Control of workers' exposure to airborne endotoxins and formaldehyde during the use of metalworking fluids

The study evaluated the effects of triazine use and machine enclosure on workers' exposure to bacteria, endotoxins, and formaldehyde in the use of metalworking fluids (MWF). Concentrations of triazine and bacterial contaminants were monitored in bulk samples of MWF from two machines in one workplace. One of the machines was used normally; triazine was added to the other when needed. Air sampling was used to estimate workers' exposure to endotoxins at 18 workplaces near enclosed and open machines. Concentrations of triazine in MWF and formaldehyde in the air were measured. Some recirculating local exhaust ventilation systems were also tested. The endotoxin and bacteria concentrations in the biocide test of MWF rapidly increased when the biocide levels decreased below 500 ppm. Airborne concentrations of endotoxins were substantially lower near enclosed machines than near open ones. Concentrations of airborne formaldehyde were below the Finnish occupational exposure limit at the existing levels of triazine in MWF. Concentrations of triazine in MWF correlated well with those of formaldehyde in the air near the machines (correlation coefficient r=.69). The results showed that the triazine levels in MWF should continuously be kept high enough (>500 ppm) to prevent workers' exposure to endotoxins and bacteria. Overdosing with triazine, however, should be avoided, so that the levels of airborne formaldehyde remain low. Triazine levels in MWF can be followed by the method described in this article. Workers' exposure to contaminants of MWF can be reduced substantially by enclosing the machines and equipping them with local exhausts.     

Priming of cytokine release and increased levels of bactericidal permeability-increasing protein in the blood of animal facility workers

Objective: To investigate cellular immune responses in laboratory animal workers who are exposed to high levels of animal allergens but also to other biologically active substances containing lipopolysaccharides (LPS), i.e., endotoxins. Methods: A survey among 20 animal facility workers and 20 matched (gender, smoking) controls was conducted using exposure measurements (endotoxin, colony-forming units of bacteria and fungi) and a questionnaire on respiratory symptoms. Blood samples were taken to determine the ex vivo whole-blood release of tumor necrosis factor-alpha (TNF) and interleukin-8 (IL-8) as well as plasma levels of LPS-binding protein (LBP), bactericidal permeability-increasing protein (BPI), the 75-kDa soluble TNF receptor (sTNFR75), and total/specific IgE. Results: Although exposure to endotoxin was low (range 0.05–2.8 ng/m³), a significant (P < 0.05) increase in plasma BPI (4-fold) and srTNF75 (1.2-fold) was found, suggesting a response to inhalation of LPS. Also, the capacity of blood leukocytes to release TNF and IL-8 in response to ex vivo exposure to workplace dust was increased. Data were not confounded by specific allergies, levels of IgE, smoking, or respiratory symptoms. Conclusions: A profound effect on the cellular immune response was seen in animal workers with low endotoxin exposure and a high antigenic load. It remains to be determined which other biologically active substance(s) are involved in this effect. Received: 4 November 1998 / Accepted: 2 March 1999     

Determination of N-nitrosodiethanolamine in urine by gas chromatography thermal energy analysis: application in workers exposed to aqueous metalworking fluids

 Objective: The aim of this study was to describe a detailed and validated methodology designed for the analysis of carcinogenic N-nitrosodiethanolamine (NDELA) down to sub-μg/l levels in urine and its application to a number of workers exposed to NDELA-contaminated aqueous metalworking fluids (MWF). Methods: Following a work-up procedure based on solid-phase extraction of NDELA, the urinary extracts were analysed without derivatization by gas chromatography on a polar wide-bore column with chemiluminescent detection using a thermal energy analyser (TEA). N-Nitroso-(2-hydroxypropyl)amine was used as an internal standard. The method was applied to 12 workers using “nitrite-free” or “nitrite-formulated” MWF and to 15 unexposed subjects. The NDELA content of the MWF was also determined using a similar, but simpler method able to easily quantify NDELA down to at least 0.1 mg/l. Results: Contamination by NDELA traces of some chemicals used for the sample preparation, particularly ethyl formate, must be carefully checked since it can give rise to false-positive results of up to 1 or 2 μg/l. The response was linear in the range of 0–500 μg/l. Between 0.5 and 10 μg/l, the recovery rate was close to 95%, while repeatability ranged from 12.5 to 6.4% (n = 5). The detection limit was 0.3 μg/l (Signal/noise = 3). No detectable NDELA could be observed in the control workers. There was no significant increase in NDELA levels at the end of shift spot samples from an exposed worker over 1 week. Higher NDELA concentrations were found in two workers (4.3 and 10.7 μg/l) exposed to “nitrite-formulated” fluids (contaminated with 65 and 18 mg NDELA per l, respectively) than in nine workers (range, 0.4–1.3 μg/l exposed to “nitrite-free” fluids with lower levels of NDELA (range, 0.5–6.6 mg/l). Conclusion: The detailed methodology described in this work and applied to a limited industrial situation was found to be suitable for monitoring NDELA in the urine of workers exposed to aqueous MWF. A much larger screening has been undertaken with the aim of obtaining better information on the real exposure of workers sometimes exposed to “nitrite-formulated” fluids that are still used. Received: 8 December 1998 / Accepted: 3 April 1999     

