Urinary naphthols as an indicator of exposure to naphthalene

OBJECTIVE: The relationship between exposure to naphthalene and urinary excretion of naphthols was examined. METHODS: Concentrations of naphthalene and naphthols in breathing-zone air during a workshift and 1-naphthol and 2-naphthol in urine collected after the workshift were determined for 102 male workers. Gas chromatography with a flame ionization detector (GC-FID) was used to determine the air concentration. Urine naphthols were extracted after acid hydrolysis by solid-phase extraction and separated by the GC-FID method. Naphthalene homologues in air and their metabolites in urine samples were identified by gas chromatography-mass spectrometry. RESULTS: 1-Naphthol, 2-naphthol and 1,4-naphthoquinone were identified in the urine samples. The time-weighted average concentrations of naphthalene and naphthols in the breathing-zone air showed that the exposure level of the workers was rather low. The geometric mean values were as follows: 0.77 and 0.87 mg/m3 for naphthalene, 0.016 and 0.034 mg/m3 for 1-naphthol, 0.012 and 0.067 mg/m3 for 2-naphthol during tar distillation and naphthalene oil distillation, respectively. The corresponding urinary concentrations of 1- and 2-naphthols were 693.1 and 264.4 micromol/mol and 264.4 and 297.7 micromol/mol creatinine, respectively. The correlation coefficients between the naphthol concentrations in urine and the breathing-zone air concentrations of naphthalene were statistically significant, varying in the range of 0.64--0.75 for 1-naphthol and 0.70--0.82 for 2-naphthol. There was linear dependence (r = 0.76) between the summary concentration of naphthols in urine and the naphthalene concentration in air. CONCLUSIONS: Workers in tar distillation and naphthalene distillation are exposed to rather low concentrations of naphthalene and methylated naphthalenes and naphthols. Naphthols and 1,4-naphthoquinone identified in the urine appear to be the products of the hydroxylation of naphthalene present in the breathing-zone air. These findings suggest that the summary concentration of naphthols in urine can be used as a biomarker for naphthalene exposure.     

Azithromycin and clarithromycin inhibition of 50S ribosomal subunit formation in Staphylococcus aureus cells

A mercapturic acid attached to the aromatic ring of toluene was for the first time detected in human urine as a metabolite of toluene. Since the metabolism of toluene is usually considered to take place at the side-chain, this gives, besides the biosynthesis of cresols, a further hint of a metabolic conversion of the aromatic system. We examined a group of 33 workers occupationally exposed to toluene, determining the concentrations of toluene in ambient air and in whole blood, o-cresol and hippuric acid in urine and p-toluylmercapturic acid (p-TMA) in urine. All blood and urine samples were collected post-shift. The renal excretion of S-p-toluylmercapturic acid showed highly significant correlations with established parameters of a biological monitoring of toluene. The median ambient air concentration was 63 ppm, ranging from 13 to 151 ppm, the median concentration of toluene in whole blood was 804 microg/l, corresponding to median urinary concentrations for o-cresol of 2.3 mg/l, hippuric acid of 2.3 g/l and p-TMA of 20.4 microg/l. p-TMA was not detectable in urine samples of a control group of 10 non-exposed persons. Both the German Biological Tolerance Values (BAT-values) for toluene in blood (1000 microg/l) and o-cresol in urine (3 mg/l) correspond to a mean p-TMA elimination of approximately 50 microg/l, and thus are in agreement with each other. According to our results p-TMA reflects internal toluene exposure diagnostically sensitive and specifical. With the developed analytical procedure we determined a median benzylmercapturic acid (BMA) concentration of 190 microg/l in the urine samples of the toluene exposed persons. We also determined a median BMA concentration of 30 microg/l in the control samples of non-exposed persons. However, these results are preliminary and require further confirmation as the reliability of the method was determined only for p-TMA.     

