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Proteolytic detergent enzymes enhance the allergic antibody responses of guinea pigs to nonproteolytic detergent enzymes in a mixture: implications for occupational exposure.

A guinea pig intratracheal test was developed to assess the respiratory allergenicity of enzymes used in the detergent industry. Information gained from this test was used in a process for setting operational exposure guidelines to protect worker health. Mixtures of enzyme proteins were given to guinea pigs once per week for 10 weeks to determine whether there were interactions among enzymes that affected the induction of antibody responses to each enzyme in the mixture. Passive cutaneous anaphylaxis antibody titers against each enzyme were measured in sera. Mixtures of two or three enzymes always consisted of a protease (Alcalase, Savinase; Novo Industri A/S) with an alpha-amylase (Termamyl; Novo Industri A/S), a lipase (Lipolase; Novo Industri A/S), or both. Control animals were exposed to single enzymes. The antibody titers to Termamyl and Lipolase were significantly greater in animals dosed with the protease-containing mixtures as compared with control animals dosed with a single enzyme. Antibody titers to the protease were unchanged in the presence of additional enzymes in the mixture. Complete inactivation of protease activity abrogated the enhanced antibody response to Lipolase. Inhalation exposure of guinea pigs to a mixture of Alcalase and Lipolase also resulted in higher antibody titers to Lipolase as compared with animals exposed by inhalation to Lipolase alone, showing that the enhanced response was not due to intratracheal delivery of antigen to the respiratory tract. These results show that proteolytic enzymes in a mixture enhance antibody responses to other enzymes. This should be considered when defining exposure guidelines for protease-containing enzyme mixtures.

Administration, Inhalation↗

Cell proliferation in lung following acute fly ash exposure.

Cell proliferation was examined in the lung parenchyma, the ciliated airway epithelium and the lymph nodes of Fischer-344 rats following a 6-h exposure to fly ash obtained from the baghouse of an experimental fluidized bed combustor. The fly ash concentration was 142 mg/m3 with a mass median aerodynamic diameter (MMAD) of approximately 3.0 micron and a geometric standard deviation (sigma g) of approximately 2.6. Lung deposition of fly ash was measured in the right lung to be 90 +/- 20 and 80 +/- 30 mg for male and female rats, respectively, resulting in a calculated value for male rats of (140 +/- 30 micrograms/animal) and for female rats of 130 +/- 50 micrograms/animal). Autoradiographic methods were used to detect cells that incorporated [3H] thymidine. About a 10-fold increase in labeling of the lung epithelial type II cells was observed following the 6-h fly ash exposure. There was also an increase in [3H] thymidine incorporation into DNA of alveolar macrophages. Labeling activity of macrophages within the lung was increased for up to 4 days following fly ash exposure; however, the size of the macrophage population was not altered. Following exposure, a higher labeling index was also observed in the epithelial cells of the airways. Labeling in the trachea reached a peak at 4 days after exposure while in the bronchi and in small airways (inside diameter of less than 0.35 mm) the highest level of labeling was observed at 1 day after exposure. Labeling in airway epithelial cells was increased 2-4 times above that of sham-exposed animals. Lung-associated lymph nodes accumulated particulate material and had variable amounts of [3H]thymidine incorporation. These results demonstrate that acute inhalation exposure to fly ash initiated cell division or DNA synthesis in several cell populations of lung parenchyma and airways.

Animals↗

Exposure of traffic police to Polycyclic aromatic hydrocarbons in Beijing, China.

Exposure of on-duty traffic police in Beijing to polycyclic aromatic hydrocarbons (PAHs) was investigated during the summer, 2004 using a personal sampling technique in measuring both particulate and gaseous phase PAHs. The results were then compared with those from two control sites away from the street. Exposure levels to gaseous and particulate PAHs for the traffic police were found to be 1525 +/- 759 ngm(-3) and 148 +/- 118 ngm(-3), respectively, representing 2-2.5 times higher levels than those at the control sites. The daily inhalation exposure of the police was estimated to be 277 ngkg(-1)d(-1). Most of the PAHs exposure came from the vapor phase, particularly NAP, FLO and PHE. Based on calculated PAH diagnostic ratios, the major source of PAHs exposure was from vehicle exhaust. The effects of temperature, humidity and atmospheric stability on exposure levels are also discussed.

