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Biomedical subjects

J W Healy

Publications and source records attributed to J W Healy.

10 recordsLinked to original sources
PubMed1989

Estimation of human gonadal Pu and Ce concentrations from animal data.

Data were obtained from the literature for gonad and body weights and for the Pu or Ce content of the gonads and body at death for several laboratory animal species, five human Pu injection cases, and 731 human adults exposed environmentally to Pu in fallout. Data for Pu concentration in gonads, liver, and bone samples of 59 male and five female occupational Pu cases (including four completely analyzed whole bodies) were obtained from the U.S. Transuranium Registry. A logarithmic function was used to relate fractional Pu or Ce concentration in testes and ovaries to body weight of the animals and to predict fractional Pu or Ce concentrations in human gonads, [Pu]G . PuB-1 = aBWb, where [Pu]G or [Ce]G is the nuclide concentration in gonads (Bq g-1 of wet weight), PuB or CeB is the nuclide content of the body at death, and BW is body weight (kg). The fractional Pu and Ce concentrations in both the testes and ovaries are inverse and nearly linear functions of body weight. The regression lines of fractional Pu or Ce concentration in testes and ovaries have similar slopes (b = -1.07 +/- 0.14); however, the nuclide concentrations (coefficient a) in ovaries are six times greater than in testes. Extrapolation of the animal data yielded fractional Pu concentrations in human testes and ovaries that agree with those calculated for the occupational cases and those recommended by the International Commission on Radiological Protection. The good agreement between the fractional concentrations of Pu and Ce in the testes and in the ovaries suggests that these data can be substituted in metabolic models of chemically similar elements for which gonadal data are scarce.

Animals↗
PubMed1988

H.M. Parker lecture. Radiation protection standards: a historical perspective.

The historical development of radiation standards limiting exposure to people is given in this paper. Since its purpose was to provide information to the public, the number of units is limited to two, and mathematical expressions are avoided. Emphasis is placed on the role of the National Council on Radiation Protection and Measurements and the International Commission on Radiological Protection rather than on regulations because the recommendations of these groups have played a strong part in the formulation of regulations.

Government Agencies↗
PubMed1985

Plutonium in gonads: a summary of the current status.

A review of the literature was carried out to investigate the following: the fraction of Pu in the body that was in the gonads; the necessity for a localization factor in calculating the genetic dose to humans; and the possibility that an unexpectedly high relative biological effectiveness (RBE) causing genetic effects could occur for alpha particles. Human autopsy data from both occupationally exposed persons and the public were relied on to determine the amount of Pu in the gonads. It was found that an average fraction of 3 X 10(-3) of the Pu in the body was in the ovaries and testes but there was a wide variation among individuals. While a localization factor over the average of 2.5-4 is needed to calculate the dose to the sensitive cells for rodents, no such factor is required for the human. Information on the RBE for various genetic effects shows RBEs for Pu alpha's about as would be expected from neutron irradiation. The usual quality factor applied in calculating dose equivalent is appropriate and may be conservative, particularly for females.

Alpha Particles↗
PubMed1984

Plutonium partitioning among internal organs.

An estimate of partitioning of plutonium among skeleton, liver, and other organs is needed to estimate the radiation dose to individual organs. This review was done to provide an analysis of the coefficients currently used for the translocation of plutonium from blood to other organs and excreta. Data from both experimental animals and human autopsy cases were used in our analysis. The analysis of data from 257 experimental animal and 169 human subjects led to a conclusion that a 70-30% split of plutonium distribution between skeleton and liver, respectively, would be appropriate for use in plutonium organ distribution models. Analysis of data from other organs and early excreta indicated that these other compartments generally comprised less than 3% of the total early body burden. The variability of plutonium distribution within all compartments is emphasized, with the conclusion that the coefficients of uptake to individual organs are adequate to estimate average organ doses for an exposed population but use for estimating doses for an individual will lead to uncertain results.

Animals↗
PubMed1978

What is hazardous? What is safe?

The definition of an acceptable risk involves many facets most of which are outside the control of the decision maker, but they must be recognized if a proper definition is to be made. Six of the principal factors are stated and discussed. (1) nothing is absolutely safe; (2) each individual or group of individuals has his own standards by which he judges risk; (3) perceptions of risk vary with the conditions at any one time in history; (4) there must be a compensatory benefit for taking any risk; (5) societal perception of a risk may be different from the actual risk; and (6) safety is only one of the many factors that must be considered in the design of a product or service.

Environmental Pollution↗