Biodegradation of Mixtures of Phenolic Compounds in an Upward-Flow Anaerobic Sludge Blanket Reactor

The anaerobic biodegradability of mixtures of phenolic compounds was studied under continuous and batch systems. Continuous experiments were carried out in up-flow anaerobic sludge bed (UASB) reactors degrading a mixture of phenol and p-cresol as the main carbon and energy sources. The total chemical oxygen demand (COD) removal above 90% was achieved even at organic loading rates as high as 7 kg COD/m3/day. Batch experiments were conducted with mixtures of phenolic compounds (phenol, p-cresol, and o-cresol) to determine the specific biodegradation rates using unadapted and adapted anaerobic granular sludge. Phenol and p-cresol were mineralized by adapted sludge with rates several orders of magnitude higher than unadapted sludge. Additionally, an UASB reactor was operated with the mixture phenol, p-cresol, and o-cresol. After 54 days of operation, 80% of o-cresol (supplied at 132 mg/L) was eliminated. The phenol biodegradation was not affected by the presence of o-cresol. These results demonstrate that major phenolic components in petrochemical effluents can be biodegraded simultaneously during anaerobic treatment.     

Allylmercapturic acid as urinary biomarker of human exposure to allyl chloride

OBJECTIVE: To evaluate the use of urinary mercapturic acids as a biomarker of human exposure to allyl chloride (3-chloropropene) (AC). During three regular shut down periods in a production factory for AC, both types of variables were measured in 136 workers involved in maintenance operations. METHODS: Potential airborne exposure to AC was measured by personal air monitoring in the breathing zone. In total 205 workshifts were evaluated. During 99 workshifts no respiratory protection equipment was used. Mercapturic acid metabolites were measured in urinary extracts by gas chromatography-mass spectrometry (GC-MS). RESULTS: During 86 work shifts when no respiratory protection was used the air concentrations of AC were below the Dutch eight hour time weighted average (8 h-TWA) occupational exposure limit (OEL) of AC (3 mg/m3), whereas in 13 workshifts the potential exposure, as measured by personal air monitoring, exceeded the OEL (3.3 to 17 mg/m3). With the aid of GC-MS, 3-hydroxypropylmercapturic acid (HPMA) was identified as a minor and allylmercapturic acid (ALMA) as a major metabolite of AC in urine samples from the maintenance workers exposed to AC. The concentrations of ALMA excreted were in a range from < 25 micrograms/l (detection limit) to 3550 micrograms/l. The increases in urinary ALMA concentrations during the workshifts correlated well with the 8h-TWA air concentrations of AC (r = 0.816, P = 0.0001, n = 39). Based on this correlation, for AC a biological exposure index (BEI) of 352 micrograms ALMA/g creatinine during an eight hour workshift is proposed. In some urine samples unexpectedly high concentrations of ALMA were found. Some of these could definitely be attributed to dermal exposure to AC. In other cases garlic consumption was identified as a confounding factor. CONCLUSION: The mercapturic acid ALMA was identified in urine of workers occupationally exposed to airborne AC and the increase in ALMA concentrations in urine during a workshift correlated well with the 8 h-TWA exposure to AC. Garlic consumption, but not smoking, is a potential confounding factor for this biomarker of human exposure to AC.     

Effects of a new topic amikacin formulation on chemotaxis and release of profibrotic factors by human monocytes

OBJECTIVE: The aim of the present study was to develop valid methods for monitoring of occupational exposure to dichloromethane (DCM). METHODS: Carbon cloth as an adsorbent in diffusive sampling was tested for its capacity to adsorb DCM vapor and to retain adsorbed DCM after termination of the exposure. Urine samples collected from DCM-exposed workers were analyzed for DCM by the head-space technique. After extraction with carbon disulfide, DCM in the cloth was analyzed on a DB-WAX capillary column by flame-ionization detection gas chromatography (FID-GC) and DCM in urine was analyzed by electron-capture detection (ECD)-GC. RESULTS: The diffusive sampling with carbon cloth as an adsorbent is applicable to 4-h monitoring of exposure to up to 100 ppm DCM vapor. DCM concentrations detected in end-of-shift urine samples correlated linearly with time-weighted average DCM concentrations measured in the breathing-zone air of the exposed workers; essentially the same exposure-excretion relationship was obtained by vapor monitoring for the afternoon 4-h period as compared with a whole day (8-h) of vapor monitoring. There was no sex difference in the exposure-excretion relation. CONCLUSIONS: Both personal diffusive sampling (at up to 100 ppm DCM and for up to 4 h) and biological exposure monitoring by urinalysis for DCM are applicable in occupational health as reliable measures of exposure to this chlorinated hydrocarbon solvent.     

