Occupational exposure to polycyclic aromatic hydrocarbons and DNA damage by industry: a nationwide study in Germany.

Exposure to polycyclic aromatic hydrocarbons (PAH) and DNA damage were analyzed in coke oven (n = 37), refractory (n = 96), graphite electrode (n = 26), and converter workers (n = 12), whereas construction workers (n = 48) served as referents. PAH exposure was assessed by personal air sampling during shift and biological monitoring in urine post shift (1-hydroxypyrene, 1-OHP and 1-, 2 + 9-, 3-, 4-hydroxyphenanthrenes, SigmaOHPHE). DNA damage was measured by 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) and DNA strand breaks in blood post shift. Median 1-OHP and SigmaOHPHE were highest in converter workers (13.5 and 37.2 microg/g crea). The industrial setting contributed to the metabolite concentrations rather than the air-borne concentration alone. Other routes of uptake, probably dermal, influenced associations between air-borne concentrations and levels of PAH metabolites in urine making biomonitoring results preferred parameters to assess exposure to PAH. DNA damage in terms of 8-oxo-dGuo and DNA strand breaks was higher in exposed workers compared to referents ranking highest for graphite-electrode production. The type of industry contributed to genotoxic DNA damage and DNA damage was not unequivocally associated to PAH on the individual level most likely due to potential contributions of co-exposures.

Biological monitoring as a useful tool for the detection of a coal-tar contamination in bitumen-exposed workers.

In our research project entitled "Chemical irritative and/or genotoxic effect of fumes of bitumen under high processing temperatures on the airways," 73 mastic asphalt workers exposed to fumes of bitumen and 49 construction nonexposed workers were analyzed and compared with respect to polycyclic aromatic hydrocarbons (PAHs) exposure and exposure-related health effects. In order to assess the internal exposure the monohydroxylated metabolites of pyrene, 1- hydroxypyrene (1-OHP), and phenanthrene, 1-, 2- and 9-, and 3- and 4-hydroxyphenanthrene (OHPH) were determined in pre- and post-shift urinary samples. Significantly higher concentrations 1-OHP and OHPH were detected in the post-shift urine samples of 7 mastic asphalt workers working on the same construction site compared to the reference workers and all other 66 mastic asphalt workers. The adjusted mean OHPH in the reference, 66 mastic worker, and 7 worker subgroups was 1022, 1544, and 12919 ng/g creatinine (crn) respectively, indicating a marked rise in the 7 worker subgroup. In addition, there was a more than 12-fold increase of PAH metabolites from pre- to post-shift in these 7 workers, whereas in the other mastic asphalt workers there was only a twofold rise in PAH-metabolite concentration between pre- and post-shift values. The analysis of a drilling core from the construction site of the seven workers led to the detection of the source for this marked PAH exposure during the working shift as being coal tar plates, which were, without knowledge of the workers and coordinators, the underground material of the mastic asphalt layer. The evaluation of the stationary workplace concentration showed enhanced levels of phenanthrene, pyrene, fluorene, anthracene, and acenaphthene during working shifts at the construction site of these seven workers. Our study shows that biological monitoring is also a useful tool for the detection of unrecognized sources with high PAH concentrations.

Dose-response modeling of occupational exposure to polycyclic aromatic hydrocarbons with biomarkers of exposure and effect.

