CHAPTER 9: Allometric Modeling of Mammalian Cyanogen Chloride Inhalation Lethality

New human estimates for the lethal effects of cyanogen chloride (CK) via inhalation were derived from a review and statistical analysis of existing mammalian lethality data and related information. Allometric modeling was used to scale CK toxicity from smaller mammals to humans. Pertinent experimental data (i.e. median lethal dosages, quantal responses, etc.) were collected from 16 studies dating back to WWI. Test animal species included: mice, rats, rabbits, monkeys, cats, dogs, guinea pigs and goats. The resulting human estimates are expressed in the form of the toxic load model, Cⁿ × t = k, where n = 1.45, with concentration C in mg m⁻³ and time t in min. It was found for CK that k scaled to the species body mass raised to the (−0.18) power. Using this model for humans, the 2 min lethal dosage, 50% (LCt₅₀) estimate was found to equal 4100 and 3300 mg min m⁻³ for the healthy subpopulation and the general population, respectively. The recommended log base 10 probit slope (with respect to concentration) is 12 for the healthy subpopulations and 9 for the general population. These estimates represent the first general population exposure values for CK that are based on the total dataset, which was previously unavailable to civilian regulatory agencies.