Assessment of 3-nitro-1,2,4-triazol-5-one as a potential endocrine disrupting chemical in rats using the Hershberger and uterotrophic bioassays.

The explosive 3-nitro-1,2,4-triazol-5-one (NTO) is an insensitive formulation developed to replace high energetics that are susceptible to accidental detonation from heat, shock, and impact. Although studies have shown NTO to be nontoxic at acute exposures, recent subacute and subchronic tests have demonstrated effects on testes and subsequent sperm production in rats. This study assessed endocrine disruption as a potential mechanism for these reproductive effects via the Hershberger and uterotrophic bioassays. These assays are 2 of the US Environmental Protection Agency's tier 1 in vivo screens for the Endocrine Disruptor Screening Program that measure differences in androgen- and estrogen-sensitive tissue weights in castrated and ovariectomized rats. The gonadectomized rats were orally exposed to NTO in a corn oil vehicle at doses of 250, 500, or 1000 mg/kg body weight (bw)/d for 10 and 3 days for the Hershberger and uterotrophic assays, respectively, according to standard protocols. Male rats also received testosterone (0.2 mg/kg/d, subcutaneous) and antiandrogenic flutamide (3mg/kg/d, oral) as negative and positive controls, and females received 17 α-ethynyl estradiol (0.3 µg/d, subcutaneous) as positive controls. 3-Nitro-1,2,4-triazol-5-one caused neither a decrease in androgen-sensitive male reproductive selected tissue (seminal vesicles with fluid/without fluid, glans penis, Cowper gland, ventral prostrate, and levator ani-bulbocavernosus) weights nor a change in uterine weights. The results of this study provide no evidence to suggest that NTO acts like an estrogenic or antiandrogenic endocrine disruptor in rats at these doses.

Characteristics of the human and pet populations in animal bite incidents recorded at two Air Force bases.

Animal bites reported at Scott Air Force Base, Ill., and Whiteman Air Force Base, Mo., were investigated to determine the incidence of reported bites and possible causes. Data were collected by abstracting information contained in animal bite files maintained by the Base veterinary Office. A total of 696 bite incidents were reported for the 24 months from January 1976 through December 1977. An overall incidence rate of 1,390 bites per 100,000 persons was calculated from these statistics. This rate is far greater than the previous estimates of 800 animal bites per 100,000 for an urban population. Males less than 18 years old were the group most frequently bitten; they had an incidence rate of 2,419 bites per 100,000. These data support the hypothesis that animal bites occur more frequently than previous studies have shown. Most bites resulted in minor injuries to the victim and were inflicted on the extremities. The incident occurred most commonly on the owner's property. The highest incidence of bites occurred during the summer months and in the early afternoon and evening. Animals in the study had a bite rate of 7.36 per 100 animals. The rate was significantly higher for male dogs 1 to 4 years old (12.1 bites per 100 male dogs). Certain breeds of dogs were more frequently involved. Collies and German shepherds ran twice the risk of being biters as mixed breed dogs. Working breeds and sporting breeds also had a higher risk of being biters than toy breeds as well as a higher rate of more severe bites than toy breeds.

Microscale modification of a cation-exchange column procedure for plasma ammonia.

A column cation-exchange resin procedure for plasma ammonia was modified to require only 100 mul of plasma per determination. Mean analytical recovery of standard from resin (six samples) was 98% (range, 94-100%) as compared to a mean of 63% (range, 58-70) for nine samples when a batch cation-exchange procedure was used. Absorbance was proportional to sample concentration up to 800 mumol/liter. Analytical recovery of standard from plsma (six samples) was complete (mean, 103%; range, 90-113). Thirteen aliquots of a specimen of fresh plasma from a single adult individual gave a mean value of 20 mumol/liter (range, 11-26). The mean plasma venous ammonia concentration for 27 adults was 16 mumol/liter (range, 0-39), and for 15 newborns it was 60 (range, 34-102). Values for capillary plasma measured at the same time were higher, and we discuss possible explanations for this. Values are given for infants and children from one month to 14 years of age. Effects of storage time and temperature on plasma ammonia concentration are discussed.

Erythrocyte porphyrin analysis in the detection of lead poisoning in children: evaluation of four micromethods.

We evaluated four procedures for determination of erythrocyte porphyrin: double extraction with ethyl acetate/acetic acid-HCl, single extraction with ethanol, single extraction with acetone, and direct solubilization with detergent-buffer. The ethyl acetate procedure, when used with two portions of HCl, apparently gives complete recovery of porphyrin and is suitable for reference as a comparison method. The ethanol procedure gives a high and consistent recovery and is technically simpler. The acetone procedure gives low and variable recovery of porphyrin, and the detergent-buffer method is subject to serious hemoglobin interference; neither of these two procedures offers any technical advantage. Stability of samples and methods for standardization were explored. A procedure for expressing results in terms of erythrocyte Zn-protoporphyrin content is given. Because of its stability, coproporphyrin is useful as a daily working standard. The ethyl acetate and ethanol methods are about equally efficient for detecting lead intoxication. Because of its simplicity, the ethanol method seems to be the best for use in screening.