Detection of mutagens in the urine of rats following topical application of hair dyes.

Mutagens were detected in the urine of rats following topical application of two commercial oxidative-type hair dye preparations. The test system used was induction of back mutation with the bacterial tester strain TA1538, a histidine-dependent mutant of Salmonella typhimurium. Various quantities of dye were applied to the shortened hair on the backs of the test animals. The dye was allowed to remain on the hair for 20 min after application and was then removed by shampooing and thorough rinsing. Maximal levels of mutagenic activity occurred with urine collected during first 24 h following dye application, and a dose--response was observed when increasing volumes of mutagenic urine were tested. Mutagens were detected in rat urine after intraperitoneal injection, and also after topical application of 4-nitro-o-phenylenediamine, one of the constituents of the hair-dye preparations.     

Detection of mutagens in the urine of rats following topical application of hair dyes

Mutagens were detected in the urine of rats following topical application of two commercial oxidative-type hair dye preparations. The test system used was induction of back mutation with the bacterial tester strain TA1538, a histidine-dependent mutant of Salmonella typhimurium. Various quantities of dye were applied to the shortened hair on the backs of the test animals. The dye was allowed to remain on the hair for 20 min after application and was then removed by shampooing and thorough rinsing. Maximal levels of mutagenic activity occurred with urine collected during the first 24 h following dye application, and a dose—response was observed when increasing volumes of mutagenic urine were tested.Mutagens were detected in rat urine after intraperitoneal injection, and also after topical application of 4-nitro-o-phenylenediamine, one of the constituents of the hair-dye preparations.     

Diagnostic aids for the detection of urine in the equine ejaculate

An experiment was conducted to evaluate three commercially available test kits, the Azostix, Multistix and Uric-acid test, for the detection of urine in the equine ejaculate. Azostix, which tests for urea nitrogen, consistently detected urine in the equine ejaculate. Urine contamination was evident when a color change occurred in the reagent pad, going from yellow to green after 10 sec of exposure. The sensitivity of Azostix to urea nitrogen in contaminated samples was 39 mg/dl. The Multistix test kit also successfully detected urine in semen. In the Multistix nitrite pad the color changed from yellow to organge after 3.5 min of exposure to urine-contaminated semen. The Uricacid test kit did not accurately detect urine-contaminated samples. It constantly elicited false positive results in all the control trials. The results of this study show that Azostix and Multistix are cost effective ($1.25 per analysis) and accurate diagnostic aids for detecting urine in the stallion ejaculate.     

Excretion of corticosteroid metabolites in urine and faeces of rats.

Stress enhances the production of corticosteroids by the adrenal cortex, resulting in the increased excretion of their metabolites in urine and faeces. An intraperitoneal injection of radioactive corticosterone was applied to adult, male Sprague-Dawley rats to monitor the route and delay of excreted metabolites in urine and faeces. Peak concentrations appeared in urine after 3.2 +/- 1.9 h and in faeces after 16.7 +/- 4.3 h. Altogether about 20% of the recovered metabolites were found in urine and about 80% in faeces. Using high-performance liquid chromatography (HPLC), several peaks of radioactive metabolites were found. Some metabolites were detected by enzyme immunoassay (EIA) using two different antibodies (corticosterone, 11beta-OH-aetiocholanolone). There was a marked diurnal variation with low levels of faecal corticosterone metabolites in the evening and higher values in the morning. This diurnal variation was influenced neither by the intraperitoneal injection of isotonic saline nor by ACTH. However, the administration of dexamethasone eliminated the morning peak for 2 days.     

Urinary biomarkers of 1,3-butadiene in environmental settings using liquid chromatography isotope dilution tandem mass spectrometry

