Two-generation reproduction study of lewisite in rats.

Lewisite, a potent toxic vesicant and chemical warfare agent, is used in a number of research laboratories, is stored in large quantities at depot sites throughout the USA and is occasionally transported to distant sites. Thus, the potential for environmental or occupational exposure exists where lewisite is present. A 42-week two-generation study was conducted to determine the reproductive consequences of lewisite in parental male and female rats and their offspring. Rats were administered lewisite in sesame oil (0, 0.10, 0.25 or 0.60 mg kg-1 day-1 for 5 days a week) via intragastic intubation before mating, during mating and after mating until the birth of their offspring. The dams continued to receive lewisite during lactation. At weaning, male and female offspring of each group were selected to continue the study, receiving lewisite during adolescence, mating and throughout gestation and lactation. Lewisite had no adverse effect on reproduction performance, fertility or reproductive organ weights of male or female rats through two consecutive generations. No adverse effects to offspring were attributed to lewisite exposure. Minor changes in growth were the only maternal effects observed. Lewisite exposure of parental rats caused no gross or microscopic lesion in testes, epididymis, prostate, seminal vesicles, ovaries, uterus or vagina. The no-observable-effect level (NOEL) for the reproductive effects of Lewisite would be > 0.60 mg kg-1 day-1.

Two-generation reproduction study of sulfur mustard in rats.

Comprehensive data are not available to evaluate the potential risk to reproduction from exposure to sulfur mustard (HD), [bis(2-chloroethyl) sulfide]; thus, the reproductive effects of HD were evaluated in Sprague-Dawley rats. Groups, of rats (27 females and 20 males/group/generation) were gavaged with 0, 0.03, 0.1, or 0.4 mg/kg HD 5 d/week for 13 weeks prior to mating and throughout gestation, parturition, and lactation in a 42-week, 2-generation study. Growth of adult F1 rats of both sexes was reduced by the 0.4 mg/kg exposure. There were no significant effects on reproductive function or pregnancy outcome in either generation, except for an altered sex ratio in the 0.4 mg/kg group. Although not different at birth, growth of the 0.4 mg/kg F1 and F2 offspring was depressed during lactation. A dose-related lesion of the squamous epithelium of the forestomach was observed in adults of both sexes and both the F1 and F2 generation. For a given treatment, the incidence was approximately the same for each sex at each generation. When animals were pooled by sex and generation, approximately 70% (66 out of 94) of the low dose group had only mild microscopic lesions, 72% (68 out of 94) of the intermediate dose group had moderate lesions, and 81% (76 out of 94) of the high group had marked lesions. The lesion, acanthosis, was characterized by thickening of the squamous musoca with varying degrees of hyperkeratosis. Benign neoplasms of the forestomach were found in about 10% of the intermediate and high dose groups in both F0 and F1 generations. Based on these results, the No-Observable-Adverse-Effect-Level (NOAEL) is 0.1 mg/kg/d.

Toxicology and pharmacology of the chemical warfare agent sulfur mustard.