In regulatory toxicology, the dose-response relationship between occupational exposure and biomarkers is of importance in setting threshold values. We analyzed the relationships between occupational exposure to polycyclic aromatic hydrocarbons (PAH) and various biomarkers of internal exposure and DNA damage with data from 284 highly exposed male workers. Personal exposure to phenanthrene and other PAHs was measured during shift and correlated with the sum of 1-, 2+9-, 3-, and 4-hydroxyphenanthrenes in post-shift urine. PAHs and hydroxyphenanthrenes were associated with DNA damage assessed in WBC as 8-oxo-7,8-dihydro-2'-deoxyguanosine/10(6) dGuo and strand breaks by Comet assay as Olive tail moment. Hydroxyphenanthrenes correlated with phenanthrene (Spearman r(s) = 0.70; P < 0.0001). No correlations could be found between strand breaks and exposure (r(s) = 0.01, P < 0.0001 for PAHs; r(s) = -0.03, P = 0.68 for hydroxyphenanthrenes). Correlations with 8-oxo-7,8-dihydro-2'-deoxyguanosine/10(6) dGuo were weakly negative (r(s) = -0.22, P = 0.004 for PAHs) or flat (r(s) = -0.08, P = 0.31 for hydroxyphenanthrenes). Linear splines were applied to assess the relationships between the log-transformed variables. All regression models were adjusted for smoking and type of industry. For hydroxyphenanthrenes, 51.7% of the variance could be explained by phenanthrene and other predictors. Up to 0.77 microg/m(3) phenanthrene, no association could be found with hydroxyphenanthrenes. Above that point, hydroxyphenanthrenes increased by a factor of 1.47 under a doubling of phenanthrene exposure (slope, 0.56; 95% confidence interval, 0.47-0.64). Hydroxyphenanthrenes may be recommended as biomarker of occupational PAH exposure, whereas biomarkers of DNA damage in blood did not show a dose-response relation to PAH exposure.

Biological monitoring of occupational exposure to polycyclic aromatic hydrocarbons (PAH) by determination of monohydroxylated metabolites of phenanthrene and pyrene in urine.

OBJECTIVES: The aim of our study was to assess individual polycyclic aromatic hydrocarbon (PAH) exposure of workers coming from three different industrial branches by several parameters of external and internal exposure. By analysing the relationships between those markers the suitability of individual parameters [e.g. monohydroxylated phenanthrene (Phe) metabolites] for exposure surveillance should be evaluated. METHODS: The total study population consisted of 255 male workers (age: 19-62, mean: 39.61 years), who were employed in coke production (n=40), production of graphite electrodes and special carbon products (92), or production of refractory materials (123), respectively. For each worker external PAH exposure was determined by personal air sampling of 16 PAH, including Phe, pyrene (Pyr) and benzo[a]pyrene (BaP). For determination of internal PAH exposure the excretion of the PAH metabolites 1-, 2 + 9-, 3-, 4-hydroxyphenanthrene and 1-hydroxypyrene was measured in post-shift urine samples of all workers. RESULTS: In the total study population median total PAH exposure and exposure to BaP were 30.62 and 0.27 microg/m(3), respectively. A calculation of PAH profiles resulted in substantial branch-related variations with Phe being a major component. Considering all branches the median excretions of 1-hydroxypyrene and hydroxyphenanthrenes (sum) were 6.68 and 11.22 microg/g creatinine. A correlation analysis yielded a good correlation between total ambient PAH exposure and excretion of hydroxyphenanthrenes in urine (r=0.662; P<0.01), but no significant correlation between Phe metabolites and the carcinogenic BaP. For 1-hydroxypyrene and BaP a weak but significant association was found (r=0.235; P<0.01). CONCLUSIONS: Considering the results of the correlation analysis hydroxyphenanthrenes in urine should reflect an uptake of lowly condensed volatile PAH rather than an incorporation of highly condensed PAH like BaP which should be reflected better by 1-hydroxypyrene. Therefore, the determination of hydroxyphenanthrenes in addition to the well-established marker 1-hydroxypyrene could offer some further information about the exposure situation at a particular work place.

Irritative effects of fumes and aerosols of bitumen on the airways: results of a cross-shift study.