Although, 1,3-butadiene is a known human carcinogen emitted from mobile sources, little is known about traffic-related human exposure to this toxicant. This pilot study was designed to characterize traffic-related environmental exposure to 1,3-butadiene and evaluate its urinary mercapturic acids as biomarkers of exposure in these settings. Personal air samples and multiple urine samples were collected on two separate occasions from three groups of individuals that differed by spatial proximity as well as intensity of traffic: (i) toll collectors, (ii) urban-weekday and (iii) suburban-weekend group. Air samples were analyzed using thermal desorption followed by GC/MS and urine samples were analyzed using isotope dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS) for two mercapturic acids of 1,3-butadiene: monohydroxy-3-butenyl mercapturic acid (MHBMA) and 1,2-dihydroxybutyl mercapturic acid (DHBMA). Exposure differed between groups (p<0.05) with median values of 2.38, 1.62 and 0.88 microg/m(3) for toll collectors, the urban-weekday group and the suburban-weekend group, respectively. A refined ID-LC-MS/MS method enabled detection of MHBMA, previously detected only in occupational settings, with high frequency. MHBMA and DHBMA were detected in 95 and 100% of urine samples at levels (mean+/-S.D.) of 9.7+/-9.5, 6.0+/-4.3 and 6.8+/-2.6 ng/mL for MHBMA and 378+/-196, 258+/-133 and 306+/-242 ng/mL for DHBMA for the three different groups, respectively. Mean biomarker levels were higher among the toll collectors compared to the other two groups, however, the differences were not statistically significant (p>0.05). This study is the first to evaluate 1,3-butadiene biomarkers for subtle differences in environmental exposures. However, additional research will be required to ascertain whether the lack of statistical association observed here is real or attributable to unexpectedly small differences in exposure between groups (<1 microg/m(3)), non-specificity of the biomarker at low exposure, and/or small sample size.     

Absorption,metabolism and excretion of 3-acetyl don in pigs

The absorption, metabolism and excretion of 3-acetyldeoxynivalenol (3-aDON) in pigs were studied. Pigs with a faecal microflora known to be able to de-epoxidate trichothecenes were used in the experiment. The pigs were fed a commercial diet with 3-aDON added in a concentration of 2.5 mg/kg feed for 2.5 days. No traces of 3-aDON or its de-epoxide metabolite were found in plasma, urine or faeces. Deoxynivalenol (DON) was detected in plasma as soon as 20 min after start of the feeding. The maximum concentration of DON in plasma was reached after 3 h and decreased rapidly thereafter. Only low concentrations close to the detection limit were found in plasma 8 h after start of the feeding. A significant part of the DON in plasma was in a glucuronide-conjugated form (42 ± 7%). No accumulation of DON occurred in plasma during the 60 h of exposure. The excretion of DON was mainly in urine (45 ± 26% of the toxin ingested by the pigs) and only low amounts of metabolites of 3-aDON (2 ± 0.4%) were recovered in faeces. De-epoxide DON constituted 52 ± 15% of the total amount of 3-aDON-metabolites detected in faeces. The remaining part in faeces was DON. DON was still present in the urine and faeces at the end of the sampling period 48 h after the last exposure. The results show that no de-epoxides are found in plasma or urine in pigs after trichothecene exposure, even in pigs having a faecal microflora with a de-epoxidation activity. The acetylated form of the toxin is deacetylated in vivo. Furthermore, the experiment shows that the main part of DON is rapidly excreted and does not accumulate in plasma, but a minor part of the toxin is retained and slowly excreted from the pigs.     

Enzyme-immunoassay for the determination of metallothionein in human urine: application to environmental monitoring

The objectives of this study were to develop an enzyme immunoassay for metallothioneins in human urine using a polyclonal antiserum and to demonstrate a possible relationship between the level of this biomarker and heavy metal exposure. The antiserum was raised in sheep against horse metallothionein conjugated to carboxylated bovine serum albumin. The antibody was used to construct a two-step competitive ELISA procedure. Human urine was treated with activated charcoal powder to remove traces of metallothioneins and known amounts of pure metallothioneins were added to provide standards for a standard curve. Metallothionein levels were measured in two groups of children living in areas of mild and high environmental pollution due mainly to heavy metals. A comparison was made between the biomarker levels and the levels of cadmium and lead in urine samples in the two groups. A group of children from a non-polluted area acted as controls. The results show that the detected levels of metallothioneins appear to correspond to levels of the two heavy metals studied and that there was an apparent relationship to the environmental exposure. Thus according to results of this study the increase in the metallothionein excretion seems to provide an indication of previous of exposure to metals. The ELISA procedure is sensitive and robust and can be used to screen large numbers of samples and is more rapid than the physical procedures currently used for analysis of these proteins. The assay can therefore be used as an additional tool for screening at-risk populations where either environmental or occupational exposure to divalent heavy metals is suspected.     

