Assessment of radiological hazards from radioactivity natural of cement used in Dwellings in Rio de Janeiro, Brazil.

Brazil is the fourth largest cement consumer in the world and the largest producer in Latin America, around 1.3% of global production. The main inputs in the manufacture of cement are limestone and clay. Few studies have been carried out in the country on the risk of these materials used in civil construction. Therefore, the objective of this present work is to evaluate the radiological danger that they can present to society. Gamma spectrometry analysis on 16 samples of different brands of cement used as construction material in Rio de Janeiro (Brazil) was performed in this study, using an HPGe detector and the Genie 2000 data acquisition software. Samples were set to count for an accumulation time of 14,400 s (4 h) and all measurements were corrected to eliminate background and backscattering. Activity concentrations are determined for 226Ra was from (41.2 ± 1.6 to 174.9 ± 3.9) Bq kg-1, 232Th was from (15.7 ± 0.5 to 43.1 ± 0.7) Bq kg-1 and 40K was from (82.6 ± 7.2 to 254 ± 17) Bq kg-1. To assess radiological health risks: mean values of Radium Activity Equivalent 150.0 ± 3.4 Bq kg-1, Annual Gonadal Dose Equivalent 468 ± 11 µSv year-1 and Lifetime Excess Cancer Risk (ELCR) 2.42 ± 0.06 were calculated. Total Absorbed Dose Rates ranged from 72.2 ± 1.7 to 225.1 ± 5.2 nGy h-1. The damage to collective health was also estimated from the annual effective dose rates with an estimated total cost of damage to health of US$ 130 million. Values are generally within global limits reported by UNSCEAR.

Assessment and estimation of the effective dose due to external exposure from natural radioactivity of sands used in civil construction in the state of Rio de Janeiro,Brazil.

The presence of naturally occurring radioactivity in sand and other building materials results in indoor and outdoor exposure to the public. Sand is one of the main components in civil construction alongside cement, crushed stone and bricks. Thus, this research was carried out in twenty sand samples with the objective of investigating the hazard indices of natural radiation, due to the presence of 238U, 226Ra, 232Th and 40K in sand samples collected in some locations in the state of Rio de Janeiro (Brazil), analyzing by gamma spectrometry and using an HPGe detector. The technique used for gamma analysis was gamma spectrometry, and the software used to analyze peaks and obtain counts was LabSOCS. In this context, the average activity concentration values of 226Ra (66.7 ± 1.2) and 40K (647 ± 31) Bq kg-1 are higher than the world mean activity concentration of 50, 50 and 500 Bq kg-1 for these three radionuclides. However, the value of 232Th (40.6 ± 0.7) Bq kg-1 and Raeq (175 ± 5) Bq kg-1 are less than the world average of 50 Bq kg-1 and 370 Bq kg-1, respectively. The estimation of the average values for Annual Effective Dose (0.51 ± 0.01) and Dutch Radiation Performance Index (0.52 ± 0.01) was carried out, with values below the maximum recommended limit for the public. Only one sample had a higher value and the other samples are within the levels required for environmental control. However, the mean values found in this present study, when compared to those of other authors mentioned here, showed higher values. Therefore, most samples have safe values to be used by people in building their homes.

Radiometric analysis of Brazilian commercial ornamental stones.