A follow-up study on occupational exposure to inhaled anaesthetics in Eastern European surgeons and circulating nurses

Objective: Although no dose-response relationship exists for the health risks associated with the occupational exposure to inhaled anaesthetics, public health authorities recommend threshold values. The aim of the present study was to assess whether and to what extent these threshold values are exceeded in surgeons and circulating nurses of an Eastern European university hospital, before and after measures had been taken to reduce occupational exposure. Methods: At nine workplaces, occupational exposure to nitrous oxide and the volatile anaesthetic used (halothane or isoflurane) was measured within the breathing zones of surgeons and circulating nurses by means of photoacoustic infrared spectrometry. The measurements were carried out in 1996 and were repeated in 1997 after the installation of active scavenging devices at five workplaces, and an air-conditioning system at one workplace. Results: Occupational exposure to nitrous oxide and halothane or isoflurane was lower in 1997 compared with that of 1996. In 1996, 89% of the nitrous oxide values were above the European threshold value of 100 ppm, whereas in 1997 approximately 50% were above this limit. In 1996 the majority of the measurements for the volatile anaesthetics were already below 5 ppm halothane and 10 ppm isoflurane and the number of measurements exceeding these limits was further reduced in 1997. Conclusion: The measures taken were effective in reducing waste gas exposure. Nevertheless, further efforts are necessary, especially for nitrous oxide, to reach Western European standards and to minimise possible health risks. These efforts comprise the installation of (active) scavenging devices, air-conditioning systems and new anaesthesia machines at all workplaces, the use of low-flow anaesthesia, the replacement of inhaled anaesthetics by intravenous anaesthetics and an appropriate working technique. Received: 27 April 2000 / Accepted: 26 July 2000     

Long-term monitoring of sister chromatid exchanges and micronucleus frequencies in pharmacy personnel occupationally exposed to cytostatic drugs

Objectives: Many antineoplastic drugs were found to have carcinogenic, mutagenic and teratogenic potential. The aim of this study was to carry out cytogenetic and internal dose monitoring of hospital pharmacy personnel regularly involved in the preparation of cytostatic agents, in order to test possible cytostatics-induced genotoxic effects due to occupational exposure under routine working conditions, and in cases of accidental contamination. Methods: Platinum in whole blood and anthracyclines in plasma were measured to assess internal exposure to cytostatics. The level of cytogenetic damage was determined in peripheral blood lymphocytes with the micronucleus test and the sister chromatid exchange assay. Five series of monitoring were performed over a period of 2 years. Results: No significant differences in the mean frequencies of sister chromatid exchanges (SCE) and micronuclei (MN) were found between occupationally exposed probands and controls (9.9 ± 1.4 vs 10.1 ± 1.2 SCEs/cell and 21.2 ± 7.2 vs 23.3 ± 7.5 MN/2000 binucleated (BN) cells, n=16). Significant elevations of SCE or MN were detected in seven out of 12 cases of accidental contamination at the workplace, whereas no increase in platinum in blood and anthracyclines in plasma was observed in these probands. Two cases of non-reported contamination were identified by measurement of epirubicin in plasma. Smoking was found to increase the SCE significantly. No correlation between individual SCE scores and MN scores was observed. Conclusions: Our findings support a transient increase in SCE or MN after relevant exposure to cytostatic drugs in cases of accidental contamination. The lack of significant differences in SCE and MN between hospital pharmacy personnel and unexposed controls, points to high standards of safety at the corresponding workplaces. Received: 11 October 1999 / Accepted: 25 April 2000     

Variation in the ratio of respirable particulates over inhalable particulates by type of dust workplace

