Determining additional risk of carcinogenicity and non-carcinogenicity of heavy metals (lead and arsenic) in raw and as-consumed samples of imported rice in Tehran, Iran

Rice is considered the most main food in Iranian diet. Its chemical contamination with heavy metals can lead to adverse effects to human health. In the present study, 60 imported rice samples from 20 different brands were collected and examined in terms of lead and arsenic levels in Tehran. Besides, point estimation and uncertainty analysis were used to determine the additional risk of carcinogenicity and non-carcinogenicity in raw and as-consumed rice. The results showed that the means of lead and arsenic (mg/kg fresh weight) in raw sampled rice were 0.0352 +/- 0.0398 and 0.106 +/- 0.049, respectively, and they were 0.0226 +/- 0.0360 and 0.0689 +/- 0.046 in as-consumed rice, respectively. Additionally, lead and arsenic amounts were 5% and 15% higher than the value set by Institute of Standards and Industrial Research of Iran respectively, while assessment of the non-carcinogenicity risk of lead and arsenic in point estimation and uncertainty analysis showed the hazard quotient and hazard index values were less than 1 and in safe ranges in both raw and as-consumed rice and were not considered a threat to the public health. The additional risk of arsenic carcinogenicity in point estimation and uncertainty analysis in raw and as-consumed rice samples found higher than the 1E-06 EPA's acceptable level of risk. So, these results could be applicable and encourage researchers to perform more detailed studies with more samples for considering by food authorities.