Possible health hazards of fumes and aerosols of bitumen are in discussion, and data on their adverse effects on human airways under current exposure conditions are limited. To assess the irritative effects of exposure to fumes and aerosols of bitumen on the airways, a cross-sectional cross-shift study was conducted including external and internal exposure measurements, spirometry and especially non-invasive methods like nasal lavage collection and induction of sputum in order to identify and evaluate more precisely inflammatory process in the upper and lower airways. The cross-shift study comprised 74 mastic asphalt workers who were exposed to fumes and aerosols of bitumen and 49 construction workers without this exposure as reference group. Questionnaire, spirometry, ambient monitoring and urinary analysis were performed. Humoral and cellular parameters were measured in nasal lavage fluid (NALF) and induced sputum. For data analysis, a mixed linear model was performed on the different outcomes with exposure group, time of measurement (pre-, post-shift), current smoking, German nationality and age as fixed factors and subjects as random factor. Based on personal exposure measurements during shift, mastic asphalt workers were classified into a low (< or =10 mg/m(3); n = 46) and a high (>10 mg/m(3); n = 28) exposure group. High exposure was accompanied by significant higher urinary post-shift concentrations of 1-hydroxypyrene and the sum of hydroxyphenanthrenes. Acute respiratory symptoms were reported more frequently in the high exposure group after shift. Significant cross-shift declines in lung function parameters (forced expiratory volume in 1 s [FEV(1) (% predicted)] and forced vital capacity [FVC (% predicted)]) were measured in mastic asphalt workers. Pre-shift FEV(1) (% predicted) and FVC (% predicted) were higher in the low exposure group. In pre- and post-shift NALF samples, interleukin (IL)-1beta-, IL-8- and total protein concentrations were lower in the low exposure group compared to the reference and the high exposure group. Pre- and post-shift neutrophil percentages in both nasal and sputum samples were also lower in the low exposure group. Significantly higher pre- and post-shift sputum concentrations of IL-8, IL-6, nitrogen oxide (NO) derivatives and total protein were detected especially in highly exposed workers. Irritative effects of exposure to fumes and aerosols of bitumen on the upper and lower airways were apparent, especially in mastic asphalt workers with exposure above 10 mg/m(3).

External and internal exposure to polycyclic aromatic hydrocarbons (PAH) among workers in the production of fire-proof materials - proposal of a biological monitoring guidance value.

In 1999, we introduced the German polycyclic aromatic hydrocarbons (PAH) study. The study was designed as a nation-wide investigation on workers exposed to PAH. One aim of the study was to establish biological monitoring guidance values (BMGVs) for different branches. Here, we report on the production of fire-proof materials. This branch of industry is typically confronted with high exposure to PAH and with PAH-induced occupational (cancer) diseases. One hundred and thirty-five employees participated in the course of seven sampling dates in four different plants in Germany. External exposure was determined by personal air monitoring of the 16 EPA-PAH. Human biological monitoring was accomplished by the determination of 1-hydroxypyrene and monohydroxyphenanthrenes in post-shift spot urine samples. Concentrations of PAH in the air of the workplaces ranged up to 1102.6microg/m(3). Maximum benzo[a]pyrene concentration was 38.2microg/m(3). The internal PAH exposure of workers was much higher compared with that of the general population. Median concentration for 1-hydroxypyrene was 6.4microg/g creatinine (maximum 279.6, 90th percentile 23.9microg/g creatinine) and for the sum of monohydroxyphenanthrene metabolites 13.3microg/g creatinine (maximum 313.4, 90th percentile 70.8microg/g creatinine). The following BMGVs for the non-smokers of this branch of industry are proposed: for 1-hydroxypyrene 18microg/g creatinine and for the sum of hydroxyphenanthrenes 77microg/g creatinine in urine measured at the end of the shift.

Assessment of DNA damage in WBCs of workers occupationally exposed to fumes and aerosols of bitumen.

We conducted a cross-shift study with 66 bitumen-exposed mastic asphalt workers and 49 construction workers without exposure to bitumen. Exposure was assessed using personal monitoring of airborne bitumen exposure, urinary 1-hydroxypyrene (1-OHP), and the sum of 1-, 2 + 9-,3-,4-hydroxyphenanthrene (OHPH). Genotoxic effects in WBC were determined with nonspecific DNA adduct levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) and the formation of DNA strand breaks and alkali-labile sites. Concentration of fumes and aerosols of bitumen correlated significantly with the concentrations of 1-OHP and OHPH after shift (r(s) = 0.27; P = 0.03 and r(s) = 0.55; P < 0.0001, respectively). Bitumen-exposed workers had more DNA strand breaks than the reference group (P < 0.0001) at both time points and a significant correlation with 1-OHP and OHPH in the postshift urines (r(s) = 0.32; P = 0.001 and r(s) = 0.27; P = 0.004, respectively). Paradoxically, we measured higher levels of DNA strand breaks, although not significant, in both study groups before shift. 8-OxodGuo adduct levels did not correlate with DNA strand breaks. Further, 8-oxodGuo levels were associated neither with personal exposure to bitumen nor with urinary metabolite concentrations. Significantly more DNA adducts were observed after shift not only in bitumen-exposed workers but also in the reference group. Only low-exposed workers had significantly elevated 8-oxodGuo adduct levels before as well as after shift (P = 0.0002 and P = 0.02, respectively). Our results show that exposure to fumes and aerosols of bitumen may contribute to an increased DNA damage assessed with strand breaks.

