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     

Indoor exposure to polycyclic aromatic hydrocarbons and carbon monoxide in traditional houses in Burundi

Objectives: Wood combustion is used as a major energy source in African countries and could result in indoor, pollution-related health problems. This exploratory study was undertaken to estimate polycyclic aromatic hydrocarbon (PAH) and carbon monoxide exposure in individuals living in traditional rural houses in Burundi. Methods: Standard methods were used to determine indoor air concentrations of 12 PAHs, and carbon monoxide. The urinary excretion of 1-hydroxypyrene (1-OHP) was measured in occupants of traditional houses, and compared with that of individuals living in the town of Bujumbura, the capital of Burundi. Results: Mean airborne concentration of four volatile PAHs, naphthalene, fluorene, phenanthrene and acenaphthene, exceeded 1 μg/m³, and that of benzo(a)pyrene was 0.07 μg/m³. Naphthalene was by far the main PAH contaminant, with a mean concentration (±standard deviation) of 28.7 ± 23.4 μg/m³, representing on average 60–70% of total PAH concentration. Carbon monoxide mean concentration (±standard deviation) was 42 ± 31 mg/m³, and correlated with total PAH concentration. Geometric mean urinary 1-OHP excretion (range) in people living in traditional houses was 1.50 (0.26–15.62) μmol/mol creatinine, a value which is on average 30 times higher than that of people living in the capital (0.05 (0.009–0.17) μmol/mol creatinine). Conclusions: It appears that the substantially high concentrations of the studied contaminants constitute a potential health hazard to the rural population of Burundi. Received: 15 July 1999 / Accepted: 20 November 1999     

Assessment of biological chromium among stainless steel and mild steel welders in relation to welding processes

Air and biological monitoring were used for assessing external and internal chromium exposure among 116 stainless steel welders (SS welders) using manual metal arc (MMA), metal inert gas (MIG) and tungsten inert gas (TIG) welding processes (MMA: n = 57; MIG: n = 37; TIG: n = 22) and 30 mild steel welders (MS welders) using MMA and MIG welding processes (MMA: n = 14; MIG: n = 16). The levels of atmospheric total chromium were evaluated after personal air monitoring. The mean values for the different groups of SS welders were 201 μg/m³ (MMA) and 185 μg/m³ (MIG), 52 μg/m³ (TIG) and for MS welders 8.1 μg/m³ (MMA) and 7.3 μg/m³ (MIG). The curve of cumulative frequency distribution from biological monitoring among SS welders showed chromium geometric mean concentrations in whole blood of 3.6 μg/l (95th percentile = 19.9), in plasma of 3.3 μg/l (95th percentile = 21.0) and in urine samples of 6.2 μg/l (95th percentile = 58.0). Among MS welders, mean values in whole blood and plasma were rather more scattered (1.8 μg/l, 95th percentile = 9.3 and 1.3 μg/l, 95th percentile = 8.4, respectively) and in urine the value was 2.4 μg/l (95th percentile = 13.3). The analysis of variance of chromium concentrations in plasma previously showed a metal effect (F = 29.7, P < 0.001), a process effect (F = 22.2, P < 0.0001) but no metal–process interaction (F = 1.3, P = 0.25). Concerning urinary chromium concentration, the analysis of variance also showed a metal effect (F = 30, P < 0.0001), a process effect (F = 72, P < 0.0001) as well as a metal–process interaction (F = 13.2, P = 0.0004). Throughout the study we noted any significant differences between smokers and non-smokers among welders. Taking in account the relationships between chromium concentrations in whole, plasma or urine and the different welding processes, MMA-SS is definitely different from other processes because the biological values are clearly higher. These higher levels are due to the very significant concentrations of total soluble chromium, mainly hexa- valent chromium, in welding fumes. Received: 9 May 1996 / Accepted: 14 March 1997     

Comparison between blood and urinary toluene as biomarkers of exposure to toluene

