Effect of Age and Head Position on Total and Regional Aerosol Deposition in Three-Dimensional Models of Human Intranasal Airways Using a Mucosal Atomization Device.

This study examined the effect of age and head position on total and regional deposition of aerosol delivered by a mucosal atomization device (MAD™) in three-dimensional (3D) models of the intranasal airways of an 18-, 5-, and 2-year-old human. Models consisted of four pieces: anterior nose and nasal cavity that was divided horizontally into upper, middle, and lower thirds. Models were tested six times at supine, supine with head backward at 45° (supine45), and sitting with head backward at 45° (sitting45).

Acute toxicity when concentration varies with time: A case study with carbon monoxide inhalation by rats.

Exposure to time-varying concentrations of toxic compounds is the norm in both occupational settings and daily human life, but little has been done to investigate the impact of variations in concentration on toxic outcomes; this case study with carbon monoxide helps fill that gap. Median acute lethality of 10-, 20-, 40-, and 60-min continuous exposures of rats to carbon monoxide was well described by the toxic load model (k = C(n) × t; k is constant, C = test concentration, n = toxic load exponent, and t = exposure duration) with n = 1.74.

Evaluating the validity and applicable domain of the toxic load model: impact of concentration vs. time profile on inhalation lethality of hydrogen cyanide.

The ten Berge model (or "toxic load" model) is often used to estimate the acute toxicity for varying combinations of inhaled concentration and duration. Expressed as C(n) × t = toxic load (TL), TLs are assumed constant for various combinations of concentration (C) and time (t). Experimental data in a recent acute inhalation study of rats exposed to time-varying concentrations of hydrogen cyanide (HCN) supported the validity of the toxic load model except under very brief, discontinuous, high concentration exposures.

Comparison of sarin and cyclosarin toxicity by subcutaneous, intravenous and inhalation exposure in Gottingen minipigs.

Sexually mature male and female Gottingen minipigs were exposed to various concentrations of GB and GF vapor via whole-body inhalation exposures or to liquid GB or GF via intravenous or subcutaneous injections. Vapor inhalation exposures were for 10, 60 or 180 min. Maximum likelihood estimation was used to calculate the median effect levels for severe effects (ECT50 and ED50) and lethality (LCT50 and LD50).

Impact of non-constant concentration exposure on lethality of inhaled hydrogen cyanide.

The ten Berge model, also known as the toxic load model, is an empirical approach in hazard assessment modeling for estimating the relationship between the inhalation toxicity of a chemical and the exposure duration. The toxic load (TL) is normally expressed as a function of vapor concentration (C) and duration (t), with TL equaling C(n) × t being a typical form. Hypothetically, any combination of concentration and time that yields the same "toxic load" will give a constant biological response.

Gender difference in the miotic potency of soman vapor in rats.

The present study was undertaken to investigate the miotic potency of soman vapor in the rat, as well as gender differences in the miotic response to soman vapor that have been reported previously for other nerve agents. The results of the present study demonstrate that the miotic potency of soman vapor is significantly less than that of other nerve agents, and that female rats are 2.5-3.

Comparison of low-level sarin and cyclosarin vapor exposure on pupil size of the Gottingen minipig: effects of exposure concentration and duration.

The current studies estimated effective (miosis) concentrations of the nerve agents' sarin (GB) and cyclosarin (GF) as a function of exposure duration in the Gottingen minipig and determined dependency of the median effective dosage (ECT50) over time. Male and female Gottingen minipigs were exposed to various concentrations of vapor GB or GF for 10, 60, or 180 min. Infrared images of the pig's pupil before, during, and after nerve agent exposure were captured digitally and pupil area was quantified.