Intravenous exposure to di(2-ethylhexyl)phthalate (DEHP): metabolites of DEHP in urine after a voluntary platelet donation.

In this study we investigated human metabolism and excretion of DEHP after intravenous exposure. For this purpose we determined the five major DEHP metabolites in urine samples of a volunteer before and after a platelet donation (dual-needle technique). Plateletpheresis procedures are known to cause a significant DEHP exposure. We observed a sharp increase in urinary DEHP metabolite concentrations after the procedure. Maximum concentrations of 5OH-MEHP, 5oxo-MEHP, 5cx-MEPP and MEHP observed 4 h after the procedure were 822, 729, 577 and 388 microg/l respectively. 2cx-MMHP was excreted at highest concentrations after 8 h (201 microg/l). Due to longer elimination half-times, 5cx-MEPP and 2cx-MMHP were the major metabolites excreted in urine 24 h after the exposure. The 24-h-cumulative excretion of 363 microg 5cx-MEPP, 353 microg 5OH-MEHP, 309 microg 5oxo-MEHP, 178 microg MEHP and 133 microg 2cx-MMHP indicates an absolute exposure of our volunteer of about 2.6 mg DEHP. Related to the body weight this equals a dose of 31.6 microg/kg body weight/day. This indicates that current risk or preventive limit values for DEHP such as the RfD of the US EPA (20 microg/kg/day) and the TDI of the European Union (20-48 microg/kg/day) can be exceeded on the day of the plateletpheresis. The amount of the dose excreted in urine, distribution of the metabolites in urine and all other elimination characteristics after intravenous DEHP exposure are comparable to oral exposure. There are no indications that toxicokinetic behaviour and the toxicity of DEHP are fundamentally different after the two routes of exposure. Therefore, toxicological endpoints observed for DEHP after oral application should also be considered relevant for medical procedures causing intravenous DEHP exposure, like apheresis procedures. Especially women in their reproductive age need to be protected from DEHP exposures exceeding the above mentioned preventive limit values.

DNA adduct formation of benzo[a]pyrene in white blood cells of workers exposed to polycyclic aromatic hydrocarbons.

The major DNA adducts of anti-benzo[a]pyrene diolepoxide (BPDE) were determined by high performance liquid chromatography with fluorescence detection (HPLC-FLD) in white blood cells (WBC) of workers exposed to benzo[a]pyrene (B[a]P). In addition, ambient concentrations of B[a]P at the workplace were determined by personal air sampling. Workers in a refractory setting were examined before (n=26) and 3 months after (n = 33) changing the production material (binding pitch). Furthermore, 9 coke oven workers were examined. The change in the production process in the refractory setting led to a decrease in the median of ambient B[a]P concentrations (0.14 to <0.07 microg/m3). The median of BPDE-DNA adduct levels in WBC also decreased from 0.9 adducts/10(8) nucleotides before changing the production material to <0.5 adducts/10(8) nucleotides 3 months afterwards. The B[a]P concentrations at the workplace for the coke oven workers were found to be significantly higher than in the refractory setting. However, BPDE-DNA adduct concentrations in coke oven workers and refractory setting workers showed no significant difference, which was probably due to the low number of studied subjects in the coke-oven setting. No significant differences could be observed for BPDE-DNA adduct levels between current smokers (n=21) and non-smokers (n=14; p = 0.93) from both plants. In addition, no correlation between B[a]P concentrations in the air and DNA adduct levels in refractory workers and in coke oven workers could be found (r = -0.03, p = 0.87). Because of the missing correlation between personal air sampling and BPDE-DNA adduct levels in WBC, the results may indicate that their formation is either influenced by other routes of exposure to B[a]P (e.g., skin absorption, dietary habits) or interindividual differences in their formation and repair.

Current external and internal exposure to naphthalene of workers occupationally exposed to polycyclic aromatic hydrocarbons in different industries.