Objectives: To compare blood toluene (TOL-B) and urinary toluene (TOL-U) as biomarkers of occupational exposure to toluene, and to set a suitable procedure for collection and handling of specimens. Method: An assay based on headspace solid-phase microextraction (SPME) was used both for the determination of toluene urine/air partition coefficient (λ_urine/air) and for the biological monitoring of exposure to toluene in 31 workers (group A) and in 116 non-occupationally exposed subjects (group B). Environmental toluene (TOL-A) was sampled during the work shift (group A) or during the 24 h before specimen collection (group B). Blood and urine specimens were collected at the end of the shift (group A) or in the morning (group B) and toluene was measured. Results: Toluene λ_urine/air was 3.3 ± 0.9. Based on the specimen/air partition coefficient, it was calculated that the vial in which the sample is collected had to be filled up to 85% of its volume with urine and 50% with blood in order to limit the loss of toluene in the air above the specimen to less than 5%. Environmental and biological monitoring of workers showed that the median personal exposure to toluene (TOL-A) during the work-shift was 80 mg/m³, the corresponding TOL-B was 82 μg/l and TOL-U was 13 μg/l. Personal exposure to toluene in environmentally exposed subjects was 0.05 mg/m³, TOL-B was 0.36 μg/l and TOL-U was 0.20 μg/l. A significant correlation (P < 0.05) was observed between TOL-B or TOL-U and TOL-A (Pearson's r=0.782 and 0.754) in workers, but not in controls. A significant correlation was found between TOL-U and TOL-B both in workers and in controls (r=0.845 and 0.681). Conclusion: The comparative evaluation of TOL-B and TOL-U showed that they can be considered to be equivalent biomarkers as regards their capacity to distinguish workers and controls and to correlate with exposure. However, considering that TOL-U does not require an invasive specimen collection, it appears to be a more convenient tool for the biological monitoring of exposure to toluene. Received: 20 October 1999 / Accepted: 4 March 2000     

Urinary lead as a possible surrogate of blood lead among workers occupationally exposed to lead

Objectives: The aim of the present study is to investigate whether lead (Pb) in urine (Pb-U) can be a valid surrogate of lead in blood (Pb-B), the traditional biomarker of exposure to lead in occupational health. Methods: Blood and spot urine samples were collected from 258 workers of both sexes occupationally exposed to lead. The samples were analyzed for lead by graphite furnace atomic absorption spectrometry, and the correlation between Pb-B and Pb-U was examined by linear regression analysis before and after logarithmic conversion. Results: The correlation coefficient (0.824; P < 0.01) was largest when the relationship between Pb-B and Pb-U was examined with 214 cases of one sex (i.e., men) after Pb-U was corrected for a specific gravity (1.016) of urine (Pb-Usg) and both Pb-B and Pb-Usg were converted to logarithms. The geometric means (GMs) of Pb-B and Pb-Usg for the 214 men were 489 μg/l and 81 μg/l, respectively. When Pb-Usg was assumed to be 100 μg/l in this set of correlations, the 95% confidence range of Pb-B for the group mean was narrow, i.e., 543–575 μg/l (with GM of 559 μg/l), whereas that for individual Pb-B values was as wide as 355–881 μg/l. Conclusions: The correlation of Pb-U with Pb-B among workers occupationally exposed to Pb was close enough to suggest that Pb-U may be a good alternative to Pb-B on a group basis, but not close enough to allow Pb-U to predict Pb-B on an individual basis. Received: 6 April 1999 / Accepted: 17 July 1999     

Urinary N -acetyl-β-glucosaminidase as an indicator of renal dysfunction in electroplating workers

Objectives: To investigate chromium-induced renal dysfunction in electroplating workers. Methods: A cross-sectional study was used to evaluate four biochemical markers of renal function. A total of 178 workers were divided into 3 comparable groups consisting of 34 hard-chrome plating workers, 98 nickel-chrome electroplating workers, and 46 aluminum anode-oxidation workers, who represented the reference group. Ambient and biological monitoring of urinary chromium were performed to measure exposure concentrations. Results: Overall, urinary chromium concentrations were highest among hard-chrome plating workers (geometric mean 2.44 μg/g creatinine), followed by nickel-chrome electroplating workers (0.31 μg/g creatinine) and aluminum workers (0.09 μg/g creatinine). Airborne chromium concentrations were also highest in the hard-chrome plating area (geometric mean 4.20 μg/m³), followed by the nickel-chrome electroplating area (0.58 μg/m³) and the aluminum area (0.43 μg/m³). A positive correlation was found between urinary chromium and airborne concentrations (r = 0.54, P < 0.01). Urinary concentrations of N-acetyl-β-d-glucosaminidase (NAG) were also highest among hard-chrome plating workers (geometric mean 4.9 IU/g creatinine), followed by nickel-chrome workers (3.4 IU/g creatinine) and aluminum workers (2.9 IU/g creatinine). The prevalence of “elevated” NAG (>7 IU/g creatinine) was significantly highest among hard-chrome plating workers (23.5%), then among nickel-chrome workers (7.1%) and aluminum workers (8.7%). Differences in β₂-microglobulin, total protein, and microalbumin were not significant. Conclusion: The author's evidence indicates that NAG is an early indicator of renal dysfunction in hard-chrome plating workers.     