There have been reports of chemical attacks in which sulfur mustard might have been used (a) on Iranian soldiers and civilians during the Gulf War in 1984 and 1985 and (b) in an Iraqi chemical attack on the Iranian-occupied village of Halbja in 1988, resulting in many civilian casualties. Heavy use of chemical warfare in Afghanistan by the Soviet military is a recent innovation in military tactics that has been highly successful and may ensure further use of chemical agents in future military conflicts and terrorist attacks as a profitable adjunct to conventional military arms. Mustard is a poisonous chemical agent that exerts a local action on the eyes, skin, and respiratory tissue, with subsequent systemic action on the nervous, cardiac, and digestive systems in humans and laboratory animals, causing lacrimation, malaise, anorexia, salivation, respiratory distress, vomiting, hyperexcitability, and cardiac distress. Under extreme circumstances, dependent upon the dose and length of exposure to the agent, necrosis of the skin and mucous membranes of the respiratory system, bronchitis, bronchopneumonia, intestinal lesions, hemoconcentration, leucopenia, convulsions with systemic distress, and death occur. Severe mustard poisoning in humans is associated with systemic injury, which is manifested as headache, epigastric distresses, anorexia, diarrhea, and cachexia and is usually observed at mustard doses of 1000 mg/min/m3 with damage to hematopoietic tissues and progressive leucopenia. Sulfur mustard is a cell poison that causes disruption and impairment of a variety of cellular activities that are dependent upon a very specific integral relationship. These cytotoxic effects are manifested in widespread metabolic disturbances whose variable characteristics are observed in enzymatic deficiencies, vesicant action, abnormal mitotic activity and cell division, bone marrow disruption, disturbances in hematopoietic activity, and systemic poisoning. Indeed, mustard gas readily combines with various components of the cell such as amino acids, amines, and proteins. Although evidence of an association between lung cancer and mustard gas encountered on the battlefields of World War I is at best suggestive if not problematical (Case and Lea, 1955; Beebe, 1960; Norman, 1975), the epidemiological data accumulated from the poison gas factories in Japan (Yamada et al., 1953; Wada et al., 1968; Inada et al., 1978; Shigenobu, 1980; Nishimoto et al., 1983; Hirono et al., 1984; Takuoka et al., 1986), in Germany (Weiss, 1958; Hellmann, 1970a; Weiss and Weiss, 1975; Klehr, 1984) and in England (Manning et al., 1981; Easton et al., 1988) are substantial (International Agency for Research on Cancer, 1975). Unfortunately, attempts to seek confirmatory and substantial evidence in laboratory animals such as mice (Boyland and Horning, 1949; Heston, 1950; Heston, 1953a; McNamara et al., 1975) and rats (Griffin et al., 1951; McNamara et al., 1975; Sasser et al., 1996) have not been consistent. Sulfur mustard has been shown to be mutagenic in a variety of different species using many different laboratory techniques from fruit flies, microorganisms and mammalian cell cultures (Fox and Scott, 1980). Evidence is slowly accumulating from human data (Hellmann, 1970a; Lohs, 1975; Wulf et al., 1985). Evidence for the teratogenicity of mustard has been negative in assessment of fetotoxicity and adverse effects of mustard on the reproductive potential of both human and animal studies. Indeed, investigations of women adversely affected by mustard are minimal because most of the studies have been performed on former men employees of poison gas factories and have been negative or questionable. We have recently emphasized the need to assess the affect of a suspected teratogen on maternal toxicity in laboratory animals before any conclusions can be made.(ABSTRACT TRUNCATED)

Subchronic toxicity evaluation of lewisite in rats.

Health and exposure criteria have not been established for lewisite [dichloro(2-chlorovinyl)arsine], a potent toxic vesicant that reacts with the sulfhydryl groups of proteins through its arsenic group. Sixty Sprague-Dawley rats of each sex, 6-7 wk old, were divided into 6 groups (10/group/sex) and gavaged with either 0, 0.01, 0.1, 0.5, 1.0, or 2.0 mg/kg of lewisite in sesame oil 5 d/wk for 13 wk. No significant dose-related change in body weight was observed. At the high dose, serum protein, creatinine, SGOT, and SGPT were decreased in males; lymphocytes and platelets were increased in females. A treatment-related lesion was detected in the forestomach of both sexes at 2.0 mg/kg. These lesions were characterized by necrosis of the stratified squamous epithelium accompanied by infiltration of neutrophils and macrophages, proliferation of neocapillaries, hemorrhage, edema, and fibroblast proliferation. Mild acute inflammation of the glandular stomach was also observed in some cases at 1.0 and 2.0 mg/kg. Early deaths were attributed to severe inflammation of the upper and/or lower respiratory tract, possibly from deposition or reflux of test material into the pharynx. Estimated dose range for NOEL appears to be >0.5 and <1.0 mg/kg when administered orally.

Developmental toxicity of sarin in rats and rabbits.

Sarin (Agent GB, isopropyl methylphosphonofluoridate) is an organophosphate cholinesterase inhibitor. Sarin (Type I or Type II) was administered by gavage to CD rats on d 6-15 of gestation at dose levels of 0, 100, 240, or 380 micrograms/kg/d and to New Zealand White (NZW) rabbits on d 6-19 of gestation at dose levels of 0, 5, 10, or 15 micrograms/kg/d. Females were weighed on gestational days (GD) 0, 6-16 for rats and 6-20 for rabbits, and immediately prior to termination (GD 20 for rats and GD 29 for rabbits). All animals were monitored daily for clinical signs of toxicity throughout dosing and until sacrifice. At necropsy, gravid uteri were weighed and examined for the number and status of implants (live, resorbed, or dead). Individual fetal body weight, malformations, and variations (external, visceral, and skeletal) were recorded. Rat and rabbit dams in the high-dose groups exhibited significant signs of maternal toxicity and increased maternal mortality. Examination of gravid uteri revealed no statistical differences among treatment groups in the incidence of resorptions or of dead or malformed fetuses, or in average body weight of live fetuses per litter. These results show no evidence or developmental toxicity in the CD rat or NZW rabbit following exposure to either Type I or Type II sarin during embryonic differentiation and major organogenesis, even at a dose that produced maternal toxicity.