Air Pollutants, Occupational↗

Camphor Poisoning: an evidence-based practice guideline for out-of-hospital management.

A review of national poison center data from 1990 through 2003 showed approximately 10,000 annual ingestion exposures to camphor-containing products. A guideline that determines the threshold dose for emergency department referral and need for pre-hospital decontamination could potentially avoid unnecessary emergency department visits, reduce health care costs, optimize patient outcome, and reduce life disruption for patients and caregivers. An evidence-based expert consensus process was used to create the guideline. Relevant articles were abstracted by a trained physician researcher. The first draft of the guideline was created by the primary author. The entire panel discussed and refined the guideline before distribution to secondary reviewers for comment. The panel then made changes based on the secondary review comments. The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial management of patients with suspected exposures to camphor-containing products by 1) describing the manner in which an exposure to camphor might be managed, 2) identifying the key decision elements in managing cases of camphor exposure, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This guideline applies to camphor exposure alone. Co-ingestion of additional substances, such as in commercial products of camphor combined with other ingredients, could require different referral and management recommendations depending on the combined toxicities of the substances. This guideline is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline, and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. This guideline does not substitute for clinical judgment. Recommendations are in chronological order of likely clinical use. The grade of recommendation is in parentheses. 1) Patients with stated or suspected self-harm or who are the recipients of malicious administration of a camphor-containing product should be referred to an emergency department immediately, regardless of the amount ingested (Grade D). 2) Patients who have ingested more than 30 mg/kg of a camphor-containing product or who are exhibiting symptoms of moderate to severe toxicity (e.g., convulsions, lethargy, ataxia, severe nausea and vomiting) by any route of exposure should be referred to an emergency department for observation and treatment (Grade D). 3) Patients exhibiting convulsions following a camphor exposure should be transported to an emergency department by pre-hospital emergency medical care providers (Grade D). A benzodiazepine should be used to control convulsions (Grade C). 4) Patients who have been exposed to a camphor product and who remain asymptomatic after 4 hours can be safely observed at home (Grade C). 5) Induction of emesis with ipecac syrup should not be performed in patients who have ingested camphor products (Grade C). 6) Activated charcoal administration should not be used for the ingestion of camphor products. However, it could be considered if there are other ingredients in the product that are effectively adsorbed by activated charcoal or if other substances have been co-ingested. (Grade C). 7) For asymptomatic patients with topical exposures to camphor products, the skin should be thoroughly washed with soap and water and the patient can be observed at home for development of symptoms (Grade C). 8) For patients with topical splash exposures of camphor to the eye(s), the eye(s) should be irrigated in accordance with usual poison center procedures and that referral take place based on the presence and severity of symptoms (Grade D). 9) Patients with camphor inhalation exposures should be moved to a fresh air environment and referred for medical care based on the presence and severity of symptoms. It is unlikely that symptoms will progress once the patient is removed from the exposure environment (Grade D).

Camphor↗

Evaluation of agricultural worker exposure to, and absorption of, pesticides.

The evaluation of the occupational exposure of agricultural workers to pesticides is an integral part of the risk assessment for product safety and regulatory purposes. At present, there is no internationally accepted, harmonized approach to this exposure evaluation. This paper reviews the currently available methods for the measurement of exposure to, and absorption of, pesticides by workers involved in their use and in associated agricultural activities. Biological monitoring is recommended as the most precise means of estimating the absorbed dose of a pesticide, particularly if supported by human metabolism and pharmacokinetic data. A 'whole-body' sampling method is recommended for the measurement of dermal exposure. For concurrent exposure and biological monitoring a refined 'whole-body' method is recommended which involves the use of clothing representing that which workers normally wear under the prevailing conditions. A personal air sampling method is recommended for the measurement of inhalation exposure, to collect the 'inspirable' fraction (and/or, where necessary, vapour component) of pesticide. These ambient exposure monitoring methods may be conducted simultaneously with biological monitoring. Guidelines are proposed for the conduct of field studies to evaluate exposure to, and absorption of, pesticides to satisfy the requirements of regulatory authority and other organizations.

Absorption↗

Mercury vapor and female reproductive toxicity.