Exposure-response relationships in rhinitis and conjunctivitis caused by methyltetrahydrophthalic anhydride

Objective: To examine exposure-response relationships in the occurrence of symptoms of the eyes and airways in workers exposed to methyltetrahydrophthalic anhydride (MTHPA). Methods: A population of 111 workers from 2 condenser plants (A and B) using epoxy resin with MTHPA underwent a questionnaire survey and serology investigations, and data obtained on 95 subjects in assembly and inspection lines were analyzed for this study. Results: In all, 24 (65%) of 37 workers in plant A and 38 (66%) of 58 workers in plant B had positive MTHPA-specific IgE. The air levels of MTHPA detected in assembly and inspection lines were higher in plant A than in plant B (geometric mean 25.5–63.9  and 4.93–5.49 μg/m³, respectively). IgE-sensitized workers in each plant had significantly (P < 0.05) more complaints regarding the eyes and nose than did unsensitized workers, suggesting that there is an IgE-mediated mechanism in most of these symptoms. The sensitized workers in plant A had higher frequencies for symptoms of the eyes, nose, and pharynx than did those in plant B (P < 0.02). Furthermore, only 15% of persons often displayed work-related symptoms among the 20 symptomatic workers in plant B as compared with 73% of the 26 symptomatic workers in plant A (P < 0.0001). These results can be explained by the difference in the MTHPA levels measured in the lines between the two plants. In plant B the minimal level of MTHPA that was associated with work-related symptoms was 15–22 μg/m³, which was lower than the geometric mean levels detected in assembly and inspection lines in plant A. Conclusions: These results suggest that MTHPA exposure at levels above 15 μg/m³ should be avoided to prevent the development of occupational allergic diseases in most workers. Received: 4 May 1998 / Accepted: 4 August 1998     

Human biomonitoring of antimony

Objectives : The aim of the study was to test the suitability of 24-h urine, blood, and scalp-hair samples as surrogates for the determination of internal exposure to antimony in case of a strongly elevated soil contamination with antimony. Methods : The biomonitoring was performed using graphite-furnace atomic absorption spectrometry. Blood and scalp-hair samples were decomposed by microwave digestion. Results : No elevated content of antimony could be detected in 24-h urine, blood, or scalp-hair samples from the study participants geogenically exposed to antimony. The results did not show a correlation between the antimony contents in the soil of the housing area and those in urine, blood, or hair. Surprisingly, the reference group (n=47) showed a significantly higher median antimony excretion rate than did the exposed group (n=89; 1.23 versus 0.60 μg Sb/24 h). Additionally, the scalp-hair contents of the reference group were also significantly higher than those of the exposed persons (0.045 versus 0.026 mg Sb/kg). Blood contents of the two study groups were 0.57 and 0.48 μg Sb/l, respectively. The detection limit for urine and blood was 0.5 μg Sb/l and that for scalp hair was 0.005 mg Sb/kg. Of all samples of urine, blood, and scalp hair analyzed, 31.2%, 49.3%, and 10.3%, respectively, were below the limit of analytical detection. Conclusions : The antimony contents recorded for both study groups in urine, blood, and scalp hair can be judged as being within the normal range. The rate of transfer of antimony from the soil to humans in the exposure case described seemed to be very low. With respect to analytical practicability and validity, urine was the surrogate which deemed most useful for determination of internal exposure to antimony. Received: 21 July 1997 / Accepted: 5 November 1997     

Carcinogenicity assays of wood dust and wood additives in rats exposed by long-term inhalation