Subchronic toxicity evaluation of sulfur mustard in rats.

Occupational exposure criteria have not been established for sulfur mustard (bis(2-chlorethyl) sulfide), a strong alkylating agent with known mutagenic properties. Seventy-two Sprague-Dawley rats of each sex, 6-7 weeks old, were divided into six groups (12 of each sex per group) and gavaged with 0, 0.003, 0.01, 0.03, 0.1 or 0.3 mg kg-1 sulfur mustard in sesame oil for 5 days a week for 13 weeks. No dose-related mortality was observed. A significant decrease (P > 0.05) in body weight was observed in both sexes of rats only in the 0.3 mg kg-1 group. Hematological evaluations and clinical chemistry measurements found non consistent treatment-related effects at the doses studied. The only treatment-related lesion associated with gavage exposure upon histopathological evaluation was epithelial hyperplasia of the forestomach of both sexes at 0.3 mg kg-1 and of males at 0.1 mg kg-1. The hyperplastic change was minimal and characterized by cellular disorganization of the basilar layer, apparent increase in mitotic activity of the basilar epithelial cells and thickening of the epithelial layer due to the apparent increase in cellularity. The estimated no-observed-effect level (NOEL) for sulfur mustard in this 90-day study was 0.1 mg kg-1 day-1 when administered orally.

The comparative metabolism of diisopropyl methylphosphonate in mink and rats.

This study reports the metabolism of carbon-14labeled diisopropyl methylphosphonate (DIMP) in mink and rats, undertaken to better understand the dose-related mortality reported for mink in a previous study. In both male and female mink and rats, DIMP was rapidly absorbed after oral administration; it was metabolized by a saturable pathway to a single metabolite, isopropyl methylphosphonate (IMPA), which was rapidly excreted, primarily in the urine (90%). Fecal radioactivity, also identified as IMPA, was 1.7-3.1% of the administered dose. Female rats had a slower rate of conversion of DIMP to IMPA and less total excretion of IMPA than male rats. Metabolism of DIMP administered intravenously was not very different from that given orally in both species. These data indicate that mink absorb, metabolize, and excrete DIMP (as IMPA) in a manner very similar to mice, rats, and dogs.

Subchronic oral toxicity study of diisopropyl methylphosphonate in mink.

Diisopropyl methylphosphonate (DIMP), produced during manufacture of the chemical agent GB (Sarin), is a groundwater contaminant at Rocky Mountain Arsenal, Colorado. DIMP was fed for 90 days to dark brown "Ranch Wild" mink housed under controlled indoor conditions. One-year-old mink, 10 of each sex, were fed 0, 50, 450, 2700, 5400, or 8000 ppm in standard ranch diet. Actual DIMP consumption was 0, 8, 73, 400, 827, and 1136 mg/kg body wt/day, respectively. Two additional groups of 10 served as "pair-fed" controls. Body weight and food intake were recorded weekly. Complete blood count and 15 chemical analytes were measured at Weeks 0, 3, 7, and 13. Necropsy and microscopic examination were performed on all mink. No clinical morbidity or deaths occurred. Both sexes fed 8000 ppm ate approximately 20% less and weighed approximately 20% less than the controls; 5400 ppm females had a 10% weight decrement. Plasma cholinesterase (ChE) decreased in the top three dose groups starting at Week 3. At 13 weeks, decrements were approximately 50% but returned to normal after 1 week without DIMP. Erythrocyte ChE was not reduced. Heinz bodies occurred in 10-15% of RBCs in 50% of 8000 ppm mink at 13 weeks, and 0.1-2.0% of RBCs in 25% at 2700 ppm. There were mild decreases in RBC count, hematocrit, and hemoglobin, and increases in reticulocyte count, at the 5400 and 8000 ppm doses. All recovered within 3 weeks after DIMP was withdrawn. The 8000 ppm group had marginal splenic hematopoiesis, histologically. No other treatment-related changes were noted. The 450 ppm dose was a clear no-effect level (approximately 73 mg DIMP/kg body wt/day). Compared to reports of similar studies of DIMP in rats and dogs, these mink displayed no unique species susceptibility.

Genotoxicity of the phosphoramidate agent tabun (GA).