Metabolic interferences in subjects occupationally exposed to binary styrene-acetone mixtures

OBJECTIVE: To investigate the excretion of styrene metabolites (mandelic acid, MA, and phenylglyoxylic acid, PGA) in workers employed in plastic manufacturing to verify the possible influence of coexposure to acetone on styrene metabolism. METHODS: This study was carried out on 50 workers employed in 3 factories producing polyester buttons. The workers were divided into three groups according to three different levels of acetone exposure. The trend of excretion for metabolites was examined during and after work shifts. Styrene and acetone were monitored on Thursday during the entire work shift by passive dosimeters placed on the lapel of the workers' uniforms, desorbed by carbon disulfide, and analyzed by gas chromatography. Biological monitoring was performed by determination of the urinary metabolites of styrene in urine samples collected on Thursday at the middle and the end of the work shift. MA and PGA were determined by a high-pressure liquid chromatographic method. RESULTS: The styrene concentrations ranged between 16 and 439 mg/m3, and in ten samples they exceeded the TLV-TWA (213 mg/m3). The acetone concentration ranged between 15 and 700 mg/m3 (TLV-TWA 1780 mg/m3), with the mean value being 208 mg/m3. During cleaning operations higher exposures to acetone demonstrated, with concentrations ranging between 500 and 3400 mg/m3. The amounts of MA and PGA determined at the end of workshifts did not significantly differ between the groups with different levels of acetone coexposure. Analysis of variance (ANOVA) between the groups confirmed that MA and PGA excretion did not significantly differ, although the metabolite values measured on the "morning of the day after" appeared higher in those groups with high levels of acetone exposure and were related to the average airborne concentrations of the solvent. In addition, the range and degree of correlation between styrene in air and biological levels of metabolites were modified by coexposure to acetone. CONCLUSIONS: Our data demonstrate that amounts of MA and PGA did not differ in groups with different levels of acetone exposure, but when the acetone air concentration increased the degree of correlation between styrene and MA and PGA decreased. Furthermore, coexposure to acetone levels similar to those described herein may hamper the use of urinary metabolites for the assessment of exposure to styrene, especially on an individual basis.     

Ocular effects of exposure to triethylamine in the sand core cold box of a foundry

OBJECTIVES: To assess the acute and chronic ophthalmological effects of triethylamine exposure among foundry workers. METHODS: Ocular effects on people currently, previously, and never exposed to triethylamine in a foundry cold box were studied at two points in time. The initial phase included an ocular examination with a slit lamp to assess corneal health, a visual acuity test, and a questionnaire to assess vision symptoms. The follow up included measurements of corneal thickness with an ultrasonic pachymeter and the vision symptoms questionnaire before and after the shift and at the beginning and end of the week. Personal air measurements for triethylamine were also obtained during the follow up. RESULTS: The vision symptoms of blurriness, halos around lights, and blue hazy vision occurred more often in currently exposed workers than those previously or never exposed to triethylamine. Air concentrations of triethylamine ranged from < 0.33 mg/m3 to 20.3 mg/m3. Among currently exposed workers, symptoms were more common among those with exposure to > 10 mg/m3 of triethylamine (odds ratio (OR) = 3.0, 95% confidence interval (95% CI) 0.35-25.6). No differences in corneal thickness were found in currently or previously exposed workers and those never exposed. No increase in corneal thickness was found after v before the shift. CONCLUSION: Despite low concentrations of triethylamine and no corneal oedema, workers exposed to triethylamine reported vision symptoms. Possible explanations for these symptoms without corneal oedema are that triethylamine affects ciliary muscle function or that the corneal oedema was transient and not present when corneal thickness measurements were taken. No chronic effects were found in previously exposed workers. Further research is needed to elucidate the mechanism for the reported vision symptoms, which occurred below the current United States eight hour time weighted standard of 100 mg/m3 and the American Conference of Governmental Industrial Hygienists (ACGIH) recommended value at the time of our study of 40 mg/m3. We recommend that air concentrations be maintained to meet the current recommended ACGIH threshold of 4.1 mg/m3.     