Objective: This study evaluates whether wood dust and/or wood preservatives develop a carcinogenic potential against the tissues of the airways of rats. Methods: The formation of tumors of the respiratory tract after exposure to wood dust was studied in six groups of approximately 60 female Fischer 344 rats exposed by long-term inhalation to mean concentrations of (1) 18 mg/m³ of untreated oak wood dust, (2) wood preservatives containing ca. 1 μg/m³ lindane and 0.2 μg/m³ of pentachlorophenol (PCP) in the exposure air, or lindane and 18 μg/m3 of PCP (group lindane/PCP vapors, and group oak wood treated with lindane/PCP), (3) 21 or 39 μg/m³ of sodium dichromate (calculated as CrO₃, group chromate aerosol and group oak wood with chromate), and 72 μg/m³ of N-nitrosodimethylamine vapors as positive control. The negative control group consisted of 115 animals (sham-exposed). Results: Tumors of the nasal cavity developed in two rats exposed to chromate aerosol or in combination with wood dust (2/102, 2%). Malignant tumors of the lower respiratory tract were induced only in exposed groups of rats (three adenocarcinomas of the lung and four bronchiolar lung carcinomas, 7/254, 2.8%). More respiratory tract tumors were observed in rats exposed to chromate or wood with chromate (5/102, 5%), also in groups exposed to oak wood dust (oak untreated, oak + chromate, oak + lindane/PCP; together 5/155, 3.2%). Analysis of `unpreserved' oak wood dust revealed up to 5 μg/m³ of chromate. When this exposure was taken into account, eight of nine animals with respiratory tract tumors (including nasal cavity) had exposure to chromate, while only one tumor occurred in the group lindane/PCP. Otherwise the incidence of systemic tumors was increased in animals exposed to lindane/PCP, due in particular to a significantly increased incidence of liver tumors (OR=3.7; 1.24–11.3; P=0.019). Fatal (mucoepidermoid) tumors were induced by N-nitrosodimethylamine (NDMA) in the positive control (14/46, 30%). No such tumors of the respiratory tract were observed in the negative control. Conclusions: Tumors in the respiratory tract were found only in exposed animals, predominantly in the groups which inhaled oak wood dust and chromate stain. Chromate may play a decisive role for the etiology of tumors of the nasal cavity in wood workers. This assumption should be supported by further dose-response studies. Received: 23 May 2000 / Accepted: 13 September 2000     

Human toxicokinetics of inhaled monochlorobenzene: latest experimental findings regarding re-evaluation of the biological tolerance value

Objective: The aim of this study was to obtain toxicokinetic data on the absorption and elimination of monochlorobenzene (MCB) in blood and its main metabolite 4-chlorocatechol (4-ClCat) as well as on the isomeric chlorophenols (o-ClPh, m-ClPh, and especially p-ClPh as the main ClPh metabolite) in urine for re-evaluation of the biological tolerance (BAT) value of MCB. Methods: Eight subjects performed 8-h inhalation tests daily over five successive days in an exposure chamber, at a maximum allowable concentration at the workplace (MAK) value of 10 ppm MCB. Five and two probands carried out the test series during physical activity levels of 75 and 50 W, respectively, for 10 min/h on a bicycle ergometer, and one subject was exposed continuously while at rest. MCB and its metabolites were analyzed by gas chromatography in combination with mass spectrometry. Results: The mean MCB blood concentration of the five subjects exposed during physical activity of 75 W was 217 ± 42 μg/l. The relationship of the mean blood concentration measured under the conditions of rest or 50 and 75 W activity levels was in a ratio of about 1:1.7:2.8. The half-life values in the first hour after ending the exposures were 53 min and 150 min for the ensuing period, with steady-state being reached after 45 min. The mean 4-ClCat concentration in urine at the end of the five days was 150 ± 13 mg/g creatinine in the case of the subjects exposed at 75 W, which decreased to 25 mg/g creatinine at the beginning of the next exposure. The analogous p-ClPh concentrations were 25 ± 2 and 9 ± 2 mg/g creatinine. The elimination half-life values of the ClPh isomers ranged from 12.4 to 16.5 h, and the half-life of 4-ClCat was 6.4 h. There was no apparent tendency for MCB and its metabolites to accumulate in blood or urine. Conclusions: The results are in accordance with relevant field and laboratory studies. Taken into consideration with the 95th percentile, the evaluated BAT values should be set at levels of 300 μg MCB/l blood, 175 mg 4-ClCat/g creatinine or alternatively at 30 mg p-ClPh/g creatinine in urine after the end of a shift. At the beginning of the next shift, the BAT values of the metabolites should be 35 and 15 mg/g creatinine, respectively. Received: 20 December 1999 / Accepted: 25 April 2000     