Objective: The aim of the present study was to clarify the quantitative relationship between respirable particulates and inhalable particulates in various dust workplaces. Methods: Both respirable particulate and inhalable particulate concentrations were measured in 1644 dust workplaces by means of elutriation, and the ratio of respirable particulate mass over that of inhalable particulate (R/I ratio) was calculated for each workplace. Results: Statistical analyses showed that the R/I ratio varied substantially, depending on the type of dust work. The ratio was highest in welding workplaces (mean ± SD: 53 ± 19%) and lowest in foundries (23 ± 16%); the former value suggests that respirable particulate exposure may be underestimated in substantial parts of welding work when only the occupational exposure limit for inhalable particulates is taken for compliance testing. Conclusions: Simple compliance with the limit for inhalable particulates is not sufficient, and the limit for respirable particulates should also be simultaneously cleared. Received: 21 February 1997 / Accepted: 17 July 1997     

Occupational exposure to alkoxysilanes in a fibreglass manufacturing plant

Objective: To assess the exposure of workers to alkoxysilanes and to determine the main route of exposure during the manufacture of fibreglass. Methods: Occupational hygiene samples were taken from workers and their environment in a fibreglass factory during filament forming and the handling of coated fibres. The total exposure of workers to silanes was assessed by the collection of air samples into impinger flasks at stationary sampling sites, by the use of absorbent patch samples on workers' clothes or skin and from handwash samples. During the time of our field survey, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane were being used in different sizing mixtures. The samples were analysed by gas and liquid chromatography. Results: The silane concentrations in the air samples were below the detection limits of the analytical methods. The mean dermal exposure to 3-glycidoxypropyltrimethoxysilane, analysed from the patch samples, was 2,800 mg h⁻¹ in the forming room and 800 mg h⁻¹ in the winder room. The corresponding figures for 3-methacryloxypropyl-trimethoxysilane were 3 and 9 mg h⁻¹. As determined in the handwash samples, the mean exposure to 3-glycidoxypropyltrimethoxysilane through the hands was 1,500 mg h⁻¹ in the forming room and 1,800 mg h⁻¹ in the winder room, the respective values for 3-methacryloxypropyltrimethoxysilane being 110 mg h⁻¹ and 90 mg h⁻¹. Only small quantities of 3-aminopropyltriethoxysilane were found in a few handwash samples. Conclusions: Our results showed that the workers in the fibreglass factory were clearly exposed to silanes. The main route of potential exposure was through the skin, especially the hands, which emphasised the importance of wearing appropriate protective gloves. According to the patch sampling, on average two thirds of the total dermal exposure was caused by exposure of the forearm, as indicated by the amounts of silanes analysed in the forearm patches. Since almost every worker was wearing protective gloves, the main occupational health finding concerning exposure to silanes was that short-sleeved T-shirts did not provide any protection to the arms. Received: 19 April 1999 / Accepted: 17 July 1999     

Risk of lung cancer in workers producing stainless steel and metallic alloys

Objectives: The mortality of workers involved in the production of stainless and alloyed steel from 1968 to 1992 was studied, in order to investigate the risk of lung cancer due to exposure to metals, i.e. iron oxides, chromium and/or nickel compounds. Methods: The study design was a historical cohort mortality study and a nested case-control study concerning lung cancer. Standardized mortality ratios (SMRs) were computed using regional mortality rates as an external reference for comparing observed and expected numbers of deaths, adjusting for age, sex and calendar time. Conditional logistic regression was used to estimate odds ratios (ORs). Occupational exposure was assessed through the complete job histories of cases and controls and a specific job-exposure matrix. Results: The cohort comprised 4,288 male and 609 female workers. The observed overall mortality was significantly lower than expected [649 deaths; SMR = 0.91; 95% confidence interval (CI) 0.84–0.98]. No significant SMR was observed for mortality from lung cancer (54 deaths; SMR = 1.19; CI 0.88–1.55). The case-control study was based on 54 cases and 162 individually matched controls. Smoking habits were available for 71%. No lung cancer excess was observed for exposure to (1) metals and/or their compounds, i.e. iron (OR = 0.94, CI 0.48–1.86), chromium and/or nickel (OR = 1.18, CI 0.62–2.25), and cobalt (OR = 0.64, CI 0.33–1.25), (2) acid mists (OR = 0.43, CI 0.17–1.10), and (3) asbestos (OR =  1.00, CI 0.54–1.86). With respect to exposure to polycyclic aromatic hydrocarbons (PAHs) and silica, which are often found together in workplaces, (1) high and statistically significant lung cancer excesses were observed, the ORs being 1.95 (CI 1.03–3.72) and 2.47 (CI 1.28–4.77) respectively, (2) quantitative exposure parameters revealed upward trends reaching statistical significance (P < 0.05), and (3) adjustments for tobacco consumption did not reveal any confounding factors from smoking. Conclusion: This study failed to detect any relationship between lung cancer and exposure to iron, chromium, nickel and/or their compounds. High and statistically significant relative risks, along with increasing trends, were observed for simultaneous exposure to PAHs and silica. Received: 12 April 1999 / Accepted: 2 October 1999     