Septicemia due to Shigella. A case report and review of the literature

To develop a proper protocol for biological exposure monitoring of acetone, we evaluated whether exposure to acetone on the previous day affects the biological monitoring value at the end of a work day. One hundred and ten male workers exposed to acetone in three acetate fiber manufacturing plants were monitored using a liquid passive sampler on two consecutive working days after 2 days without exposure. Urine samples were collected at the start of the workshift and the end of the shift on both days for each subject. For ten exposed workers urine samples were collected approximately every 2 h during and after the first working day until the following morning. Acetone concentrations in urine (Cu) at the start of the first working day were 1.3 +/- 2.4 (range: ND-14.1) mg/l in nonexposed workers and 2.4 +/- 5.6 (range: ND-40.3) mg/l in exposed workers. The urinary acetone concentration at the beginning of the second working day indicated that urinary levels of acetone do not decline to background level by the following morning when exposure concentration exceeds 300 ppm. However, linear regression analysis demonstrated that the relationship between environmental exposure level and urine level was similar on the 1st day and the 2nd day. Thus, although urine acetone levels did not return completely to baseline after high exposures, under the present exposure levels the exposure on the previous day did not significantly affect urinary acetone at the end of the workshift of the next day.     

Quantitation of o-, m- and p-cresol and deuterated analogs in human urine by gas chromatography with electron capture detection

A gas chromatographic method for the analysis of cresol metabolites of toluene and [2H8]toluene in urine was developed. Cresol glucuronides and sulfates in urine were hydrolyzed with beta-glucuronidase and arylsulfatase. Following extraction with tert.-butyl methyl ether and solvent exchange into benzene, the cresols were derivatized with heptafluorobutyric anhydride to form the heptafluorobutyrate esters. The derivatives were analyzed by gas chromatography with electron capture detection. Chromatographic resolution was achieved between all cresol isomers and their 2H7 analogs. Calibration ranged from 0.001 to 500 microg/ml. Recoveries were 55-97% and showed no trend with respect to analyte concentration. Within-day precision of analyses of benchmark urine samples had a coefficient of variation of less than 4%. The assay sensitivity was limited by chromatographic background but was sufficient for quantification of the unlabeled cresols in urine from men with only environmental exposure to toluene. Average levels in urine samples from 45 men were 0.023, 0.054 and 37 microg/ml for o-, m- and p-cresol, respectively.     

Religiosity as a protective or prognostic factor of depression in later life; results from a community survey in The Netherlands

OBJECTIVES: This study explored the possibility of using urinary 1-naphthol excretion as a marker of complex exposure among workers handling creosote. METHODS: Urine specimens of 6 workers from a creosote impregnation plant, where railroad ties were impreganted with coal tar creosote, were collected during 1 workweek, and the concentration of 1-naphthol was determined. 1-Naphthol in spot urine samples of 5 occupationally nonexposed male smokers was used as the background reference. Concurrently, naphthalene and 10 different polycyclic aromatic hydrocarbons (PAH) were determined in personal air samples. RESULTS: The mean airborne exposure of the workers was 1.5 mg/m3 for vaporous naphthalene, 5.9 micrograms/m3 for particulate PAH and 1.4 micrograms/m3 for PAH with 4-6 aromatic rings. The mean urinary concentration of 1-naphthol at the end of the workshift was 20.5 (range 3.5-62.1) mumol/l, whereas the referents' urinary concentration was below the detection limit (0.07 mumol/l). Airborne naphthalene correlated fairly well with 1-naphthol when measured at the end of the shift (r = 0.745). CONCLUSIONS: This method of analysis for 1-naphthol is sufficiently sensitive for measuring low occupational exposures to naphthalene. Low background exposures are, however, unlikely to result in detectable urinary levels of 1-naphthol. Since naphthalene is the most abundant compound in creosote vapor, urinary 1-naphthol determination serves well as a biological marker of exposure to vaporous creosote. Urinary 1-naphthol alone is not, however, a suitable marker for inhalatory or cutaneous exposure to PAH originating from creosote.     

