Public ingestion exposure to 226Ra in Ramsar, Iran

Abstract

Ramsar, in the north of Iran by the Caspian Sea, has been known for the highest natural radiation background on Earth due to the local geology and hydrogeology. The residents and visitors use the hot springs that distribute the natural radionuclides especially 226Ra and its decay products in the areas. Many studies have been undertaken to measure the absorbed dose rate in Ramsar's air, however, no survey has been done to assess public internal exposure from ingestion of natural radionuclides, such as, a broad survey for 226Ra was conducted in foodstuffs and drinking water. This study presents the results of public annual activity intake (Bq) and effective dose (μSv) from ingestion of 226Ra in foodstuffs and drinking water in Ramsar city. The total mean annual intake for adults was found to be 24.8 Bq. The annual average effective dose due to ingestion exposure to 226Ra was found to be 6.9 μSv for adults that were slightly more than the estimated global averages reported by UNSCEAR, 2000 (6.3 μSv). The contribution of drinking water and foodstuffs represent respectively about 30% and 70% of the total mean annual effective dose due to 226Ra. The highest effective dose from ingestion of 226Ra for adults was estimated to be 80.6 μSv y−1. Based on the results of this study, even with the largest 226Ra value in our survey, maximum annual effective dose due to consumption of foodstuffs and drinking water for children was 164.2 μ b Sv y−1.