Evaluation of worker exposure to asphalt paving fumes using traditional and nontraditional techniques

Forty-five workers at 11 paving sites across the United States were evaluated for exposure to paving asphalt (bitumen) fumes. Traditional measures of exposure such as total particulate matter (TPM) and benzene soluble matter (BSM) were monitored. In addition, total organic matter (TOM), which includes both the BSM residue and the more volatile components that pass through the filter and are collected on sorption material, was quantified and further characterized using a gas chromatography technique and a recently developed fluorescence test. The latter method, which indirectly estimates the content of four- to six-ring polycyclic aromatic compounds, is used as a predictor of carcinogenicity. The correlation between fluorescence emission intensity and carcinogenicity for 36 laboratory generated fume fractions, as measured in a mouse skin-painting bioassay, was then used to estimate the carcinogenic potential of worker monitoring samples. Emission levels, and therefore predicted carcinogenicity, for these samples were at least 17-fold below the value corresponding to a minimal carcinogenic effect. This result was consistent with more extensive chemical analysis (using gas chromatography/mass spectrometry) of two of the samples, which showed the predominant constituents to be alkanes, monocycloparaffins, alkyl-benzenes, alkyl-naphthalenes, and alkyl-benzothiophenes. The geometric mean exposures for all worker studies were 0.21 mg/m3 (TPM), 0.06 mg/m3 (BSM), and 1.23 mg/m3 (TOM).     

Inhalation study on exposure to bitumen fumes. Part 2: Analytical results at two exposure levels

During the hot application of bitumen-containing materials, e.g. in road paving or roofing, fumes are emitted that contain traces of polycyclic aromatic compounds (PACs). Although worker's exposure to these fumes is low, it might lead to health problems. For studying DNA adduct formation as a consequence of inhalation of bitumen fumes we developed and validated an inhalation system (a dynamic fume generator plus a nose only inhalation chamber). This paper presents and discusses the analytical results from the different laboratories involved in this study on the fumes sampled in the inhalation chamber during three series of experiments where the animals were exposed to fumes at the 5 mg/m3 and 50 mg/m3 level, coming from bitumen heated at 200 degrees C and, as a positive control, fumes from coal tar, heated to 110 degrees C at the 5 mg/m3 level. The following parameters were controlled: temperatures at different key places in the generator; humidity of the chamber; the bitumen or coal tar flow rate; and Total Particulate Matter (TPM). Analyses were performed for Benzene Soluble Matter (BSM), the EPA polycyclic aromatic hydrocarbon (PAH) mixture and for a number of heteroatom-containing PACs. The data show that the coal tar fumes produced at 110 degrees C were very volatile and that most of the differences in particulate matter found between the laboratories can be attributed to evaporative losses. The bitumen fumes boil 25-50 degrees C higher and contain higher boiling compounds. A comparison is made between the PAC exposure profiles for bitumen experiments aimed at 5 and 50 mg/m3. Although the same molecules are found in both fumes their proportion is dramatically different. This effect is largest with the 2- and 3-ring PACs, the ratio of the concentrations found in the 50 mg/m3 TPM concentration to that in the 5 mg/m3 experiment gradually declines from 5500 for acenaphthene to 500 for pyrene, for the 5-ring PACs this ratio is 20-30. As function of their vapour pressure, the ratios of the concentrations of the hetero PACs follow the same trend as that of the 16 EPA PAHs and are of the same order of magnitude. In conclusion, for the compounds investigated, the equipment delivers a fume atmosphere in a reproducible manner. The 50 mg/m3 bitumen fumes are not representatives of field fumes. The reason for these quantitative differences is unclear and further work would be needed to clarify this. Nevertheless it was felt that these fumes at 50 mg/m3 might be a useful tool for qualitative detection of DNA adducts in an animal exposure study.     

