Dermal absorption and pharmacokinetics of isopropanol in the male and female F-344 rat.

Isopropanol (IPA), as a 70% aqueous solution, was applied under occluded conditions to the shaved backs of male and female Fischer F-344 rats for a period of 4 hr. Maximum analyzed blood concentrations of IPA were attained at 4 hr and decreased steadily following removal of the test material. Blood concentrations were below the limit of quantification at 8 hr. Acetone (ACE) blood levels rose steadily during the 4-hr exposures and continued to rise following removal of the test material, reaching peak analyzed levels at 4.5 hr (male) and 5 hr (females). ACE blood concentrations were below the limit of quantification at 24 hr. Basic pharmacokinetic parameters were similar for male and female rats with mean, first-order elimination half-lives for IPA and ACE of 0.8 to 0.9 hr and 2.1 to 2.2 hr, respectively. Following iv administration of [14C]IPA, 50-55% of the dose was eliminated as 14CO2 with lesser amounts recovered as expired volatiles or in urine. Total recoveries following iv administration were 83% for both males and females. Following a 4-hr dermal exposure to [14C]IPA (70% aqueous solution), 84-86% of the dose was recovered from the application site. Dermal absorption rates were calculated by two independent methods. The values obtained were 0.78 +/- 0.03 and 0.85 +/- 0.04 mg/cm2/hr for males and 0.77 +/- 0.13 and 0.78 +/- 0.16 mg/cm2/hr for females. Calculated permeability coefficients of 1.37 to 1.50 x 10(-3) cm/hr for males and 1.35 to 1.37 x 10(-3) cm/hr for females indicate that in the rat, IPA is rapidly absorbed dermally when applied under occluded conditions.

Estrogen modulation: tiered testing for human hazard evaluation. American Industrial Health Council, Reproductive and Developmental Effects Subcommittee.

Recent concerns about the potential of certain chemicals to modulate estrogen-regulated processes have led to questions as to how chemicals should be tested for such effects. Therefore, AIHC has developed a comprehensive, resource-efficient, and flexible tiered strategy for estrogen modulation (EM) testing. Levels of evaluation include Tier 0, in which exposure, along with alerts based on structure-activity, persistence, bioaccumulation, and other data, are assessed to prioritize chemicals for preliminary testing. In Tier I, short term in vitro, ex vivo, and/or in vivo assays are used to obtain a preliminary indication of EM potential. Among these, an in vivo response assay is considered the most reliable at this time. However, none of these tests are intended for risk assessment, but rather to aid in choosing chemicals for further testing and in guiding the extent of that testing. Tier II is aimed at risk assessment and involves whole animal tests that contain EM-sensitive end points (e.g., two-generation reproduction study). Tier III consists of hypothesis-driven research reserved for situations where targeted research can reduce levels of uncertainty. This tiered approach provides a framework for the strategic and effective application of EM test methods to address specific information needs on a case by case basis.

Isopropanol: summary of TSCA test rule studies and relevance to hazard identification.

The toxicity of isopropanol (IPA) has been extensively studied as a result of a Test Rule under Section 4 of the Toxic Substances Control Act. In general, the data showed that IPA has a low order of acute and chronic toxicity; does not produce adverse effects on reproduction; is neither a teratogen, a selective developmental toxicant, nor a developmental neurotoxicant; and is not genotoxic or an animal carcinogen. IPA is, however, a potential hazard for transient central nervous system depression at high exposure levels. In addition, IPA produced effects to several rodent toxicity endpoints at high dose levels (i.e., motor activity, male mating index, and exacerbated renal disease) which are of unclear relevance to human health. The data generated by these studies confirmed that IPA acts as a typical short-chain alcohol in mammalian biological systems. It produces a significant narcotic effect upon exposure at high levels for extended periods of time, with no irreversible effects even after repeated exposure, which is consistent with other short-chain alcohols. The metabolism of IPA appears equivalent across species with rapid conversion to acetone and carbon dioxide. Overall, these studies demonstrate IPA exposure is a low potential hazard to human health. This information will allow for an improved assessment of the human health risks from IPA exposure.

Two-generation reproduction toxicity study with isopropanol in rats.

