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PubMed2004

Inhaled isobutyl nitrite inhibited macrophage inducible nitric oxide by blocking NFkappaB signaling and promoting degradation of inducible nitric oxide synthase-2.

We previously reported that inhaled isobutyl nitrite inhibited macrophage tumoricidal activity by inhibiting inducible nitric oxide (NO) production. In the present study, a much shorter inhalant exposure regimen (five daily exposures) inhibited inducible NO and the NO synthase (NOS2). One of the ways in which NO and NOS2 are regulated is by ubiquitin-dependent NOS2 degradation. Immunoprecipitated NOS2 showed increased poly-ubiquitination, following exposure to the inhalant. In addition, Western blots of macrophage nuclear extracts for the NFkappaB subunit, p65, showed that exposure to the inhalant inhibited NFkappaB signaling, necessary for induction of NOS2. The inhalant blocked phosphorylation of the NFkappaB inhibitor, IkappaBalpha. The inhibition of NFkappaB signaling following inhalant exposure was confirmed using mice transgenic for the kappaB-dependent promoter of the HIV 5' LTR linked to luciferase. The data suggested that inhalant exposure likely inhibited macrophage NO production by blocking NFkappaB-mediated activation signaling and promoting poly ubiquitination of NOS2.

Administration, Inhalation↗
PubMed1996

Developmental neurotoxicity of methanol exposure by inhalation in rats.

The possibility of widespread methanol exposure via inhalation stemming from its adoption as an automotive fuel or fuel component arouses concerns about the potential vulnerability of the fetal brain. This project was designed to help address such concerns by studying the behavior of neonate and adult rats following perinatal exposure to methanol vapor. Four cohorts of pregnant Long-Evans hooded rats, each cohort consisting of an exposure and a control group, were exposed to 0 parts per million (ppm) (control) or 4,500 ppm methanol vapor for six hours daily beginning on gestation day (GD) 6 with dams and pups then being exposed postnatal day (PND) 21. Exposures took place in 2-m3 Rochester-type inhalation chambers while the animals remained in their plastic breeder cages. Prenatal and postnatal blood methanol concentrations were determined by gas chromatography. Blood methanol concentrations of the dams, measured immediately following a six-hour exposure, were approximately 500 to 800 micrograms/mL throughout gestation and lactation. Average blood methanol concentrations of the pups were about twice those of the dams. Because such results appeared consistently across the other cohorts, we decided to obtain additional data with Cohort 4. Once it had undergone the standard exposure protocol, we selected sets of extra pups from those that had not been assigned previously to the adult phase of behavioral testing. Each set was exposed once, at ages that extended out to PND 52, for one additional six-hour session of exposure to 4,500 ppm methanol. The blood methanol concentrations of these pups declined until about PND 48, at which time they approximated those of the dams. These findings might be accounted for by a process of metabolic maturation in the pups that remains to be identified.

Animals↗
PubMed2003

A study on the effect of inhalative formaldehyde exposure on water labyrinth test performance in rats.

We investigated the effects of repeated inhalative exposure to several formaldehyde concentrations (2 hours/day, 10 consecutive days) on the behavior of adult male and female LEW.1K rats during a period in which they learned to perform a water labyrinth task. We also examined the effects on the histology of some organ tissues. While the controls needed increasingly shorter swimming periods to complete the water labyrinth test and made fewer errors with advancing trial duration, such progress could not be observed in the learning behavior of the exposed animals. They took significantly longer swimming periods to reach the finish and made significantly more errors in comparison to the controls. The statistical comparison between the collected data in the formaldehyde exposed male and female rats reveals that females in general reached the end point of the swimming labyrinth in significantly less time. On some trial days, however, they made more mistakes than males. In the highest concentration group, no gender differences were evident in the frequency of errors. The histological examination revealed no pathological changes attributable to formaldehyde exposure. Since the water labyrinth test is used to investigate changes in memory and learning behavior in animals, we conclude that under investigational conditions, formaldehyde affects the learning behavior and the memory of male and female rats.

Administration, Inhalation↗
PubMed2002

Personal sampling for inhalable aerosol exposures of carbon black manufacturing industry workers.