OBJECTIVES: External and internal exposure to naphthalene was examined in the most important industries that are typically concerned with polycyclic aromatic hydrocarbon (PAH)-induced diseases (cancer). Furthermore, a control collective from the general population was investigated. METHODS: External naphthalene was determined by personal air sampling (n = 205). The internal exposure was examined by urinary metabolites 1-naphthol and 2-naphthol (n = 277). RESULTS: Highest median concentrations of naphthalene in air were found in converter infeed (93.2 microg/m3) and coal-tar distillation (35.8 microg/m3). Moderate and low levels were determined in coking plants (14.5 microg/m3) and in the production of refractories (6.1 microg/m3) and graphite electrodes (0.7 microg/m3). Biological monitoring revealed concentrations of the sum of both metabolites [(1+2)-NOL] in smokers to be increased by 1.6-6.4 times compared with that in non-smokers at the same workplaces. Among non-smokers we found high median (1+2)-NOL levels in converter bricklayers (120.1 microg/l), in coal-tar distillation workers (56.0 microg/l) and in coking plant workers (29.5 microg/l). (1+2)-NOL concentrations around 10 microg/l were found in the production of refractories and graphite electrodes. There was a rough coherency between external and internal naphthalene exposure. In the controls, median (1+2)-NOL concentrations were 10.9 microg/l in non-smokers' urine and 40.3 microg/l in smokers' urine samples. CONCLUSIONS: Actual conditions of occupational hygiene at the workplaces investigated in this comprehensive study are better than those that current limit values of 50,000 microg/m3 (TLV, TRK) seem to induce. It has become obvious that tobacco smoking is a crucial confounding factor in biological monitoring of naphthalene-exposed humans, making interpretation of occupationally increased naphthol excretions very difficult at low exposure levels.

Exposure of nursery school children and their parents and teachers to di-n-butylphthalate and butylbenzylphthalate.

OBJECTIVES: Some phthalates, among them di-n-butylphthalate (DnBP) and butylbenzylphthalate (BBzP), are known reproductive and developmental toxicants in animals and suspected endocrine disruptors in humans. Children are probably the most susceptible to these effects. To obtain an estimate of internal exposure to DnBP and BBzP we compared the excretion of their metabolites in the urine of nursery school children with that of their teachers and parents. METHODS: We measured the urinary mono-ester metabolites of DnBP, mono-n-butylphthalate (MnBP), and BBzP, monobenzylphthalate (MBzP), in first-morning voids of 36 children (median age 4.7 years) and 19 adults (37.4 years). RESULTS: In all samples both metabolites were detected. Urinary MnBP concentrations (in microgrammes per litre) of the children and adults were 139 and 91.8 (median), respectively. MBzP concentrations were 22.1 microg/l and 12.7 microg/l (median), respectively. Concentrations in microgrammes per gramme creatinine for MnBP were 161 for the children and 91.8 for the adults (median). The maximum concentration found for children (2249 microg/g) was approximately 15-times higher than that for adults (149 microg/g). This maximum value for children was attributed to medication that contained DnBP. If this child was excluded, the maximum concentration was 517 microg/g. MBzP concentrations for children and adults were 37.0 microg/g and 9.8 microg/g (median), respectively. The maximum concentration found for children (193 microg/g) was approximately seven-times higher than that for adults (26.7 microg/g). Creatinine-adjusted concentrations were significantly higher for children for both MBzP and MnBP (P<0.0001). MnBP and MBzP exposures were found to correlate statistically significantly within the children's cohort (r=0.723, P<0.001). Within the children's cohort we found elevated MnBP exposure to be caused by augmented use of skin-care products (P<0.05). CONCLUSION: We have shown that the internal exposure to MnBP and MBzP in children is approximately two- to four-times higher than in adults. Correlation of internal MnBP with MBzP exposure points to common sources of exposure for both phthalates. DnBP exposure seems, at least in part, to be connected with the use of body/skin care products and certain medications.

New metabolites of di(2-ethylhexyl)phthalate (DEHP) in human urine and serum after single oral doses of deuterium-labelled DEHP.

