Biomedical subjects

K W Terry

Publications and source records attributed to K W Terry.

4 recordsLinked to original sources

PubMed1998

The establishment of a radioactive waste disposal facility in Western Australia for low level waste.

The Radiation Health Section of the Health Department of Western Australia has been a repository for unwanted radioactive sources for many years. They had been placed in the radioactive store located on the Queen Elizabeth II Medical Centre Campus. After a collection period of more than 20 years the storage facilities of the Radiation Health Section were nearing capacity. A decision was made to relocate these sources into a permanent near surface burial facility. Following extensive community consultation and site investigations, waste originating in Western Australia was disposed of at Mt Walton (East), 80 km North East of Koolyanobbing, Western Australia in November 1992.

Environmental Monitoring↗

PubMed1995

Thorium excretion in feces by mineral sands workers.

An attempt has been made to correlate the thorium excreted in the feces of two male workers in the monazite section of a mineral sands dry separation plant over a ten-day period with personal air sampling measurements. The air-borne radioactivity was measured on a daily basis using a total (inspirable) dust filter, an integrating personal dosimeter, and a personal cascade impactor. The thorium content of the feces was measured using inductively coupled plasma mass spectrometry. The results suggest that thorium fecal analyses are able to detect acute and chronic exposures to the inhalation of thorium bearing dusts and to confirm the amount of inhaled thorium predicted from air sampling programs and metabolic models.

Administration, Inhalation↗

PubMed1995

Thorium lung burdens of mineral sands workers.

Thorium lung burdens have been measured in workers in the dry separation plants operated by the mineral sands industry in Western Australia. The data have been compared with historical employment records of the worker's exposure to thorium-bearing airborne dusts in order to assess the reliability of personal air sampling and with the predictions of the new Task Group lung model. The thoron exhaled in the breath of 62 workers was measured using a double filter tube. Six of the workers also underwent in-vivo gamma counting to determine their thorium lung burden. A thoron exhalation rate of 4.7% was obtained from a comparison of the two data sets. The estimated thorium lung burdens from the thoron-in-breath measurements had a geometric mean value of 10 Bq. The workers had a geometric mean employment period in the industry of 9.2 y and a geometric mean total inhaled alpha activity of 9,000 Bq, estimated from contemporary personal air sampling data and a retrospective assessment of previous workplace conditions. This exposure corresponds to a mean daily intake of 232Th of 0.45 Bq. Predictions from the new Task Group lung model indicate that, for the 45 workers with a thorium lung burden in excess of the minimum detectable level (6 Bq), the daily intake of 232Th is a factor of 1.6 higher than expected. This result suggests that previous intake of radioactive dust was higher than generally assumed for some workers. The application of the new Task Group lung models to the bioassay data results in an estimated mean annual committed effective dose for the workers of 8 mSv. Two workers (3%) were found to have been exposed for many years in excess of the 50 mSv y-1 annual limit for occupational exposure, while eight workers (13%) exceeded the ICRP's proposed new occupational standard of an average of 20 mSv y-1. All eight had been employed for more than 6 y and the majority of their exposure was attributed to early employment years, prior to extensive workplace improvements in dust control.

Air Pollutants, Radioactive↗

PubMed1995

Alpha self-absorption in monazite dusts.

Measurements have been made of the self-absorption effects in monazite of alpha particles of the 232Th decay series. Samples of six size fractions of monazite were deposited on filters at different dust concentrations and then the gross alpha activity determined. Self-absorption effects were negligible in monazite particles up to 8 microns diameter provided dust concentrations were less than 1 mg cm-2. Significant self-absorption effects occurred for both larger particle sizes and higher dust loadings. As reported AMAD values in the mineral sands industry range up to 15 microns, which is equivalent to an actual mean size of 8 microns diameter monazite particle, minimal self-absorption occurs in samples collected in air monitoring programs conducted in the industry provided that dust concentrations on the filters are less than 1 mg cm-2.

Absorption↗