The study was concerned with the measurement of inhalable aerosol exposures in the carbon black production industry. The primary goal of the study was to determine the extent to which inhalable aerosol exposure, as measured by the Institute of Occupational Medicine (IOM) personal inhalable sampling head, compared to "total" aerosol exposure, as measured by traditional methodology. A secondary objective was the evaluation of another inhalable aerosol sampler for carbon black aerosol measurement. In addition, an exploratory evaluation of the applicability of the National Institute for Occupational Safety and Health (NIOSH) analytical method (Method 5040) for the determination of carbon black, measured as elemental carbon, was conducted. A field study was carried out in a number of North American carbon black production plants using three samplers: the 2 Lpm IOM sampler as a reference sampler for the inhalable fraction, the 2 Lpm closed-face 37-mm plastic cassette that has been used for many years for total aerosol, and the 3.5 Lpm GSP sampler that has recently been identified by some as a possible candidate for inhalable aerosol. No such studies have previously been reported for the carbon black industry. Further, there have been no reports of the GSP performance in direct comparison to a reference instrument like the IOM sampler. The results showed that inhalable aerosol exposures for workers in carbon black production and packing areas were higher than the corresponding total aerosol exposures by a factor of nearly three, implying the presence of significantly coarser aerosol than previously thought based simply on knowledge of the carbon black production process. The fact that the aerosols collected in portions of the process comprised high proportions of non-elemental carbon particulate was thought likely to be responsible, underlining the need to consider whether gravimetric assessment for such exposure is the most appropriate metric. In addition, and somewhat surprisingly, the GSP sampler emerged clearly as a good alternative to the IOM sampler for collecting inhalable aerosol in carbon black industry workplaces like those studied (although this conclusion cannot yet be extended to other workplaces).

Aerosols↗
PubMed1999

Toxicity of middle distillates from dermal exposure.

This report focuses on recent studies that investigated the effects of kerosine dermal exposure on neurotoxicity and reproductive/developmental toxicity. Background toxicity information will also be reviewed for kerosine range mid distillates. The kerosine range mid distillates have a carbon range of C9-C16 and have a boiling range of 302-554 degrees F (150-290 degrees C). This category includes kerosine, aviation fuels (e.g., Jet A, JP-5 and JP-8), no. 1 fuel oil and diesel fuel oil. In general, the kerosine range mid distillates demonstrate relatively low acute toxicity by any route of exposure. High inhalation exposures can induce central nervous system depression characterized by ataxia, hypoactivity and prostration. Kerosines are known to cause skin irritation and inflammation under conditions of acute and repeated exposure in animals and humans, but are only slightly irritating to the eye and are not skin sensitizers. In addition, the absorption of kerosine range mid distillates through the skin has been demonstrated to be fairly rapid, but limited to approximately 10-15% of the applied dose after 24 hours. The kerosine range mid distillates are generally inactive in genetic toxicity tests although positive studies have been reported. Positive results, while at times equivocal, have been reported for straight run kerosine and jet fuel A in the mouse lymphoma assay with metabolic activation, and hydrodesulfurized kerosine (mouse) and jet fuel A (rat) in the bone marrow cytogenetic assay. Effects on the nervous and reproductive systems have been reported in humans and experimental animals under conditions where inhalation and dermal exposure to specific kerosine type fuels are sometimes difficult to separate. Recent laboratory studies have addressed this point and examined the effects of dermal exposure. In these studies, rats were exposed to hydrodesulfurized kerosine by skin application to determine the potential of dermal contact to cause reproductive/developmental toxicity (OECD Guideline 421) or neurotoxicity (TSCA Guidelines on subchronic inhalation and neurotoxicity studies). These studies demonstrated that the highest dose level of kerosine does not induce reproductive/developmental or neurotoxicity effects by skin exposure in rodent studies. The dermal NOEL for HDS kerosine in rats was > or = 494 mg/kg for both neurotoxicity, and reproductive/developmental toxicity.

Abnormalities, Drug-Induced↗
PubMed2000

Occupational exposure to inhalative irritants and methacholine responsiveness.

