Investigation of distribution of radioactivity with effects of heavy metals in toothpastes from Penang markets.

This study was carried out to determine the concentration of 222Rn, 226Ra, and 238U in 25 different toothpastes available in the local market in Penang, Malaysia, using a CR-39 detector. The results showed the maximum concentration of radon/ radium/uranium to be 4197.644 Bq.m-3, 54.369 Bq.Kgm-1, and 0.044 ppm in Colgate4; the annual effective dose was found (0.402 mSvy-1) in S07. The average concentration of radon (42 %, 3.224 KBq.m-3) was higher than the concentration of 214Po, 218Po in POS (32 %, 2.415 KBq.m-3) and POW (26 %, 1.979 KBq.m-3). Also the values of pH of samples ranged from 4.21 (highly acidic) in S04 to 9.97 (highly basic) in S07, with an average of 6.33 which tended towards an acidic behavior; a low or high pH for a long period of time can cause harmful side-effects and enamel erosion. Concentrations of heavy metals varied from the maximum value 56.156 ppm in the Ca elements in the Colgate 4 sample to a minimum value of -0.858 ppm in the Cd elements in Colgate 6 (Ca 56.156 ppm > Cd 51.572 ppm > Zn 41.039 ppm > Mg 11.682 ppm > Pb 11.009 ppm]. Monitoring the accumulation of these metals in toothpaste samples is very important: the average annual effective dose (0.3118 mSvy-1) was below the range (3-10 mSvy-1) reported by ICRP (1993), and therefore there is no evidence of health problems. Significant strong positive correlations were found (r = 1, Pearson correlation, p < 0.000) in concentration of radon, radium, uranium, annual effective dose, pH, and electrical conductivity.