Measurements of 222Rn activity concentration in domestic water sources in Penang, northern peninsular Malaysia.

Measurements of (222)Rn activity concentration were carried out in 39 samples collected from the domestic and drinking water sources used in the island and mainland of Penang, northern peninsular, Malaysia. The measured activity concentrations ranged from 7.49 to 26.25 Bq l(-1), 0.49 to 9.72 Bq l(-1) and 0.58 to 2.54 Bq l(-1) in the raw, treated and bottled water samples collected, respectively. This indicated relatively high radon concentrations compared with that from other parts of the world, which still falls below the WHO recommended treatment level of 100 Bq l(-1). From this data, the age-dependent associated committed effective doses due to the ingestion of (222)Rn as a consequence of direct consumption of drinking water were calculated. The committed effective doses from (222)Rn resulting from 1 y's consumption of these water were estimated to range from 0.003 to 0.048, 0.001 to 0.018 and 0.002 to 0.023 mSv y(-1), for age groups 0-1, 2-16 and >16 y, respectively.

Entrance surface dose of the common radiological investigations in Abuth, Zaria.

The entrance surface Dose (ESD) was determined among patients who presented for routine radiological examinations using thermoluminescent dosimeter (TLD) chips placed on averagely built adult [(30 cm) chest width, 60-90kg weight and 20-40years)] by multiplying the incident dose/entrances dose by the back scattered factor [BSF] gotten from an experiment. The values obtained from ESD measurements are as follows 8.03 mGy for Abdomen, 0.13 mGy for chest AP, 0.69 mGy for chest lateral, 0.5 mGy for cervical spine; AP: 0.38 mGy for cervical spine lateral; 4.75 mGy for hip AP: 12.83 mGy for hip lateral: 5.74mGy for lumbar spine, AP lumbar spine lateral is 15.15 mGy. 1.38m Gy is for pelvis AP. 2.93mGy for skull AP/PA 1.2mGy for skull lateral, 5.46mGy for thorax AP, while the lateral is 14.90m Gy. The average dose value is 9.28mGy Range 0.13-14.90mGy (Percentage standard error; +/- 1.45). From this studies Radiation doses delivered for routine investigations are generally lower than IAEA reference doses. Using these values for optimization of radiation protection practices for patient should be ensured since it does not rule out options for stochastic radiation.

A survey of gross alpha and beta activity concentrations in groundwater from Katsina area of Northern Nigeria.

Stratified sampling procedure was employed to collect a total of 40 samples; 2 from each stratum, measuring an approximate dimension of 3.25 km(2) of the actual sample site. Appropriate volumes were then evaporated and transferred into clean stainless steel planchets (ISO 9696 and ISO 9697). An eight channel gas-flow proportional counting system connected to a microprocessor loaded with a spreadsheet programme (Quarttro-Pro) and graphic programme (Multiplan) initially calibrated for efficiency was employed to count the background and the prepared samples. A mean efficiency of 33.44 and 41.24 % for the respective alpha and beta sources was obtained. A low background activity was also observed with a mean of 0.165 Bq for alpha and 1.119 Bq for beta. The gross alpha and beta activity concentrations in the water were found to range from 80 +/- 0.05 to 2300 +/- 0.41 Bq m(-3) and 120 +/- 0.08 to 4970 +/- 0.78 Bq m(-3), respectively. This clearly indicate areas of elevated alpha and beta activity concentrations of 37.5 and 47.5 %, respectively when compared with the International Commission for Radiological Protection (1991) maximum acceptable values of 500 Bq m(-3) for alpha and 1000 Bq m(-3) for beta.

Heavy ion-induced DNA double-strand breaks in yeast.

DNA double-strand break (dsb) induction in diploid yeast was measured by neutral sucrose sedimentation after exposure to very heavy ions with values of linear energy transfer (LET) ranging from about 300 to 11500 ke V/microns. Linear fluence dependencies were found in all cases from which dsb production cross-sections (sigma dsb) could be calculated. Corresponding cross-sections for cell killing (sigma i) were derived from final slopes of survival curves measured in parallel and for the same fluence range. A close correlation was found between sigma i and sigma dsb. It is calculated that over the entire LET range, including 30 MeV electron irradiation, about 22 dsb are induced per lethal event when high exposures are considered.