A survey of personal exposures to benzene in Mexico City.

Benzene is a widely distributed environmental contaminant that causes leukemia. It is an important component in gasoline, it is used frequently as a solvent or chemical feedstock in industry, and it is emitted as a product of incomplete combustion. In Mexico City, investigators suspect that benzene exposure might be elevated and may pose a risk to the population; however, no published data are available to confirm or disconfirm this suspicion. We, therefore, conducted a survey in 3 occupational groups in Mexico City. Forty-five volunteers who used portable passive monitors measured their personal exposure to benzene during a workshift. None of the participants smoked during the monitoring period. Benzene exposure was significantly higher among service-station attendants (mean = 359.5 microg/m3 [standard deviation = 170.4 microg/m3]) than among the street vendors (83.7 microg/m3 and 45.0 microg/m3, respectively) and office workers (45.2 microg/m3 and 13.3 microg/m3, respectively). However, the benzene exposure levels observed among office workers were substantially higher than levels reported elsewhere for general populations. Our results highlight the need for more complete studies by investigators who should assess the potential benefits of setting environmental standards for benzene in Mexico.     

Traffic-related occupational exposures to PM2.5, CO, and VOCs in Trujillo, Peru

A traffic-related exposure study was conducted among 58 workers (drivers, vendors, traffic police, and gas station attendants) and 10 office workers as controls in Trujillo, Peru, in July 2002. PM2.5 was collected, carbon monoxide (CO) was measured, volatile organic compounds (VOCs) were sampled and analyzed. Newspaper vendors had the highest full-shift CO exposures (mean +/- SD: 11.4 +/- 8.9 ppm), while office workers had the lowest (2.0 +/- 1.7 ppm). Bus drivers had the highest full-shift PM2.5 exposures (161 +/- 8.9 microg/m3), while gas station attendants (64 +/- 26.5 microg/m3) and office workers (65 +/- 8.5 microg/m3) were the lowest. Full-shift benzene/toluene/ethylbenzene/xylene exposures (BTEX) among gas station attendants (111/254/43/214 microg/m3) were much higher than those among van and taxi drivers. Several of the traffic-related occupational exposures studied were elevated and are of occupational health concern.     

Traffic-related Occupational Exposures to PM2.5, CO,and VOCs in Trujillo,Peru

Abstract

A traffic-related exposure study was conducted among 58 workers (drivers, vendors, traffic police, and gas station attendants) and 10 office workers as controls in Trujillo, Peru, in July 2002. PM_2.5 was collected, carbon monoxide (CO) was measured, volatile organic compounds (VOCs) were sampled and analyzed. Newspaper vendors had the highest full-shift CO exposures (mean ± SD: 11.4 ± 8.9 ppm), while office workers had the lowest (2.0 ± 1.7 ppm). Bus drivers had the highest full-shift PM_2.5 exposures (161±8.9 pg/m³), while gas station attendants (64 ± 26.5 pg/m³) and office workers (65 ± 8.5 μg/m³) were the lowest. Full-shift benzene/toluene/ethylbenzene/xylene exposures (BTEX) among gas station attendants (111/254/43/214 μg/m³) were much higher than those among van and taxi drivers. Several of the traffic-related occupational exposures studied were elevated and are of occupational health concern.     

Blood lead survey of children, pregnant women, professional drivers, street workers, and office workers in Trujillo, Peru

In this pilot study, conducted in summer 2002, the authors measured blood lead levels (BLLs) for 118 subjects in the city of Trujillo, Peru, where leaded gasoline is in the process of being phased out. Subjects included bus drivers, combi (minivan) drivers, street vendors, newspaper vendors, traffic police, taxi drivers, gas station attendants, children living both near and distant from gas stations, pregnant women, and office workers (controls). The highest BLLs were 9.2 microg/dl and 9.3 microg/dl from a child who lived near a gas station and from a traffic policeman, respectively; however, all BLLs were below the U.S. Centers for Disease Control and Prevention's advisory level of concern (10 microg/dl). Office workers (n = 8) and pregnant women (n = 36) had significantly lower BLLs (geometric mean +/- standard deviation = 2.1 +/- 0.7 microg/dl, p < 0.022; and 2.5 +/- 1.1 microg/dl, p < 0.008, respectively) than total traffic-exposed workers (n = 48; 3.2 +/- 1.8 microg/dl). BLLs of children living near gas stations (n = 17; 3.7 +/- 2.2 microg/dl) were marginally higher (p = 0.07) than for children not living near gas stations (n = 9; 2.9 +/- 1.1 microg/dl). The study was limited by small sample size and the fact that the data were based on a convenience sample not fully representative of the cohorts studied. Nevertheless, the authors' findings suggest that leaded gasoline use in Trujillo continues to affect BLLs in traffic-exposed populations.     

