In a article published in science direct entitled as "Preliminary investigation of naturally occurring radionuclides in some traditional medicinal plants used in Nigeria", the author used the following formula for calculation of threshold consumption rate due to ingestion of medicinal plant in Nigeria. (link of the article Article Preliminary investigation of naturally occurring radionuclid...
Cr=3*Eave/Sum of (DCFi*Ai)
where; Eave=0.3 mSv/yr is the threshold average annual committed effective dose due to ingestion of NORMs in the medicinal plants as published by UNSCEAR (2000), A1 A2 and A3 are Specific activity concentrations of 40K, 226Ra and 232Th respectively in the medicinal plant samples, DCF1, DCF2 and DCF3 are the DCFing for 40K, 226Ra and 232Th (i.e 6.2 106 mSv/ Bq, 2.8 104 mSv/Bq and 2.3 104 mSv/Bq for 40K, 226Ra and 232Th respectively).
In our study we observed that 40K and 232Th are present in the samples and the activity concentration of Ra-226 is below the detection level of our system. As we found two radionuclides (namely 40K and 232Th) in our measurement then what would be formula for consumption rate?
If I rewrite the formula as given below
Cr=2*Eave/Sum of (DCFi*Ai)
then it would be right or not???