Inhalation exposure of rats to vapors of 1-nitropropane at 100 ppm

Male and female Long-Evans rats were exposed by inhalation to vapors of 1-nitropropane at 100 ppm. The animals were exposed 7 hr per day, 5 days per week for periods up to $\text{21}\text{1}\text{2}$ months. Groups of rats were killed after 1, 3, 12, and 18 months of exposure and additional groups of exposed rats were removed from the exposure chamber after 3 and 12 months and held under nonexposure conditions for the remainder of the study. All animals remaining alive were killed $\text{21}\text{1}\text{2}$ months after the start of the study. The results of gross necropsies of the animals did not disclose any effects of exposure to 1-nitropropane on any of the organs or tissues. There were no histopathologic effects on the liver and, in particular, no induction of hepatocarcinomas. No effects were observed on final body weights or the weights of liver, kidney, or brain. There were no effects on serum chemistry or hematology.     

Evaluation of worker exposure to asphalt roofing fumes: influence of work practices and materials

A field study was conducted on 42 asphalt-roofing workers at 7 built-up roofing sites across the United States. Sixteen out of 42 samples show levels of exposure to asphalt fumes that exceed the current American Conference of Governmental Industrial Hygienists' (ACGIH)-recommended threshold limit value of 0.5 mg/m(3) as benzene extractable inhalable particulate. Statistically, the geometric mean of all 42 worker samples was 0.27 mg/m(3) (geometric standard deviation = 3.40), the average was 0.70 mg/m(3) (standard deviation = 1.69) and the median value was 0.24 mg/m(3). The impact of work practices is discussed including the use of a novel product that uses a polymer skin to reduce fumes from built up roofing asphalt. Its use resulted in a reduction of benzene soluble matter (BSM) of >70%. Other testing measures utilized included total particulate matter, total organic matter, simulated distillation, and fluorescence analysis. Additionally, a controlled pilot study using 16 kettle-area and 16 worker samples clearly showed that when the temperature of the kettle was reduced by 28 degrees C, there was a 38-59% reduction in fume exposure and a 54% reduction in fluorescence with standard asphalts. Reduction of BSM exposures using fuming-suppressed asphalt was also confirmed during this pilot plant study (81-92%), with fluorescence lowered by 88%. Confounding agents such as roof tear-off materials were also analyzed and their contribution to worker exposure is discussed.     

Inhalation exposure to welding fumes of arc welders in processing Cr-Ni steel in large chemical industry

For clearing up the inhalative load by welding fumes and gases of arc welders in industrial workshops mainly working on Cr-Ni-steels the following welding processes were studied: tungsten inert-gas (TIG), electrode-by-hand (EH), metal inert-gas (MIG), and plasma cutting (plasma). From the total load by welding fumes follows the rank TIG less than EH less than plasma less than MIG. Observing the maximum allowable concentration (MACD) for the total welding fume, no MACD for Cr and Ni was found exceeded. Regarding the welding gases ozone and CO no limit values were exceeded. From the results conclusions were made.     

Inhalation study on exposure to bitumen fumes. Part 1: Development and validation of the equipment

Bitumen fumes emitted during road paving or roofing contain polycyclic aromatic hydrocarbons (PAHs). Experimental studies have been previously performed to test the carcinogenic potency of bitumen fumes. Some of them have been criticised either on the grounds that the fume condensates were not representative of fumes to which humans are exposed or because the fumes were never characterised in terms of particle size and poorly in terms of composition and concentration in the chambers. For a nose-only inhalation study, we have evaluated the ability of a new fume generation system to deliver stable and reproducible atmospheres of bitumen fumes to an inhalation chamber and investigated the representativity of the fumes generated at a concentration level of 5 mg/m3. The fume generator comprises: (1) an insulated 20 l heated kettle (200 degrees C for bitumen); (2) an insulated inlet pipe with a needle valve to adjust the flow of the test compound from the kettle; (3) a fume generation chamber equipped with a series of interchangeable channels of different width. The fume concentration in the exposure chamber can be controlled by changing the channel width or by restricting the evaporation surface with aluminium foil, and/or by changing the flow rate. Samples of the atmosphere in the chamber were collected and analysed for quantitative determination of total particulate matter (TPM), soluble matter, benzo[a]pyrene (B[a]P) content of the fumes and other PAHs, and evaluation of the particle size distribution. The representativeness of the fumes has been tested by comparison with fumes generated in the Shell small-scale fume rig, which was previously validated against field fumes collected during paving operations. Evaporative losses from the filters during sampling, transport and storage have been also assessed. At 5 mg/m3 TPM, the agreement between laboratories was quite good for the TPM analyses and was good for the soluble matter and B[a]P. Evaporative losses may lead to underestimation of the true exposure level in the inhalation chambers but the use of an XAD-2 cartridge backup is one approach to partially recover losses which occur on the filter. The particle size distributions are somewhat different from those reported for fumes associated with roofing and indoor mastic laying works, in that we found more than 85% of particles to be smaller than 1 micron, compared with 40% particles in the previous analyses. In conclusion, this equipment allows reproducible generation of fumes at the 5 mg/m3 TPM that are fairly representative of those produced in the field with the same bitumen.     