A two-generation reproduction toxicity study was conducted in rats with isopropanol. Thirty rats of each sex per group (P1) were dosed once daily by oral gavage with 0, 100, 500 or 1000 mg isopropanol kg-1 for at least 10 weeks prior to mating. Parental animals were mated within groups for up to 3 weeks. Parental females were dosed during mating, gestation and lactation; parental males were dosed during mating through delivery of their last litter sired. The P2 adults were selected from the F1 litters and were dosed for 10-13 weeks before mating to produce a single litter. Findings in the parental animals included increased lactation body weight gain in the mid- and high-dose females, increased liver and kidney weights in the mid- and high-dose groups of both sexes and centrilobular hepatocyte hypertrophy in some P2 males. There was also accumulation of hyaline droplets and other microscopic findings in the kidneys from the mid- and high-dose P1 males and from all treated groups of the P2 males. Increased mortality was observed in the high-dose F1 offspring during the early postnatal period, although no other clinical signs of toxicity were observed in the offspring of either generation. In addition, offspring body weight was reduced during the early postnatal period in the high-dose F1 males and in the high-dose F2 pups of both sexes. Eighteen out of 70 F1 weanlings in the 1000 mg kg-1 group died or were euthanized prior to P2 selection. No treatment-related post-mortem findings were observed in the offspring from either generation.(ABSTRACT TRUNCATED AT 250 WORDS)

Charles H. Best, the Canadian Red Cross Society, and Canada's first national blood donation program.

This article examines how Canada's first national blood donation program originated during World War II. It focuses on the genesis of Charles H. Best's serum project at the University of Toronto, and the federal government's decision in 1940 to sponsor it as the nation's most viable blood banking option. While Best's personal initiatives were crucial, his project's success was also a result of the larger scientific, political, and institutional circumstances of Canadian medicine. The article also analyzes why the federal government gave responsibility for blood collection to the Canadian Red Cross Society. It shows how the organization's traditional association with military medicine, its more recent involvement with community health services (including blood transfusion), and its flexible national structure suited it for this task. Moreover, Ottawa's willingness to assign this role to a volunteer agency was an indication of the structural deficiencies in Canada's primitive health-care system. The decisions of 1940 flowed from the immediate wartime pressures and individual initiatives. They reflected as well the deeper scientific, institutional, and cultural realities of the time.

In vitro and in vivo assays of isopropanol for mutagenicity.

To assess the mutagenic potential of isopropanol, an in vitro Chinese hamster ovary (CHO) cell/HGPRT gene mutation assay and a bone marrow micronucleus study in mice were conducted. In the CHO/HGPRT assay, concentration levels ranged from 0.5 to 5.0 mg/ml. No elevated mutant frequencies attributable to treatment were observed in the test under either activated or non-activated conditions. In the micronucleus assay, mice were injected intraperitoneally (IP) with either 350, 1,173, or 2,500 mg/kg of isopropanol at constant volumes of 10 ml/kg. No increased incidence of micronuclei was observed in bone marrow polychromatic erythrocytes (PCEs) harvested at 24, 48, or 72 hr post-dosing. In both assays, negative and positive control mutant frequencies were within historical control ranges. These results, in conjunction with previously published data, clearly demonstrate that isopropanol is not a mutagen.

An evaluation of the acute toxic properties of liquids derived from oil sands.

The acute toxicity of three materials derived from Athabasca Oil Sands--(1) bitumen plus naphtha, (2) untreated naphtha (0-250 degrees C) and (3) synthetic crude oil (0-500 degrees C)--was assessed in a battery of tests. In acute oral studies, all three test materials exhibited a low order of toxicity (LD50 greater than 5.0 g kg-1). The acute dermal LD50 was also low (greater than 3 g kg-1) for each test material. All three materials were judged to be 'slight' ocular irritants. Acute inhalation studies (6-h exposures at the maximum attainable concentrations) produced varied responses. Bitumen plus naphtha administered at a concentration of 1.46 mg l-1 did not cause mortality in exposed rats or mice. Lung discoloration was the only necropsy finding of note. Untreated naphtha administered at a concentration of 10.6 mg l-1 was lethal to essentially all of the mice; but only two rats died. Necropsy findings included elevated weights in the liver and kidneys of the exposed mice, elevated lung weights in male rats and elevated liver weights in female rats. Synthetic crude oil administered at a concentration of (4 mg l-1) was lethal to 5/10 mice, but none of the rats (0/10) died. Severe hair loss was noted in the surviving mice, and slight alopecia was also observed in rats. Both species exhibited elevated liver weight, and elevated lung weight was noted in female rats.

Evaluation of the systemic toxicity of coal liquefaction-derived materials following repeated dermal exposure in the rabbit.