Occupational exposure to polycyclic aromatic hydrocarbons in a fireproof stone producing plant: biological monitoring of 1-hydroxypyrene, 1-, 2-, 3- and 4-hydroxyphenanthrene, 3-hydroxybenz(a)anthracene and 3-hydroxybenzo(a)pyrene

Objectives: Assessment of external and internal exposure to polycyclic aromatic hydrocarbons (PAH) in a fireproof stone producing plant. Methods: Five personal and four stationary air measurements were performed to determine the concentrations of benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, chrysene, dibenz(a,h)anthracene, fluoranthene, phenanthrene and pyrene, in air. To estimate internal exposure, we determined the urinary excretion of 1-hydroxypyrene, 1-, 2-, 3-, and 4-hydroxyphenanthrene, 3-hydroxybenz(a)anthracene and 3-hydroxybenzo(a)- pyrene in 19 workers, using a sensitive and reliable high-performance liquid chromatographic method with fluorescence detection. Results: During the production of fireproof stones, the German technical exposure limit (TRK) for benzo(a)pyrene of 2 μg/m³ was exceeded in two cases. The mean values of the sum of eight PAHs were 12.6 μg/m³ (stationary air measurement) and 22.2 μg/m³ (personal air measurement). Urinary 1-hydroxypyrene excretion predominated, with a median of 11.1 μg/g creatinine (creat.), followed by 3-hydroxyphenanthrene (median 2.2 μg/g creat.), 1-hydroxyphenanthrene (median 1.9 μg/g creat.) and 2-hydroxyphenanthrene (median 1.6 μg/g creat.). 4-Hydroxyphenanthrene (median 0.3 μg/g creat.) and 3-hydroxybenz(a)anthracene (median 0.17 μg/g creat.) were found in far lower concentrations, while 3-hydroxybenzo(a)pyrene was found only in very low concentrations (median 0.014 μg/g creat.). No correlations could be detected for a relationship between external and internal exposure. A significant correlation between urinary metabolite concentrations could be calculated only for 3-hydroxybenz(a)anthracene and 1-hydroxypyrene. Conclusions: In comparison with other industries, the internal PAH exposure at workplaces in a fireproof stone producing plant is high. This is probably caused by dermal PAH-absorption. Therefore, biological monitoring must be performed in the health surveillance of fireproof stone producing workers. The urinary PAH metabolites should be determined: 3-hydroxybenz(a)anthracene could probably be used as a biomarker representing the group of carcinogenic PAH. Received: 3 November 1999 / Accepted: 26 January 200     

Manganese exposure in foundry furnacemen and scrap recycling workers

Objectives: Cast iron products are alloyed with small quantities of manganese, and foundry furnacemen are potentially exposed to manganese during tapping and handling of smelts. Manganese is a neurotoxic substance that accumulates in the central nervous system, where it may cause a neurological disorder that bears many similarities to Parkinson's disease. The aim of the study was to investigate the sources and levels of manganese exposure in foundry furnacemen by a combined measuring of blood-manganese (B-Mn) and manganese in ambient air (air-Mn). Methods: During a period of 16 months, Air-Mn and B-Mn (denoted `exposure values') were measured involving 24 furnacemen employed in three small size foundries and 21 scrap recycling workers from one plant. In the study period, 18 furnacemen had B-Mn measured 3–4 weeks after decreasing or stopping exposure (denoted `post-exposure values'). The reference group for the B-Mn measurements consisted of 90 Danish male subjects. Results: Furnacemen who work in insufficiently ventilated smelting departments inhale, absorb, and retain significant amounts of manganese in their blood (approx. 2.5–5 μg/l above reference values) despite a generally low measured airborne level of manganese fumes (0.002–0.064 mg/m³). The `exposure values' compared with `post-exposure values' revealed a significant decrease in the B-Mn (on average 3.7 μg/l) level of the most exposed furnacemen. Two persons in our study were suspected of suffering clinically subacute manganese intoxication as both had B-Mn levels beyond the normal limit (25 and 29 μg/l, respectively). The potential problem disappeared completely after cessation of exposure, and the B-Mn levels decreased to 9.4 and 14.1 μg/l, respectively. Conclusions: Risk assessment based on combined measurements of B-Mn and air-Mn seems to be valid in the interpretation of workers' hazard. Our study indicates that B-Mn may be a valuable parameter for estimating recent exposure (within 1–2 weeks). However, more knowledge is needed about the B-Mn level and its relation to neurological symptoms. Received: 20 January 1999 / Accepted: 14 June 1999     