Modelling of exposure to respirable and inhalable welding fumes at German workplaces

Abstract

The International Agency for Research on Cancer classified welding fumes as carcinogenic to humans, and occupational exposure limits should be established to protect welders. The aim of this study is to estimate exposure levels to inhalable and respirable welding fumes by welding process to use them for exposure assessment in epidemiological studies and to derive occupational exposure limits. In total, 15,473 mass concentrations of inhalable and 9,161 concentrations of respirable welding fumes could be analyzed along with welding-related and sampling information, which were compiled in the German database MEGA between 1983 and 2016. In both particle-size fractions, model-based geometric means of the concentrations were estimated by welding process and material for frequently used welding processes adjusted for sampling time and median-centered for calendar years. The inhalable concentrations were approximately twice the respirable concentrations, with medians of 3?mg/m³ (inter-quartile range: 1.2–7.0?mg/m³) and 1.5?mg/m³ (inter-quartile range: < limit of detection ?3.8?mg/m³), respectively. The adjusted geometric means of flux-cored arc welding, metal inert and active gas welding, shielded metal arc welding and torch cutting ranged from 0.9 to 2.2?mg/m³ for respirable welding fumes and from 2.3 to 4.7?mg/m³ for inhalable fumes. In both particle-size fractions, geometric means were between 0.1 and 0.9?mg/m³ when performing tungsten inert gas, autogeneous, resistance, laser, and plasma welding or spraying. Results derived from this large dataset are useful for a quantitative exposure assessment to estimate health risks of welders.     

Risk of developing lung cancer in relation to exposure to fumes from Chinese-style cooking.

In an evaluation of the association between exposure to indoor air pollution from Chinese-style cooking and the risk of lung cancer, epidemiologic and experimental studies were reviewed. The 9 case-referent studies that were identified showed consistent positive associations between the risk of lung cancer and a variety of indices of exposure to indoor air pollution arising from Chinese-style cooking. Three experimental studies showed that volatile emissions from oils heated in woks are mutagenic in several in vitro short-term test systems. Several toxic agents, including some accepted or suspected carcinogens, have been detected in the emissions of the heated cooking oils. While experimental data support the epidemiologic data, it may be premature to conclude that the association is causal. However, simple precautions can be taken to reduce the risk in the event that exposure to indoor air pollution arising from Chinese-style cooking is indeed a cause of lung cancer.     

Short-term exposure to stone minerals used in asphalt affect lung function and promote pulmonary inflammation among healthy adults

ObjectiveStone minerals are a partially ignored environmental challenge but a significant contributor to urban air pollution. We examined if short-term exposure to two stone minerals – quartz diorite and rhomb porphyry – commonly used in asphalt pavement would affect lung function, promote pulmonary inflammation, and affect bronchial reactivity differently.MethodsOur randomized crossover study included 24 healthy, non-smoking young adults exposed to the stone minerals quartz diorite, rhomb porphyry, and control dust (lactose). Exposure occurred in an exposure chamber, in three separate 4-hour exposure sessions. Fractional exhaled nitric oxide (FeNO) and lung function were monitored before exposure, then immediately following exposure, and 4 and 24 hours after exposure. In addition, methacholine was administered 4 hours following exposure, and exhaled breath condensate (EBC) was collected before exposure, then immediately and 4 hours after exposure. EBC was analyzed for pH, thiobarbituric acid reactive substances (TBARS), intercellular adhesion molecule 1 (ICAM-1), interleukin-6 (IL-6), IL-10, P-Selectin, surfactant protein D (SP-D), and tumor necrosis factor-α (TNF-α).ResultsOur results showed significantly elevated concentrations of FeNO after exposure to quartz diorite compared to rhomb porphyry, suggesting that quartz diorite is more likely to trigger pulmonary inflammation after short-term exposure. Moreover, short-term exposure to rhomb porphyry was associated with a modest but statistically significant decline in forced vital capacity (FVC) compared to quartz diorite.ConclusionThese results emphasize that using stone material in asphalt road construction should be reconsidered as it may affect lung inflammation and lung function in exposed subjects.     