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     

A comparison of different lead biomarkers in their associations with lead-related symptoms

Objectives: To evaluate whether dimercaptosuccinic acid (DMSA) -chelatable lead, an estimate of current bioavailable lead stores, is a better predictor of lead-related symptoms than are other commonly used lead biomarkers. Methods: A total of 95 male lead workers from three lead industries (one secondary lead smelting facility, one polyvinyl chloride-stabilizer manufacturing plant, and one lead-acid storage battery factory), and 13 workers without occupational lead exposure recruited from an occupational health institute, were studied. Blood lead, blood zinc protoporphyrin (ZPP), 4 h DMSA-chelatable lead (after oral administration of 10 mg/kg DMSA), urine lead, and urinary δ-aminolevulinic acid levels were evaluated as predictors of 15 lead-related symptoms, assessed by self-administered questionnaire, with linear and logistic regression controlling for covariates. Total symptoms and symptoms in three categories (gastrointestinal, neuromuscular, and general) were evaluated. Results: The mean (SD) 4 h DMSA-chelatable lead level was 288.7 (167.7) μg, with a range from 32.4 to 789 μg in the 95 lead workers. The mean (SD) in the non-exposed subjects was 23.7 (11.5) μg with a range from 10.5 to 43.5 μg. Blood lead, blood ZPP, and spot urine lead levels ranged from 21.4 to 78.4 μg/dl, 40 to 331 μg/l, and 7.5 to 153.0 μg/l, respectively, in the lead workers, and from 4.0 to 7.2 μg/dl, 27 to 52 μg/l, and 2.9 to 15.5 μg/l in the non-exposed controls, respectively. The overall mean symptom score (SD), derived as the sum of 0 or 1 point for absence or presence of 15 symptoms, of the lead workers was 3.7 (2.0), compared to 1.2 (1.5) for the non-exposed workers. DMSA-chelatable lead was the best predictor of symptom scores in both crude and adjusted analyses, compared with the other biomarkers. Lead workers with DMSA-chelatable lead values greater than the median (260.5 μg) were 6.2 times more likely to have frequent tingling or numbness of the arms or legs and 3.3 times more likely to have muscle pain than subjects with lower chelatable lead values. Three symptoms (tingling or numbness of arm or leg, muscle pain, and feeling irritation at the slightest disturbance) evidenced a dose-dependent relationship with DMSA-chelatable lead levels. Conclusions: DMSA-chelatable lead was found to be the best predictor of lead-related symptoms, particularly of both total symptom scores and neuromuscular symptoms, than were the other other lead biomarkers. Received: 27 January 1999 / Accepted: 29 January 2000     

Urinary beryllium – a suitable tool for assessing occupational and environmental beryllium exposure?

Objectives: The reasons for the slow progress and lack of new knowledge in the biological monitoring of beryllium (Be) are to be found in the presumed small number of working activities involving exposure to the metal, and the lack of adequate analytical methods. The reference values for urinary Be reported earlier in the literature appear to be too high, due to the poor specificity and sensitivity of the adopted methods. The aim of this study was to correlate Be air concentrations and Be urinary levels to ascertain whether the biological indicator was suitable for assessing occupational exposure to the metal. Methods: To investigate the relationship between the Be concentrations in air and those excreted in urine, we examined 65 metallurgical workers exposed to very low levels of the metal, and 30 control subjects. The exposed workers were employed in two electric steel plants and two copper alloy foundries. The alloys were produced in electric furnaces, starting with scrap containing Be as an impurity. The Be concentrations in the air were monitored by area samplers and the levels of Be in the urine of the workers were determined in samples taken at the end of the shift. Both determinations were carried out by ICP-MS. Results: The median airborne Be concentrations in the copper alloy plants were 0.27 μg/m³ in the furnace area and 0.31 μg/m³ in the casting area. Median values of 0.03 to 0.12 μg/m³ were determined in the steel plants, the relatively wide range probably due to differing amounts of Be in the scrap. Regression analysis was performed on the median values from four work areas and the corresponding urinary samples. A significant correlation was found for the relationship between external and internal exposure. The urinary Be levels were in the range between 0.12 and 0.15 μg/l with observation of the recommended TLV-TWA for inhalable dust of 0.2 μg/m³ (0.2 μg/l at the upper 95th percentile). Conclusions: Sufficient data are not currently available to be able to propose a BEI for urinary Be. Our results show that new investigations are necessary to improve the evaluation of dose indicators and the relationship between external and internal exposure to Be. Received: 15 May 2000 / Accepted: 8 September 2000     