DNA damage and repair detected by the comet assay in lymphocytes of african petrol attendants: a pilot study

Petrol attendants are exposed to petrol volatile organic compounds (VOCs) which may have genotoxic and carcinogenic effects. The single-cell gel electrophoresis assay (comet assay) is a method highly sensitive to DNA damage induced by environmental and occupational exposure to carcinogenic and mutagenic agents. The aim of this study was to evaluate the level of exposure of petrol attendants to petrol VOCs and also to determine their effect on DNA damage and repair in lymphocytes of African petrol attendants. The exposed group consisted of 20 subjects, randomly selected from three petrol stations. A control group of 20 unexposed subjects was also chosen and matched for age and smoking habits with the exposed group. Sorbent tubes were used to assess personal exposure of petrol attendants. The comet assay was used to investigate the basal DNA damage and repair capacity in isolated lymphocytes of petrol attendants and unexposed subjects. Blood samples were taken from the petrol attendants at the end of their 8-h working shift and also from the unexposed subjects. The petrol attendants were found to be exposed to levels of petrol VOCs lower than the South African occupational exposure limit for constituent chemicals. A significant relationship was found between the volume of petrol sold during the shift and the average concentrations of benzene, toluene and the total VOCs measured. However, relative humidity had a negative correlation with the average concentrations of benzene, toluene, xylene and the total VOCs. Significantly higher basal DNA damage was observed with the exposed group compared to the unexposed group. The period of exposure influenced the level of DNA damage and the calculated repair capacity. Smoking and age had a significant influence on the level of DNA damage. DNA repair capacity was delayed in smokers of both exposed and unexposed group.     

Blood Lead Survey of Children,Pregnant Women,Professional Drivers,Street Workers,and Office Workers in Trujillo,Peru

In this pilot study, conducted in summer 2002, the authors measured blood lead levels (BLLs) for 118 subjects in the city of Trujillo, Peru, where leaded gasoline is in the process of being phased out. Subjects included bus drivers, combi (minivan) drivers, street vendors, newspaper vendors, traffic police, taxi drivers, gas station attendants, children living both near and distant from gas stations, pregnant women, and office workers (controls). The highest BLLs were 9.2 μg/dl and 9.3 μg/dl from a child who lived near a gas station and from a traffic policeman, respectively; however, all BLLs were below the U.S. Centers for Disease Control and Prevention's advisory level of concern (10 μg/dl). Office workers (n = 8) and pregnant women (n = 36) had significantly lower BLLs (geometric mean ± standard deviation = 2.1 ± 0.7 μg/dl, p < 0.022; and 2.5 ± 1.1 μg/dl, p < 0.008, respectively) than total traffic-exposed workers (n = 48; 3.2 ± 1.8 μg/dl). BLLs of children living near gas stations (n = 17; 3.7 ± 2.2 μg/dl) were marginally higher (p = 0.07) than for children not living near gas stations (n = 9; 2.9 ± 1.1 μg/dl). The study was limited by small sample size and the fact that the data were based on a convenience sample not fully representative of the cohorts studied. Nevertheless, the authors' findings suggest that leaded gasoline use in Trujillo continues to affect BLLs in traffic-exposed populations.     

