G. Maranelli

Breath and blood levels of benzene, toluene, cumene and styrene in non-occupational exposure

SummaryBenzene, toluene, cumene and styrene were measured in the breath and blood of two groups of individuals. The first group included individuals belonging to a hospital staff, the second group included chemical workers who were not exposed to the abovementioned chemicals. The chemical workers were examined in plant infirmaries on the morning before the start of the workshift, and the hospital staff in the hospital infirmaries. One environmental air sample was taken in the infirmaries for each individual at the moment of the biological samplings. The environmental concentrations of benzene and styrene were significantly higher in the infirmaries of the chemical plant than in the infirmaries of the hospital. On the other hand, the environmental concentrations of toluene and cumene were not significantly different in the plant infirmaries and in the hospital infirmaries. In the hospital staff the alveolar concentrations of benzene, toluene and styrene were significantly lower than those in the chemical workers. In the hospital staff the blood concentrations of benzene, toluene and styrene were not significantly different from those in the chemical workers. Only the blood cumene concentration was significantly higher in the chemical workers. In hospital staff, smokers showed alveolar and blood concentrations of benzene and toluene that were significantly higher than those measured in the non smoker hospital staff. With reference to chemical workers, only alveolar benzene concentration was significantly higher in smokers than in non smokers. A significant blood benzene difference was found between the non smoker hospital staff and the non smoker chemical workers. A correlation between alveolar and environmental concentrations was found for benzene, toluene and cumene, but not for styrene. In the two groups of individuals, correlations between blood and alveolar concentrations of the four compounds were also studied.

Reference values for blood benzene in the occupationally unexposed general population.

SummaryBlood benzene was determined by gas chromatography-mass spectrometry in 431 “normal” subjects, subdivided into 155 rural subjects and 276 urban subjects. Blood benzene (mean value 262 ng/l) was significantly lower in rural (200 ng/l) than in urban (296 ng/l) workers, as well as differing significantly between 293 non-smokers and 138 smokers (205 ng/l and 381 ng/l, respectively). Among non-smokers, values were significantly higher (307 ng/l) in 76 chemical workers. In the total study population, in 95% of cases blood benzene was less than 718 ng/l, the 95th percentile being 514 ng/l in non-smokers vs 901 ng/l in smokers and 576 ng/l in rural vs 822 ng/l in urban subjects. Within each population subgroup, the difference between non-smokers and smokers was statistically significant, except among office workers (non-smokers 234 ng/l, smokers 304 ng/l). Blood benzene (y) was directly proportional to the number of cigarettes smoked (x) (y = 201 + 12x; r = 0.44; n = 431), and inversely proportional to the interval between the last cigarette and the time at which the blood sample was taken (z) (log y = 6.167 − 0.0015 z; r = −0.461; n = 135). The blood half-life of benzene was about 8h. The multiple correlation between blood benzene (Cb), number of cigarettes per day (x) and time since the last cigarette (z) is: Cb = 417 + 7.2x − 0.41z (n = 135; R = 0.20; P < 0.00001).

Blood acetone concentration in normal people and in exposed workers 16 h after the end of the workshift

SummaryAcetone levels were measured by gas chromatography mass spectrometry (GC-MS) in environmental and alveolar air, blood and urine of 89 non-occupationally exposed subjects and in three groups of workers exposed to acetone or isopropanol. Acetone was detected in all samples from non-exposed subjects, with mean values of 840 μg/l in blood (Cb), 842 μg/l in urine (Cu), 715 ng/l in alveolar air (Ca) and 154 ng/l in environmental air (Ci). The ninety-fifth percentiles were 2069 μg/l in Cb, 2206 μg/l in Cu and 1675 ng/l in Ca. The blood/air partition coefficient of acetone was 597. Correlations were found in Cb, Cu and Ca. In specimens sampled at the end of the workshift from subjects occupationally exposed to acetone, a correlation was found in the blood, urine, alveolar and environmental air concentrations. The blood/air partition coefficient of acetone was 146. On average, the blood acetone levels of workers were 56 times higher than the environmental exposure level, and the concentration of acetone in alveolar air was 27% more than that found in inspiratory air. The half-life for acetone in blood was 5.8 h in the interval of 16 h between the end of the workshift and the morning after. The morning after a workshift with a mean acetone exposure of 336 μg/l, blood and urinary levels were 3.5 mg/l and 13 mg/l, respectively, which were still higher than those found in “normal” subjects. It can be concluded that endogenous production of acetone and environmental exposure to acetone or isopropanol do not affect the reliability of biological monitoring of exposed workers, even 16 h after low exposure.