The subchronic toxicity of two materials produced by the EDS direct coal liquefaction process was investigated using adult New Zealand white rabbits as the test species. Recycle solvent (RS: 204-427 degrees C) and fuel oil (FO: 204-538 degrees C) were applied to the intact dorsal surface of rabbits, 5 days per week for 4 weeks. Materials were applied as suspensions (2.5 and 10.0 g 100 ml-1) in white oil. White oil alone was administered to concurrent control groups. Both RS and FO elicited gross signs of toxicity including severe dermal irritation, loss of body weight (16-25%) and mortality (4/20 in the high-dose group treated with RS). Systemic effects included liver enlargement as evidenced by histologic findings of diffuse hepatocytomegaly, cytoplasmic degeneration and hepatocellular vacuolation as well as elevated serum cholesterol. There was also evidence of testicular, seminal vesicle and thymic atrophy. More pronounced effects were apparent in the high-dose groups. Testes and epididymides from four of the five FO-treated male rabbits were unremarkable at the microscopic level. The testes, epididymides and seminal vesicles of the fifth animal were atrophic. Three of ten RS treated rabbits showed testicular atrophy associated with hypospermatogenesis in the testes, aspermia in the epididymides and vesiculitis in the seminal vesicles. Four additional animals showed evidence of seminal vesicle atrophy. The liver enlargement was probably due to compensatory metabolism; however, exposure to similar materials at higher levels has resulted in liver toxicity. Thymic and testicular atrophy may have been a secondary response to dermal irritation, stress or body weight loss.

The acute toxicity of coal liquefaction-derived materials.

The acute toxicity of a series of potential streams from the EDS coal liquefaction process have been assessed in animal bioassays. In general, the materials present minimal acute toxic hazards. However, there was some evidence of ocular and dermal irritation. These results indicate that eye and dermal contact should be minimized, particularly when the process streams contain high concentrations of phenolic materials.

Preclinical toxicology studies with acyclovir: teratologic, reproductive and neonatal tests.

Five studies were done to define the potential of Acyclovir (ACV), a new nucleoside analog for antiviral chemotherapy, to produce adverse effects on reproduction and development in laboratory animals. ACV produced no adverse effects when given by gavage to F0 generation mice at 50, 150 and 450 mg/kg/day in a two generation reproduction/fertility study. Some mice were evaluated for teratologic effects and others for postnatal development, including behavior, with negative results. ACV was not embryotoxic and did not increase the incidence of fetal malformations when given by subcutaneous injection to pregnant rats and rabbits at dose levels of 12, 25 and 50 mg/kg/day during the periods of major organogenesis. A comparative LD50 study revealed that 3-day-old rats were not more sensitive to acute toxic effects of ACV than more mature rats. Finally, in a comprehensive multidose toxicity study ACV was given subcutaneously to neonatal rats at 5, 20 and 80 mg/kg/day for 19 consecutive days. There was minimal effect on body weight gain in neonates treated at 20 mg/kg/day and a significant decrease in body weight gain at 80 mg/kg/day. Minimal renal lesions occurred at 80 mg/kg/day but no other signs of adverse effects on developing organ systems were observed. Except for decreased body weight gain in neonatal rats treated at 80 mg/kg/day, ACV did not produce adverse effects on mammalian development when tested in a variety of preclinical toxicology studies.

An evaluation of human sperm as indicators of chemically induced alterations of spermatogenic function. A report of the U.S. Environmental Protection Agency Gene-Tox Program.

To evaluate the utility of sperm tests as indicators of chemical effects on human spermatogenesis, the literature on 4 sperm tests used to assess chemically induced testicular dysfunction was reviewed. The tests surveyed included sperm count, motility, morphology (seminal cytology), and double Y-body (a fluorescence-based test thought to detect Y-chromosomal nondisjunction). There were 132 papers that provided sufficient data for evaluation. These reports encompassed 89 different chemical exposures: 53 were to single agents; 14 to complex mixtures; and 22 to combinations of 2 or more identified agents. Approximately 85% of the exposures were to experimental or therapeutic drugs, 10% were to occupational or environmental agents, and 5% were to drugs for personal use. The most common sperm parameter studied was sperm count (for 87 of the 89 exposures reviewed). Sperm motility was evaluated for 59 exposures, morphology for 44, and double Y-bodies for only 4. The 89 exposures reviewed were grouped into 4 classes: those which adversely effected spermatogenesis, as measured by one or more of the sperm tests (52); those suggestive of improving semen quality (11); those showing inconclusive evidence of adverse effects from exposure (14); and those showing no significant changes (12). Since the reviewed reports had a large variety of study designs, and since every attempt was made to include all reports with interpretable data, these classifications were based on reviewing committee decisions rather than on uniform statistical criteria. This review gives strong evidence that human sperm tests can be used to identify chemicals that affect sperm production, but because of our limited understanding of underlying mechanisms, the extent to which they can detect mutagens, carcinogens or agents that affect fertility remains uncertain. For the very few agents studied with both human and mouse sperm tests, similar test-responses were seen; thus sperm tests in mice and other laboratory mammals may have a potential role in hazard identification. An overall comparison of the 4 human sperm tests suggests that no one test is biologically more responsive than another; all of them may thus be needed when testing for chemically induced changes from agents of unknown activity. This review also gives evidence that sperm tests can be used to assess the extent and the potential reversibility of induced spermatogenic damage. The reviewing committee recommends further studies to determine (a) the dose-response characteristics of the human sperm tests, (b) details of the reversibility of induced changes with time after exposure, (c) the relative responses in the 4 sperm tests in exposed individuals, (d) the mechanism of action, (e) the biological and genetic implications of chemically induced effects, and (f) the comparison of responses among different species for risk assessment. The reviewing committee outlines specific considerations for planning new sperm studies on chemically exposed men.