Environmental and biological monitoring of traffic wardens from the city of Rome

A molecular epidemiological study on Roman policemen is ongoing. The results of a first assessment of the occupational exposure to aromatic compounds of 66 subjects engaged in traffic control and of 33 office workers are presented in this paper. Passive personal samplers and urinary biomarkers were used to assess exposure to benzene and polycyclic hydrocarbons during work shifts. The results obtained indicate that benzene exposure in outdoor workers is about twice as high as in office workers (geometric mean 7.5 and 3.4 micrograms/m3, respectively). The distribution of individual exposure values was asymmetrical and skewed toward higher values, especially among traffic wardens. Environmental benzene levels recorded by municipal monitoring stations during work shifts (geometric mean 11.2 micrograms/m3) were in the first instance comparable to or greater than individual exposure values. However, several outlier values were observed among personal data that greatly exceeded average environmental benzene concentrations. Among the exposure biomarkers investigated, only blood benzene correlated to some extent with previous exposure to benzene, while a seasonal variation in the excretion of 1-hydroxypyrene and trans-muconic acid was observed in both study groups. In conclusion, these results suggest that outdoor work gives a greater contribution than indoor activities to benzene exposure of Roman citizens. Moreover, relatively high-level exposures can be experienced by outdoor workers, even in the absence of large-scale pollution episodes.     

Benzene exposure monitoring of Tunisian workers

To monitor benzene exposure and to check reliability of urinary trans,trans-Muconic Acid (t,t-MA) as a bio-marker of benzene exposure in local conditions, a study was conducted on 30 Tunisian exposed workers (20 tanker fillers and 10 filling station attendants). The analyses were carried out on environmental air and urinary t,t-MA before (t,t-MAA) and at the end of work shift (t,t-MAB). 20 nonoccupationally exposed subjects were also investigated. The average value of environmental benzene concentration was 0.17 ppm. The differences between t,t-MAA and t,t-MAB concentrations and between t,t-MAB and t,t-MA measured in controls (t,t-MAC) were both significant (p < 0.001). Benzene air concentrations were well correlated with t,t-MAB: R = 0.76. In the nonexposed group, average t,t-MA concentrations is significantly higher among smokers than nonsmokers (P < 0.02). Analysis of urinary t,t-MA offers a relatively simple and suitable method for benzene exposure monitoring.     

Evolution of occupational exposure to environmental levels of aromatic hydrocarbons in service stations

During refuelling, people may easily be exposed to extremely high levels of gasoline vapour for a short time, although such exposure takes on more importance in the case of service station attendants. The volume of gasoline sold in refuelling operations and the ambient temperature can significantly increase the environmental level of benzene, toluene and xylene (BTX) vapours and, subsequently, the occupational risk of service station attendants. This is especially true in the case of benzene, the most important component of gasoline vapours from a toxicological point of view. The European Directive 98/70/EC, limiting the benzene composition of gasoline, and 94/63/EC, concerning the use of vapour recovery systems in the delivery of gasoline to services stations, were applied in Spain from January 2000 and 2002, respectively. In addition, a new limit value for occupational exposure of 3.25 mg/m(3) was fixed for benzene in Directive 97/42/EC, applied from June 2003. However, recent years have seen the growing use of diesel as well as of unleaded and reformulated gasoline. In this study, we analyse the differences found between air concentration levels of BTXs in 2000 and 2003, analysing samples taken from the personal breathing-zone of occupationally exposed workers in service stations. The results are compared with those obtained in a similar study carried out in 1995 (before the new regulations came into force). The study was carried out in two phases. The first phase was carried out in 2000, after application of the new legal regulation limiting the benzene concentration in gasoline. In this case, an occupationally exposed population of 28 service station attendants was sampled in July, with a mean ambient temperature of 30-31 degrees C. In the second phase, 19 exposed subjects were sampled in July 2003, one of the warmest months in recent years with mean temperatures of 35-36 degrees C during the time of exposure monitoring. The results were then compared with those obtained in 1995, for similar summer weather conditions (environmental temperature between 28 and 30 degrees C). A significant relationship between the volume of gasoline sold and the ambient concentration of aromatic hydrocarbons was found for each worker sampled in all three of the years. Furthermore, a significant decrease in the environmental levels of BTXs was observed after January 2000, especially in the case of benzene, with mean time-weighted average concentrations for 8 h of 736 microg/m(3) (range 272-1603) in 1995, 241 microg/m(3) (range 115-453) in 2000 and 163 microg/m(3) (range 36-564) in 2003, despite the high temperatures reached in the last mentioned year.     

