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Biomedical subjects

D K Craig

Publications and source records attributed to D K Craig.

31 records · Page 2Linked to original sources
PubMed1975

The alveloar deposition of inhaled plutonium aerosols in rodents.

The alveolar burden following nose-only aerosol exposure of rodents to highly toxic radioactive materials depends upon the percentage of the inhaled aerosol that is deposited beyond the animals' ciliated epithelium. The quantity inhaled was estimated from the product of the aerosol concentration (nCi/liter), the exposure time (minutes) and the mean minute volume (liter/min) of the animals. For rats exposed to Pu(NO3)4 and sacrificed within an hour, the mean alveolar deposition was 19.2 plus or minus 9.19% for 36 groups of both -239Pu and -238Pu. No important correlations between any of the measured parameters and this initial percentage deposition were observed, in contrast with the results for -239PuO-2 deposition measured in rats sacrified 24 or 48 hours postexposure. In these, the aerosol activity median aerodynamic diameter (AMAD) was strongly correlated with aerosol concentration and percentage deposition (mean-7.9 plus or minus 3.9% for 32 groups) with AMAD over the range of 1.5 to 4.5 mum. The 200-fold lower mass concentration of -238Pu compared with -239Pu for a given activity level may explain the fact that the AMAD was correlated with concentration for -239Pu oxide and nitrate, but not for -238Pu compounds.

Aerosols↗
PubMed1975

Chronic inhalation of nickel oxide and cigarette smoke by hamsters.

Chronic inhalation of NiO and cigarette smoke (CS) by hamsters eventually caused pneumoconiosis whose development was unaffected by CS. No carcinogenic or cocarcinogenic effect of NiO and CS was observed, CS exposure increased laryngeal lesions, reduced body weight, and increased lifespan.

Air Pollutants↗
PubMedDate not supplied

Derivation of temporary emergency exposure limits (TEELs).

Short-term chemical concentration limits are used in a variety of applications, including emergency planning and response, hazard assessment and safety analysis. Development of emergency response planning guidelines (ERPGs) and acute exposure guidance levels (AEGLs) are predicated on this need. Unfortunately, the development of peer-reviewed community exposure limits for emergency planning cannot be done rapidly (relatively few ERPGs or AEGLs are published each year). To be protective of Department of Energy (DOE) workers, on-site personnel and the adjacent general public, the DOE Subcommittee on Consequence Assessment and Protective Actions (SCAPA) has developed a methodology for deriving temporary emergency exposure limits (TEELs) to serve as temporary guidance until ERPGs or AEGLs can be developed. These TEELs are approximations to ERPGs to be used until peer-reviewed toxicology-based ERPGs, AEGL or equivalents can be developed. Originally, the TEEL method used only hierarchies of published concentration limits (e.g. PEL- or TLV-TWAs, -STELs or -Cs, and IDLHs) to provide estimated values approximating ERPGs. Published toxicity data (e.g. lc(50), lc(LO), ld(50) and ld(LO) for TEEL-3, and tc(LO) and td(LO) for TEEL-2) are included in the expanded method for deriving TEELs presented in this paper. The addition here of published toxicity data (in addition to the exposure limit hierarchy) enables TEELs to be developed for a much wider range of chemicals than before. Hierarchy-based values take precedence over toxicity-based values, and human toxicity data are used in preference to animal toxicity data. Subsequently, default assumptions based on statistical correlations of ERPGs at different levels (e.g. ratios of ERPG-3s to ERPG-2s) are used to calculate TEELs where there are gaps in the data. Most required input data are available in the literature and on CD ROMs, so the required TEELs for a new chemical can be developed quickly. The new TEEL hierarchy/toxicity methodology has been used to develop community exposure limits for over 1200 chemicals to date. The new TEEL methodology enables emergency planners to develop useful approximations to peer-reviewed community exposure limits (such as the ERPGs) with a high degree of confidence. For definitions and acronyms, see Appendix.

Animals↗