Outcome of occupational asthma due to platinum salts after transferral to low-exposure areas

Objective: To assess the health effects of transferral to low-exposure jobs on subjects with occupational asthma (OA). Methods: We performed a cross-sectional survey of 83 workers in 2 platinum (Pt) refineries and 2 catalyst production plants, all with diagnosed OA due to Pt salts. In all, 9 workers (group A; 11%) continued to be exposed at the time of examination, 16 subjects (group B; 19%) had been transferred to other workplaces within the production building, 39 subjects (group C; 47%) had been transferred to areas outside the building but inside the plant, and 19 subjects (group D; 23%) had left the plant. The median period from transferral to examination was 54 months (lower quartile 23 months, upper quartile 84 months, n = 74). Symptoms, skin-prick tests (SPT) with environmental allergens and Pt salt, total serum IgE, lung function, and bronchial hyperresponsiveness were assessed by standard procedures. Results: Asthma symptoms were reported by all subjects in the production area but by only 37 of 74 subjects (50%) after transferral, with no difference being found between groups B, C, and D. Both the proportion of subjects sensitized to Pt salts (100%, 88%, 67%, and 42% in groups A, B, C, and D, respectively) and the degree of sensitization were associated with exposure (P < 0.0002). Total IgE was higher in group A as compared with groups B, C, or D (P < 0.002). There was no association between bronchial hyperresponsiveness and exposure. Although no univariate difference in FEV₁ was found between the groups, regression analysis showed an association between FEV₁ and exposure (P < 0.002). In all, 13 subjects demonstrated a predicted FEV₁ value of <80% (22%, 6%, 10%, and 32% in groups A, B, C, and D, respectively). They were older (median 49 versus 37 years; P < 0.002) and had worked over longer periods in high-exposure areas in spite of symptoms (median 43 versus 10 months; P < 0.003). Fifteen subjects of groups C or D had been removed from areas B previously, eight of them due to respiratory symptoms. Conclusions: For the majority of subjects with OA due to Pt salts transfer to low exposure areas as defined in this study may not be associated with a more unfavorable outcome as compared with complete removal from exposure sources. Received: 16 April 1998 / Accepted: 3 September 1998     

Antioxidative stress response in workers exposed to carbon disulfide

Objective: To study the effects of carbon disulfide (CS₂) on antioxidative stress systems of exposed workers. Methods: Enzyme-linked immunosorbent assay (ELISA) and thiobarbituric acid test (BAT) were conducted on 67 exposed workers and 88 controlled ones in a viscose rayon factory to determine their serum cuprozinc-superoxide dismutase (CuZnSOD) and malonyldialdehyde (MDA) levels. Results: The average levels of CuZnSOD in workers exposed to CS₂ both above and below 10 mg/m³ were higher than those in the control group (P < 0.0001), showing some dose-effect and dose-response relationships. SOD levels increased when the exposure index (EI) was less than 300, and remained at a high level at the range of 300 to 900. When EI was higher than 900, SOD tended to decrease. Meanwhile, the serum MDA levels increased. Both CS₂ concentrations and exposure time contribute to the MDA levels. Conclusions: CS₂ exposure could influence the stress response of the oxidative-antioxidative system of workers. Increased SOD levels could be considered as the stress response of antioxidative system to CS₂ exposure in the early stages, and the influence of CS₂ on SOD might be bi-directional. SOD and MDA might become objective indices in workers' health surveillance. The role of these two indices in the intoxication mechanism still needs to be clarified. Received: 3 August 1999 / Accepted: 25 April 2000     

Exposure assessment and sensitisation in workers exposed to organic acid anhydrides