Distribution and ultrastructure of the stomata connecting the pleural cavity with lymphatics in the rat costal pleura

Ethylene glycol levels were measured in 154 breathing zone air samples and in 117 urine samples of 33 aviation workers exposed to de-icing fluid (basket operators, de-icing truck drivers, leads and coordinators) studied during 42 worker-days over a winter period of 2 months at a Montreal airport. Ethylene glycol as vapour did not exceed 22 mg/m3 (mean duration of samples 50 min). Mist was quantified at higher levels in 3 samples concerning 1 coordinator and 2 basket operators (76-190 mg/m3, 45-118 min). In 16 cases workers' post-shift or next-morning urine contained quantities of ethylene glycol exceeding 5 mmol/mol creatinine (up to 129 mmol/mol creatinine), with most of these instances occurring in basket operators and coordinators, some of whom did not wear paper masks and/or were accidentally sprayed with de-icing fluid. Diethylene glycol was also found in a few air and urinary samples at levels around one tenth those of ethylene glycol. Urinary concentrations of albumin, beta-N-acetyl-glucosaminidase, beta-2-microglobulin and retinol-binding protein were measured and compared over various periods, according to subgroups based on exposure level and according to the frequency of extreme values. These analyses did not demonstrate acute or chronic kidney damage that could be attributed to working in the presence of ethylene glycol. In conclusion, this study does not suggest important health effects of exposure to de-icing fluid in this group of workers. Potential for overexposure exists, however, in certain work situations, and recommendations on preventive measures are given. In addition, these results suggest that other routes of absorption than inhalation, such as the percutaneous route, may be important and that urinary ethylene glycol may be a useful indicator of exposure to ethylene glycol.     

The effect of occupational exposure to metallic mercury on selected parameters of hemostasis

The group investigated comprised 60 workers under conditions of chronic exposure to metallic mercury vapours (mean exposure duration--9.3 yrs; mean age of subjects--38.5 yrs). The control group was composed of 24 non-exposed persons (mean age--39.9 yrs). The workers exposed were divided into three groups according to the air concentration of metallic mercury vapours at the workpost, group A--0.15-0.17 mg/m3, group B--0.03-0.08 mg/m3 and group C--0.02-0.03 mg/m3. The workers qualified for the study did not receive any medication containing acetylsalicylic acid derivatives, and did not consume alcoholic drinks for few days prior to the study. Persons with the diagnosis or the history of blood disorders, venous or arterial thrombosis as well as those with diabetes and hyperlipidaemia were excluded from the study. The haemostasis assessment was based on the results of laboratory tests, PLT, TBT, ACT, APTT, HTCT, INR and Fg, AT III, alpha 2 M, FDP, and FM concentrations. The comparison of the exposed and control groups revealed a statistically significant decrease in ACT and AT III concentrations. When particular groups under exposure were compared with one another and the controls, the increased INR and Fg concentrations were found in group A. Moreover, this group showed an increased platelet count, as well as decreased TBT and alpha 2 M concentrations. However, the differences between the groups were statistically insignificant. The results of the study indicated that chronic exposure to mercury may impair haemostasis and lead to hypercoagulability. The latter may result from the deficiency of natural coagulation inhibitors.     

African-American physicians'' and dentists'' perceptions of smoking cessation: solo versus HMO practices

OBJECTIVES: Exposure to monoterpenes (alpha-pinene, beta-pinene and delta 3-carene) in joinery shops was studied in Sweden during the processing of Scot's pine, and the acute respiratory effects among the employees were evaluated. METHODS: A cross-sectional study of 38 workers was carried out in 4 joinery shops. The investigation included personal air sampling of monoterpenes, biological monitoring of metabolites of alpha-pinene in the workers' urine, interviews following a standardized questionnaire, and dynamic spirometry. RESULTS: The personal exposure to monoterpenes in the joinery shops was 10-214 mg/m3. The correlation (correlation coefficient = 0.69) between exposure to alpha-pinene and verbenols (metabolites from alpha-pinene) in urine was relatively good. No acute effects on forced vital capacity or forced expiratory volume during 1 s were detected. The workers had significantly reduced preshift lung function values when compared with the values of a local reference group, even when smokers and ex-smokers were excluded. CONCLUSIONS: Personal exposure to the monoterpenes alpha-pinene, and delta 3-carene in joinery shops may exceed the present Swedish occupational exposure limit of 150 mg/m3 during the winter season when workroom air is commonly recirculated. The determination of metabolites of alpha-pinene (verbenols) in urine can be used as an index of exposure to fumes released during wood-treating processes. The results from the lung function tests indicate chronic rather than acute reactions in the airways. The fact that there were no major changes in lung function over a workshift indicates chronic reaction in the airways.     