Enzyme-immunoassay for the determination of metallothionein in human urine: application to environmental monitoring

The objectives of this study were to develop an enzyme immunoassay for metallothioneins in human urine using a polyclonal antiserum and to demonstrate a possible relationship between the level of this biomarker and heavy metal exposure. The antiserum was raised in sheep against horse metallothionein conjugated to carboxylated bovine serum albumin. The antibody was used to construct a two-step competitive ELISA procedure. Human urine was treated with activated charcoal powder to remove traces of metallothioneins and known amounts of pure metallothioneins were added to provide standards for a standard curve. Metallothionein levels were measured in two groups of children living in areas of mild and high environmental pollution due mainly to heavy metals. A comparison was made between the biomarker levels and the levels of cadmium and lead in urine samples in the two groups. A group of children from a non-polluted area acted as controls. The results show that the detected levels of metallothioneins appear to correspond to levels of the two heavy metals studied and that there was an apparent relationship to the environmental exposure. Thus according to results of this study the increase in the metallothionein excretion seems to provide an indication of previous of exposure to metals. The ELISA procedure is sensitive and robust and can be used to screen large numbers of samples and is more rapid than the physical procedures currently used for analysis of these proteins. The assay can therefore be used as an additional tool for screening at-risk populations where either environmental or occupational exposure to divalent heavy metals is suspected.     

Enzyme-immunoassay for the determination of metallothionein in human urine: application to environmental monitoring.

The objectives of this study were to develop an enzyme immunoassay for metallothioneins in human urine using a polyclonal antiserum and to demonstrate a possible relationship between the level of this biomarker and heavy metal exposure. The antiserum was raised in sheep against horse metallothionein conjugated to carboxylated bovine serum albumin. The antibody was used to construct a two-step competitive ELISA procedure. Human urine was treated with activated charcoal powder to remove traces of metallothioneins and known amounts of pure metallothioneins were added to provide standards for a standard curve. Metallothionein levels were measured in two groups of children living in areas of mild and high environmental pollution due mainly to heavy metals. A comparison was made between the biomarker levels and the levels of cadmium and lead in urine samples in the two groups. A group of children from a non-polluted area acted as controls. The results show that the detected levels of metallothioneins appear to correspond to levels of the two heavy metals studied and that there was an apparent relationship to the environmental exposure. Thus according to results of this study the increase in the metallothionein excretion seems to provide an indication of previous of exposure to metals. The ELISA procedure is sensitive and robust and can be used to screen large numbers of samples and is more rapid than the physical procedures currently used for analysis of these proteins. The assay can therefore be used as an additional tool for screening at-risk populations where either environmental or occupational exposure to divalent heavy metals is suspected.     

Analysis of theaflavins in biological fluids using liquid chromatography–electrospray mass spectrometry

A HPLC–MS procedure for the sensitive and specific analysis of the black tea flavonoid theaflavin in human plasma and urine was developed. Levels were measured after enzymatic deconjugation, extraction into ethyl acetate, and separation by HPLC, using tandem mass spectrometry as a detecting system. Two healthy volunteers consumed 700 mg theaflavins, equivalent to about 30 cups of black tea. The maximum concentration detected in blood plasma was 1.0 μg l⁻¹ in a sample collected after 2 h. The concentration in urine also peaked after 2 h at 4.2 μg l⁻¹. Hence, only minute amounts of theaflavins can be detected in plasma and urine samples of healthy volunteers after ingestion.     

Human exposure to mycotoxins in Egypt

This investigation examined the exposure of Egyptian infants to Aflatoxin M₁ (AfM₁) and of lactating mothers to Aflatoxin B₁, using AfM₁ in human milk as a biomarker for exposure to AfB₁. The presence of ochratoxin A (OA) in human milk was also investigated to determine the levels of infants exposure to OA from human milk. The results indicated that AfM₁ was found in 66 (55 %) of 120 human milk samples with a mean of 0.3 ± 0.53 ng/mL (range 0.02 to 2.09 ng/mL). OA was found in 43 (35.8 %) of 120 human milk samples with a mean of 21.1 ± 13.7 ng/mL (range 5.07 to 45.01 ng/mL), which will cause a daily intake of OA from human milk exceeding the suggested tolerable dose of 5 ng/kg_-1 of OA body weight. On the other side AfM₁ was found in 25 % of blood samples (5 out of 20 samples), at a mean of 1.18 ng/mL, but it was detected only in one urine sample (1 out of 20 samples). OA was detected only in 2 out of 13 blood samples (15.4 %) with an average 3.67 ng/mL. Whereas OA was not detected in all analyzed urine samples.     

Comparison of a novel thin-layer chromatographic—fluorescence detection method with a spectrofluorometric method for the determination of 7-hydroxycoumarin in human urine

A novel method for the determination of 7-hydroxycoumarin in human urine which combines thin-layer chromatography (TLC) with fluorescence detection (FD) has been devised. The limit of detection (1 ng/ml) enables determination of 7-hydroxycoumarin after both administration of coumarin and environmental exposure to this fragrance material. When compared to a spectroflourometric method of analysis, the TLC—FD method proved to be more selective for the analysis of 7-hydroxycoumarin in human urine.     