Urinary cotinine concentration in flight attendants, in relation to exposure to environmental tobacco smoke during intercontinental flights

Objectives: To measure and compare the urinary cotinine concentration (U-cotinine) in non-smoking cabin attendants (C/A) working with the Scandinavian Airlines System, before and after work on intercontinental flights with exposure to environmental tobacco smoke (ETS). Methods: The study material consisted of 24 cabin attendants and one pilot, all volunteers and all without exposure to ETS in the home, working on 15 intercontinental flights. Information on age, gender and occupation was gathered, as well as possible sources of ETS exposure in other places, outside work and during previous flights, during a 3-day period prior to the investigation. Urine samples were taken before departure and after landing, on board, and were kept frozen (−20 °C) until analysis. Cotinine was analyzed by a previously developed gas chromatographic method, using mass spectrometry (MS) with selected-ion monitoring (SIM). The difference in U-cotinine before and after the flight was compared. Moreover, the change in U-cotinine during the flight was related to occupation (work in the forward or aft galley) and observed degree of smoking during each flight. Results: The median U-cotinine was 3.71 μg/g crea; 2.4 μg/l (unadjusted) (interquartile range 2.08–8.67 μg/g crea) before departure, and 6.37 μg/g crea; 7.1 μg/l (interquartile range 3.98–19 μg/g crea) after landing, a significant difference (P < 0.003). C/A in the aft galley had a significantly higher concentration of U-cotinine after landing than subjects working in the front of the aircraft (P=0.01). In C/A working in the aft galley, the median increase of U-cotinine was 3.67 μg/g crea; 3.2 μg/l (interquartile range 0.04–13.8 μg/g crea) during flight. In contrast, those seven subjects working in the forward part of the aircraft had no increase in U-cotinine during the flight (median increase 0.97 μg/g crea; 0.5 μg/l interquartile range 0.27–2.65 μg/g crea). Conclusion: Tobacco smoking in commercial aircraft may cause significant exposure to environmental tobacco smoke among C/A working in the aft galley, despite high air exchange rates and spatial separation between smokers and non-smokers. This agrees with earlier studies, as well as measurements on the aircraft, showing a higher degree of ETS-related air pollution in the aft galley than in the forward galley. The average cotinine concentration in urine was similar to that in other groups with occupational exposure to ETS, e.g., restaurant staff, police interrogators and office workers. Since smoking in commercial aircraft may result in an involuntary exposure to ETS among non-smokers, it should be avoided. Received: 1 February 1999 / Accepted: 29 May 1999     

Cadmium exposure of women in general populations in Japan during 1991–1997 compared with 1977–1981