OBJECTIVES: Occupational exposures to inhalative irritants have been associated with an increased reporting of respiratory symptoms in previous studies. Methacholine responsiveness represents a continuous measure of airway responsiveness. As such, it may be less subject to recall bias and more sensitive to detecting effects of occupational exposure on airways. Such effects may be stronger among atopic persons. The objective of the study was to examine the relationship between self-reports of occupational exposure to dusts, gases, vapors, aerosols, and fumes and methacholine responsiveness. METHODS: A sample was studied of never smokers (N=3044) chosen randomly from 8 areas in Switzerland. Atopy was defined as any positive skin test to 8 inhalative allergens. Nonspecific bronchial reactivity was tested using methacholine chloride and quantified by calculating the slope of the dose-response. RESULTS: The methacholine slopes were 19% [95% confidence interval (95% CI) 6-32] higher for never smokers with exposure to dusts, fumes, vapors, gases, or aerosols than for the unexposed group. When only atopic never smokers were examined. the increase was larger (37%, 95% CI 7-75), and for persons with >2 positive skin prick tests the effect was still higher (42%, 95% CI -1.5-104). Exposure to vapors and aerosols was strongly associated with increased methacholine slopes among the atopic subjects. CONCLUSIONS: Occupational exposure, particularly to dusts and fumes, was associated with increased bronchial reactivity in never smokers in this study. The magnitude of the effect was larger among atopic subjects.

Adolescent↗
PubMed2001

Repeated exposure to inhaled toluene induces behavioral and neurochemical cross-sensitization to cocaine in rats.

RATIONALE: Toluene is a solvent found in many commercial products and is frequently abused by inhalation. Whether previous exposure to toluene alters subsequent responses to other drugs of abuse is not known. OBJECTIVES: This study determined the effects of repeated toluene exposure on the acute motor-stimulant response to cocaine and on cocaine-induced dopamine (DA) concentrations in the nucleus accumbens (NAc). METHODS: One week following bilateral cannulae implantation over the NAc, 27 adult, male Wistar rats began a daily 30-min exposure regimen to either toluene (8,000 ppm) or air for ten sessions. Approximately 24 h or 96 h after their last exposure, animals were injected with either saline or cocaine (15 mg/kg, i.p.) and locomotor activity and DA concentrations in the NAc were measured. RESULTS: Exposure to toluene rendered the rats immobile, and the time required for recovery of normal posture decreased across the ten sessions. In all animals tested, systemic cocaine administration enhanced both locomotor activity and DA concentrations in the NAc. These increases, however, were significantly greater in rats previously exposed to toluene. CONCLUSIONS: Overall, these findings show that repeated toluene exposure enhances behavioral and neurochemical responses to subsequent cocaine administration.

Administration, Inhalation↗
PubMed1984

Induction of formaldehyde sensitivity in guinea pigs.

Occupational exposure to formaldehyde (HCHO) has been implicated in development of both dermal hypersensitivity and pulmonary hypersensitivity. The purpose of this study was to assess the route of exposure most likely to cause sensitization in animals and the potency of formaldehyde as a sensitizing chemical. Three routes of exposure were utilized: inhalation, dermal, and injection (with Freund's complete adjuvant). For inhalation exposure, groups were exposed to 6 ppm (Group I) or 10 ppm HCHO (Group II) for 6 hr/day or 8 hr/day (Group III) on 5 consecutive days. Animals were evaluated for skin sensitivity, production of anti-HCHO antibody, and respiratory sensitivity (both immediate- and delayed-onset) to HCHO. Of the animals receiving inhalation exposure, two of four animals in Group III displayed dermal sensitivity. No antibodies or pulmonary sensitivity were detected in any animals in any of these groups. Animals exposed to HCHO by injection displayed extensive dermal reactions when skin tested. In addition, two of four animals in this group developed antibodies to HCHO in low titer. No pulmonary sensitivity was detected. Animals exposed to HCHO by dermal contact developed neither pulmonary sensitivity nor antibodies to HCHO. However, all of these animals developed skin sensitivity. The severity of the contact sensitivity response, as well as the percentage of animals sensitized, increased with exposure dose. These results indicated that HCHO was a skin sensitizer in the guinea pig without causing detectable respiratory hypersensitivity.