An evaluation of the mouse sperm morphology test and other sperm tests in nonhuman mammals. A report of the U.S. Environmental Protection Agency Gene-Tox Program.

The literature on the mouse sperm morphology test and on other sperm tests in nonhuman mammals was reviewed (a) to evaluate the relationship of these tests to chemically induced spermatogenic dysfunction, germ-cell mutagenicity, and carcinogenicity, and (b) to make an interspecies comparison to chemicals. A total of 71 papers were reviewed. The mouse sperm morphology test was used to assess the effects of 154 of the 182 chemical agents covered. 4 other murine sperm tests were also used: the induction of acrosomal abnormalities (4 agents), reduction in sperm counts, (6 agents), motility (5 agents), and F1 sperm morphology (7 agents)). In addition, sperm tests for the spermatogenic effects of 35 agents were done in 9 nonmurine mammalian species; these included analyses for sperm count, motility, and morphology, using a large variety of study designs. For the mouse sperm morphology test, 41 agents were judged by the reviewing committee to be positive inducers of sperm-head shape abnormalities, 103 were negative, and 10 were inconclusive. To evaluate the relationship between changes in sperm morphology and germ cell mutagenicity, the effects of 41 agents on mouse sperm shape were compared to available data from 3 different mammalian germ-cell mutational tests (specific locus, heritable translocation, and dominant lethal). The mouse sperm morphology test was found to be highly sensitive to germ-cell mutagens; 100% of the known mutagens were correctly identified as positives in the sperm morphology test. Data are insufficient at present to access the rate of false positives. Although it is biologically unclear why one might expect changes in sperm morphology to be related to carcinogenesis, we found that (a) a positive response in the mouse sperm morphology test is highly specific for carcinogenic potential (100% for the agents surveyed), and (b) overall, only 50% of carcinogens were positive in the test (i.e., sensitivity approximately equal to 50%). Since many carcinogens do not produce abnormally shaped sperm even at lethal doses, negative findings with the sperm test cannot be used to classify agents as noncarcinogens. We conclude that the mouse sperm morphology test has potential use for identifying chemicals that induce spermatogenic dysfunction and perhaps heritable mutations. Insufficient numbers of chemicals agents have been studied by the other sperm tests to permit similar comparisons. A comparison of 25 chemicals tested with sperm counts, motility, and morphology in at least 2 species (including man, mouse and 9 other mammals) demonstrated good agreement in response among species. With further study, interspecies comparisons of chemically induced sperm changes may be useful for predicting and evaluating human effects.

Mutagenicity of dimethylsulfoxide (DMSO): in vivo cytogenetics study in the rat.

Various concentrations (1%, 10%, 50%, and 100%) of laboratory grade dimethylsulfoxide (DMSO) were administered by intraperitoneal injection to male Sprague-Dawley rats for five consecutive days. Femoral bone marrow cells were harvested 24 hours after the last injection and were analyzed for cytogenetic aberration frequencies including chromosome breaks, chromatid breaks, markers, and severely damaged cells. Chromosome breaks revealed no differences between treated and control groups. Chromatid breaks were significantly elevated over the controls in all treated groups except at the 10% level. The incidence of markers was significantly elevated when compared to the controls in all treated groups. Only the high-level (100%) group showed a significant increase in the incidence of severely damaged cells. When the above data were combined, the resultant percent of aberrant cells per animal was found to increase from 10% aberrant cells at the 1% DMSO level to 68.67% aberrant cells at the 100% DMSO level. The incidences of aberrant cells in all treated groups were significantly elevated when compared to the control (4% aberrant cells) group. These observations suggest that DMSO effectively disrupts the integrity of rat chromosome structure, and further investigation of the genetic activity of DMSO is warranted.

