kg and in prawn in the range 0.07 to 0.10 Bq per kg with a mean value of 0.08 Bq per kg. The radioactivity in non-vegetarian meals was found to vary in the range 0.22 to 0.34 Bq per kg with a mean value of 0.29 Bq per kg and that in vegetarian meal found to vary in the range 0.09 to 0.16 Bq per with a mean value of and 0.12 Bq per kg.

What do these values mean to common people? They need to know that although not very harmful, their non veg diet that includes marine fish has more radioactive radium, may compete with normal Calcium in body. The values of radium in vegetable samples of Goa are in range of 0.08 to 0.17 and are much above world range of 0.04 to 0.07 reported by Maul and O’Hara. This is indeed alarming but not at all threatening, at least for now. Values for rice in Goa ranged from 0.10 to 0.25.

There are two radioactive radionuclides cesium-137 and strontium-90 which enter Goa from radioactive fallout with atmospheric circulation. The activity of cesium-137 in non-vegetarian and vegetarian meals was found to vary in the range 0.03 to 0.09 Bq per kg and BDL 0.15 Bq per kg respectively with corresponding mean value of 0.048 Bq per kg and 0.080 Bq per kg. Similarly, the activity of strontium-90 observed in non-vegetarian and vegetarian meals varied in the range BDL 0.07 Bq per kg and BDL 0.05 Bq per kg respectively with corresponding mean values of 0.060 Bq per kg and 0.035 Bq per kg.

In the next part we shall see the dietary intake of radionuclides (daily intake of radioactivity) that enters our body - a fact, although benign, is considered unimportant by public health authorities, the FDA and the Science, Technology and Environment department. This information is specific to Goa and therefore readers have the right to know what they and their kids are consuming.

(To be concluded)