Determination of nicotine and its main metabolites in urine by high-performance liquid chromatography

Nicotine and its main metabolites (cotinine, trans-3'-hydroxycotinine, trans-3'-hydroxycotinine glucuronide, nicotine-1'-N-oxide and 3-pyridylcarbinol) were analysed in urine after liquid—liquid extraction by high-performance liquid chromatography using norephedrine as internal standard, ultraviolet detection at 260 nm and scanning ultraviolet spectra with a photodiode-array detector. The conjugated trans-3'-hydroxycotinine was determined after enzymatic hydrolysis. Specific determination of 3-pyridylcarbinol was also carried out. Owing to its good selectivity, sensitivity and reproducibility, the method was applied to the analysis of urine samples from smokers and non-smokers. The results obtained suggest that the urinary markers used to assess active smoking or exposure to environmental tobacco smoke must be not only nicotine and cotinine, but also their main free and conjugated metabolites.     

Some effects of exposing rainbow trout (Salmo gairdneri Richardson) to phenol solutions

Phenol (C₆H₅OH) at non-lethal concentrations in hard water had no effect on the urine flow rate or haematocrit of rainbow trout for exposure times of 24 h. Phenol was detected in the urine in a non-conjugated form and unchanged phenol was also extracted from muscle, blood and brain. Uptake of phenol into tissue was found to be rapid with an equilibrium concentration being reached in 3 h. Loss of phenol after exposure was as rapid. The equilibrium concentration for muscle was similar to the phenol concentration to which the fish were exposed. Blood and brain contained smaller amounts. Close to or above the lethal threshold concentration (48-h lc₅₀9 mg 1^-l; 15°C) the fish had higher than ambient concentrations in their tissues most notably in the brain. Above the lethal threshold there is evidence of a large uptake of phenol by erythrocytes.     

Persistence of experimental Rocio virus infection in the golden hamster (Mesocricetus auratus)

Rocio virus (ROCV) is an encephalitic flavivirus endemic to Brazil. Experimental flavivirus infections have previously demonstrated a persistent infection and, in this study, we investigated the persistence of ROCV infection in golden hamsters (Mesocricetus auratus). The hamsters were infected intraperitoneally with 9.8 LD50/0.02 mL of ROCV and later anaesthetised and sacrificed at various time points over a 120-day period to collect of blood, urine and organ samples. The viral titres were quantified by real-time-polymerase chain reaction (qRT-PCR). The specimens were used to infect Vero cells and ROCV antigens in the cells were detected by immunefluorescence assay. The levels of antibodies were determined by the haemagglutination inhibition technique. A histopathological examination was performed on the tissues by staining with haematoxylin-eosin and detecting viral antigens by immunohistochemistry (IHC). ROCV induced a strong immune response and was pathogenic in hamsters through neuroinvasion. ROCV was recovered from Vero cells exposed to samples from the viscera, brain, blood, serum and urine and was detected by qRT-PCR in the brain, liver and blood for three months after infection. ROCV induced histopathological changes and the expression of viral antigens, which were detected by IHC in the liver, kidney, lung and brain up to four months after infection. These findings show that ROCV is pathogenic to golden hamsters and has the capacity to cause persistent infection in animals after intraperitoneal infection.     