Lack of correlation between environmental or biological indicators of benzene exposure at parts per billion levels and micronuclei induction

Despite growing concern for possible carcinogenic effects associated with environmental benzene exposure in the general population, few studies exist at parts per billion (ppb) levels. We investigated the existence of a relationship between airborne/biological measurements of benzene exposure (i.e., personal/area sampling and unmodified urinary benzene/trans,trans-muconic acid; t,t-MA) and micronuclei induction (cytochalasin B technique) among exposed chemical laboratory workers (n=47) and traffic wardens (n=15). Although urinary t,t-MA (106.9+/-123.17 microg/L(urine)) correlated (R(2)=0.37) with urinary benzene (0.66+/-0.99 microg/L(urine)), neither biological measurement correlated with environmental benzene exposure (14.04+/-9.71 microg/m(3); 4.39+/-3.03ppb), suggesting that, at ppb level (1ppb=3.2 microg/m(3)), airborne benzene constitutes a fraction of the total intake. Traffic wardens and laboratory workers had comparable numbers of micronuclei (4.70+/-2.63 versus 5.76+/-3.11; n.s.), similar to levels recorded in the general population. With univariate/multivariate analysis, no association was found between micronuclei induction and air/urinary benzene exposure variables. Notably, among the personal characteristics examined (including age, gender, smoking, drinking, etc.), high body mass index correlated with micronuclei induction while, among females, use of hormonal medication was associated with less micronuclei. Thus the present study provides no evidence that ppb levels of environmental benzene exposure appreciably affect micronuclei incidence (against the background of other relevant factors). However, this should not be taken as an argument against efforts aiming to reduce environmental benzene pollution.     

Childcare needs of female street vendors in Mexico City

This article reports on strategies developed by female street vendors (vendedoras ambulantes) in Mexico City to ensure the care of their young children in the absence of a specific and operational government policy to fulfil this need. The information concerning child care and health was gathered by a survey of 426 street traders selected by multi-stage random cluster sampling in four of the administrative districts (delegaciones politicas) of Mexico City during 1990. It was found that, as mothers of young children, street vendors most frequently looked after their children personally on the street or left them with other members of the family. Related factors were availability of alternative child care providers in the family, the age of the children and working conditions of the mother. Children who remained on the streets with their mothers suffered more frequently from gastro-intestinal diseases and accidents than the national average. The incidence of acute respiratory diseases, however, was similar in the cases of maternal care in the street and care by family members in another environment. Existing public health measures show a greater concern for the health of food consumers than that of workers in this area. Current public policy seeks to regulate street vending activities and to concentrate traders in ad hoc areas and facilities. Our research results document the need for actions that can contribute to an improvement in the care and health conditions of these young children.     

Jet fuel and liver function

The impact of occupational exposure to jet fuel on antipyrine elimination was studied in 91 fuel-filing attendants. The mean antipyrine clearance was enhanced to 68.4 (SD 19.5) ml/min during exposure to jet fuel compared to 57.9 (SD 18.1) ml/min after an exposure-free period of two to four weeks. The corresponding values for 47 office workers (referents) were 62.7 (SD 22.2) ml/min and 56.4 (SD 22.3) ml/min. The median jet fuel concentration in the breathing zone of the fuel-filling attendants was 31 (range 1-1 020) mg/m3. No known inducing factor could be identified in the work environment of the office workers. No difference in the concentration of aspartate aminotransferase and alkaline phosphatase in serum was found either within or between the groups. Our study indicates that jet fuel, which is a mixture of aliphatic and aromatic organic solvents resembling gasoline and white spirit, is an inducer of hepatic drug metabolism in man.     