Objectives: To clarify whether the intensity of exposure to organic acid anhydrides (OAAs) is associated with the risk of sensitisation to these allergens. Methods: The investigations were carried out in three different manufacturing plants (A, B, and C) where OAAs were used in the production of epoxy resins. Methyltetrahydrophthalic acid anhydride (MTHPA) was used in all three plants. The exposure assessment included stationary and ambient air monitoring (OAAs in the air) and biological monitoring (metabolites in urine). In plant A 20, in plant B 86 and in plant C 113 employees were examined by a physician (anamnesis, skin-prick test, specific IgE, spirometry). In plants B and C, the exposure areas were classified as high, medium, and low, without the results of the exposure assessment being known. Results: The ambient air concentrations (in μg/m³) of MTHPA were 37.2 and 58.5 in plant A (number of samples n=2), ranged from <0.5–26.2 in plant B (n=5) and from 2.1–57.9 in plant C (n=3) with stationary air collecting, and from 8–45 (n=6), from <4.7–35.7 (n=3) and from 2–37.8 (n=3) with personal air collection. The metabolites of OAAs in urine (in nmol/mmol creatinine) ranged from 5.7–645 (median of MTHPA: 346) in plant A, from <1–213 (median of MTHPA: 10.1) in plant B and from 0.1–830 (median of the sum of the OOA metabolites: 108.6) in plant C. The prevalence of sensitisation was 35% in plant A, 21% in plant B and 29% in plant C. A higher prevalence in the highly exposed areas, however, could not be seen. Levels of IgE specific for conjugates of MTHPA were not associated with the metabolites in the end of shift urine. Levels of IgG specific for conjugates of MTHPA, however, were associated with the metabolites in the end of shift urine. Conclusions: The data showed that biological monitoring is a useful tool in the exposure assessment of OAAs. Comparing the prevalence of sensitisation and the results of biological monitoring, between the three plants, we found that sensitisation increased with increasing exposure. Within a plant a higher risk of sensitisation in persons working in highly exposed areas at the time of the examination could not be seen, possibly due to frequent job rotation. Received: 2 August 1999 / Accepted: 29 January 2000     

Dermal absorption of N,N-dimethylacetamide in human volunteers

Objectives: We investigated the potential for the dermal absorption of N,N-dimethylacetamide (DMAC: CAS No. 127-19-5) vapor, the biological half-life of N-methylacetamide (NMAC) in urine as the biological exposure item of DMAC, and the adjustment method for urinary concentrations. Methods: Twelve healthy male volunteers (mean age 25.2 years, range 21–43 years) were exposed to DMAC for 4 h on two occasions at intervals of 96 h or above. Each volunteer sat inside a whole-body-type exposure chamber for the dermal exposure experiment or outside the chamber for the inhalation exposure experiment. The temperature and relative humidity in the chamber were controlled at approximately 26 °C and 40% in order to keep the skin (90% naked) of the volunteers dry. DMAC concentrations were 6.1 ± 1.3 ppm for dermal exposure and 6.1 ± 1.3 ppm for inhalation exposure. Urine samples were collected from 0 h through 36 h and at 48 h and 72 h after the exposure. Extrapolations from exposure concentrations for 4 h to 10 ppm for 8 h were performed. Results: Mean dermal absorption was estimated to be 40.4% of the total DMAC uptake. The biological half-lives of urinary NMAC were 9.0 ± 1.4 h and 5.6 ± 1.3 h via skin and lung, respectively. Mean NMAC in urine just after 5 consecutive workdays (8 h/day) at 10 ppm DMAC exposure was assumed to be 33.7 mg/g · Cr (18.6–70.0 mg/g · Cr). Creatinine-adjusted NMAC concentration in urine for each volunteer within 12 h after the exposure was more closely correlated with the total excretion amount of NMAC up to 36 h than with urinary-volume-adjusted or specific-gravity-adjusted NMAC concentration in both the dermal and inhalation exposure experiments. Conclusions: DMAC vapor was significantly absorbed through the skin. Estimated NMAC values indicate that 20 mg/g · Cr NMAC seems to be appropriate as the biological exposure index. Received: 6 August 1999 / Accepted: 9 September 1999     

Field evaluation of a passive sampler for the exposure assessment of 2-methoxyethanol

