RELATIVE SUSCEPTIBILITY TO ARSENIC IN SUCCESSIVE INSTARS OF THE SILKWORM
The susceptibility of the silkworm to arsenic decreases during its larval development. Relative susceptibility may be expressed numerically as a ratio of areas under dosage-effect curves.
Toxic response as a quantitative function of body size.
Abstract Lethal response (96-hr) studies were conducted exposing mature male guppies (Poecilia reticulata) in lots representing different weight classes to ambient concentrations of six discrete toxicants: dieldrin, potassium pentachlorophenate, potassium cyanide, and copper, zinc, and nickel chlorides. Linear regressions with high correlation coefficients were defined for each toxicant by the equation, Y = a − b log ( M W h ) , where Y = % mortality as probits, M = mean toxicant concentration, W = weight of each lot, and h = an exponent of weight. The computed value of h was 0.81 for dieldrin, 0.72 for pentachlorophenate, cyanide, and copper, 0.67 for nickel, and 0.30 for zinc. Additional lethal response studies were conducted exposing mature females of different size, juveniles of different size, and newborn guppies of similar size to dieldrin. The dose-response functions of each age group were found to incorporate the weight factor previously computed for adult males, i.e., W0.81. Discrete, parallel regressions represented each life stage and sex. When compared on a weight factor basis, guppies became progressively more susceptible to dieldrin with each successive age class. Comparing adults only, males were more resistant than females. Evidence was gathered from the literature to show that the above equation applies furthermore to dose-response studies in which animals of varying size are given known amounts of toxicant, toxin, or drug. Consequently, the above equation may be generally employed to empirically establish the character of the relationship between dose and response when the size of the animals differ. Relative measures of toxic potency, e.g., LD50 and LC50, representing different sizes of an animal may be derived from the above equation and expressed in the useful form, LD50 = XWh, where X is the antilog of the abscissal value of log ( M W h ) corresponding to the 50% response level. This latter equation may also be derived from the commonly used function log LD50 = log a + b log W.
Using Infrared Thermography to Detect Moisture in Historic Masonry: A Case Study in Indiana
Nondestructive testing mapped water infiltration in the decoratively painted interior of a Masonic Temple in Muncie, Indiana.