G. Lehnert

Frequent k- ras -2 mutations and p16(INK4A)methylation in hepatocellular carcinomas in workers exposed to vinyl chloride.

Vinyl chloride (VC) is a know animal and human carcinogen associated with liver angiosarcomas (LAS) and hepatocellular carcinomas (HCC). In VC-associated LAS mutations of the K-ras-2 gene have been reported; however, no data about the prevalence of such mutations in VC associated HCCs are available. Recent data indicate K-ras-2 mutations induce P16 methylation accompanied by inactivation of the p16 gene. The presence of K-ras-2 mutations was analysed in tissue from 18 patients with VC associated HCCs. As a control group, 20 patients with hepatocellular carcinoma due to hepatitis B (n=7), hepatitis C (n=5) and alcoholic liver cirrhosis (n=8) was used. The specific mutations were determined by direct sequencing of codon 12 and 13 of the K-ras-2 gene in carcinomatous and adjacent non-neoplastic liver tissue after microdissection. The status of p16 was evaluated by methylation-specific PCR (MSP), microsatellite analysis, DNA sequencing and immunohistochemical staining. All patients had a documented chronic quantitated exposure to VC (average 8883 ppmy, average duration: 245 months). K-ras-2 mutations were found in 6 of 18 (33%) examined VC-associated HCCs and in 3 cases of adjacent non-neoplastic liver tissue. There were 3 G → A point mutations in the tumour tissue. All 3 mutations found in non-neoplastic liver from VC-exposed patients were also G → A point mutations (codon 12- and codon 13-aspartate mutations). Hypermethylation of the 5′ CpG island of the p16 gene was found in 13 of 18 examined carcinomas (72%). Of 6 cancers with K-ras-2 mutations, 5 specimens also showed methylated p16. Within the control group, K-ras-2 mutation were found in 3 of 20 (15%) examined HCC. p16 methylation occurred in 11 out of 20 (55%) patients. K-ras-2 mutations and p16 methylation are frequent events in VC associated HCCs. We observed a K-ras-2 mutation pattern characteristic of chloroethylene oxide, a carcinogenic metabolite of VC. Our results strongly suggest that K-ras-2 mutations play an important role in the pathogenesis of VC-associated HCC.

Internal exposure to organic substances in a municipal waste incinerator

SummaryFifty-three persons occupied in a municipal waste incinerator were examined with respect to their internal exposure to organic substances which may be produced during pyrolysis of organic matter. For this purpose the levels of benzene in blood, polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) in plasma, and mono- (MCPs), di- (DCPs), tri- (TCPs), tetra-(TECPs) and pentachlorophenol (PCP) and hydroxypyrene in urine were determined. For control purposes, 431 men and women were examined. Significantly higher values for the workers were found for the excretion of hydroxypyrene [median (m): 0.24vs 0.11 μg/l; non-smokers], 2,4/2,5-DCP (m: 10.5 vs 3.9 μg/l) and 2,4,5-TCP (m: 1.2 vs 0.8 μg/l) and for the HCB level in plasma (m: 4.4 vs 2.8 μg/l). For the concentrations of 4-MCP and 2,3,4,6/2,3,5,6-TECP, the controls had significantly higher concentrations in urine than did the workers in the incineration plant (m: 4-MCP 1.7 vs 1.2; 2,3,4,6/2,3,5,6-TECP: 1.2 vs 0.3 μg/l). No significant differences between workers and controls were detected with respect to benzene in blood (m: 0.20 vs 0.28 μg/l; non-smokers), 2,4,6-TCP and PCPs in urine (m: 0.85 vs 0.60 and 2.2 vs 2.2 μg/l) or the levels of PCB congeners in plasma (m: Σ 138, 153, 180: 5.6 vs 4.1 μg/l). The elevated levels of hydroxypyrene, 2,4/2,5-DCP, 2,4,5-TCP and HCB in biological material may be related to the incineration of the waste. These elevations, however, are very small and are of interest more from the environmental than from the occupational point of view.

External and internal antimony exposure in starter battery production

In the production of lead batteries two antimony compounds occur: in the casting of grids antimony trioxide (Sb2O3), and in the formation of lead plates stibine (SbH3). Seven workers from the gridcasting area and 14 workers from the formation area were examined with regard to the antimony concentration in blood (Sb-B) and urine (Sb-U). Antimony air concentrations (Sb-A) were measured by means of personal air samplers. Urine samples were collected at the end of the working week, at the beginning (U1) and the end (U2) of the shift, and at the beginning of work following a weekend without Sb exposure (U3). At U2 among the casters the median Sb-A exposure was 4.5 (1.18–6.6) μg Sb/m3 and among the formation workers, 12.4 (0.6–41.5) μg Sb/m3. The exposure in both groups is more than 10 times lower than the present threshold limit values. The median Sb-B concentrations in the preshift samples was 2.6 (0.5–3.4) μg Sb/l for the casters and 10.1 (0.5–17.9) μg Sb/l for the formation workers. The average Sb-U values (U2) were 3.9 (2.8–5.6) μg Sb/g creatinine in the casting area and 15.2 (3.5 23.4) μg Sb/g creatinine in the forming area. Our investigation indicates that the two antimony compounds show virtually equal pulmonary absorption and renal elimination. The statistically significant correlations between Sb-A/Sb-B and Sb-A/Sb-U form the basis for proposals regarding appropriate biological exposure limits for occupational antimony exposure.