Objective: This paper presents a field evaluation of 3 M 3500 passive badges for measuring 2-methoxyethanol (ME) in a humid working environment. Methods: A total of 93 pairs of side-by-side active/passive samples, 48 pairs of duplicate active samples, 52 pairs of duplicate passive samples, and three groups of six replicate active/passive samples were compared. Three groups of six replicate active charcoal/active charcoal tube with drying tube samples were also compared to evaluate the humidity effect. Results: No statistical difference was found between the passive badges and active samplers. Linear regression showed the correlation to be high (r = 0.992, slope  =  0.973, n = 93) over the range of 0.17–163 ppm. The mean concentration difference was −0.34 ppm and the mean relative error was 3.50%. The intraclass correlation coefficients of 48 duplicate active samples and 52 duplicate passive samples were 0.994 and 0.989, respectively. The precision of replicate passive, active, and active/drying tube samples (n = 6) were 3.84%, 7.14%, and 5.12%, respectively. Conclusions: The humidity effect for active samples was insignificant at the low sampling rate (36.3 ml/min). It is therefore concluded that the use of the passive samplers to assess ME exposure produces comparable findings to that of active sampling. Received: 5 March 1999 / Accepted: 9 September 1999     

Metalworking fluid bioaerosols at selected workplaces in a steelworks

BACKGROUND: Exposure to metalworking fluid (MWF) aerosols has been shown to be associated with a variety of respiratory and skin diseases of workers. METHODS: Measurements of particulate aerosols, bacterial bioaerosol, and endotoxins and 3-hydroxy fatty acids (3-OH FAs) content in water-based and straight oil MWFs were done during an 8 hr work shift in the grindery and oil basement sections of a steelworks located in Upper Silesia, Poland. RESULTS: Particulate aerosol concentrations were below NIOSH recommended occupational exposure level. Differences in concentration and taxonomical composition of airborne bacteria between grindery and oil basement were found, due to the more aggressive creation of oil mist during machining operations and different MWF characteristics, which favor growth of different bacterial strains. CONCLUSIONS: The GC-MS analysis of 3-OH FAs as a marker of endotoxin contamination of the MWF and of the air seems to be a promising tool for evaluation of occupational exposure to bacterial bioaerosols.     

Effects of occupational metallic mercury vapour exposure on suppressor-inducer (CD4+CD45RA+) T lymphocytes and CD57+CD16+ natural killer cells

Objectives: To examine the effects of metallic mercury vapour on the cellular and humoral immune system. Methods: We measured T lymphocyte and natural killer (NK) cell subpopulations, B lymphocytes, and serum immunoglobulins (i.e. IgG, IgA and IgM) together with total T (CD3+) lymphocytes and total lymphocytes in blood samples from 20 male, fluorescent-lamp makers (mercury workers) and the same number of gender-, age- and smoking-matched controls. Urinary concentrations of inorganic mercury (UHg) in the 20 workers ranged from 1.8 to 163.5 (mean 44.8) μg/l. They had been exposed to mercury vapour for 4 to 62 (mean 31) months. Results: Numbers of CD4+CD45RA+ (suppressor-inducer) T lymphocytes and total CD4+ T lymphocytes in the mercury workers were significantly smaller than those in the controls (paired-sample t-test, P < 0.01). The number of CD57+CD16+ NK cells was inversely correlated with UHg. Conclusion: It is suggested that numbers of CD4+CD45RA+ T lymphocytes and CD57+CD16+ NK cells are inversely affected by exposure to metallic mercury vapour in workers, with an average urinary inorganic mercury concentration of 45 μg/l being found. Received: 7 September 1999 / Accepted: 6 May 2000     

Biological monitoring of workers exposed to N,N-dimethylformamide in the synthetic fibre industry

