Exposure, respiratory symptoms, lung function and inflammation response of road-paving asphalt workers.

BACKGROUND: Controversy exists as to the health effects of exposure to asphalt and crumb rubber modified (CRM) asphalt, which contains recycled rubber tyres. OBJECTIVE: To assess exposures and effects on airway symptoms, lung function and inflammation biomarkers in conventional and CRM asphalt road pavers. METHODS: 116 conventional asphalt workers, 51 CRM asphalt workers and 100 controls were investigated. A repeated-measures analysis included 31 workers paving with both types of asphalt. Exposure to dust, nitrosamines, benzothiazole and polycyclic aromatic hydrocarbon (PAH) was measured in worksites. Self-reported symptoms, spirometry test and blood sampling were conducted prework and postwork. Symptoms were further collected during off-season for asphalt paving. RESULTS: Dust, PAHs and nitrosamine exposure was highly varied, without difference between conventional and CRM asphalt workers. Benzothiazole was higher in CRM asphalt workers (p<0.001). Higher proportions of asphalt workers than controls reported eye symptoms with onset in the current job. Decreased lung function from preworking to postworking was found in CRM asphalt workers and controls. Preworking interleukin-8 was higher in CRM asphalt workers than in the controls, followed by a decrement after 4 days of working. No differences in any studied effects were found between conventional and CRM asphalt paving. CONCLUSION: CRM asphalt workers are exposed to higher benzothiazole. Further studies are needed to identify the source of nitrosamines in conventional asphalt. Mild decrease in lung function in CRM asphalt workers and work-related eye symptoms in both asphalt workers were observed. However, our study did not find strong evidence for severe respiratory symptoms and inflammation response among asphalt workers.

Comparison and Evaluation of Multiple Users' Usage of the Exposure and Risk Tool: Stoffenmanager 5.1.

Stoffenmanager is an exposure and risk assessment tool that has a control banding part, with risk bands as outcome and a quantitative exposure assessment part, with the 90th percentile of the predicted exposure as a default outcome. The main aim of the study was to investigate whether multiple users of Stoffenmanager came to the same result when modelling the same scenarios. Other aims were to investigate the differences between outcomes of the control banding part with the measured risk quota and to evaluate the conservatism of the tool by testing whether the 90th percentiles are above the measured median exposures. We investigated airborne exposures at companies in four different types of industry: wood, printing, metal foundry, and spray painting. Three scenarios were modelled and measured, when possible, at each company. When modelled, 13 users visited each company on the same occasion creating individual assessments. Consensus assessments were also modelled for each scenario by six occupational hygienists. The multiple users' outcomes were often spread over two risk bands in the control banding part, and the differences in the quantitative exposure outcomes for the highest and lowest assessments per scenario varied between a factor 2 and 100. Four parameters were difficult for the users to assess and had a large impact on the outcome: type of task, breathing zone, personal protection, and control measures. Only two scenarios had a higher measured risk quota than predicted by the control banding part, also two scenarios had slightly higher measured median exposure value than modelled consensus in the quantitative exposure assessment part. Hence, the variability between users was large but the model performed well.

N-nitrosamines in the southern Swedish rubber industries - exposure, health effects, and immunologic markers.

OBJECTIVES: The aim of this study was twofold: (i) to evaluate the air levels of N-nitrosamines in the Swedish rubber industry and (ii) to estimate the risk of symptoms and changed levels of immunologic markers in relation to these levels. METHODS: Using adsorption tubes, we collected samples of N-nitrosamines in the breathing zone of 96 rubber workers and analyzed them with liquid chromatography tandem mass spectrometry. Of these 96 workers, 66 were included in a medical examination and blood analysis together with an additional 106 rubber workers and 118 unexposed subjects. Medical and occupational histories were obtained in structured interviews, symptoms were recorded and immunologic markers analyzed in blood. RESULTS: The sum of N-nitrosamines ranged from less than the limit of detection to 36 microg/m (3)and differed with the vulcanization (ie, curing process) method used. Workers vulcanizing with a salt bath had the highest levels (median 4.2 microg/m (3)). Compared to the unexposed subjects, the rubber workers had an increased risk of nosebleeds, eye and throat symptoms, hoarseness, cough, nausea, headache, and changed levels of eosinophils and total immunoglobulin G (IgG). However, we found no clear exposure-response relationship with the symptoms or the immunologic markers studied. CONCLUSIONS: High levels of N-nitrosamines were found and must be lowered considerably in order to decrease the risk of cancer. There is a need for an occupational exposure limit for N-nitrosamines in Sweden. The lack of exposure-response relationships with the subacute symptoms examined in this study may be due to a healthy-worker selection or to the possibility that the symptoms are caused by an exposure not co-varying with N-nitrosamines.

Emissions into the Air from Bitumen and Rubber Bitumen-Implications for Asphalt Workers' Exposure.

The risk among asphalt workers of developing adverse health effects may increase due to their occupational exposure. One area of special concern arises when rubber granules are mixed into bitumen to enhance asphalt properties. This research characterizes and compares bitumen and rubber bitumen regarding the emissions of and workers' exposure to particulates, polycyclic aromatic hydrocarbons (PAHs) and benzothiazole. A laboratory and a field study were carried out. In the laboratory, two types of bitumen, one with and one without rubber, were heated up to two temperatures (140°C and 160°C). The concentrations and chemical compositions of the emissions were determined. In the field at asphalt work sites, both emissions and worker exposure measurements were performed. The methods applied included direct-reading sampling techniques next to the asphalt work area and personal sampling techniques on asphalt workers. The exposure measurements on asphalt workers for respirable dust, total dust, particle number and mass, and total PAH concentrations showed similar concentrations when both standard and rubber bitumen were used. The asphalt-surfacing machine operators were the workers with the highest observed exposure followed by the screed operators and roller drivers. Both laboratory and field measurements showed higher concentrations of benzothiazole when rubber bitumen was used, up to 7.5 times higher in the laboratory. The levels of naphthalene, benzo(a)pyrene, and total particles were lower for both types compared with the Swedish occupational exposure limits, 8-h time weighted average concentrations. Benzo(a)pyrene exceeded however the health-based guideline value given by the WHO for both types of bitumen. The study concludes that several air pollutants such as benzothiazole and PAHs are emitted into the air during asphalt work, but it is not evident if exposure to rubber bitumen possesses a higher risk than exposure to standard bitumen in terms of asphalt worker exposure.