Determination of environmental caused chlorophenol levels in urine of the general population

SummaryA sensitive, specific and analytically reliable method for the determination of mono-, di-, tri- and tetrachlorophenols in human urine has been elaborated. After acid hydrolysis and a simultaneous steam distillation of the urine samples, spiked with an internal standard, the chromatographically concentrated chlorophenols have been derivatized with pentafluorobenzoylchloride and analyzed by capillary gas chromatography/mass spectrometry. The detection limits for the chlorophenols ranged from 0.2 to 2.5 μg/l. Using this method we were able to detect 4-MCP, 2,4-+2,5-DCP, 2,4,6-TCP, 2,4,5-TCP and 2,3,4,6-+2,3,5,6-TeCP in urine samples of a group of 258 men and women which had no known occupational contact to hazardous chemical substances. The 95 percentiles for the concentrations of these substances in the urine samples under investigation were 7.5 (4-MCP); 33.6(2,4-+2,5-DCP); 4,7 (2,4,6-TCP); 4,5 (2,4,5-TCP) and 22.2 (2,3,4,6-+2,3,5,6-TeCP) μg per liter. That means, that these chlorophenols are constituents of urine of the normal population in concentrations which in part are greater than that of pentachlorophenol (PCP).

Gehörschäden durch Freizeitlärm

ZusammenfassungLärm gefährdet die Gesundheit. Heute muß festgestellt werden, daß eine erhebliche Gefährdung durch Freizeitlärm, insbesondere bei Kindern, Jugendlichen und jungen Erwachsenen, besteht. Epidemiologische Untersuchungen an Jugendlichen, die noch keiner beruflichen Lärmbelastung ausgesetzt waren, lassen steigende Zahlen mit nachweisbaren, irreversiblen Innenohrschäden erkennen. Als wesentliche Ursachen werden die weite Verbreitung sehr lauter Kinderspielzeuge (Pistolen, Knackfrosch), Feuerwerkskörper sowie die heute ubiquitäre Verfügbarkeit elektroakustischer Verstärkung für Musik, z.B. mittels tragbarer Abspielgeräte, in Diskotheken oder in Musik-Großveranstaltungen angesehen. Der Schutz vor einer medizinisch unheilbaren Gehörschädigung durch Freizeitlärm ist daher eine wichtige Aufgabe der Präventivmedizin. Durch Aufklärungsmaßnahmen sollte auf die Gefahren der Gehörgefährdung durch laute Freizeitbeschäftigungen aufmerksam gemacht werden. Zum Schutz von Kindern und Jugendlichen, aber auch von Erwachsenen ist der Gesetzgeber gefordert, Möglichkeiten von Schallpegelbegrenzungen für Diskotheken, Konzerte und Musikabspielgeräte zu prüfen und entsprechende Richtwerte in Normen oder Richtlinien zu verankern.SummaryAlthough noise in general can induce hearing loss, environmental noise represents an important risk for children, teenagers and young adults. Epidemiological investigations now support the occurrence of an increasing number of irreversible hearing losses in these groups. Major causes of hearing loss are toys (guns), explosives and electroacoustically amplified music delivered by head sets or heard in discotheques and open air concerts. Clinical indications are discussed.

Internal and external quality control in the toxicological analysis of blood and urine samples in the Federal Republic of Germany.

SummaryDue to a technical rule for dangerous agents (TRGS 410), issued by the Ministry of Labor in the Federal Republic of Germany in 1979, toxicological analyses in biological materials must be carried out under conditions of “statistical quality control”. This quality-control scheme provides internal and external control programmes. For internal quality control, the results of many years of experience with five commercially available control specimens and one “home-made” control have been evaluated. The control samples showed good, comparable results over a long period. Except in a few cases, there was good agreement between our results and the assigned values. Since 1982, the German Society of Occupational Medicine has offered eight intercomparison programmes for external quality. In samples from 80–90 laboratories, 6 metals in blood and around 20 inorganic and organic parameters in urine in 2 concentration adjustments have been analysed. Successful participation was certified if both results obtained for one parameter were within the tolerance range (assigned] value ± 3 SD). The average success rate was around 60%.