Objectives: The Japanese people are known to have high environmental exposure to cadmium (Cd). The present survey was initiated to elucidate possible changes in the intensity of Cd exposure to the population by comparison of the present exposure level with the situation some 15 years ago. Methods: During 1991–1997, 24-h food-duplicate samples, peripheral blood specimens and morning spot urine samples were collected from 588 non smoking women from 27 survey sites in six regions, where food-duplicate and blood samples had also been obtained during 1977–1981 from 399 women. The samples were wet-ashed (after homogenization in the case of food-duplicates), and Cd in the wet-ashed samples was analyzed by inductively-coupled plasma mass spectrometry for Cd intake via foods (Cd-F), Cd concentration in blood (Cd-B) and Cd concentration in urine (Cd-U). The Cd-F and Cd-B were compared with the Cd-F and Cd-B obtained at the same sites in the 1977–1981 survey. Results: The exposure levels during 1991–1997 were such that Cd-F, Cd-B and Cd-Ucr (Cd–U after correction for creatinine concentration) were 25.5 μg/day, 1.90 μg/l and 4.39 μg/g creatinine. Comparison with the 1977–1981 survey results (i.e., 37.5 μg/day for Cd-F and 3.47 μg/l for Cd-B) showed that there were significant reductions (by 32 and 45%) in both parameters respectively during the last 15 years. The dietary route was an almost exclusive (i.e., 99% of the sum of dietary and respiratory uptake) route of Cd uptake, of which Cd in rice (11.7 μg/day) contributed about 40% of the total dietary intake. When compared among survey sites, inter-site variation in dietary Cd intake was primarily due to differences in the intake through boiled rice. Despite the recent reduction in Cd exposure, the current exposure level for Japanese people is still higher than the levels among other rice-dependent populations in Asia as well as in other parts of the world. Comparison was made between the present findings in general populations and observations among known Cd-pollution cases in Japan. Conclusions: Dietary uptake is an almost exclusive route of Cd exposure in the general Japanese population. Boiled rice is a strong determinant of variation in dietary Cd intake. Whereas there was a substantial reduction in Cd exposure among Japanese populations in the last 15 years, the current level is still high when compared internationally. Received: 1 March 1999 / Accepted: 17 July 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     

Biological monitoring of workers exposed to 4,4′-methylene-bis-(2-orthochloroaniline) (MOCA)

Objective: The objective of the study was to validate a new and simple method to determine MOCA in the urine of exposed workers. Methods: The separation, identification and quantification of urinary MOCA were performed in spiked urines by a sensitive and practical high-performance liquid chromatography (HPLC) method and applied to urine samples of 11 workers occupationally exposed to MOCA; the postshift urinary levels of MOCA in their urine samples with and without hydrolysis, “total” and “free” MOCA respectively, were determined. In addition, we investigated the use of citric or sulfamic acid as preservatives of urine samples. Results: The “total” and “free” MOCA were extracted with isooctane from hydrolysed and nonhydrolysed 20-ml urine samples respectively. After evaporation, the residue was dissolved in 4 ml of 2 · 10⁻² M aqueous hydrochloric acid and analysed by an isocratic HPLC system using both ultraviolet (UV) detection at 244 nm and electrochemical detection working in oxidation mode (0.9 V) with an Ag/AgCl reference electrode. Mobile phase (50% acetonitrile in water containing 0.4% acetate buffer solution pH = 4.6) was used to complete the 20-min analysis. “Free” and “total” MOCA were chromatographed on a reversed-phase C8 column (5 μm; 250 mm × 4 mm). The standard curve of MOCA was linear over the range 5–500 μg/l in human urine. The detection limit was 1 μg/l for a 20-μl injection volume; the repeatability ranged from 5.6 to 1.3% (n = 6) for spiked urines at 5 and 500 μg/l, with a percentage recovery of 94 ± 3%. The reproducibility of the method was 7.3% (n = 4) for spiked urine at 10 μg/l. The use of sulfamic acid as a preservative of urine samples is important to improve the precision and accuracy of the analysis. Conclusion: The results indicate that these analytical procedures using conventional apparatus may be used routinely and reliably with large numbers of urine samples for biological monitoring of the exposure to MOCA. The occupational exposure to MOCA in some factories in France is studied in the second part of this work. Received: 10 November 1998 / Accepted: 25 March 1999     

Further reduction in lead exposure in women in general populations in Japan in the 1990s, and comparison with levels in east and south-east Asia