The metabolism of di(2-ethylhexyl)phthalate (DEHP) in humans was studied after three doses of 0.35 mg (4.7 microg/kg), 2.15 mg (28.7 microg/kg) and 48.5 mg (650 microg/kg) of D4-ring-labelled DEHP were administered orally to a male volunteer. Two new metabolites, mono(2-ethyl-5-carboxypentyl)phthalate (5cx-MEPP) and mono[2-(carboxymethyl)hexyl]phthalate (2cx-MMHP) were monitored for 44 h in urine and for 8 h in serum for the high-dose case, in addition to the three metabolites previously analysed: mono(2-ethyl-5-hydroxyhexyl)phthalate (5OH-MEHP), mono(2-ethyl-5-oxohexyl)phthalate (5oxo-MEHP) and mono(2-ethylhexyl)phthalate (MEHP). For the medium- and low-dose cases, 24 h urine samples were analysed. Up to 12 h after the dose, 5OH-MEHP was the major urinary metabolite, after 12 h it was 5cx-MEPP, and after 24 h it was 2cx-MMHP. The elimination half-lives of 5cx-MEHP and 2cx-MMHP were between 15 and 24 h. After 24 h 67.0% (range: 65.8-70.5%) of the DEHP dose was excreted in urine, comprising 5OH-MEHP (23.3%), 5cx-MEPP (18.5%), 5oxo-MEHP (15.0%), MEHP (5.9%) and 2cx-MMHP (4.2%). An additional 3.8% of the DEHP dose was excreted on the second day, comprising 2cx-MMHP (1.6%), 5cx-MEPP (1.2%), 5OH-MEHP (0.6%) and 5oxo-MEHP (0.4%). In total about 75% of the administered DEHP dose was excreted in urine after two days. Therefore, in contrast to previous studies, most of the orally administered DEHP is systemically absorbed and excreted in urine. No dose dependency in metabolism and excretion was observed. The secondary metabolites of DEHP are superior biomonitoring markers compared to any other parameters, such as MEHP in urine or blood. 5OH-MEHP and 5oxo-MEHP in urine reflect short-term and 5cx-MEHP and 2cx-MMHP long-term exposure. All secondary metabolites are unsusceptible to contamination. Furthermore, there are strong hints that the secondary oxidised DEHP metabolites-not DEHP or MEHP-are the ultimate developmental toxicants.

Biological monitoring of the five major metabolites of di-(2-ethylhexyl)phthalate (DEHP) in human urine using column-switching liquid chromatography-tandem mass spectrometry.

We present a fast and reliable on-line clean-up HPLC-method for the simultaneous determination of the five major urinary metabolites of di-(2-ethylhexyl)phthalate (DEHP) namely mono-(2-ethyl-5-carboxypentyl)phthalate (5carboxy-MEPP), mono-[2-(carboxymethyl)hexyl]phthalate (2carboxy-MMHP), mono-(2-ethyl-5-hydroxyhexyl)phthalate (5OH-MEHP), mono-(2-ethyl-5-oxohexyl)phthalate (5oxo-MEHP) and mono-(2-ethylhexyl)phthalate (MEHP). These metabolites represent about 70% of an oral DEHP dose. We for the first time succeeded to reliably quantify 5carboxy-MEPP and to identify 2carboxy-MMHP as major metabolites in native urines of the general population. The analytical procedure consists of an enzymatic hydrolysis, on-line extraction of the analytes from urinary matrix by a restricted access material column (RAM), back-flush transfer onto the analytical column (betasil phenylhexyl), detection by ESI-tandem mass spectrometry and quantification by isotope dilution (limit of detection (LOD) 0.25 microg/l). Median concentrations of a small collective taken from the general population (n=19) were 85.5 microg/l (5carboxy-MEPP), 47.5 microg/l (5OH-MEHP), 39.7 microg/l (5oxo-MEHP), 9.8 microg/l (MEHP) and about 37 microg/l (2carboxy-MMHP). The presented method can provide insights into the actual internal burden of the general population and certain risk groups. It will help to further explore the human metabolism of DEHP-an occupational and environmental toxicant of great concern.

Pilot study on the naphthalene exposure of German adults and children by means of urinary 1- and 2-naphthol levels.