LYSINE METABOLISM IN THE RAT BRAIN: THE PIPECOLIC ACID-FORMING PATHWAY

Employing both the intraventricular and intraperitoneal injection techniques, ¹⁴C-l -lysine at non-overloading concentrations was found to be metabolized to l -¹⁴C-pipecolic acid at significantly high levels in the rat. Labeled pipecolic acid in the brain and liver was only found at rather low levels 24 h after intraperitoneal administration of ¹⁴C-l -lysine regardless of non-labeled lysine metabolite overload. A marked enhancement of pipecolic acid labeling was only found in the brain when ¹⁴C-l -lysine was intraventricularly administered to animals under various lysine metabolite overloads. While overloading doses of non-labeled saccharopine or α-aminoadipate did not significantly alter the labeling patterns of pipecolic acid in the brain, liver or urine when ¹⁴C-l -lysine was intraperitoneally administered, pipecolate overloading markedly reduced labeled pipecolic acid levels in the brain, liver and urine. These results indicate: pipecolic acid formation is subject to product inhibition, and saccharopine is not in the pathway of pipecolic acid synthesis from l -lysine. The labeling pattern of lysine metabolites was not significantly affected by the overloading injection of pipecolic acid when ¹⁴C-l -lysine was intraventricularly administered suggesting a blood-brain barrier for pipecolate. Besides ¹⁴C-pipecolic acid, labeled α-aminoadipic acid was also found at significant levels mostly in the brain. Labeled saccharopine was not detected in any tissues or urine samples analyzed. The ¹⁴C-l -lysine metabolic pattern of the newborn rats did not seem to be any different from the adult rats, i.e. labeled pipecolic acid was also detected in substantial quantities in the brain, liver and urine 5 h after injection. ¹⁴C-d -Lysine was mainly metabolized to l -¹⁴C-pipecolic acid through either route of administration. These experimental evidences indicate that the pipecolic acid-forming pathway is a significant route for lysine metabolism in the rat, and that the rat brain probably utilizes this pathway mainly for lysine metabolism. The present study also discusses the potential neurological significance of the pipecolic acid pathway in relation to the major lysine metabolic pathway (the saccharopine pathway).     

Determination of micronucleus frequency by acridine orange fluorescent staining in peripheral blood reticulocytes of mice treated topically with different lubricant oils and cyclophosphamide

To ascertain whether used and re-refined lubricant oil absorbed through the skin can produce a genotoxic effect or cytotoxicity in mouse bone marrow cells, we examined the induction of micronucleated erythrocytes of peripheral blood after cutaneous application. Both re-refined and used lubricant oils showed a weak but significant induction of micronucleated polychromatic erythrocytes compared with control, while virgin oil did not show micronucleus induction. Cyclophosphamide (CP) was used not only as positive control but also to compare the sensitivity between intraperitoneal and dermal routes of administration of the test compounds in mice. The efficacy of intraperitoneal injection of CP is well known. On the other hand, dermal exposure is not so common and when CP was diluted in glycerin statistically significant values (P = 0.0036) of micronuclei were also found. Topically applied lubricant oils (virgin, re-refined and used) have the capacity to interfere with mouse bone marrow hematopoiesis evidenced by a statistically significant decrease in the proportion of polychromatic erythrocytes in the peripheral blood. Physical and chemical analysis revealed that used oil is more viscous than other lubricants, suggesting the presence of insoluble compounds, oxidized products and water as well as aromatic hydrocarbons. Used oil differs from other lubricant oils in metal and polyaromatic hydrocarbon content. Re-refined oil revealed a neutral value typical of pure mineral oil. This assay is an important tool to evaluate environmental pollutants that cause genotoxicity and/or cytotoxicity through skin exposure.     

GC-FPD measurement of urinary dialkylphosphate metabolites of organophosphorous pesticides as pentafluorobenzyl derivatives in occupationally exposed workers and in a general population in Shanghai (China)

Measurement of organophosphorus (OP) pesticide metabolites in human biological fluids is an important biomarker of pesticides exposure. We measured the urinary excretion of OP pesticide metabolites to evaluate occupational and non-occupational exposure to OP pesticides in the Chinese population in Shanghai (Eastern China). We collected urine samples from 30 exposed workers in a dimethoate emulsion packing division and from 60 healthy adults without any report of occupational exposure. DMP, DMTP, DMDTP, DEP, DEDP and DEDTP were measured by GC-FPD after derivatization with pentafluorobenzyl bromide. The LOQ values (1 mL urine) were 2.0 μg/L for DMP and DETP, 4.0 μg/L for DEP and DEDTP, 8.0 μg/L for DMDTP, and 10.0 μg/L for DMTP. Dimethyl phosphates were detected in the majority of the urine samples, i.e., 90–100% in the exposed group and 80–87% in the control group. The concentration of the urinary diethyl phosphates DEP and DETP was above the LOQ values in 40 and 20% of samples for the exposed group, and in 50 and 30% of the samples for the control group, respectively. DEDTP was not detectable in the urine samples except for a post-shift exposed worker (detection frequency, 6.7%). Median creatinine-adjusted values (μg/g cr.) for DAP in Chinese with pre-shift, post-shift and without occupational exposure to OP were 316, 584 and 170 for DMP, below LOQ, 115 and 114 for DEP, 840, 1730 and 693 for DMTP, and 255, 756 and 135 for DMDTP, respectively. In all subjects, the highest excretion levels were found for DMTP. Several OP pesticide metabolites were frequently detected in urine samples of both populations studied.     

