Evaluation of natural radioactivity and assessment of health risk due to the consumption of medicinal plants grown in the Western Ghat region of India

ABSTRACT

The radioactivity concentrations in soil and medicinal plants from the Western Ghat region of India were determined using NaI(Tl) gamma spectrometry. The mean activity of ²³²Th, ²²⁶Ra and ⁴⁰K in soil was found to be 15.0 ± 0.9 Bq kg⁻¹, 35.8 ± 2.1 Bq kg⁻¹ and 65.1 ± 2.2 Bq kg⁻¹. In medicinal plants, the mean activity was found to be 9.3 ± 1.1 Bq kg⁻¹, 28.4 ± 2.8 Bq kg⁻¹ and 76.3 ± 3.7 Bq kg^−1, respectively. The calculated transfer factors from soil to plant range from 0.70 to 2.88, 0.49 to 1.64 and 0.37 to 1.53 for ⁴⁰K, ²²⁶Ra and ²³²Th, respectively. The mean transfer factor of ⁴⁰K is greater than that of ²²⁶Ra and ²³²Th, showing a substantial increase of ⁴⁰K in the plant by root uptake. The estimated average yearly effective dosage for the age group of 15 years and older in the study is much lower than the world average, whereas, for the age group of 5 years, the Mesua ferrea, Moringa oleifera, and Piper betle medicinal plant are above the recommended word average of 0.3 mSv y⁻¹ for an individual as reported UNSCEAR, 2000. As a result, the consumption of medicinal plants does not pose a substantial health risk and is radiologically safe for intake by people aged 15 years and above, but not to individuals under the age of 5. The possible impact of natural radiation on a human has been assessed by calculating the hazard parameters and all values within the internationally recommended limits. The impact of soil physico-chemical properties on soil-medicinal plant transfer factor was assessed. The study will serve as a baseline data on the transfer of radionuclides from the soil to medicinal plants and from medicinal plants to human as well as guidelines on the development of herbal drugs for future pharmacological and phytochemical studies.

KEYWORDS:

• Gamma spectroscopy
• natural radioactivity
• soil
• medicinal plants
• annual committed effective dose
• physico-chemical properties

Disclosure statement

The authors declare that they have no conflict of interest.