Administration, Topical↗
PubMed2005

Exposure and inhalation risk assessment in an aluminium cast-house.

To date the exposure, absorption and respiratory health effects of cast-house workers have not been described since most studies performed in the aluminium industry are focused on exposure and health effects of potroom personnel. In the present study, we assessed the external exposure and the absorbed dose of metals in personnel from the aluminium cast house. This was combined with an evaluation of respiratory complaints and the lung function of the personnel. 30 workers from an aluminium casting plant participated and 17 individuals of the packaging and distribution departments were selected as controls. The exposure was assessed by the quantification of total inhalable fume with metal fraction and by the determination of urinary aluminium, chromium, beryllium, manganese and lead concentration. Carbon monoxide (CO), carbon dioxide (CO2), aldehydes and polyaromatic hydrocarbons and man-made mineral fibres concentration were assessed as well. In order to evaluate their respiratory status each participant filled out a questionnaire and their lung function was tested by forced spirometry. Total inhalable fume exposure was maximum 4.37 mg m(-3). Exposure to the combustion gases, man-made mineral fibres and metal fume was well below the exposure limits. Beryllium could not be detected in the urine. The values of aluminium, manganese and lead in the urine were all under the respective reference value. One individual had a urinary chromium excretion above the ACGIH defined biological exposure index (BEI) of 30 microg g(-1) creatinine. There was no significant difference in any of the categories of the respiratory questionnaire and in the results of the spirometry between cast house personnel and referents (Chi-square, all p > 0.05). Exposure in cast houses seem to be acceptable under these conditions. However, peak exposure to fumes cannot be excluded and the potential risk of chromium and beryllium exposure due to the recycling of aluminium requires further attention.

Air Pollutants, Occupational↗
PubMed2002

Evaluation of potential dermal exposure of pesticide spray operators in greenhouses by use of visible tracers.

In the present study, the potential dermal and inhalation exposure of the operator was measured, following simulation of insecticide application with the dye tracer Sunset Yellow in greenhouse cucumbers and tomatoes. For the monitoring of operator exposure, the whole body technique was used. The potential inhalation exposure was measured with a personal air sampler equipped with a glass fiber filter. The potential dermal operator exposure ranged from 84.4 to 526.7 ml of spray solution (s.s.)/h for the whole body and from 18.5 to 62.5 ml s.s./h for hands in the case of greenhouse cucumbers. The respective inhalation exposure was between 0.17 and 1.0 ml s.s./h. For greenhouse tomatoes, the potential body exposure was in the range of 22.4 to 62.1 ml s.s./h. The hand exposure varied from 5.5 to 6.1 ml s.s./h. The potential inhalation exposure was in the range of 0.33 to 0.43 ml s.s./h. The potential dermal operator exposure is a highly variable parameter, with a variation factor higher than 100% in many cases. One of the most critical factors for the determination of both potential dermal and inhalation exposure is the application pressure. Other field and operational conditions, including unpredictable factors, are also important for the determination of operator exposure levels. The measured potential dermal operator exposure values were above the levels of exposure estimated with mathematical models.

Agricultural Workers' Diseases↗
PubMed1997

Hexavalent chromium-contaminated soils: options for risk assessment and risk management.

Risk assessment involves establishing scientifically defensible dose-response relationships for end points of concern. For Cr(VI)-contaminated soils, this includes conducting dose-response assessments for blood, liver, and kidney toxicity following oral exposure; lung cancer following inhalation exposure; and allergic contact dermatitis following dermal exposure. This dose-response information is then integrated with a site-specific exposure assessment (or default assumptions) in order to develop a site-specific (or generic) soil criterion within the framework of a comprehensive risk characterization. Risk managers develop cleanup standards designed to protect against all possible adverse effects, taking into account these site-specific (or generic) criteria and other factors such as technical feasibility, cost-benefit analyses, and socio-political concerns. Recently a push for cost-benefit analyses of environmental decisions has occurred, further supporting the need for risk assessors to prepare a comprehensive risk characterization, with its attendant uncertainties. These risk assessment and management issues are brought to the forefront by risk assessors and risk managers dealing with Cr(VI)-contaminated soils. This article offers a review and analysis of the risk characterization of Cr(VI)-contaminated soils, showing that the differing toxicities with route of exposures do not necessarily lead to different characterizations or risk. Soil concentrations in the range of 130 to 450 ppm appear to protect against noncancer toxicity from oral exposure, cancer toxicity from inhalation exposure, and allergic contact dermatitis from dermal exposure.