Epidemiological studies finding menstrual cycle abnormalities among women occupationally exposed to Hg degrees prompted us to investigate the mechanisms of reproductive toxicity of Hg degrees in the female rat. Nose-only Hg degrees vapor inhalation exposures were conducted on regularly cycling rats 80-90 days of age in dose-response and acute time-course studies, which have previously proven useful as a model to identify ovarian toxicants. Vaginal smears were evaluated daily and serum hormone levels were correlated with cycle and with ovarian morphology at necropsy. Exposure concentration-related effects of Hg degrees were evaluated by exposing rats to 0, 1, 2, or 4 mg/m3 Hg degrees vapor 2 h/day for 11 consecutive days. Tissue Hg levels correlated with exposure concentration and duration. Exposure of rats to 4 mg/m3 (but not 1 or 2 mg/m3) Hg vapor for 11 days resulted in significant decreases in body weights relative to controls. Estrous cycles were slightly prolonged in the 2 and 4 mg/m3 dose groups, and serum estradiol and progesterone levels were significantly different in the 4 mg/m3 group compared to controls. The alterations in cycle and hormones at the 4 mg/m3 exposure concentration were attributed to body weight loss and generalized toxicity. In the time-course study, rats were exposed to 2 mg/m3 Hg degrees or air beginning in metestrus and evaluated daily for 8 days. A lengthening of the cycle was detected and morphological changes were observed in the corpora lutea (CL) after exposure for 6 days. To determine if changes in the CL and cyclicity correlated with a functional defect, rats were exposed to Hg degrees vapor and evaluated for pregnancy outcome. There were no significant effects on pregnancy rate or numbers of implantation sites when rats were exposed to 1 or 2 mg/m3 Hg degrees for 8 days prior to breeding, or when exposed for 8 days after breeding. These studies indicate that exposure to Hg degrees vapor altered estrous cyclicity, but had no significant effect on ovulation, implantation, or maintenance of first pregnancy during exposure of short duration in female rats.

Administration, Inhalation↗

The comparative toxicology of narasin in laboratory animals.

The toxicology of narasin has been extensively investigated in several species of laboratory animals. Acute median lethal po doses varied considerably between species (> 10 to 40.8 mg/kg). Animals of various species given acutely toxic doses of narasin manifested similar clinical signs of toxicity, including anorexia, hypoactivity, leg weakness, ataxia, depression and diarrhea. Clinical effects were usually delayed 1 to several days, depending on the dose, and some were reversible even with continued narasin administration. In repeated dose toxicity studies, narasin dosages have been demonstrated at which animals could be exposed daily for long periods of time without producing harmful effects. The no-observed effect levels (NOELs) by the dietary route were 60 ppm in mice and 15 ppm in rats after 3 mo of dosing and 15 ppm in rats after 1 y. In dogs, NOELs were 1 mg/kg body weight after 3 mo and 0.5 mg/kg body weight after 1 y of dosing. In breeding animals, narasin did not affect reproductive performance through 4 generations and was not teratogenic. Two-y chronic bioassays in 2 rodent species showed that narasin did not produce cumulative toxicity or carcinogenicity. In genetic toxicity tests narasin was not mutagenic to bacterial or mammalian cells and did not induce DNA repair or sister chromatid exchange. Narasin neither caused dermal toxicity nor skin sensitization, but was a severe eye irritant in rabbits. In dogs, local irritation and systemic toxicity occurred following repeated inhalation exposure to narasin aerosol concentrations greater than 0.114 mg/M3 of air.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗

Evaluation of the hazards of industrial exposure to tricresyl phosphate: a review and interpretation of the literature.