Concentrations of 1- and 2-naphthol were measured in urine of 72 adults and 35 young children from Germany to assess the internal exposure to naphthalene of the general population. Naphthols could be detected in more than 90% of the urine samples. Levels of naphthols (sum of 1- and 2-naphthol) were 4-fold higher in smokers (median: 37.6 microg/g creatinine) compared to non-smoking adults (8.2 microg/g creatinine). On a creatinine basis young children had slightly lower naphthol levels in urine compared with adults (7.5 microg/g creatinine). Preliminary reference values for the sum of 1- and 2- naphthol in urine as means of the 95th percentile are proposed: 41.2 microg/g creatinine (non-smoking adults) and 23.5 microg/g creatinine (young children). It is concluded that 1- and 2-naphthol levels in urine are suitable for human biomonitoring of the naphthalene exposure in environmental medicine.

Simultaneous determination of 1- and 2-naphthol in human urine using on-line clean-up column-switching liquid chromatography-fluorescence detection.

We developed a new 3-D HPLC method for on-line clean-up and simultaneous quantification of two important naphthalene metabolites, 1-naphthol and 2-naphthol, in human urine. Except an enzymatic hydrolysis no further sample pre-treatment is necessary. The metabolites are stripped from urinary matrix by on-line extraction on a restricted access material pre-column (RAM RP-8), transferred in backflush mode onto a silica-based CN-(cyano)phase column for further purification from interfering substances. By another successive column switching step both analytes are transferred with a minimum of overlapping interferences onto a C12 bonded reversed phase column with trimethylsilyl endcapping where the final separation is carried out. The entire arrangement is software controlled. Eluting analytes are quantified by fluorescence detection (227/430 nm) after an external calibration. Within a total run time of 40 min we can selectively quantify both naphthols with detection limits in the lower ppb range (1.5 and 0.5 microg/l for 1- and 2-naphthol, respectively) with excellent reliability (ensured by precision, accuracy, matrix-independency and FIOH quality assurance program participation). First results on a collective of 53 occupationally non exposed subjects showed mean levels of 11.0 microg/l (1-naphthol) and 12.9 microg/l (2-naphthol). Among smokers (n=21) a significantly elevated mean level of urinary naphthols was determined (1-naphthol: 19.2 microg/l and 2-naphthol: 23.7 microg/l) in comparison to non smokers (n=32; 1-naphthol: 5.6 microg/l, 2-naphthol: 5.6 microg/l).

Naphthalene--an environmental and occupational toxicant.

For many years naphthalene had been considered as a non-carcinogenic polycyclic aromatic hydrocarbon (PAH). Airborne naphthalene concentrations have always been observed to be below the limit values of various national committees, such as the threshold limit value (TLV) of the American Conference of Governmental Industrial Hygienists (ACGIH) and the MAK of the Deutsche Forschungsgemeinschaft (DFG) (10 ppm). Since 2000, when the US National Toxicology Program revealed clear evidence of the carcinogenic activity of naphthalene in rats, international agencies [the International Agency for Research on Cancer (IARC), the US Environmental Protection Agency (US EPA), DFG] have reclassified naphthalene as a potential human carcinogen, and the European Union (EU) is currently preparing a new risk assessment report. It is presently unknown how to protect humans from health risks resulting from occupational and environmental naphthalene exposure. Knowledge about the external and internal exposure of humans serves as the key determinant in a comprehensive risk assessment. We review here ambient monitoring studies concerning the external naphthalene exposure that results from ubiquitous environmental sources (indoor and outdoor air, water, soil, food) and from a variety of critical workplaces (coking plants, creosote impregnation, distillation of coal tar and naphthalene, manufacture of refractories, graphite electrodes, aluminium and mothballs). Based on results of ambient monitoring studies published so far, a new hygiene-based exposure limit of 1.5 mg naphthalene per cubic metre of air (0.3 ppm) is proposed. Furthermore, results from biological monitoring studies are summarised in this article. The internal burden was almost exclusively determined by means of the urinary metabolites 1-naphthol and 2-naphthol, but it is currently not possible for one to evaluate a biological tolerance level (BAT) or a biological exposure index (BEI). Based on the toxicokinetics and metabolism of naphthalene, the central question on its carcinogenicity is briefly sketched. Naphthoquinones play an important role in this context. Their adducts with macromolecules may be the parameters of choice for the estimation of effects to human health.