The term "commercial ornamental stones" comprises different natural stones with different mineralogical components and the distribution and amount of natural radionuclides depended on the mineralogy. Few studies on natural radioactivity in ornamental stones carried out in Rio de Janeiro (Brazil) and the present work were carried out in order to analyze the distribution of activity concentration in these materials. The activity concentration of 238U, 235U, 226Ra, 232Th and 40K in Ornamental Stones measured using γ-ray spectrometry to estimate the radiation hazard as well as establishing a database for radioactivity levels. Samples were collected in stores in Rio de Janeiro, carefully transported, weighed, packed with PVC film and left to rest for at least 45 days to reach secular equilibrium. Samples analyzed by gamma spectrometry using a hyper pure germanium detector (HPGE). Detection efficiency for each sample was obtained using LabSOCS software. The activity concentrations for samples were within the ranges (0.83 ± 0.15 to 39.96 ± 1.19, 8.04 ± 2.54 to 111.36 ± 13.33, 0.43 ± 0.03 to 264.58 ± 0.98, BDL to 8.17± 0.65 and 1.30 ± 0.57 to 1567.01 ± 65.08) Bq⋅kg-1 for 238U, 226Ra, 232Th, 235U and 40K, respectively. The world average for building materials is 50 Bq⋅kg-1 for 238U, 50 Bq.kg-1 for 232Th and 500 Bq⋅kg-1 for 40K. In the present work, the average for granite was 19.43 ± 0.39 Bq⋅kg-1 for 238U, 56.70 ± 1.13 Bq⋅kg-1 for 232Th and 1113.28 ± 20.27 Bq⋅kg-1 for 40K, thus the values for 232Th and 238U are above the world average. Analyzing for the granite that showed the highest concentrations of activity the average values of Transport Rate was 3.12 ± 0.04 Bq⋅m-2⋅s-1, Emanation Rate was 0.16 ± 0.00 Bq⋅kg-1⋅s-1, Exhalation Flow was 530.26 ± 6.05 Bq⋅m-3, Effective Equivalent Dose Due to Radon Exposure was 0.78 ± 0.01 WLM⋅year-1 and Annual Effective Dose Due to Radon and Thoron was 7.02 ± 0.10 mSv⋅year-1. Annual Effective Dose Due to Radon and Thoron it is above the annual limit for public individuals which is 1 mSv⋅year-1 and below the occupationally exposed individual, which is 20 mSv⋅year-1 in an average of 5 years, it does not exceed the maximum level recommended by ICRP-60.

An assessment of committed effective dose and lifetime cancer risk due to the ingestion of infant milk.

Infant milk is a manufactured food designed for feeding babies and infants under 12 months of age. This product is indicated when, for some reason, the baby can not be fed by breast milk. It is used in case of intolerance to milk from farmed animals and is widely used for the nutrition of newborns in artificial lactation, in place of breastfeeding. It can be used as a complete or partial substitute for human milk. In the current study, the committed effective dose and lifetime cancer risk due to ingestion of 4 K, 226Ra, and 228Ra were estimated using activity concentration obtained from high-resolution gamma spectrometry. Consumption data and dose coefficients were obtained from Brazilian Institute of Geography and Statistics and data published by ICRP 119. Infant milk and water samples were collected in the Rio de Janeiro trade, placed in a polystyrene container, and then sealed to reach the secular radioactive equilibrium condition (at least 45 days). The samples were analyzed by gamma spectrometry using a High Purity Germanium (HPGE). Detection efficiency for each sample was obtained with LabSOCS software. For infant milk samples, the highest values of activity concentrations were (242 ± 9) Bq.kg-1 for 4 K, (5 ± 1) Bq.kg-1 for 228Ra and presented values below the detection limit for 226Ra. The higher values obtained for water samples were (10 ± 1) Bq.l-1, (5 ± 1) Bq.l-1, (5.3 ± 0.1) Bq.l-1 for 4 K, 226Ra and 228Ra, respectively. These values of committed effective dose are below the values stipulated by UNSCEAR (290 µSv.y-1) and by the ICRP (1 mSv.y-1). The values obtained for lifetime cancer risk are considered negligible, once they are below the limit considered for taking action (10-4). It can be concluded that the values calculated do not present a significant risk regarding the intake of infant milk in the first two years of the child's life.

Radiological evaluation of Ra-226, Ra-228 and K-40 in tea samples: A comparative study of effective dose and cancer risk.

Activity concentrations of tea samples were determined using high resolution gamma spectrometry.The values ranged from (421.00 ± 17.00) to (732.00 ± 30.00) Bq.kg -1 for K-40 and from (3.00 ± 0.80) to (27.00 ± 3.00) Bq.kg-1 for Ra-228. The values for Ra-226 were below 27.00 Bq.kg-1. The committed effective dose was estimated at 4.74-78.89 µSv.y-1 for adults and 13.55-445.84 µSv.y-1 for children. The cancer risk was higher for females. However, results showed that the tea consumption do not represent a radiological health risk to the population.