Development of an inhalation system of high melting point metal fumes and its use for exposure of rats to chromium and nickel fumes

An experimental inhalation system was developed for fumes generated from powders of high melting point metals such as chromium, nickel, manganese and iron. The system consisted of a plasma flame metal sprayer as a fume generator, a granular bed type fume collector, a fluidized bed aerosol generator, an exposure and a control chamber of a horizontal-flow type and inhalant monitoring and controlling units. Performance of the chambers was ensured by a distribution test using flyash as a test aerosol. Using this system, rats were exposed to chromium fumes for one week or to nickel fumes for two months. The exposure concentrations of the chromium and nickel fumes were 1.85 +/- 0.55 mg/m3 and 0.51 +/- 0.15 mg/m3 (mean +/- SD), near the target levels of 2 mg/m3 and 0.5 mg/m3, respectively. The mass median aerodynamic diameter and the geometric standard deviation of the chromium fumes were 2.1 microns and 2.00, respectively. Those of the nickel fumes were 3.7 microns and 1.74, respectively. Species analysis of these fume particles revealed that 26.4% of the total chromium was hexavalent and the residue was trivalent and that 1-3% of the total nickel was nickel(III) and the residue was nickel(II). Inhaled-metal concentrations in the lungs showed steady increases with the exposure periods and were within the normal range of variation. On the basis of these results, it is concluded that this system is useful for long-term inhalation experiments using high melting point metal fumes.     

Cadmium content of lung,liver and kidney in rats exposed to cadmium oxide fumes

Summary Young male rats were submitted to five consecutive exposures to atmospheres containing cadmium oxide particles (280 min × mg/m³) and sacrificed at different times of a three months post-exposure period. Time-course evolution of lung, liver and kidney weight as well as cadmium content of these organs were studied by polynomial regression analysis.Growth of lungs was profoundly disturbed in rats exposed to the aerosol and some degree of permanent damage of pulmonary lobes could be evidenced by macroscopic examination. Liver growth was affected to a less extent and no effect on the growth of kidneys was observed.Results showed that 12% of inhaled cadmium are deposited in lungs. Clearance of pulmonary cadmium was slow, exponential and monophasic (half-life 56 days). A slight, but statistically significant, accumulation of the toxic element in liver and kidney was seen.The results suggest that 60% of the lung-deposited cadmium are absorbed.     

急性铬化物暴露肺损伤的剂量效应与时间过程

经一次气管灌注不同剂量可溶性六价铬酸钠（Ｎａ２ＣｒＯ４）后第２天和一次灌注０．９８ｍｇ·ｋｇ－１Ｎａ２ＣｒＯ４后不同时间，观察了ＳＤ大鼠支气管肺泡灌洗液（ＢＡＬＦ）和血液生化改变的剂量效应与时间过程。结果表明，Ｎａ２ＣｒＯ４的无效应剂量与阈剂量分别为０．００８和０．０４ｍｇ·ｋｇ－１，染毒剂量≥０．２０ｍｇ·ｋｇ－１时，ＢＡＬＦ中绝大多数生化参数呈现显著的剂量依赖性增加；严重中毒剂量（≥０．９８ｍｇ·ｋｇ－１）可引起ＢＡＬＦ和血液中几乎所有测试参数的显著增加，这种现象约持续一周，至少需要４周才能恢复正常。分析本次研究结果，可得出以下结论：≥０．９８ｍｇ·ｋｇ－１的Ｎａ２ＣｒＯ４可导致包括肺内细胞损伤、弥漫性肺泡炎和肺水肿在内的急性肺损伤；Ｎ－乙酰－β－Ｄ－氨基葡糖苷酶（ＮＡＧ）、溶菌酶（ＬＹＳ）、碱性磷酸酶（ＡＬＰ）、白蛋白（ＡＬｂ）和血管紧张素转换酶（ＡＣＥ），可能是评价接触较低剂量Ｎａ２ＣｒＯ４（＜０．９８ｍｇ·ｋｇ－１）后所致急性肺损伤的最有价值的早期敏感指标     