Delayed and Competitively Inhibited Excretion of Urinary Hippuric Acid in Field Workers Coexposed to Toluene,Ethyl Benzene,and Xylene

The purpose of this study was to investigate whether the metabolic suppression of hippuric acid (HA) occurs in field workers coexposed to toluene, xylene and ethyl benzene. Eleven male spray painters were recruited into this study and monitored for 2 weeks using a repeated-measures study design. The sampling was conducted for 3 consecutive working days each week. Toluene, ethyl benzene, and xylene in the air were collected using 3M 3500 organic vapor monitors. Urine samples were collected before and after work shift, and urinary HA, methyl hippuric acid, mandelic acid, and phenylgloxylic acid concentrations were determined. In the first week, toluene concentrations were 2.66 ± 0.95 (mean ± SE) ppm, whereas ethyl benzene and xylene concentrations were 27.84 ± 3.61 and 72.63 ± 13.37 ppm, respectively, for all subjects. Pre–work shift HA concentrations were 230.23 ± 37.31 mg/g creatinine, whereas pre–work shift HA concentrations were 137.81 ± 14.15 mg/g creatinine. Mean urinary HA concentration was significantly greater in the pre–work shift samples than in the pre–work shift samples (p = 0.043). In the second week, toluene concentrations were much lower (0.28 ppm), whereas ethyl benzene and xylene were 47.12 ± 8.98 and 23.88 ± 4.09 ppm, respectively, for all subjects. Pre–work shift HA concentrations were 351.98 ± 116.23 mg/g creatinine, whereas pre–work shift HA concentrations were 951.82 ± 116.23 mg/g creatinine. Mean urinary HA concentration was significantly greater in the pre–work shift samples than in the pre–work shift samples (p <0.01); a significant correlation (r = 0.565; p = 0.002) was found between pre–work shift urinary HA levels and ethyl benzene exposure. This study showed that urinary HA peak was delayed to next morning for workers coexposed to toluene, ethyl benzene, and xylene; xylene and ethyl benzene probably played competitive inhibitors for metabolism of toluene. The study also presumed that urinary HA became the major metabolite of ethyl benzene at the end of work shift, when the exposure concentrations of ethyl benzene were 2.0 times those of xylene.     

Environmental and biological monitoring of benzene during self-service automobile refueling

Although automobile refueling represents the major source of benzene exposure among the nonsmoking public, few data are available regarding such exposures and the associated uptake of benzene. We repeatedly measured benzene exposure and uptake (via benzene in exhaled breath) among 39 self-service customers using self-administered monitoring, a technique rarely used to obtain measurements from the general public (130 sets of measurements were obtained). Benzene exposures averaged 2.9 mg/m(3) (SD = 5.8 mg/m(3); median duration = 3 min) with a range of < 0.076-36 mg/m(3), and postexposure breath levels averaged 160 microg/m(3) (SD = 260 microg/m(3)) with a range of < 3.2-1,400 microg/m(3). Log-transformed exposures and breath levels were significantly correlated (r = 0.77, p < 0.0001). We used mixed-effects statistical models to gauge the relative influences of environmental and subject-specific factors on benzene exposure and breath levels and to investigate the importance of various covariates obtained by questionnaire. Model fitting yielded three significant predictors of benzene exposure, namely, fuel octane grade (p = 0.0011), duration of exposure (p = 0.0054), and season of the year (p = 0.032). Likewise, another model yielded three significant predictors of benzene concentration in breath, specifically, benzene exposure (p = 0.0001), preexposure breath concentration (p = 0.0008), and duration of exposure (p = 0.038). Variability in benzene concentrations was remarkable, with 95% of the estimated values falling within a 274-fold range, and was comprised entirely of the within-person component of variance (representing exposures of the same subject at different times of refueling). The corresponding range for benzene concentrations in breath was 41-fold and was comprised primarily of the within-person variance component (74% of the total variance). Our results indicate that environmental rather than interindividual differences are primarily responsible for benzene exposure and uptake during automobile refueling. The study also demonstrates that self-administered monitoring can be efficiently used to measure environmental exposures and biomarkers among the general public.     

Antipyrine and metronidazole metabolism during occupational exposure to gasoline

Summary Antipyrine and metronidazole clearance was measured in 18 fuel-filling attendants by the single-sample method while the attendants were being exposed occupationally to gasoline; the measurements were repeated after 2–4 weeks with no exposure. Eighteen office workers were investigated simultaneously. The median concentration of gasoline in the breathing zone of the fuel-filling attendants during filling and cleaning operations was 270mgm^–3 (range 18–1758mgm^–3). Antipyrine clearance was 18% higher during exposure to gasoline than after 2–4 weeks of vacation (P<0.01), while antipyrine clearance was unchanged in the office workers. No change was found in metronidazole clearance in either group. Antipyrine clearance was on average 26% higher in the smokers than in the nonsmokers (P<0.05), while metronidazole clearance was similar in smokers and nonsmokers. We conclude that gasoline is an inducer of antipyrine elimination, with no impact on metronidazole elimination. This indicates that gasoline has a differential inducing effect on the hepatic drug metabolizing enzymes of man.     