Administration, Inhalation↗
PubMed2005

Two generation reproduction study of styrene by inhalation in Crl-CD rats.

This study was conducted to evaluate the potential adverse effects of styrene on reproductive capability from whole-body inhalation exposure of F0 and F1 parental animals. Assessments included gonadal function, estrous cyclicity, mating behavior, conception rate, gestation, parturition, lactation, and weaning in the F0 and F1 generations, and F1 generation offspring growth and development. Four groups of male and female Crl:CD(SD)IGS BR rats (25/sex/group) were exposed to 0, 50, 150, and 500 ppm styrene for 6 hr daily for at least 70 consecutive days prior to mating for the F0 and F1 generations. Inhalation exposure for the F0 and F1 females continued throughout mating and gestation through gestation day 20. Inhalation exposure of the F0 and F1 females was suspended from gestation day 21 through lactation day 4. On lactation days 1 through 4, the F0 and F1 females received styrene in virgin olive oil via oral gavage at dose levels of 66, 117, and 300 mg/kg/day (divided into three equal doses, approximately 2 hr apart). These oral dosages were calculated to provide similar maternal blood peak concentrations as provided by the inhalation exposures. Inhalation exposure of the F0 and F1 females was re-initiated on lactation day 5. Styrene exposure did not affect survival or clinical observations. Rats in the 150- and 500-ppm groups in both parental generations gained weight more slowly than the controls. There were no indications of adverse effects on reproductive performance in either the F0 or F1 generation. Male and female mating and fertility indices, pre-coital intervals, spermatogenic endpoints, reproductive organ weights, lengths of estrous cycle and gestation, live litter size and postnatal survival were similar in all exposure groups. Additionally, ovarian follicle counts and corpora lutea counts for the F1 females in the high-exposure group were similar to the control values. No adverse exposure-related macroscopic pathology was noted at any exposure level in the F0 and F1 generations. A previously characterized pattern of degeneration of the olfactory epithelium that lines the dorsal septum and dorsal and medial aspects of the nasal turbinates occurred in the F0 and F1 generation animals from the 500-ppm group. In the 500-ppm group, F2 birthweights were reduced compared to the control and F2 offspring from both the 150- and 500-ppm exposure groups gained weight more slowly than the controls. Based on the results of this study, an exposure level of 50 ppm was considered to be the NOAEL for F0 and F1 parental systemic toxicity; the NOAEL for F0 and F1 reproductive toxicity was 500 ppm or greater.

Animals↗
PubMed2001

Induction and time-dependent accumulation of micronuclei in peripheral blood of transgenic p53+/- mice, Tg.AC (v-Ha-ras) and parental wild-type (C57BL/6 and FVB/N) mice exposed to benzene by inhalation.

In this study, we determined the induction and time-dependent accumulation of micronuclei in the peripheral blood of transgenic C57BL/6 p53+/- mice (p53+/- mice), FVB/N Tg.AC v-Ha-ras mice (Tg.AC mice) and their isogenic parental strains, FVB/N and C57BL/6 following inhalation exposure to benzene. Our objective was to determine the impact of p53 heterozygosity in p53+/- mice and the v-Ha-ras transgene in Tg.AC mice on micronuclei induction following exposure to inhaled benzene. A flow cytometric technique that distinguishes micronucleated red blood cells (MN-RBC) from micronucleated reticulocytes (MN-RET) was used. Mice were exposed to 0, 100 or 200 p.p.m. benzene using three different exposure regimens that resulted in an equal weekly cumulative exposure (3000 p.p.m.x hours) to benezene: 100 p.p.m. for 6 h/day, 5 days/week, Monday to Friday (M-F); 100 p.p.m. for 10 h/day, 3 days/week, Monday, Wednesday, Friday (MWF); and 200 p.p.m. for 5 h/day, 3 days/week MWF. Significant elevations of MN-RBC and MN-RET were observed from 1 week exposure in all of the benzene-exposed groups that increased in a time-dependent manner for up to 13 weeks exposure. Fewer MN-RBC and MN-RET were induced in the 200 p.p.m. benzene exposure group than in mice exposed to 100 p.p.m. The reduction in the frequency of MN-RBC in the 200 p.p.m.x5 h benzene exposure group is probably due to metabolic saturation resulting in a lower bone marrow dose (concentration x time) than in the 100 p.p.m. exposure groups. No differences were observed in the frequency of MN-RBC or MN-RET in Tg.AC compared with the FVB/N isogenic controls. At certain time points the frequency of micronuclei was less in the heterozygous p53+/- mice than determined in the wild-type C57BL/6 isogenic parental strain. These results indicate that the heterozygous state in p53+/- mice, but not the v-Ha-ras transgene in Tg.AC mice can influence the induction of micronuclei by benzene.

