Public exposure to radioactivity levels in the Lebanese environment.

In the framework of a National Environmental Radiation Survey Program, a total of 950 samples were collected and analyzed over 7 years. The program covers different compartment of Lebanese environment, rivers, wells, marine samples, soil, and foodstuff. Air was monitored continuously through a radiation early warning network system. Data collected from 2009 to 2015 are presented in this work. Gross alpha/gross beta values in well samples were below the guidance levels stated by the WHO. Cesium-137 was detected in milk samples, whey, and jam. However, its content was much lower than the national permissible level, while its activity concentration in marine samples was lower than the values reported in studies carried out in the Mediterranean Sea. The activity concentration of 40K in food samples was comparable to studies carried out in neighboring countries and higher than the content determined in non Mediterranean countries. Concerning marine environment, the activity concentrations of natural radionuclides 238U, 232Th, and 40K were comparable to those reported in other studies carried out in different countries. As well as their content in rivers and sediments was lower than those reported in neighboring region. Potassium-40 in food and 210Po in fish were the main contributors to the internal dose. The average annual effective dose due to external exposure and internal, excluding radon gas which constitutes around 43 % of the total dose, was found to be lower than the total worldwide value, 2.4 mSv year-1. Iodine-131 was detected in grass samples, collected in 2011 during Fukushima accident; its content ranged from 0.40 ± 0.06 to 0.9 ± 0.1 Bq kg-1, as well as 137Cs was detected in some seafood samples imported from Japan and neighboring countries. Its activity concentration varied between 0.15 ± 0.04 and 0.40 ± 0.02 Bq kg-1.