Blood styrene concentrations in a “normal” population and in exposed workers 16 hours after the end of the workshift

SummaryBlood styrene was measured by a gas chromatography-mass spectrometry method in 81 “normal people” and in 76 workers exposed to styrene. In the normal subjects, styrene was also tested in alveolar and environmental air. Styrene was found in nearly all (95%) blood samples. Average styrene levels in the normal subjects were 221 ng/1 in blood (Cb), 3 ng/1 in alveolar air (Ca) and 6 ng/1 in environmental air (Ci). Styrene levels did not differ significantly between smokers and non-smokers, 95% of values being below 512 ng/1 in Cb, 7 ng/1 in Ca and 15 ng/l in Ci. In workers with an average exposure to styrene of 204 μg/l, at the end of the workshift, mean blood styrene concentration was 1211 μg/l. In blood samples collected at the end of the Thursday shift, styrene levels were significantly higher (1590 μg/1) than those found at the end of the Monday shift (1068 μg/l. A similar difference was found in samples taken the morning after exposure (60 and 119 μg/l, respectively). Significant correlations between blood and environmental styrene were found both at the end of the shift and the morning after exposure (r=0.61 and 0.41, respectively). In workers occupationally exposed to styrene, 16 h after the end of the workshift, blood styrene (94 μg/l) was significantly higher than that found in the normal subjects (0.22 μg/l). The half-life of blood styrene was 3.9 h.

Reference values for blood toluene in the occupationally nonexposed general population

SummaryBlood toluene was measured by gas chromatography — mass spectrometry in 232 occupationally nonexposed subjects, consisting of 126 rural and 106 urban workers, and 37 chemical workers. Mean blood toluene was significantly lower in rural (698 ng/l) and urban workers (984 ng/l) than in chemical workers (2789 ng/l). Blood toluene was not significantly different between the rural and urban workers or among the urban workers with different jobs. Smokers had significantly higher levels (median 606 ng/l) than nonsmokers (median 424 ng/l). Subjects who had smoked at least one cigarette in the last 2 h before blood sampling had significantly higher blood toluene (median 1170 ng/1) than those who had not smoked during this time (median 693 ng/l), for whom the level was not significantly different from that in nonsmokers. Blood toluene in the total population was less than 2863 ng/l in 95% cases.

Is hypertension a confounding factor in the assessment of blood lead reference values

In order to evaluate whether hypertension can be considered as a confounding factor in the setting up of reference values for blood lead, we examined the results of a cross sectional study which evaluated the relationship between lead in blood and hypertension in a sample of 254 males and 271 females of a general population not occupationally exposed to lead. The statistical analysis and in particular the multiple logistic regression showed that, even if some well-known confounding factors such as age, sex, overweight, smoking and alcohol are taken into account, blood lead levels are well correlated with hypertension. The results suggest that even modest lead absorption is able to influence the probability of being hypertensive. The relationship between blood lead and hypertension and their relationship with the main confounding factors involved in the determination of reference values of metals in blood are discussed.