Analysis of human spermatozoa for Y chromosomal nondisjunction.

The YFF sperm assay, which is a quantification of the incidence of sperm with two fluorescent bodies (YFF = two fluorescent bodies), was performed to measure Y chromosomal nondisjunction. Three categories of human subjects were analyzed: 1) nonexposed, 2) exposed to antineoplastic agents - ie, chemo- and radiation therapy, and 3) dibromochloropropane (DBCP)-exposed. The nonexposed individuals demonstrated a relatively constant mean YFF value of 1.3%, which was consistent with historical controls in this laboratory and with the results of other investigators. Further, a one-way analysis of variance among the means of the control samples revealed no statistical differences either between these men or within each man's samples. The individuals exposed to antineoplastic agents showed a three- to four-fold increase in the incidence of YFF sperm three to six weeks after the initiation of exposure to Adriamycin and X-irradiation. The maximum percentages of YFF per 1,000 sperm for each individual in this exposed group was analyzed by Wilcoxon's distribution free rank sum test using a one-sided alternative. The exposed individuals' maximum YFF percentages were statistically significantly increased when compared to the maximum YFF values of the nonexposed controls. The individuals exposed to the nematocide DBCP also exhibited a statistically significant increase in the number of sperm containing two Y chromosomes as determined by chi-square analysis with one degree of freedom (P less than 0.01). Data presented herein show statistically significant increases in the incidence of double Y chromosomes as measured by the presence of YFF sperm following exposure to Adriamycin, X-irradiation, and DBCP. It is suggested that men who have a history of antineoplastic therapy could be evaluated for evidence of Y-Y nondisjunction with this method. In the event of an increased YFF sperm level, genetic counseling and amniocentesis should be made available to the spouse where pregnancy has occurred. Further, because this procedure measures gametic mutation, is relatively simple, and is noninvasive, it should be considered for inclusion as part of a battery of medical tests for monitoring industrial populations.

Detection of aneuploidy in human sperm.

Adequate methods for monitoring any type of gametic mutation directly in man are virtually nonexistent. A method is presented by which one can monitor Y chromosomal nondisjunction directly in the male gamete by quantifying the number of spermatozoa with two fluorescent bodies (YFF) in 1000 sperm counted. Dried semen slides are stained with quinacrine dihydrochloride and examined under a fluorescent microscope with dark field illumination. This method eliminates the biopsy required for other meiotic studies and further eliminates bias in gametogenic selection by evaluating ejaculated mature spermatozoa. Since chromosomal numerical errors are found in 0.4% of term births and 35% of miscarriages, it is evident that chromosomal aneuploidy constitutes the major mutagenic load in man. In view of the increases observed in the incidence of YFF sperm in patients receiving antineoplastic therapy and in the DBCP-exposed workers, it may be prudent for men who have a history of exposure to mutagens and who are contemplating reproduction to be evaluated by this method prior to attempting conception. Further, this procedure could also be applied to the clinical phase of new drug testing to evaluate the effects of that agent with respect to aneuploidy since the increases in Y chromosomal nondisjunction may well act as a barometer for increases in overall autosomal nondisjunction.

Toxicity of low concentration long-term exposure to an airborne mixture of nitrous oxide and halothane.

To evaluate experimentally the questions of reproductive, teratological, cytogenetic, and tumorigenic sequelae of long-term exposures to escape levels of halothane plus nitrous oxide (N2O), male and female rats were exposed either to air, to 1 ppm halothane plus 50 ppm N2O, or to 10 ppm halothane plus 500 ppm N2O for 7 hr/day, 5 days/wk for appropriate periods of time. In one experiment, young adult female rats were exposed for 60 days, then mated and reexposed either staring with Day 1 or Day 6 of gestation until Day 15. The former were permitted to deliver naturally while the latter were delivered by C-section on Day 20. The young adult males used in breeding were also exposed for 60 days prior to mating and then for a total of 52 weeks thereafter. At termination, bone marrow cell and spermatogonial metaphase preparations were made and assessed for cytogenetic abnormalities. The mated females were evaluated for ovulation, pre- and post-implantation loss, fetal growth, fetal abnormalities, and early post-natal development, as appropriate. In a parallel experiment, 50 male and 50 female weanling rats in each group were exposed for 104 weeks to the same levels and then evaluated for tumor development with emphasis on the reticuloendothelial system. The results indicated a significant reduction in ovulation and implantation efficiency from exposure to the higher levels and slightly retarded fetal development at both levels. No teratological or abortifacient effects were noted. No tumorogenic effects were observed. However, cytogenetic damage to both bone marrow and spermatogonial cells was seen at both levels.