Animals↗
PubMed1994

Route-dependent comparative metabolism of [14C]toluene 2,4-diisocyanate and [14C]toluene 2,4-diamine in Fischer 344 rats.

This study was initiated to evaluate the pharmacokinetics/metabolism of 14C-labeled toluene 2,4-diisocyanate (2,4-[14C]-TDI) following oral and inhalation exposure in the rat. For comparison, the pharmacokinetics/metabolism of toluene 2,4-diamine (2,4-[14C]TDA) was also evaluated. Groups of 3 or 4 male rats were given either a single 60 mg/kg oral dose of 2,4-[14C]-TDI or were exposed to 2,4-[14C]TDI vapors at a target concentration of 2 ppm for a 4-hr period. Additional groups of male rats were given single 3 or 60 mg/kg oral doses or a single 3 mg/kg intravenous (iv) dose of 2,4-[14C]TDA. All rats were euthanized by 48 hr postexposure. Following oral administration of 2,4-[14C]TDI, > 93% of the administered radioactivity was recovered in the urine, feces, cage wash, and tissues. Approximately 8% of the oral dose was excreted in the urine while 81% was eliminated in the feces. It is estimated that during inhalation exposure, essentially all of the inhaled 2,4-[14C]TDI was retained by the animal. At 48 hr post-inhalation exposure approximately 15 and 47% of the recovered radioactivity was in the urine and feces, respectively. Following oral or inhalation exposure to 2,4-[14C]TDI, no radioactivity was eliminated as either expired 14C organics or 14CO2. Comparison of the 2,4-[14C]TDI inhalation group with the oral 2,4-[14C]TDI and 2,4-[14C]TDA treatment groups indicated that a larger percentage of the inhaled radioactivity was in the tissues/carcass (34% vs 2-4%) and the excretion of radioactivity into the urine was slower (t1/2 = 20 hr vs 5-8 hr) following TDI inhalation. The total amount of free+acetylated TDA metabolites detected in the urine specimens (0-12 hr) following oral and inhalation exposure to 2,4-[14C]TDI was 15 and 0.26 microgram eq 2,4-TDA, respectively. No free 2,4-TDA was detected in the urine specimen from the inhalation group. In comparison, 638 and 20 micrograms eq 2,4-TDA was detected in the urine specimen after oral administration of 60 and 3 mg/kg 2,4-[14C]TDA, respectively. Following 2,4-[14C]TDI inhalation and oral exposure approximately 90 and 65% of the quantitated urinary metabolites existed as acid-labile conjugates, respectively. In contrast, only 16-39% of the quantitated urinary metabolites existed as acid-labile conjugates following oral administration of 2,4-[14C]TDA. Inhalation exposure to 2,4-TDI primarily results in the formation of acid-labile conjugates with little or no 2,4-TDA being formed.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Inhalation↗
PubMedDate not supplied

Inhalation exposure-rate of ethylene oxide affects the level of DNA breakage and unscheduled DNA synthesis in spermiogenic stages of the mouse.