Five mutagenicity tests were performed on Agent GA (Tabun, phosphoramidocyanidic acid, dimethyl-, ethyl ester) as part of a program to demilitarize chemical warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only three of the five assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

Dominant lethal study of sulfur mustard in male and female rats.

Sulfur mustard (HD) (bis(2-chloroethyl)sulfide) is a strong alkylating agent with known mutagenic and suspected carcinogenic properties, but occupational health standards have not been established. The purpose of this study was to determine the dominant lethal effect in male and female rats dosed orally with HD, for which currently available data are ambiguous. Sprague-Dawley rats of each sex, 6-7 weeks old, were orally administered 0, 0.08, 0.20 or 0.50 mg kg-1 HD 5 days a week for 10 weeks, after which dominant lethal studies were conducted during the post-exposure period. The studies were conducted in two phases: a female dominant lethal phase in which treated or untreated males were mated with treated females and their fetuses were evaluated 14 days after copulation; and a male dominant lethal phase in which treated males cohabited with untreated females for 5 days and fetuses were evaluated 14 days after the mid-point of the week of cohabitation, for each of 10 weeks. In addition, motility, population size and morphology were measured in sperm obtained from the cauda epididymis. Parental growth rates were reduced in both sexes treated with the high level of HD. Female dominant lethal effects were not observed, although significant male dominant lethal effects were observed in HD-exposed male rats mated to untreated females at 2 and 3 weeks' post-exposure. These effects, which included increases of early fetal resorptions and preimplantation losses and decrease in total live embryo implants, were most consistently observed at a dose of 0.50 mg kg-1. A significant P(P < 0.05) increase in the percentage of abnormal sperm was detected in males exposed to 0.50 mg kg-1 HD. The timing of dominant lethal effects is consistent with an effect during the post-meiotic stages of spermatogenesis, possibly involving the generally sensitive spermatids.

Neurotoxicity of acute and repeated treatments of tabun, paraoxon, diisopropyl fluorophosphate and isofenphos to the hen.

The neuropathic potential of acute and repeated exposures of the phosphoramidates tabun (GA) and isofenphos (IFP), of diisopropyl fluorophosphate (DFP) and paraoxon (PO) were examined in the hen with treatments for up to 90 days via intramuscular injections of the highest tolerated doses with atropine protection. Plasma acetylcholinesterase (AChE), non-specific butyrylcholinesterase (BChE) and creatine kinase (CK) activities were measured in order to monitor whether the compounds were present at biologically active concentrations. Locomotor behavior was observed and tissues from the peripheral and central nervous systems were examined for signs of organophosphate-induced delayed neuropathy (OPIDN). No behavioral or histological evidence of OPIDN was observed after treatments with GA, IFP, PO, saline or atropine sulfate. DFP-treated birds displayed locomotor and neuropathological signs of OPIDN with a no effect level (NOEL) between 25 and 50 micrograms/kg.

Inorganic arsenic compounds: are they carcinogenic, mutagenic, teratogenic?

This review examines and evaluates the literature on the ability of inorganic arsenic compounds to cause cancer in humans and laboratory animals. The epidemiological data that supports the position that inorganic arsenical derivatives are carcinogenic in humans is convincing and difficult to deny because of their consistency. These data are from studies of different occupational exposures such as smelter and pesticide workers, as well as from studies of drinking water, wines and medicinal tonics that contained or were contaminated with inorganic compounds of arsenic. Indeed, positive dose-response relationships between cancer incidence or mortality with many inorganic arsenical substances have been shown. Despite the presence of data which confuse the interpretation and evaluation of epidemiological data, associated neoplasms of the lungs, skin and gastrointestinal systems have been observed as a result of exposure to inorganic arsenic compounds.The mechanism of carcinogenicity of inorganic arsenical substances in humans is unknown. Inorganic arsenic compounds are not carcinogenic in laboratory animals by most routes of administration. However, further studies (subchronic, chronic, carcinogenic) using intratracheal and other conventional routes in other animal species would appear to be warranted. Moreso, especially since there is no evidence that organic arsenic compounds are carcinogenic in numerous mammalian species. Inorganic derivatives of arsenic are not mutagenic but may be teraiogenic. This latter conclusion is dependent on the method of administration and size of the dose, as well as on the species of animal used for the study.

Developmental toxicity of soman in rats and rabbits.