On the effects of the <Emphasis Type="Italic">Fusarium</Emphasis> toxin deoxynivalenol (DON) administered per os or intraperitoneal infusion to sows during days 63 to 70 of gestation

Six pregnant sows of 180.6 ± 5.6 kg were fed either a Fusarium-contaminated (4.42 mg DON and 48.3 μg ZON per kg, DON per os, n = 3) or a control diet (0.15 mg DON and 5 μg ZON/kg) in the period of days 63 and 70 of gestation. On day 63 of gestation, sows fed the control diet were implanted with an intraperitoneal osmotic minipump (delivery rate of 10 μL/h, for 7 days) containing 50 mg pure (98%) DON in 2 ml 50% DMSO (DON ip, n = 3). Frequent plasma samples were taken to estimate the kinetics after oral and ip DON exposure. The intended continuous delivery of DON by the intraperitoneal minipump could not be shown, as there was a plasma peak (C_max) of 4.2–6.4 ng DON/mL either immediately (sow IP-2+3) or 2.5 h (sow IP-1) after implantation of the pump followed by a one-exponential decline with a mean half-time (t_1/2) of 1.75–4.0 h and only negligible DON plasma concentrations after 12 h. Therefore, the DON ip exposure has to be regarded as one single dose 1 week before termination of experiment. The DON per os sows showed a mean basis level (after achieving a steady state) of DON plasma concentration of about 6–8 ng/mL, as also indicated by the plasma DON concentration at the termination of the experiment. On day 70, caesarean section was carried out, the fetuses were killed immediately after birth, and samples of plasma, urine, and bile were taken to analyze the concentration of DON and its metabolite de-epoxy-DON. At necropsy there were no macroscopic lesions observed in any organ of either sows or piglets. Histopathological evaluation of sows liver and spleen revealed no alterations. The proliferation rate of peripheral blood mononuclear cells (PBMC) with or without stimulation was not affected by the kind of DON treatment. The exposure of pregnant sows at mid-gestation (days 63–70, period of organogenesis) to a Fusarium toxin-contaminated diet (4.42 mg DON and 0.048 mg ZON per kg) or pure DON via intraperitoneal osmotic minipump did not cause adverse effects on health, fertility, maintenance of pregnancy, and performance of sows and their fetuses. However, DON was detected in fetus plasma, indicating that this toxin can pass the placental barrier and may cause changes in the proportion of white blood cells (lower monocyte and neutrophil and higher lymphocyte proportion in DON per os fetuses).     

Biological monitoring of occupational exposure to 1-bromopropane by means of urinalysis for 1-bromopropane and bromide ion

The purposes of the present study are (1) to develop a sensitive analytical method to measure 1-bromopropane (1-BP) in urine, (2) to examine if 1-BP or bromide ion (Br) in urine is a useful biomarker of exposure to 1-BP, and (3) to identify the lowest 1-BP exposure concentration the method thus established can biomonitor. A factory survey was carried out on Friday, and 33 workers (all men) in cleaning and painting workshops participated; each worker was equipped with a diffusive sampler (carbon cloth KF-1500 as an adsorbent) to monitor 1-BP vapour for an 8-h shift, and offered a urine sample at the end of the shift for measurement of 1-BP and Br in urine. In addition, 10 non-exposed men offered urine samples as controls. The performance of the carbon cloth diffusive sampler was examined to confirm that the sampler is suitable for monitoring time-weighted average 1-BP vapour exposure. A head-space GC technique was employed for analysis of 1-BP in urine, whereas Br in urine was analysed by ECD-GC after derivatization to methyl bromide. The workers were exposed to vapours of seven other solvents (i.e. toluene, xylenes, ethylbenzene, acetone, etc.) in addition to 1-BP vapour; the 1-BP vapour concentration was 1.4 ppm as GM and 28 ppm as the maximum. Multiple regression analysis however showed that 1-BP was the only variable that influenced urinary 1-BP significantly. There was a close correlation between 1-BP in urine and 1-BP in air; the correlation coefficient (r) was >0.9 with a narrow variation range, and the regression line passed very close to the origin so that 2 ppm 1-BP exposure can be readily biomonitored. The correlation of Br in urine with 1-BP in air was also significant, but the r (about 0.7) was smaller than that for 1-BP, and the background Br level was also substantial (about 8 mg l^-1). Thus, it was concluded that 1-BP in end-of-shift urine is a reliable biomarker of occupational exposure to 1-BP vapour, and that Br in urine is less reliable.