Commercial tricresyl phosphate (TCP) is a heterogeneous mixture of isomers and aryl phosphate congeners, known for many years to induce delayed neurotoxicity (OPIDN) in humans and experimental animals. In the past the isomer tri-o-cresyl phosphate (TOCP) was thought to be the component primarily responsible for OPIDN. It is now clear that other constituents, particularly the mono-o-esters, are not only neurotoxic but also may be more potent than pure TOCP. As a generality, the toxicity potential of a particular brand of TCP is related to its content of o-phenolic residues, whereby the maximal potential is reached when o-phenolics are 33% of the mix. Historically, human TCP toxicity has resulted from inadvertent or intentional contamination of foodstuffs or beverages. TCP products with high ortho-residues synthesized by older manufacturing methods were involved in most of these cases, and were likely much more neurotoxic milligram for milligram than TOCP. Because of the great variability of TCP products, there are no conventional workplace exposure standards. Based upon data from the hen and cat, estimated human safe exposure rates for pure TOCP are estimated to be 2.5 mg/kg for a single dose, and 0.13 mg/kg/d for repetitive exposures. These levels may also be applied to TCP when o-methyl-phenyl, o-ethyl-phenyl, and o-xylenyl components are appropriately limited during manufacture such that the TCP product is less neurotoxic than TOCP. There have been relatively few reports of toxicity associated with the manufacture or use of TCP in commerce and industry. Low vapor pressures of the constituents preclude the presence of significant quantities of TCP vapor in the atmosphere. A lubricant or other formulation containing TCP may appear in the air as a mist. By these criteria the U.S. Petroleum Oil Mist exposure standard is protective when the formulation contains 4% or less of low ortho-TCP. Exposure calculations indicate that estimated safe levels are not likely to be exceeded in the well-regulated workplace. If it is of short duration, even a heavy fog of oil particulate may not exceed the 8-h-average inhalation exposure standard. Modern manufacturing practices tend to minimize the ortho content and thus the toxicity of TCP. Because individual TCP brands and synthesis methods vary, manufacturers should be consulted concerning the properties of their individual products.

Animals↗

Hematotoxicity and carcinogenicity of inhaled benzene.

CBA/Ca male mice have been exposed to benzene in air at 10, 25, 100, 300, 400, and 3000 ppm for variable intervals 6 hr/day, 5 days/week for up to 16 weeks. Two weeks of inhaling 10 ppm produced no hematologic effects; 25 ppm induced a significant lymphopenia. Inhalation of 100, 300, and 400 ppm produced dose-dependent decreases in blood lymphocytes, bone marrow cellularity, marrow content of spleen colony-forming units (CFU-S) and an increased fraction of CFU-S in DNA synthesis. Exposure of mice to 300 ppm for 2, 4, 8, and 16 weeks produced severe lymphopenia and decrease in marrow CFU-S. Recovery was rapid and complete after 2 and 4 weeks of exposure. After 8 and 16 weeks of exposure, recovery of lymphocytes was complete within 8 weeks. It took 16 weeks for the CFU-S to recover to that of the age-matched controls after 8 weeks of exposure and 25 weeks to recover to age-matched after 16 weeks of exposure. Inhalation of 3000 ppm for 8 days was less damaging than inhalation of 300 ppm for 80 days (same integral amount of benzene inhaled). The inhalation of 3000 ppm has not increased the incidence of leukemia or shortened its latency for development. Inhalation of 300 ppm 6 hr/day for 16 weeks significantly increases the incidence of myelogenous neoplasms in male CBA/Ca mice. Inhalation of 100 ppm for same interval does not influence incidence of myelogenous neoplasms but does increase incidence of solid neoplasms particularly in female CBA/Ca mice. Benzene is a potent carcinogen in CBA/Ca mice.

Administration, Inhalation↗

Physiologically based modeling of 2-butoxyethanol disposition in rats following different routes of exposure.

2-Butoxyethanol (BE) is widely used as a solvent in coatings and other consumer products and has shown hematotoxicity in laboratory animals. To provide a physiological basis for extrapolating toxicokinetic data observed in rats to humans, a blood flow rate-limited, physiologically based pharmacokinetic model was developed to describe the distribution and metabolism of BE in rats following drinking water, dermal, and inhalation exposures. The major urinary metabolite, butoxyacetic acid, represented 45 to 60% of the absorbed dose in all three routes of exposure. Other identified urinary metabolites in our studies included ethylene glycol and BE-glucuronide. A model formulation of the possible metabolic pathways based on the experimental data was proposed. The amounts of individual urinary metabolites were used to develop the model. Metabolic constants were estimated by fitting the data within the constraints of in vitro measurements. The model explained the change of profiles of urinary metabolites in different exposure routes by taking into account the differences in absorption rate and by incorporating a minor pathway for metabolism by skin. Sensitivity analysis showed that metabolic constants and blood flow rate to liver had a relatively larger influence on the production of urinary metabolites than the organ volume or the partition coefficient for BE.