Blood concentrations of carbon disulphide in dithiocarbamate exposure and in the general population

SummaryBlood carbon disulphide (CS2), both free and total, was determined by gas chromatography-mass spectrometry in 112 “normal” subjects and in 20 subjects employed in a dithiocarbamate factory, comprising ten blue-collar workers involved in dithiocarbamate production and ten white-collar office staff. The ten production workers were examined over two workshifts, the first at the beginning of the week (Monday) and the second after an intervening period of at least 1 day. Three blood samples were taken for each shift studied, one prior to starting work, one at the end of the shift and the third 16 h after the end of the shift (on the following morning). The mean CS2 blood levels measured in the 112 normal subjects was 663 ng/l for the free fraction and 3178 ng/l for the total. In 16 blood samples taken from the ten dithiocarbamate factory office workers, the mean free and total CS2 blood levels were 846 and 4140 ng/l, respectively, i.e. not significantly different from those observed in the normal subjects. At the end of the first 8-h shift, the ten dithiocarbamate factory production workers had free and total CS2 values of 1070 and 8471 ng/l, respectively, which were significantly higher than those observed prior to starting work (240 and 4738 ng/l). All the total CS2 levels measured in the shop-floor workers, with the sole exception of the values recorded prior to the start of the Monday shift (4738 ng/l), ranged from 7047 to 8471 ng/l and were significantly higher than those measured in the white-collar staff (4140 ng/l).

Ubiquitous pollution by n-hexane and reference biological levels in the general population.

Summaryn-Hexane levels were determined by gas chromatography and mass spectrometry in environmental air and in the alveolar air, blood and urine of a group of subjects aged on average of 38 years who had not been occupationally exposed to this hydrocarbon. n-Hexane was found in all environmental air samples examined (n=49), with the mean concentration being 104 ng/l (limit values, 1–279 ng/l). It was also found in all 49 samples of alveolar air, with the mean concentration being 50 ng/l (variation limit, 1–304ng/l). In 64 samples of urine, n-hexane was found in only 50 samples, with the mean concentration being 1,417 ng/l (limit values, 34–8,820 ng/l). In 77 of the 90 blood samples taken, a mean concentration of 608 ng/l was detected (variation limit, 15–7,684ng/l). Particularly the haematic and urinary concentration showed significant differences among the nine groups of individuals classified according to their work activity. The lowest levels were found in the blood and urine of farmers: 270 and 298 ng/l, respectively. The highest values were found for chemical workers (1,377 and 411 ng/1), respectively printers (585 and 2,691 ng/l respectively), and traffic wardens (740 and 8,820 ng/l, respectively). In all, 95% of the determinations of n-hexane yielded values of < 255 ng/l in environmental samples, < 105 ng/l in alveolar air, < 1,475 ng/l in blood and < 5,875 ng/l in urine. A comparison of these data revealed a significant correlation between environmental levels and alveolar (r/s = 0.769; P<0.00001), haematic (r/s = 0.624; P<0.0002), and urinary (r/s = 0.597; P<0.0005) values for n-hexane.

Tentative reference values for some elements in broncho-alveolar lavage fluid.

The concentrations of Fe, Mn, Pb and Cr have been determined in broncho-alveolar lavage (BAL) fluid of 25 subjects without occupational or abnormal environmental exposure to metals, using the AAS method. The numerous factors which can interfere with the results in pre-analytical and in analytical phases are stressed. Metals concentrations in BAL are expressed in micrograms/l. They were not correlated with the volume of fluid recovered, the total cells, alveolar macrophages and erythrocytes. The results were not modified by stratification considering age and sex. Iron concentrations were higher than others, probably due to higher environmental exposure and partly to its essential role in humans. The diagnostic significance of element determination in BAL fluid and the relationship with exposure and lung load is discussed.

Urinary thallium: Critical problems, reference values and preliminary results of an investigation in workers with suspected industrial exposure

Using a sensitive ETA ASS method, urinary thallium (Tl-U) has been measured in a group of non-exposed individuals and in two groups of workers with suspected industrial exposure. In non-exposed subjects (72 healthy males aged 41 +/- 11 years) the Tl-U mean value was 0.22 mu/l (range 0.05-0.61). Significantly higher values were found in two groups of workers (30 and 21 subjects) employed in two cement factories and two cast iron foundries (mean Tl-U value: 0.38 and 0.33 mu/l, respectively; range 0.06-1.2). Thallium has been determined in coal, raw materials and, in one factory, also in environmental samples, but no detectable levels were found. The analytical problems connected to urinary thallium determination and the preliminary results of biological monitoring in non-exposed individuals and in workers are discussed.