The effect of ethylene oxide (EtO) inhalation-exposure rate on the induction of DNA breakage in late spermatids and on unscheduled DNA synthesis (UDS) in early spermatids was studied. The exposures were 450 parts per million (ppm) for 4 h, 900 ppm for 2 h, and 1800 ppm for 1 h. Thus, the total exposure was always 1800 ppm-h. Both DNA breakage and UDS were found to increase by a factor of approximately 3 in going from the low to high EtO concentration, suggesting that the molecular dose of EtO to the testis had increased by a similar factor. Our results are consistent with the EtO exposure-rate effect found by Generoso et al. (1986) for induction of dominant-lethal mutations in late spermatids and early spermatozoa.

Administration, Inhalation↗
PubMed2003

A small whole-body exposure chamber for laboratory use.

With the development of transgenic and specialized mouse strains, there is an increased need for inhalation exposure systems designed for smaller exposure groups. An inhalation exposure chamber, designed specifically for the exposure of up to 40 mice, was characterized. The chamber was fabricated from 0.32-cm-thick ((1)/(8)-in) aluminum sheets with outside dimensions of 61 cm long by 32 cm high by 34 cm deep, resulting in an internal volume of 65 L. Two stainless-steel open-mesh cages, separated by an absorbent barrier, can be stacked within the central portion of the chamber. Access is provided through a gasketed door with a safety-glass face. Tests were performed to determine the chamber leakage rate, degree of mixing, and spatial variation of two aerosols within the chamber. Results indicated that the fractional leakage rate was 0.0003 min(-1), well below a reported criterion for an operating chamber. Chamber operation gave similar mixing performance with, or without, use of an interior fan. For aerosols with a mass median aerodynamic diameter (MMAD) of 2.56 micro m and 3.14 micro m, the spatial variation of particulate matter concentration resulted in coefficients of variation (CVs) of 4.8% and 11.0%, respectively. These CV values are comparable to those obtained from similar studies involving other inhalation exposure chambers.

Air Pollutants↗
PubMed1991

Fetal injury and abortion associated with occupational exposure to inhaled anesthetics.

While the actual risk associated with occupational exposure to inhaled anesthetics has not precisely been defined, a growing body of data has accumulated so that we may begin to make certain valid inferences. Published studies of the teratogenic, mutagenic and carcinogenic effects of exposure to nitrous oxide and isoflurane suggest that a causal role of these inhaled agents appears to be very low or nonexistent.

Abnormalities, Drug-Induced↗
PubMed2003

Cellulosic building insulation versus mineral wool, fiberglass or perlite: installer's exposure by inhalation of fibers, dust, endotoxin and fire-retardant additives.

A task-specific exposure matrix was designed for workers installing building insulation materials. A priori, a matrix element was defined by type of task (installer or helper), type of work area (attic spaces or wall cavities) and type of insulation material (slabs from mineral wool, fiberglass or flax; loose-fill cellulosic material or perlite). In the laboratory a mock-up (full scale) of a one-family house was used for simulated installation of insulation materials (four replicates per matrix element). Personal exposure to dust and fibers was measured. The dust was analyzed for content of endotoxin and some trace elements (boron and aluminum) from fire-retardant or mold-resistant additives. Fibers were characterized as WHO fibers or non-WHO fibers. In support of the exposure matrix, the dustiness of all the materials was measured in a rotating drum tester. For installers in attic spaces, risk of exposure was low for inhalation of dust and WHO fibers from slab materials of mineral wool or fiberglass. Slab materials from flax may cause high risk of exposure to endotoxin. The risk of exposure by inhalation of dust from loose-fill materials was high for installers in attic spaces and for some of the materials risk of exposure was high for boron and aluminum. Exposure by inhalation of cellulosic WHO fibers was high but little is known about the health effects and a risk assessment is not possible. For the insulation of walls, the risk of installers' exposure by inhalation of dust and fibers was low for the slab materials, while a high risk was observed for loose-fill materials. The exposure to WHO fibers was positively correlated to the dust exposure. A dust level of 6.1 mg/m3 was shown to be useful as a proxy for screening exposure to WHO fibers in excess of 10(6) fibers/m3. In the rotating drum, slabs of insulation material from mineral wool or fiberglass were tested as not dusty. Cellulosic loose-fill materials were tested as very dusty, and perlite proved to be extremely dusty.

Aluminum Oxide↗