Soman (GD; phosphonofluoridic acid, methyl-,1,2,2-trimethylpropyl ester) is an organophosphate compound with potent anticholinesterase activity. To determine developmental toxicity, soman was administered orally to CD rats on days 6 through 15 of gestation at dose levels of 0, 37.5, 75, 150, or 165 micrograms/kg/day and to New Zealand White (NZW) rabbits on days 6 through 19 of gestation at dose levels of 0, 2.5, 5, 10, or 15 micrograms/kg/day. At sacrifice, gravid uteri were weighed and examined for number and status of implants. Individual fetal body weights and external, visceral, and skeletal malformations were recorded. Mean maternal weight changes, fetal implantation status/litter, fetal weight, and fetal malformations/litter were compared between dose groups. Monitors for maternal toxicity were net body weight change, treatment weight change, mortality, and clinical signs of toxicity such as lethargy, ataxia, and tremors. Maternal rats and rabbits in the high-dose groups exhibited statistically significant increases in toxicity and mortality when compared to controls. There were no significant dose-related effects among dose groups in the prevalence of postimplantation loss, malformations, or in average body weight of live fetuses per litter. There was no evidence of increased prenatal mortality or fetal toxicity in the CD rat or NZW rabbit following exposure to soman, even at a dose that produced significant maternal toxicity.

Lewisite: its chemistry, toxicology, and biological effects.

Lewisite is an organic arsenical war gas which is a vesicant with attendant toxicities due to its ability to combine with thiol groups which are essential for activity of a variety of enzymes. Although Lewisite has been designated as a "suspected carcinogen," the indictment is not supported by the available scientific evidence. Indeed, the unwarranted conclusion is based on one specific case history of a former German soldier whose lower right leg was exposed to liquid Lewisite in 1940 with subsequent development of intraepidermal squamous cell carcinoma, and the examination of death certificates of former workers at a Japanese factory that manufactured a variety of war gases including mustard gas, hydrocyanic acid, chloracetophenome, phosgene, diphenylcyanarsine and Lewisite. It is difficult to comprehend why Lewisite was selected out of this group of toxic chemicals as one of those responsible for respiratory cancer in these workers. It would appear to be a difficult task, indeed, to disengage a specific worker from one of the other of several gases at the workplace and assign a specific gas-induced death. The evidence that organic arsenicals are carcinogenic is weak. Although the weight of evidence is such that inorganic arsenical derivatives are considered weak mutagens, the evidence that organic arsenicals are mutagenic is poor. Recent examination of the mutagenic potential of Lewisite using the Ames test has shown that Lewisite is not mutagenic under these circumstances. While oral administration of arsenical compounds, whether inorganic or organic, does not induce teratogenicity except at very high dose levels which are associated with some degree of maternal toxicity, parenteral administration has been associated with teratogenicity but information of maternal toxicity has not always been available. Indeed, maternal toxicity should be considered as an important diagnostic tool in assessing whether a chemical is teratogenic. The significance of parenteral routes for inducing teratogenicity is also problematical. Recently, Lewisite has been shown not to be teratogenic in either rats or rabbits. A monograph on arsenic, succinctly states that "no human epidemiological investigations have been conducted on the carcinogenicity of organic arsenic compounds" (WHO 1981). Indeed, the lack of such evidence eminating from epidemiological sources or from animal studies is resounding. At present, there is no evidence that Lewisite is either carcinogenic, mutagenic or teratogenic. A review of toxicological studies of other organic arsenicals has produced no evidence that they might be carcinogenic, mutagenic or teratogenic.

Neuropathy target esterase in hens after sarin and soman.

To estimate the potential of small doses of sarin (types I and II) and soman to cause delayed neuropathic effects, 400, 200, 61, and 0 micrograms/kg of sarin-I, 280, 140, 70, and 0 micrograms/kg of sarin-II, and 14.2, 7.1, 3.5, and 0 micrograms/kg of soman by gavage were compared with 510 mg/kg tri-o-cresyl phosphate (TOCP) in 14- to 18-month-old SPF white leghorn hens (4/dose) protected with atropine (100 mg/kg). The neuropathy target esterase (NTE) activity 24 hr after dosing was determined in brain, spinal cord, and lymphocytes and in plasma and brain for cholinesterase and carboxylesterase. None of the compounds showed statistically significant NTE decreases. Sarin-II showed a dose-related trend in the lymphocyte NTE (to 33% of control at 280 micrograms/kg), suggesting that longer exposure to lower doses might cause a cumulative neurotoxic insult. All of the agents decreased the activity of plasma and brain cholinesterase and carboxylesterase. Using more than 70% inhibition of brain NTE as a biochemical predictor of delayed neuropathy, sarin and soman appear unable to cause delayed neuropathy at nonlethal doses within this protocol.

