CRITICAL PERIOD OF SENSITIVITY TO PETROLEUM TOXICITY IN THE CHICKEN-EMBRYO

Microliter amounts of South Louisana crude oil (SLCO) or Prudhoe Bay crude oil (PBCO) were applied to the shell of fertile leghorn chicken eggs on day 8, 8.5 or 9 of incubation. Percent mortality and prevalence of grossly visible lesions were evaluated 96 h after treatment. The 96-h LD50s of SLCO at 8, 8.5 and 9 d of incubation were 2.6, 4.3 and 34.3-mu-l, respectively. Five mu-l PBCO caused nearly 100% mortality in 8 and 8.5-d-old embryos, while 12-mu-l caused 32% mortality in 9-d-old embryos. Liver necrosis, edema and increases in body weight and in the ratio of body weight to crown-rump length were found in embryos treated on day 8, 8.5 or 9 of incubation with either SLCO or PBCO. The 16-fold decrease in sensitivity of the embryo from day 8 to day 9 of incubation suggests that the chorioallantoic membrane may be important in the toxic action of petroleum oil.