Evaluation of doses from ionising radiation to non-human species at Trombay, Mumbai, India.

In order to meet the proposed regulatory compliances for the protection of non-human species from the ionising radiation, a comprehensive dose-evaluation process for terrestrial and aquatic biota was worked out at Trombay. During this work, dose rate (external and internal) from ionising radiation to the terrestrial plants and marine organisms (mixed varieties of fish) was evaluated by estimating the concentration of anthropogenic ((137)Cs, (90)Sr) and natural radionuclides ((238)U, (232)Th and (40)K) in environmental matrices, such as soil, vegetation, sea water and sediment. The samples were processed as per the International Atomic Energy Agency protocol for the estimation of naturally occurring and anthropogenic radionuclides. The average values of radiation exposure to the terrestrial plants for (40)K, (90)Sr, (137)Cs, (232)Th and (238)U were 632.8 +/- 40.5, 167.4 +/- 48.2, 691.2 +/- 29.9, 48769 +/- 13203 and 1801 +/- 1495 microGy y(-1), respectively. In the case of marine organisms (fish), the maximum external exposure was 195 microGy y(-1) due to (40)K concentration in bottom sediment, whereas the minimum was 0.004 microGy y(-1) due to (137)Cs in sea water. Internal exposure to fish was maximum (700 microGy y(-1)) due to (40)K, whereas the minimum of 0.12 microGy y(-1) was due to (90)Sr. Considering the dose limit of 10 mGy d(-1) (3.65 Gy y(-1)), proposed by the US Department of Energy, evaluated radiation exposure (external + internal) and dose rate in the present study to the terrestrial plants and marine organisms are orders of magnitude less.