SCE induction in Chinese hamster ovary cells (CHO) exposed to G agents.

Cultured Chinese hamster ovary (CHO) cells were exposed to two neurotoxic organophosphates, either sarin (GBI, GBII) at 1.4 X 10(-3) M or soman (GD) at 1.1 and 2.2 X 10(-3) M for 1 h, grown and their metaphase chromosomes scored for sister-chromatid exchanges (SCE). No cytotoxicity was seen with either agent at any dose level tested. Since histograms of SCE per cell showed that they were non-symmetrically arrayed around the mean, the number of SCEs were analyzed by using the nonparametric tests, Mann-Whitney and Kruskall-Wallis. Agents GBI and GBII did not show any significant increase in SCE over baseline. On the other hand, GD demonstrated a statistically significant increase in SCE with and without metabolic activation. Ethyl methanesulfonate (EMS) alone at 5 X 10(-3) M and cyclophosphamide (CP) at 10(-4) M in the presence of rat microsomes (S9) induced a 3- and 8-fold increase in SCE per cell, respectively.

Toxicity of an acute dose of agent VX and other organophosphorus esters in the chicken.

The neurotoxicities of single doses of a chemical warfare agent VX [phosphonothioic acid, methyl-S-(2-[bis(1-methylethyl)amino/ethyl) O-ethyl ester], a metabolite of the agricultural chemical parathion, paraoxon, PO (phosphonothioic acid, diethyl paranitrophenyl ester), and the known neuropathic agents DFP] phosphorofluoridic acid, bis(1-methylethyl) ester] and TOCP (phosphoric acid, tri-o-tolyl ester) were compared in the chicken. Single injections (subcutaneous, sc) of VX as high as 150 micrograms/kg (5 times the LD50, intramuscular, im) were tolerated by laying tens if atropine and 2-pralidoxime were used as antidotes before and immediately after injection. The 150 of VX for inhibition of chicken brain acetylcholinesterase was approximately 5 X 10(-10). Plasma acetylcholinesterase, but not butyrylcholinesterase, was depressed 2 h after injections of 2-20 micrograms VX/kg im without antidotes. Levels of plasma enzymes such as creatine kinase, indicative of tissue damage, were increased after exposure to both VX and PO. Injections of up to 150 micrograms/kg of VX with antidotes did not cause locomotor or histological signs of organophosphorus-induced delayed neuropathy, but single injections of 400 mg TOCP/kg did.

Toxicity of repeated doses of organophosphorus esters in the chicken.

Hens were repeatedly exposed to paraoxon (PO, phosphonothioic acid, diethyl paranitrophenyl ester), the chemical warfare agent VX/phosphorofluoridic acid, methyl-S-(2-[bis(1-methylethyl)amino/ethyl)O-ethyl ester], or the neuropathic DFP [phosphorofluoridic acid, bis(1-methylethyl)ester] as evidence was sought for nerve or other tissue damage following long-term treatments at high dose levels. Thirty-day and 90-d trials were performed in which each bird was injected 3 or 5 times per week with atropine as protection, weighed, their eggs collected, and their blood enzymes (cholinesterases creatine kinase, and lactic dehydrogenase) and locomotion periodically examined. Muscle and brain enzymes were assayed at the end of the experiments. Doses of PO and VX were at or above LD50 levels. DFP doses were lowered with each run to estimate a no-observable-effect level for organophosphate-induced delayed-neuropathy (OPIDN). No abnormalities attributable to repeated exposures to either PO or VX were found, even though acute, short-term symptoms of toxicity appeared after each injection. No evidence for OPIDN was obtained with repeated exposures to PO and VX under conditions where OPIDN was caused by DFP. Histological signs of OPIDN appeared in the spinal cord without gross symptoms of ataxia following repeated treatments of 25 mg/kg of DFP. The results of one experiment suggested that exposure to protective injections of atropine delays the appearance of the locomotor symptoms of the DFP-induced neuropathy.

A novel device for the automated administration of test compounds to laboratory animals.

A prototype instrument is described that permits efficient administration of test compounds to laboratory animals by intubation. The system integrates a balance, a computer and a volumetric dispenser. Complete animal identification, weight and dose records are kept and may be interfaced with mainframe computers. A range of doses may be delivered from a single stock solution. No carryover is evident between doses. The system is accurate, precise and rugged. The system is cost effective relative to current manual gavage techniques and offers added safety for investigators handling toxic materials.