Administration, Cutaneous↗

Cadmium-induced elevations in the gene expression of the regulatory subunit of gamma-glutamylcysteine synthetase in rat lung and alveolar epithelial cells.

The controlled step in de novo glutathione (GSH) synthesis is catalyzed by gamma-glutamylcysteine synthetase (gamma-GCS), a dimeric enzyme consisting of a heavy catalytic subunit (gamma-GCS-HS) and a light regulatory subunit (gamma-GCS-LS). We have previously reported that exposure to cadmium (Cd) induces pulmonary gamma-GCS-HS mRNA and protein, and that these alterations are accompanied by increases in GSH synthesis and its steady-state level. The current study was designed to test the hypothesis that Cd exposure also up-regulates the expression of the regulatory gamma-GCS subunit. By using northern blotting, we have demonstrated that a single Cd aerosol exposure of adult male Lewis rats results in time- and dose-dependent increases in pulmonary levels of gamma-GCS-LS mRNA. Transcripts of gamma-GCS-LS in rat lung are maximally elevated (8-fold) 2 h following Cd inhalation exposure and remain significantly higher than air controls at 24 h. This response is highly correlated with Cd dose, ranging from 0.9 to 5 mg Cd per m(3), and with lung Cd burden. We also observed Cd-induced up-regulation of gamma-GCS-LS mRNA expression in alveolar epithelial cells exposed to Cd in vitro, either acutely or after repeated passaging in Cd-containing medium. The magnitude of the gamma-GCS regulatory subunit induction observed in Cd-treated cells was approximately five times greater than the induction of the catalytic subunit. These modifications in the expression of gamma-GCS subunits may offer protection from Cd toxicity.

Aminoacyltransferases↗

Asbestos use and carcinogenicity in Germany and a comparison with animal studies.

The centralized structure of economic affairs in the former German Democratic Republic (East Germany) and the isolation from the free market led to the situation that imported asbestos was almost exclusively chrysotile. More than 90% came from the Kiembay mining area in the Ural Mountains, and about 7% was long-fibre chrysotile from Canada. Sturm and co-workers detected 1082 mesothelioma cases from 1960 to 1990 in the counties of Magdeburg and Halle. In 843 of these cases an exposure to asbestos was evident. Seventy-two cases were exposed to chrysotile only. Suspected exposure to amphiboles imported before World War II or to fibre contained in talc could not be substantiated. Up to now, there have been no analyses of lung fibre burdens from such cases. Reviewing the carcinogenicity studies in rats performed by inhalation or intra-cavitary injection of chrysotile, amosite and crocidolite fibres, the results give no clear indication of a lower carcinogenic potency per chrysotile fibre than per amphibole fibre if equal fibre numbers and fibre sizes are applied, although the chrysotile content of the lungs is relatively low. Also the mesothelioma rates after inhalation exposure to extremely high concentrations of the different asbestos fibre types are similar for chrysotile and the amphiboles and in the region of 5%. Compared with the asbestos-related cancer rates in chrysotile textile workers, rats have to be exposed to a more than 100-fold higher fibre concentration than humans to induce the same lung tumour incidence.

Animals↗

Expression of the CYP1A1 gene in peripheral lymphocytes as a marker of exposure to creosote in railroad workers.

We have conducted a pilot study to assess levels of cytochrome CYP1A1 gene expression in human peripheral lymphocytes as a molecular biomarker assay for polycyclic hydrocarbon exposure. Basal and 3-methylcholanthrene-induced levels of gene expression were measured by standard slot-blot mRNA analyses in mitogen-stimulated cultures of peripheral blood lymphocytes from creosote-exposed railroad workers and unexposed control subjects. Dermal and inhalation exposure of workers to creosote may vary substantially as a function of working conditions related to temperature. Therefore, blood specimens were collected from separate groups during the winter, fall, and summer. Basal and induced CYP1A1 gene expression levels were not elevated in workers from any of the three seasonal studies. However, induced/basal (inducibility) CYP1A1 mRNA ratios from workers sampled in the summer (when actual exposures were greatest) were significantly higher when compared to those of controls (P < 0.01). These studies demonstrate the potential usefulness of specific gene expression assays in human peripheral lymphocytes for the assessment of carcinogen exposure in human populations.

Adult↗

Metabolism of dibasic esters by rat nasal mucosal carboxylesterase.