Change in obstructive pulmonary function as a result of cumulative exposure to welding fumes as determined by magnetopneumography in Japanese arc welders

OBJECTIVES: To examine the effect of chronic exposure to welding fumes on pulmonary function by a direct estimate of fumes accumulated in the lungs. METHODS: The strength of the residual magnetic field of externally magnetised lungs (LMF) was used as an estimate of fumes accumulated in the lungs. The results of forced spirometry manoeuvres obtained in 143 of 153 male welders in the original sample were cross sectionally evaluated according to LMF. Seven conventional forced spirogram indices and two time domain spirogram indices were used as pulmonary function indices, and height squared proportional correction was performed when necessary. RESULTS: The distribution of LMF values was considerably skewed towards positive. There was a weak but significant positive relation between age and log transformed LMF. Obstructive pulmonary function indices correlated well with LMF. After adjustment for age and smoking, however, a significant association with LMF was only found with percentage rate of forced expiratory volume in one second (FEV1%) divided by forced vital capacity (FVC) and mu, and average component of assumed time constant distribution of lung peripheral units. Neither FVC nor vital capacity (VC), as indices of restrictive disorders, showed a significant association with LMF. Based on the results of multiple regression analyses, a 0.6% decrease in FEV1% and 0.039 unit increase in mu were expected for each doubling of LMF. CONCLUSION: Obstructive changes in pulmonary function were found to be related to level of cumulative exposure to welding fume in male Japanese arc welders after controlling for age and smoking, assuming that LMF adequately reflects accumulation of welding fumes in the lungs.

 

     

电离辐射心血管系统损伤途径的研究进展

不同剂量电离辐射对心血管系统的损伤途径存在一定差异,高剂量电离辐射可直接破坏微血管内皮细胞功能屏障,影响细胞黏附分子(cell adhesion molecules,CAMs)等生物大分子的表达,诱导炎性细胞渗出、组织纤维化及坏死等慢性微血管内皮细胞损伤。进而影响循环系统内环境稳态,诱发早期心血管疾病。小剂量电离辐射对心血管系统的损伤途径主要表现为电离辐射的异常DNA甲基化效应和氧化应激效应,由此产生的代谢产物如活性氧自由基(reactive oxygen species, ROS)和同型半胱氨酸(homocysteine, Hcy)均可对心血管系统造成慢性损伤,电离辐射持续暴露导致次级效应代谢产物的蓄积将加剧心血管系统损伤倾向。     

Limited exposure of rats to H2SO4 with and without O3

The purpose of this study was to determine the effects of sulfuric acid (H2SO4) alone and with ozone (O3) on rats. To accomplish this, rats were exposed for 8 hours daily to an atmosphere containing either nebulized H2SO4, H2SO4 plus 0.9 ppm O3, or 0.9 ppm O3. The atmosphere in the exposure chambers was maintained at a fairly constant temperature and humidity. Nebulized H2SO4 was delivered uniformly to provide a particle size of about 0.3 micron mass median diameter (MMD) and a mass concentration of 2 mg/m3. In preliminary experiments, animals exposed to 2 mg/m3 of H2SO4 daily for 82 days showed very slight morphologic injury to the respiratory tract. In contrast, biological effects were readily demonstrable in rats exposed to H2SO4 plus O3 or to O3 alone, possibly with some enhancement of effect in animals exposed to the mixture. The effects observed were characteristic of the response to O3 alone.