Epstein-Barr virus and CD21 expression in gastrointestinal tumors

OBJECTIVES: Animal inhalation studies and theoretical models suggest that the pattern of formation of benzene metabolites changes as exposure to benzene increases. To determine if this occurs in humans, benzene metabolites in urine samples collected as part of a cross sectional study of occupationally exposed workers in Shanghai, China were measured. METHODS: With organic vapour monitoring badges, 38 subjects were monitored during their full workshift for inhalation exposure to benzene. The benzene urinary metabolites phenol, catechol, hydroquinone, and muconic acid were measured with an isotope dilution gas chromatography mass spectroscopy assay and strongly correlated with concentrations of benzene air. For the subgroup of workers (n = 27) with urinary phenol > 50 ng/g creatinine (above which phenol is considered to be a specific indicator of exposure to benzene), concentrations of each of the four metabolites were calculated as a ratio of the sum of the concentrations of all four metabolites (total metabolites) and were compared in workers exposed to > 25 ppm v < or = 25 ppm. RESULTS: The median, 8 hour time weighted average exposure to benzene was 25 ppm. Relative to the lower exposed workers, the ratio of phenol and catechol to total metabolites increased by 6.0% (p = 0.04) and 22.2% (p = 0.007), respectively, in the more highly exposed workers. By contrast, the ratio of hydroquinone and muconic acid to total metabolites decreased by 18.8% (p = 0.04) and 26.7% (p = 0.006), respectively. Similar patterns were found when metabolite ratios were analysed as a function of internal benzene dose (defined as total urinary benzene metabolites), although catechol showed a more complex, quadratic relation with increasing dose. CONCLUSIONS: These results, which are consistent with previous animal studies, show that the relative production of benzene metabolites is a function of exposure level. If the toxic benzene metabolites are assumed to be derived from hydroquinone, ring opened products, or both, these results suggests that the risk for adverse health outcomes due to exposure to benzene may have a supralinear relation with external dose, and that linear extrapolation of the toxic effects of benzene in highly exposed workers to lower levels of exposure may underestimate risk.     

Exposure to toxic air contaminants in environmental tobacco smoke: an assessment for California based on personal monitoring data

The contribution of environmental tobacco smoke (ETS) to the exposure of adult nonsmoking Californians was determined for selected toxic air contaminants (TACs). The assessment was based on published measurements of ETS emission factors and personal exposures to volatile organic compounds. The human exposure studies were conducted in three California areas--Los Angeles, Pittsburgh/Antioch, and Woodland--between 1984 and 1990. We derived unexposed and passive population exposure distributions by randomly sampling the monitoring results for individuals classified according to exposure status (active smoker, passively exposed or unexposed to ETS during monitoring). The differences between the unexposed and passive distributions were used to estimate the ETS-only contribution for exposure to benzene, styrene, o-xylene, and m,p-xylene. Emission factors were then employed to infer the ETS-caused exposure to thirteen other compounds. The estimated arithmetic mean increments of 24-hour exposure attributable to ETS for the nonsmoking Californian population (age > or = 7) exposed to ETS are as follows (results in units of microgram m-3 exposure concentration; results using two different emission factors presented as a range): acetaldehyde 11-15; acetonitrile 7.0; acrylonitrile 0.49; benzene 1.02; 1,3-butadiene 0.75-2.3; 2-butanone 1.4; o-cresol 0.17; m,p-cresol 0.41; ethyl acrylate < 0.015; ethylbenzene 0.49-0.64; formaldehyde 6.5-8.2; n-nitrosodimethylamine 0.0028; phenol 1.4; styrene 0.36; toluene 3.1-3.2; o-xylene 0.77; m,p-xylene 0.99. The 90% confidence limits on these estimates due to the limited sample size in the studies are roughly x/ divided by 6. For four widely studied compounds, ETS is estimated to contribute the following percentages to the total inhalation exposure of all nonsmoking Californians: o-xylene 5%; m,p-xylene 3%; benzene 5%; and styrene 8%.     