Inhalation exposure of rats to dibasic esters revealed lesions of the nasal olfactory epithelium similar to those observed with other ester solvents. Female rats are more sensitive to these effects than are male rats. It has been proposed that carboxylesterase conversion of inhaled esters within nasal tissues to organic acids may be a critical biochemical step in converting these chemicals to toxic substances. These experiments measured the kinetic parameters Vmax, KM, Ksi, and V/K for the hydrolysis of the dibasic esters in the target nasal tissue, olfactory mucosa, and nontarget tissue, respiratory mucosa. It was determined that under the conditions of these experiments, diacid metabolites are not formed. Esterase activity was inhibited by pretreatment with bis p-nitrophenyl phosphate. Vmax values for the three dibasic esters were 5- to 13-fold greater in olfactory mucosa than respiratory mucosa for male or female rats. V/K values were 4- to 11-fold greater in olfactory mucosa than respiratory mucosa for male or female rats. V/K was similar between male and female olfactory mucosa when dimethyl glutarate was used as the substrate. With dimethyl succinate or dimethyl adipate as the substrate, V/K for female olfactory tissue was 0.5- or 2-fold that of males, respectively. Differences in V/K were mainly due to decreases in KM associated with increasing carbon chain length. Substrate inhibition was observed at dibasic ester concentrations greater than approximately 25 mM, which are unlikely to be achieved in vivo. These results lend further support to the hypothesis that organic acid accumulation in the target tissue, olfactory mucosa, plays a significant role in the pathogenesis of dibasic ester-induced nasal lesions. This mechanism may be applicable to a wide range of inhaled esters.

Adipates↗

A review of pregnancy outcomes after exposure to orally inhaled or intranasal budesonide.

BACKGROUND: Inadequately controlled rhinitis is associated with worsening asthma, one of the most common potentially serious causes of pregnancy complications. Recent evidence-based guidelines now stress the importance of inhaled corticosteroids as first-line therapy in controlling asthma during pregnancy, with preference given to budesonide. Both inhaled and intranasal budesonide formulations are rated Pregnancy Category B; all other inhaled and intranasal corticosteroids are rated Pregnancy Category C. OBJECTIVE: To review data from clinical and epidemiological studies investigating the effects of orally inhaled or intranasal budesonide on pregnancy outcomes. METHODS: Clinical and epidemiological studies on the effects of maternal exposure to orally inhaled or intranasal budesonide were identified through searches of the literature indexed on Medline or the Developmental and Reproductive Toxicology (DART) database through January 2005. The search terms used were: 'budesonide' and 'pregnancy'; 'pregnancy complications'; 'teratogens'; 'fetus'; 'embryo'; or 'toxicology'. The search was limited to English-language articles and those evaluating humans. Pertinent abstracts were identified from recent US asthma and allergy meetings. RESULTS: A total of five articles and three abstracts meeting the search criteria were identified. Retrospective epidemiological studies and a randomized, placebo-controlled, multicenter trial found no clinically or statistically significant effects on fetal outcomes among more than 6600 infants whose mothers were exposed to orally inhaled budesonide during pregnancy. Women who reported use of orally inhaled budesonide either during early pregnancy only or throughout pregnancy gave birth to infants of normal gestational age, birth weight, and length, with no increased rate of stillbirths, multiple births, or congenital malformations. In a retrospective case-control analysis, no association was found between inhaled budesonide or intranasal budesonide and the overall rate of infant cardiovascular defects. However, a marginally increased risk of less severe cardiovascular defects (odds ratio = 1.58, 95% confidence interval 1.02 to 2.46) was observed with intranasal budesonide in one analysis, possibly the result of a random association due to multiple testing or an unidentified confounder. CONCLUSION: Maternal exposure to orally inhaled budesonide during pregnancy is not associated with an increased risk of congenital malformations or other adverse fetal outcomes in studies of more than 6600 infants. Data on pregnancy outcomes after maternal exposure to intranasal budesonide are limited, but the totality of evidence, including pharmacological studies showing a much lower systemic exposure after intranasal administration, indicates its safety profile is at least comparable with that of orally inhaled budesonide.

Abnormalities, Drug-Induced↗

Man-made mineral fibers (MMMF): human exposures and health risk assessment.

