3.1 Maternal iAs exposure causes sex-specific changes in wean weights, adult weight gain, and final body weight ratios in of F1 offspring
To understand the effects of in utero iAs exposure on the developing embryo and primordial germ cells, we exposed F0 females to iAs treated water for 2 weeks prior to mating (Figure 1) . To ensure intergenerational effects were passed through the maternal line, unexposed male mice were placed in female cages to generate the F1 population. Male mice were separated from females after 48 hours to avoid confounding paternal exposure. Treated water was removed within 24 hours after the F1 offspring were born. F1 mice were weaned at 3 weeks of age and weekly weights were recorded until 40 weeks of age. F1 female mice (n=4 per treatment, 8 weeks of age) were bred with unexposed, unrelated C57BL/6J male mice (8 weeks of age) to produce the F2 generation. F2 mice were weaned at 3 weeks of age. None of the F1 or F2 mice were directly exposed to iAs drinking water during their lifetime.
Male and female F1 mice born to mothers exposed to 10 ppb and 2300 ppb had lower wean weights compared to control (Figure 2.A ). Over a period of 40 weeks, male F1 offspring from 10 ppb and 2300 ppb dams had lower final body weight compared to the control average (Figure 2.C ). Despite low final body weight, F1 male mice had no significant difference in body weight to fat pad mass ratio (Figure 3.B ). In contrast to F1 males, the F1 females showed no significant differences in weight gain over the 40 weeks or in body weight ot fat pad mass ratio (Figure 2.B, Figure 3.A ). Thus, maternal exposure to iAs at three ranges alters wean weight and final body weight in a sex-specific manner.