Micromanipulation and cloning studies on buffalo oocytes and embryos using nucleus transfer

1. Nine male volunteers were exposed to the pyrethroid insecticide cyfluthrin. The study was performed in an exposure room, where an aerosol containing cyfluthrin was sprayed to obtain atmospheres with mean cyfluthrin concentrations of 160 and 40 micrograms/m3. Four volunteers were exposed for 10, 30 and 60 min at 160 micrograms/m3 and another five volunteers were exposed for 60 min at 40 micrograms/m3. For 160 micrograms/m3 exposure urine samples were collected before and immediately after exposure as well as for the periods 1-2, 2-3, 3-4, 4-5, 5-6, 6-12 and 12-24 h after exposure. For 40 micrograms/m3 exposure urine samples were collected before and 2 h after exposure. 2. The main urinary cyfluthrin metabolites, cis-/trans-3-(2,2-dichlorovinyl)-2,2-dimethylycyclopropane carboxylic acid (DCCA) and 4-fluoro-3-phenoxybenzoic acid (FPBA), were determined. The limit of detection (LOD) for all metabolites was 0.0025 microgram in an urine sample of 5 ml (0.5 microgram/l). After inhalative exposure of 40 micrograms cyfluthrin/m3 air for 60 min, the amount of metabolites in urine collected in the first 2 h after exposure was less than the LOD, namely 0.14 microgram for cis-DCCA, 0.15-0.28 microgram for trans-DCCA and 0.12-0.23 microgram for FPBA. 3. Of the metabolites, 93% was excreted within the first 24 h (peak excretion rates between 0.5 and 3 h) after inhalative exposure of 160 micrograms/m3. The mean half-lives were 6.9 h for cis-DCCA, 6.2 h for trans-DCCA and 5.3 h for FPBA. 4. The mean trans-:cis-DCCA ratio was 1.9 for the time course as well as for each subject. 5. The amount of metabolites in urine depends on the applied dose, on the exposure time and shows interindividual differences.     

Simultaneous Removal of Phenol and Nitrate in an Anaerobic Bioreactor

Phenol and nitrate are two major pollutants simultaneously occurring in several industrial wastewaters. In this study, a 110-day gradual enrichment of an anaerobic culture has been carried out at 25°C in an anaerobic bioreactor for continuously treating a synthetic wastewater containing 600?mg/L phenol and 430?mg/L?NO3?–N. The results showed that the enriched culture can utilize phenol as a sole electron donor and nitrate as a sole electron acceptor. At the end of the enrichment (on Day 110), 93.3% of phenol and 98.0% of NO3?–N were simultaneously removed at a hydraulic retention time of 20.25?h in the anaerobic bioreactor. The removal of 1?g?NO3?–N required about 3.19?g chemical oxygen demand as the electron donor. Batch tests further revealed that cresol, nitrophenol, and monochlorinated phenol (MCP) could exert detrimental influences on the treatment abilities of the enriched culture. However, the inhibitory effects of cresol were impermanent, as compared to those of nitrophenol and MCP. In order to operate the anaerobic bioreactor steadily, high concentrations of cresol should be diluted before being fed while the existence of nitrophenol and MCP in the bioreactor should be avoided.     

Overcoming language barriers when teaching the Advanced Trauma Life Support course