MMMF are made by spraying or extruding molten glass, furnace slag, or mineral rock. Health concerns are based on the morphological and toxicological similarities between MMMF and asbestos, and the well-documented evidence that asbestos fibers can cause lung fibrosis (asbestosis), bronchial cancer, and mesothelioma in humans. Epidemiological evidence for human disease from inhalation exposures to fibrous glass is largely negative. Some positive associations have been reported for slag and rockwools. Most of the toxicological evidence for MMMF toxicity in laboratory animals is based on non-physiological exposures such as intratracheal instillation or intraperitoneal injection of fiber suspensions. The risks for lung fibrosis, lung cancer, and mesothelioma for industrial exposures to most fibrous glass products are either low or negligible for a variety of reasons. First, most commercial fibrous glass products have mean fiber diameters of approximately 7.5 microns, which results in mean aerodynamic diameters greater than 22 microns. Thus, most glass fibers, even if dispersed into the air, do not penetrate into the lung to any great extent. Second, the small fraction of smaller diameter fibers which do penetrate into the lungs are not persistent within the lungs for most fibrous glass products, due to mechanical breakage into shorter lengths and dissolution. Dissolution is most rapid for the smaller diameters (less than 0.1 micron) capable of producing mesothelioma. The greater hazards for slag and rockwools, in comparison to conventional fibrous glass, appear to be related to their smaller diameters and greater durability within the lungs.

Air Pollutants, Occupational↗

Cross-sectional study of pulmonary function in cadmium alloy workers.

Two groups of cadmium workers (7 and 9 men) and a group of reference workers (122 men) were studied for the purpose of determining the pulmonary effects of cadmium. Indices of pulmonary function, based on the forced expiratory flow volume curve and respiratory impedance, were measured for all the groups, and indicators of cadmium exposure and effects on renal tubular reabsorption functions were also measured in the two groups of cadmium workers. The mean blood and urinary levels of cadmium were 2.08 microgram/100 ml (185.06 nmol/l) and 32.6 microgram/l (290.04 nmol/l), respectively, and the level of inhalation exposure was estimated at about 1 mg/m3 as the 8-h average concentration for about 5 a in the high exposure group. The percentage of the predicted function values of the highly exposed workers was significantly deteriorated for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), peak expiratory flow, maximum expiratory flow at 75, 50, and 25% of the FVC, percentage of FEV1.0 to FVC, and respiratory impedance, whereas those of the slightly exposed workers were reduced only for FVC and FEV1.0. A paired comparison between the highly exposed workers and matched referents disclosed the same results. It was concluded that chronic obstructive pulmonary changes had been induced by cadmium in Japanese workers without a history of acute or subacute cadmium pneumonitis.

Adult↗

Glutathione-S-transferase is a target for covalent modification by a halothane reactive intermediate in the guinea pig liver.

The anesthetic halothane is bioactivated by the liver cytochrome P450 system to the reactive intermediate, trifluoroacetyl chloride, which can acylate liver protein. Cytosolic glutathione-S-transferase (GST) was identified as a major target for protein adduct formation in guinea pig liver slices exposed to halothane. To determine if GST is also a target in vivo, male Hartley guinea pigs were exposed to 1% halothane in 40% O2 for 4 h. At 10 h post exposure, livers were removed and microsomal and cytosolic fractions prepared. Past studies have shown these conditions resulted in maximal covalent binding of halothane intermediates to hepatic protein. Protein was isolated by ethanol precipitation and washed with trichloroacetic acid to remove unbound metabolites. Cytosolic GST was isolated by gel filtration and S-hexyl-glutathione affinity chromatography to electrophoretic purity. Protein adducts were quantified using a covalently bound fluorine assay. Covalent binding of a halothane intermediate to cytosolic and microsomal protein was determined as 2.0 +/- 0.4 and 13.2 +/- 2.3 nmol F/mg protein, respectively. Liver glutathione depletion by buthionine sulfoximine pretreatment produced an increase in covalent binding only to cytosolic proteins (3.3 +/- 0.4 nmol F/mg protein). Adduct formation to cytosolic GST was determined to be 4.7 +/- 1.6 nmol F/mg protein. Glutathione-S-transferase is a target for covalent modification in the liver following an inhalation exposure to halothane.

Administration, Inhalation↗