Annoyance and performance during the experimental chemical challenge of subjects with multiple chemical sensitivity.

OBJECTIVES: This study explored the subjective reactions and psychological test performance of smell-intolerant subjects during consecutive challenges to chemicals with contrasting neurotoxic properties. METHODS: Women with symptoms compatible with multiple chemical sensitivity (N=10) and healthy referents (N=20) were individually challenged in an exposure chamber. All the subjects attended two separate 2-hour sessions of exposure to n-butyl acetate and toluene, in counterbalanced sequence. After an initial phase without exposure, air concentrations were increased in steps ranging from 3.6 to 57 mg/m3 for n-butyl acetate and from 11 to 180 mg/m3 for toluene. The response measures comprised ratings of annoyance and smell intensity and also neurobehavioral test performance. RESULTS: Both groups showed an increase in annoyance ratings and a decrease in test performance in the initial unexposed chamber phase and also in the first phase of the chemical exposure, these results indicating slight immediate expectancy or "suggestion" effects. During the six chamber phases, the ratings of mucous membrane irritation and fatigue showed a steeper increase in the group with multiple chemical sensitivity than among the referents, while the ratings of smell intensity and smell annoyance were similar in the two groups. A reduction in test performance was observed during the chamber phases, particularly in the group with multiple chemical sensitivity. No relation was found between the ratings or performance and chemical substance. CONCLUSIONS: Stronger immediate expectancy or "suggestion" reactions than normal did not characterize the group with multiple chemical sensitivity. This group showed a stronger than normal gradual build-up of fatigue, mucous membrane irritation, and reduced performance during chemical exposure. The results offer the most support to an irritative basis for multiple chemical sensitivity.

Levels of 1-hydroxypyrene, symptoms and immunologic markers in vulcanization workers in the southern Sweden rubber industries.

OBJECTIVES: The aim of this study was to determine urinary 1-hydroxypyrene (1-HP) levels in contemporary Swedish vulcanization workers and in controls. These levels were used as an index substance for vulcanization fumes, as well as a biomarker for polycyclic aromatic hydrocarbons (PAHs). The risk of symptoms and changed levels of immunologic markers were investigated in relation to the 1-HP levels. METHODS: Included in the study were 163 exposed workers and 106 controls. Medical and occupational histories were obtained by structured interviews. Symptoms were recorded and immunologic markers analysed in blood by routine analysis methods. Levels of 1-HP were determined by liquid chromatography and fluorescence detection. RESULTS: The highest levels of 1-HP were found among exposed workers using injection and compression vulcanization and lower levels were found among exposed workers vulcanizing with salt bath, hot air, microwaves or fluid-bed. Compared to controls, exposed workers had increased risks of eye symptoms, nosebleeds, burning and dry throat, hoarseness, severe dry cough, nausea and headache. Furthermore, exposed workers had elevated levels of neutrophils and total IgG (immunoglobulin subclass G). However, only for severe dry cough an evident exposure-response relationship with urinary 1-HP levels was found. CONCLUSIONS: This work clearly shows increased levels of urinary 1-HP in Swedish vulcanization workers. Furthermore, it demonstrates an increased risk of several symptoms and elevated levels of some immunologic markers in these workers. However, no obvious exposure-response relationships were found.

Levels of 2-thiothiazolidine-4-carboxylic acid (TTCA) and effect modification of polymorphisms of glutathione-related genes in vulcanization workers in the southern Sweden rubber industries.

OBJECTIVES: Workers in the rubber industry are exposed to a complex mixture of hazardous substances and have increased risk of developing several diseases. However, there is no up to date survey examining the exposure in the Swedish rubber industry. One of the toxic compounds in the industry is carbon disulfide (CS(2)), which is biotransformed to 2-thiothiazolidine-4-carboxylic acid (TTCA). TTCA is used as a biomarker of CS(2) exposure, but there seem to exist inter- and intraindividual variability; which could partly be due to genetic variation. The aim of the study was to determine TTCA levels and the modifying effects of glutathione-related genes in a group of Swedish rubber workers. METHODS: Urine was collected from both exposed workers and controls during the last 4 h of the work shift. The level of TTCA in urine was analyzed by liquid chromatograpy tandem mass spectrometry. Genotyping of the single nucleotide polymorphisms GCLC-129, GCLM-588, GSTA1-52, GSTP1-105 and GSTP1-114 and deletions of GSTM1 and GSTT1 were performed with real-time PCR or ordinary PCR and subsequent agarose electrophoresis. RESULTS: The highest levels of TTCA were found among workers curing with salt bath, hot air, microwaves or fluid-bed, and lower levels were found among workers curing with injection and compression molding. Furthermore, with respect to GSTM1 and GSTT1 there were statistically significant differences in TTCA-levels between genotypes among exposed workers but not among controls. The other five polymorphisms had no impact on the TTCA levels. CONCLUSIONS: The present study demonstrates relatively high levels of TTCA in urine from Swedish rubber workers. Polymorphisms in GSTM1 and GSTT1 modify the levels.