OBJECTIVES: To determine whether blurred vision caused by exposure to triethylamine (TEA) can be detected by the measurement of contrast sensitivity. METHODS: 41 cold box core makers of three foundries and 82 control workers were examined. A detailed ocular and medical history was obtained from the subjects. The contrast sensitivity of the core makers was measured on Monday and Friday of the same week both before and immediately after work and also on a third day, when air samples of TEA were collected. Contrast sensitivity and visual acuity were measured by optotype figures at full contrast, 2.5% contrast, and 0.6% contrast. The changes in contrast sensitivity were used for the analysis. The results of binocular vision and the results of the dominant eye were analysed. Urine specimens for the analysis of TEA were collected on every occasion when contrast sensitivity was measured. RESULTS: 78% of the core makers had had symptoms of blurred vision, and 31% had had trouble driving or working. The breathing zone eight hour time weighted average TEA concentrations were 0.3-60 mg/m3. The mean urinary TEA concentration after the shift was 35 mmol/mol creatinine. Continuous monitoring showed high peaks of TEA leakage at a core making machine. Changes in binocular visual acuity did not differ between the exposed and unexposed workers. The contrast sensitivity decreased in 49% of the core makers and 21% of the controls (P = 0.002). CONCLUSIONS: The blurred vision caused by exposure to TEA can be documented by measuring contrast sensitivity. The mechanism by which TEA produces symptoms remains an issue of further study.     

Effect of polycyclic aromatic hydrocarbons on somatic chromosomes of coal tar workers

The genotoxic effect of polycyclic aromatic hydrocarbons (PAHs) on somatic human chromosomes obtained from lymphocytes of 49 coal tar workers exposed to 26 micrograms/m3 benzo(a)pyrene, 16 mg/m3 benzene and 0.04 mg/m3 H2S in the ambient air, compared to equal numbers of matched controls breathing air containing 1 microgram/m3 benzo(a)pyrene, 1.5 mg/m3 benzene and 0.02 mg/m3 H2S, was investigated. The mitotic index (MI), chromosome aberrations (CAs), sister chromatid exchanges (SCEs) and satellite associations (SAs) were analysed. All the parameters showed a significant increase (p < 0.01 and 0.05) in the exposed individuals compared with the controls: viz MI, 4.59-7.92; CAs, 0.77-3.0; SCEs, 5.89-6.80; and SAs, 8.18-14.26. The occurrence of the DG type of satellite associations were highest and the 3D type lowest. The frequency of SCEs was highest in coal tar workers with an exposure period of 6-10 years. It is suggested that these results show PAH is genotoxic for humans.     

Recommendations for reducing the effect of grain dust on the lungs. Canadian Thoracic Society Standards Committee

OBJECTIVE: To assess the appropriateness of the current Canadian standards for exposure to grain dust in the workplace. OPTIONS: The current permissible exposure limit of 10 mg of total grain dust per cubic metre of air (expressed as mg/m3) as an 8-hour time-weighted average exposure, or a lower permissible exposure limit. OUTCOMES: Acute symptoms of grain-dust exposure, such as cough, phlegm production, wheezing and dyspnea, similar chronic symptoms, and spirometric deficits revealing obstructive or restrictive disease. EVIDENCE: Articles published from 1924 to December 1993 were identified from Index Medicus and the bibliographies of pertinent articles. Subsequent articles published from 1994 (when the recommendations were approved by the Canadian Thoracic Society Standards Committee) to June 1996 were retrieved through a search of MEDLINE, and modification of the recommendations was not found to be necessary. Studies of interest were those that linked measurements of total grain dust levels to the development of acute and chronic respiratory symptoms and changes in lung function in exposed workers. Papers on the effects of grain dust on workers in feed mills were not included because other nutrients such as animal products may have been added to the grain. Unpublished reports (e.g., to Labour Canada) were included as sources of information. VALUES: A high value was placed on minimizing the biological harm that grain dust has on the lungs of grain workers. BENEFITS, HARMS AND COSTS: A permissible exposure limit of 5 mg/m3 would control the short-term effects of exposure to grain dust on workers. Evidence is insufficient to determine what level is needed to prevent long-term effects. The economic implications of implementing a lower permissible exposure limit have not been evaluated. RECOMMENDATIONS: The current Canadian standards for grain-dust exposure should be reviewed by Labour Canada and the grain industry. A permissible exposure level of 5 mg/m3 is recommended to control short-term effects. Further measurements that link the levels of exposure to respiratory health effects in workers across Canada should be collected to establish an exposure-response relation and possible regional differences in the effects of grain dust. VALIDATION: There has been no external review of these recommendations. However, the American Conference of Governmental Industrial Hygienists has recommended an 8-hour average exposure limit of 4 mg/m3 for wheat, oats and barley.