Objectives: Monitoring of workplace air and biological monitoring of 23 workers exposed to N,N-dimethylformamide (DMF) in the polyacrylic fibre industry was carried out on 4 consecutive days. The main focus of the investigation was to study the relationship between external and internal exposure, the suitability of the metabolites of DMF for biological monitoring and their toxicokinetic behaviour in humans.Methods: Air samples were collected using personal air samplers. The limit of detection (LOD) for DMF using an analytical method recommended by the Deutsche Forschungsgemeinschaft (DFG) was 0.1 ppm. The urinary metabolites, N-hydroxymethyl-N-methylformamide (HMMF), N-methylformamide (NMF), and N-acetyl-S-(N-methylcarbamoyl)-cysteine (AMCC), were determined in one analytical run by gas chromatography with thermionic sensitive detection (GC/TSD). The total sum of HMMF and NMF was determined in the form of NMF. The LOD was 1.0 mg/l for NMF and 0.5 mg/l for AMCC. Results and conclusions: The external exposure to DMF vapour varied greatly depending on the workplace (median 1.74 ppm, range <0.1–159.77 ppm). Urinary NMF concentrations were highest in post-shift samples. They also covered a wide range (<1.0–108.7 mg/l). This variation was probably the result of different concentrations of DMF in the air at different workplaces, dermal absorption and differences in the protective measures implemented by each individual (gloves, gas masks etc.). The urinary NMF concentrations had decreased almost to zero by the beginning of the next shift. The median half-time for NMF was determined to be 5.1 h. The concentrations of AMCC in urine were determined to be in the range from <0.5 to 204.9 mg/l. Unlike the concentrations of NMF, the AMCC concentrations did not decrease during the intervals between the shifts. For the exposure situation investigated in our study, a steady state was found between the external exposure to DMF and the levels of AMCC excreted in urine about 2  days after the beginning of exposure. AMCC is therefore excreted more slowly than NMF. The half-time for AMCC is more than 16 h. Linear regression analysis for external exposure and urinary excretion of metabolites was carried out for a sub-group of 12 workers. External exposure to 10 ppm DMF in air (the current German MAK value) corresponds to an average NMF concentration of about 27.9 mg/l in post-shift urine from the same day and an average AMCC concentration of 69.2 mg/l in pre-shift urine from the following day. NMF in urine samples therefore represents an index of daily exposure to DMF, while AMCC represents an index of the average exposure over the preceding working days. AMCC is considered to be better suited for biomonitoring purposes because (1) it has a longer half-time than NMF and (2) its formation in humans is more closely related to DMF toxicity. Received: 25 June 1999 / Accepted: 2 October 1999     

Adjustment to concentration-dilution of spot urine samples: correlation between specific gravity and creatinine

Objective: Spot urine samples were investigated to determine correlations between urinary creatinine and specific gravity, and intra- and inter-day variations other than gender- and age-dependence of urinary concentrations. Methods: Urinary creatinine concentrations and specific gravity were determined in 534 spot samples (385 from men and 149 from women). Subjects' ages ranged between 18 and 68 years. Spot urine samples were also collected from 14 male subjects before and after a 1-week work-shift for the evaluation of intra- and inter-day variations of creatinine and specific gravity. Results: In spot samples, creatinine concentrations ranged between 0.16 and 4.36 g/l and specific gravity between 1.002 and 1.037. A high correlation (r=0.82, P < 0.001) was observed between creatinine and specific gravity; male subjects showed significantly higher values of creatinine (P < 0.001) than did female subjects (1.90 ± 0.74 and 1.41 ± 0.72 g/l, respectively) and specific gravity (1.023 ± 0.006 and 1.020 ± 0.007, respectively). In addition, creatinine but not specific gravity significantly decreased (P < 0.02) in subjects older than 50 years, compared with those under 40. Conclusions: Results confirm the gender-dependence of creatinine concentrations in spot specimens and also show age-dependence, indicating the need for these aspects to be considered when the range of acceptable samples is to be set. No significant intra- or inter-day variations were observed for the two parameters. Lastly, the possibility of a comparison of differently adjusted values was indicated by a conversion formula derived from adjustments to creatinine and the corresponding specific gravity of a hypothetical urinary value, as follows: specific gravity adjusted values= 1.48 × creatinine adjusted values. Received: 14 February 2000 / Accepted: 26 July 2000     

Occupational exposure to sevoflurane during sedation of adult patients

Objectives: In a field study we evaluated the workplace pollution occurring during conscious sedation with sevoflurane in adults. Methods: Sevoflurane was given in 100% oxygen at a fresh gas flow rate of 3 l/min via a nasal mask. This was conducted in 25 patients scheduled for surgical procedures performed under regional anesthesia. Trace concentrations of sevoflurane were directly measured every minute in the breathing zone by means of a photoacoustic infrared spectrometer in an operating room with an air turnover of 20 changes/h. Results: The mean sedation time was 49.6 ± 20.4 min. The average vaporizer setting of the anesthesia machine was 1.63 ± 0.6 vol%, resulting in a patient's mean end-tidal sevoflurane concentration of 0.78 ± 0.2 vol%. The 8-h time-weighted average was calculated to be 0.58 ppm sevoflurane. Conclusions: The trace gas concentrations were low and comparable with values obtained under inhalation induction in adults and children. Although no occupational standard for sevoflurane is currently defined, the measured values are clearly under the standards recommended for enflurane (20 ppm) and isoflurane (10 ppm) by the European health authorities. We conclude that the new anesthesiologic method of conscious sedation with sevoflurane in adults using a nasal mask would not result in a violation of occupational standards, provided that the future value set for sevoflurane would be similar to those recommended for isoflurane or enflurane. Received: 3 August 1998 / Accepted: 14 November 1998