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Biomedical subjects

W F Todd

Publications and source records attributed to W F Todd.

6 recordsLinked to original sources

Evaluation of eight bioaerosol samplers challenged with aerosols of free bacteria.

The need to quantify airborne microorganisms in the commercial microbiology industry (biotechnology) and during evaluations of indoor air quality, infectious disease outbreaks, and agriculture health investigations has shown there is a major technological void in bioaerosol sampling techniques to measure and identify viable and nonviable aerosols. As commercialization of microbiology increases and diversifies, it is increasingly necessary to assess occupational exposure to bioaerosols. Meaningful exposure estimates, by using area or environmental samplers, can only be ensured by the generation of data that are both precise and accurate. The Andersen six-stage viable (microbial) particle sizing sampler (6-STG) and the Ace Glass all-glass impinger-30 (AGI-30) have been suggested as the samplers of choice for the collection of viable microorganisms by the International Aerobiology Symposium and the American Conference of Governmental Industrial Hygienists. Some researchers consider these samplers inconvenient for evaluating industrial bioprocesses and indoor or outdoor environments. Alternative samplers for the collection of bioaerosols are available; however, limited information has been reported on their collection efficiencies. A study of the relative sampling efficiencies of eight bioaerosol samplers has been completed. Eight samplers were individually challenged with a bioaerosol, created with a Collison nebulizer, of either Bacillus subtilis or Escherichia coli. The samplers were evaluated under controlled conditions in a horizontal bioaerosol chamber. During each experimental run, simultaneous samples were collected with a reference AGI-30 to verify the concentration of microorganisms in the chamber from run to run and day to day.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols

The application of dustiness tests to the prediction of worker dust exposure.

Laboratory bench tests, known as dustiness tests, have been used to evaluate and compare the potential of various powders to cause occupational dust exposure. Dustiness tests are used to develop products with reduced dust emissions. The correlation between dustiness test results and dust exposures was evaluated at two bag dumping and bag filling operations. At one bag dumping and one bag filling operation, there was evidence of a relationship between dustiness test results and dust exposures. In one case, regression analysis showed that dust exposures could be predicted to within nearly one order of magnitude. The variability in this prediction was caused by the inherent variability in the occupational dust exposures. In the other case, there was evidence of a correlation after the data had been adjusted for the effect of varying drop height. At the remaining two operations, no correlation between dust exposures and dustiness test results were observed. These results indicate that the relevance of dustiness tests to occupational dust exposure needs to be evaluated at each site. Because a better option does not exist, manufacturers should continue to use empirical dustiness tests to develop better products in the laboratory. The conclusions reached in the laboratory need to be validated by dust exposure measurements in the field, however.

Air Pollutants, Occupational

Abnormal biomechanics of flatfoot deformities and related theories of biomechanical development.

The flatfoot deformity has been investigated over this century by many leading authorities with regard to its etiologies and pathogenesis. A large number of articles in the early orthopedic literature concerning the flatfoot deformity defined the primary abnormalities of the structure without strong emphasis on its relationship to abnormal functional etiologies leading to the pathogenesis of the deformity. This article emphasizes abnormal biomechanics and theories of development.

Biomechanical Phenomena