Occupational chronic exposure to metals

SummaryExternal and internal chromate exposure of 103 stainless steel welders who were using manual metal arc welding (MMA), metal inert gas welding (MIG) and both methods, were measured by ambient and biological monitoring. At the working places the maximum chromium trioxide concentrations were 80 μg/m3. The median values were 4 μg/m3 (MMA) and 10 μg/m3 (MIG). The median chromium concentrations in erythrocytes, plasma and urine of all welders were < 0.60, 9.00 and 32.50 μg/l. For biological monitoring purposes, chromium levels in erythrocytes and simultaneously in plasma seem to be suitable parameters. According to our results, chromium levels in plasma and urine in the order of 10 and 40 μg/l seem to correspond to an external exposure of 100 μg chromium trioxide per cubic metre, the technical guiding concentration (TRK-value). Chromium concentrations in erythrocytes greater than 0.60 μg/l indicate an external chromate exposure greater than the TRK-value.

Occupational chronic exposure to organic solvents. XIII, Glycolether exposure during the production of varnishes

SummarySeventeen persons (2 women and 15 men), who were exposed to glycolethers in a varnish production plant, were examined according to their external and internal solvent exposure. The workers in the production plant (n =12) were exposed to average concentrations of ethoxyethanol, ethoxyethyl acetate, butoxyethanol, 1-methoxypropanol-2, 2-methoxypropyl-1-acetate and xylene of 2.8; 2.7; 1.1; 7.0; 2.8 and 1.7 ppm. In the air of the store (n = 3) and in the laboratory (n = 2) only minor concentrations of xylene respectively xylene and ethoxyethyl acetate could be measured. Internal exposure was estimated by measuring butoxyethanol (BE) in blood as well as ethoxyacetic acid (EAA) and butoxyacetic acid (BAA) in urine samples. Urine samples were taken pre- and post-shift. As expected, the highest values were found in the varnish production. The average post shift concentrations of BE, EAA and BAA were 121.3 μg/l; 167.8 and 10.5 mg/l. The relatively high concentrations of EAA and BAA in pre-shift samples can be explained by the long half-lives of these metabolites. According to our findings most of the glycolethers were taken up through the skin. Comparing our results with those reported in the literature we think that a future tolerable limit value for the concentration of ethoxyacetic acid in urine should be in the order of 100 to 200 mg/l.

Biomonitoring of nickel and chromium in human pulmonary tissue

SummaryNickel (Ni) and chromium (Cr) and some of its compounds may be able to induce cancer in the lungs as well as in the nose and paranasal sinuses after occupational exposure. Latency periods amount to 20 years and more. Therefore objective exposure data are not available in the most cases and expert evaluation of the causal connection is often difficult. Recent investigations have shown, that Ni and Cr can cumulate in human lung tissue after occupational exposure. For the evaluation of “normal” Ni- and Cr-values a total of 495 human lung tissue samples of 30 occupationally non-exposed persons were analysed by AAS including ZEEMAN-compensation after wet oxidative digestion. Additional samples of 10 deceased persons who have been occupationally exposed to nickel in previous times by nickel-refining and welding, especially flame spraying have been investigated. The median Ni- and Cr- concentrations in the lungs of the non-exposed persons ranged between 20–40 resp. 133–277 ng/g (wet weight). In nickel refinery workers Ni- concentrations were found which exceeded the normal range about 1,000. In welders, especially flame sprayers, also values more than 100 times higher could be analysed for Ni and Cr. Partially these concentrations were found years after the end of the inhalative exposure.

Detection and clinical relevance of a type I allergy with occupational exposure to hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride

SummaryHexahydrophthalic anhydride (HHPA) and methyltetrahydrophthalic anhydride (MTHPA) belong to the group of the acid anhydrides and, among other applications, are used in the production of epoxy resins. These substances are known as potent low-molecular allergens and induce predominantly type I allergies according to Coombs and Gell. We examined 110 employees exposed to HHPA and MTHPA. With all of them a RAST was carried out with the commercially available conjugates of phthalic anhydride (PA) and a skin prick test with 1% and 5% acetonic solutions of PA. In 109 of these sera a radio allergo sorbent test (RAST) was carried out with the not commercially available conjugates of HHPA and of MTHPA. With complaints connected with the workplace the working materials used (HHPA, MTHPA) were also checked by means of the skin prick test. With at least one positive immunological finding (in the RAST and/or skin prick test) in connection with complaints at the workplace, we performed a workplace-related inhalation test under experimental conditions. Specific IgE against acid anhydrides was detected in a total of 17 (15.4%) persons. In the challenge test, six (5.4%) sensitisations were shown to be clinically relevant. On inclusion of borderline positive findings with PA conjugates the RAST produced three false negative and one false positive finding compared with a RAST with HHPA and MTHPA conjugates. With the conjugates of trimellitic anhydride, in no case could specific IgE be detected. The skin prick test led, in comparison with the RAST, to three false positive and three false negative findings. With all clinically relevant sensitisations the skin prick test was regarded as positive. RASTs with conjugates of PA and skin prick tests with native acid anhydrides can, according to our investigations, validly ascertain workplace-related sensitisations to HHPA and MTHPA.