Objective: The objective of the study was to elucidate the current level of environmental lead (Pb) exposure of women in general population in Japan, where the use of organic Pb in automobile gasoline was phased out from 1973 to reach a zero level early in the 1980s. Methods: A survey was conducted in 27 sites throughout Japan from 1991 to 1997. Five hundred and eighty-eight non-smoking women from the sites offered 24-h food duplicate, peripheral blood, and spot urine samples. Pb in food duplicates (Pb-F), blood (Pb-B), and urine (Pb-U) were analyzed by inductively-coupled plasma mass spectrometry. The results of Pb-F and Pb-B were compared with observations from a study conducted from 1977 to 1981 on 339 women at the same sites. Log-normal distribution was assumed for the evaluation of the results. Results: Geometric means (GMs) of Pb-F, Pb-B, and Pb-U in the 1991–1997 study were 9.0 μg/day, 20.2 μg/l, and 2.18 μg/g creatinine, respectively. The values for Pb-F and Pb-B were substantially lower than the values (32.8 μg/day for Pb-F and 31.7 μg/l for Pb-B) obtained in the 1977–1981 study, which were already low when compared internationally. Cd-U values in the period from 1991 to 1997 also appeared to be among the lowest in the world. Analysis for time-dependent changes in Pb-U was, however, not possible at the time of this study because no values were available for the period from 1977 to 1981. Conclusions: Substantial reductions from 1977–1981 levels in environmental Pb exposure were observed among the study populations in Japan. Current exposure levels appear to be lower than those in other parts of Asia, the USA, and Europe. Received: 16 March 1999 / Accepted: 27 August 1999     

Occupational chronic exposure to organic solvents XVII. Ambient and biological monitoring of workers exposed to xylenes

Ambient-air and biological monitoring of occupational xylene exposure were carried out on 2 groups of workers (13 and 10 men, respectively) exposed to a mixture of xylenes during the production of paints or during spraying. Methods: Personal ambient-air monitoring was performed for one complete work shift. Blood and urine samples were collected directly at the end of the shift. Biological monitoring was based on the determination of the concentration of xylenes in blood and on the quantification of the sum of the three methylhippuric acids in urine. Results: Average xylene ambient-air concentrations were 29 ppm (production) and 8 ppm (spraying), ranging from 5 to 58 ppm and from 3 to 21 ppm, respectively. The concentrations of xylenes in blood ranged from 63 to 715 μg/l and from 49 to 308 μg/l, with average values being 380 and 130 μg/l, respectively. Accordingly, the workers engaged in paint production also excreted more methylhippuric acids in their urine (average 1221 mg/l, range 194–2333 mg/l) than did the sprayers (average 485 mg/l, range 65–1633 mg/l). Discussion: Our results as well as a literature review indicate that occupational xylene exposure on average barely exceeds the threshold limit value of 100 ppm as proposed by both American and German institutions. Biological monitoring based on the determination of xylenes in blood and of methylhippuric acids in urine provides sufficient sensitivity and specificity for occupational health surveillance. The results also confirm the current limit values (BAT values) proposed by the Deutsche Forschungsgemeinschaft for xylenes in blood (1500 μg/l) and methylhippuric acids in urine (2000 mg/l). Received: 27 May 1998 / Accepted: 3 September 1998     

Exposure to cobalt and nickel in the hard-metal production industry

Objective The shortage of cobalt (Co) on the metal market forced the industry to add nickel (Ni) to Co as a binding agent for the sintering of hard metal. This change enabled us to study (1) the exposure to Ni powder and (2) the effect of Ni on Co uptake (and vice versa). Methods Equal amounts of Co and Ni were used in the mixture in a plant employing 50 workers. Both personal ambient-air samples and single-void urine samples were taken twice in the same week, i.e., on Monday and Thursday. Atomic absorption spectroscopy (AAS) was used for analyses. Results The airborne availability of Ni (mean value 41.65 ± 6.29 μg/m³) was 2-fold that of Co (mean value 21.85 ± 24.25 μg/m³), although the two series of data (n = 20) were significantly correlated. Even if the Co and Ni urinary concentration values (n = 45) recorded on Monday morning and Thursday evening were significantly correlated, at the end of the week there was a 3-fold increase, specifically, from 7.3 to 22.28 μg/l, in Co elimination (a significant difference) and a 30% increase in Ni elimination from 11.98 to 15.83 μg/l. Moreover, on Monday morning, 90% of Ni urinary concentration values were higher than those of Co as opposed to only 33% on Thursday evening. In the six cases in which both airborne and urine determinations were performed on the 2 days, no significant relationship was found between external exposure and biological monitoring data. Conclusions Although Ni uptake was variable, it was generally low, whereas Co uptake was substantial, as had previously been observed in the same plant when Co was the only binder under use. It was therefore possible to rule out any influence of Ni exposure on Co uptake and to suggest the contrary, as has been demonstrated in bacterial species and in rats using everted intestinal sacs. Received: 18 March 1997 / Accepted: 2 October 1997