Blood concentrations of selected volatile organic compounds and neurobehavioral performance in a population-based sample

The authors analyzed data from a national sample to examine the relationships between blood concentrations of selected volatile organic compounds (VOCs) and the assessment scores of neurobehavioral evaluation tests. They calculated summary statistics to describe blood concentrations of 30 VOCs. For instance, the 95th percentiles were as follows: 1,1,1-trichloroethane, 0.799 microg/l; 1,4-dichlorobenzene, 11.081 microg/l; benzene, 0.476 microg/l; and toluene, 0.281 microg/l. For 1,4-dichlorobenzene, benzene, dibromochloromethane, and trichloroethene, a blood level higher than the 95th percentile was associated with a poorer neurobehavioral assessment score than was a blood level up to the 95th percentile. The authors found a linear relationship between blood toluene concentration and the Serial Digit Learning Test score. The findings suggest that exposure to certain VOCs may result in poor neurobehavioral performance. The study was exploratory and precludes a conclusive statement, so further investigation is warranted.     

Vertical and horizontal variability of volatile organic compounds in homes in Eastern Germany.

A German study on Indoor Factors and Genetics in Asthma (INGA) will be conducted for 10 years in towns of Eastern and Western Germany. The study will include an indoor and outdoor exposure assessment of BTEX (BTEX=benzene, toluene, ethyl benzene, ortho-xylene, and meta- plus para-xylene) volatile organic compounds (VOCs). In a pilot study, which was conducted in Erfurt, a city in Eastern Germany, during the winter of 1994, vertical and horizontal variabilities of BTEX concentrations within the homes were examined in detail. Passive sampling was conducted in the living room (at 0.7, 1.2, and 2.0 m height), bedroom (2 m), kitchen (2 m), and outside the window of the living room, in 20 homes of randomly chosen adults. The 20 houses consisted often old concrete constructions ('Altneubauten'=OLD, constructed between 1960 and 1970) and ten new concrete constructions ('Neubauten'=NEW, constructed between 1970 and 1980). At each apartment, Organic Vapour Monitor (OVM) 3500 passive sampling devices (3M Company) were exposed for 7 days. After elution with carbon disulfide (CS2), the samples were analyzed with dual column gas chromatography (GC) with flame ionization detector (FID). No significant differences between the median values of the weekly average air concentrations of the BTEX VOCs in the different heights of measurement in the living rooms could be detected. Kitchen and living room median BTEX concentrations were equal and both significantly higher than the bedroom concentrations (except benzene). The indoor BTEX air concentrations were significantly higher than the outdoor concentrations (except benzene). Significant differences in BTEX indoor concentrations between OLD and NEW buildings could not be detected (except toluene).     

职业性苯暴露反-反式粘糠酸生物接触限值研究

目的研究职业性苯暴露反．反式粘糠酸（t,t—MA）生物接触限值。方法实验室建立生产环境空气中苯浓度的气相色谱检测方法及作业工人尿中t,t—MA含量的高效液相色谱检测方法,并通过检测苯暴露现场工人8h苯暴露水平及班前、班后尿中t,t．MA含量,研究其相关性。结果苯暴露者班前、班后尿中t,t—MA含量与其苯暴露水平有明显的相关关系。班前y（mg／gCr）=0．924＋0．108X（me／m^3）,r=0．62,P〈0．01;班后y（mg／gCr）=2．103＋0．177X（mg／m^3）,r=0．791,P〈0．01。结论根据我国作业场所空气中苯的国家卫生标准,按回归方程推导出职业接触苯生物接触限值,推荐职业暴露苯的生物接触限值为工作班班后尿t,t．MA含量为3．0mg／gCr,下一班班前尿t,t．MA含量为1．5mg／gGr。