According to these results, exposure to benzene concentration lower than 15 ppm can induce depression of the circulating B-lymphocyte level and therefore this fact could be used to develop a promising method for health surveillance of benzene-exposed workers. However, considerably more effort in the research on benzene immunotoxicity, especially in the search for suitable health surveillance methods, is still required.

The aim of the study was to establish a correlation between biomarkers of exposure and cytogenetic test results in workers occupationally exposed to benzene and toluene, with special reference to confounding factors influencing the outcome of the cytogenetic test. The incidence of structural chromosome aberrations and sister chromatid exchanges was studied in the peripheral blood lymphocytes cell genome of 49 female shoe-makers, mean age 38 years, mean length of occupational exposure 17 years and in a group of 27 well-matched controls. Workers were exposed to concentrations of benzene up to 15 ppm and of toluene up to 50 ppm. The presence of benzene and toluene in the workers' blood samples, and the presence of phenol in pre-and post-shift urine were considered proof of occupational exposure. Chromosomal aberration analysis revealed a significant increase in dicentric incidence in the exposed group compared to the controls (P=0.004). However, significant correlation between cytogenetic test results and the exposure biomarkers was not established.On the contrary, correlation between the cytogenetic test results and data on confounding factors (e.g. age and alcohol consumption), was marked. The major point raised by this study is the influence of confounding factors on the cytogenetic test outcome. This imposes the need for caution in the interpretation of cytogenetic test results, and ultimately in the estimation of individual genotoxicity risk related to low level benzene exposure.

We investigated colour vision impairment in 45 male workers occupationally exposed to toluene (mean value of toluene concentration in ambient air = 119.96 ppm) and in 53 controls. Colour vision was evaluated by Lanthony-D-15 desaturated test and expressed as Age and Alcohol Intake Adjusted Colour Confusion Score (AACDS) or types of dyschromatopsia. Exposure was evaluated by measurement of toluene concentration in ambient air and blood, and hippuric acid and orthocresol determined in urine after the workshift. A statistically significant higher AACDS value was established in the exposed subjects compared to the controls (p < 0.0001). There was no significant difference between AACDS values on Wednesday morning compared to Monday morning. In the exposed group AACDS significantly correlated with the concentration of toluene in ambient air, concentration of toluene in blood and the concentration of hippuric acid in urine after the workshift (all p < 0.0001). Dyschromatopsias were detected in both groups, although no significant difference between groups was established. In the exposed group concentration of toluene in ambient air, alcohol intake and age explained 35.1%, concentration of toluene in blood, age and alcohol intake explained 19.9%, and concentration of hippuric acid in urine and age explained 19.2% of the variation in type III dyschromatopsia. Concentration of toluene in ambient air and age explained 28.3% of the variation in total dyschromatopsia, and concentration of hippuric acid and age explained 13.8%. In the control group, age and alcohol intake explained 19.6% of the variation in type III dyschromatopsia. In exposed workers a significant difference was found in the AACDS value compared to controls. However, no significant difference was found in the prevalence of colour vision loss in the yellow-blue and/or red-green axis. Based on the results of this study the authors conclude that the effect of toluene on colour vision can be chronic and that the possible reparation period in colour vision impairment is longer than 64 hours.

This study suggests that toluene can impair color vision.

Digital photoplethysmography and skin thermometry are both measures of circulation in the skin of the fingers. These methods and a cold provocation test were performed on 29 chain-saw workers grouped in stages 0, 1, 2, or 3 according to the Stockholm Workshop scale of hand-arm vibration syndrome, and on 16 controls. The reduction of photoplethysmographic amplitude after the cold test reflects the degree of vasoconstriction, and the recovery rate demonstrates passive vasodilatative capacity. Both tests were found to distinguish all vibration--exposed subjects, including those without clinically manifest vibration-induced white fingers, from the controls. With a 75% reduction in photoplethysmographic amplitude as a discriminating threshold, the sensitivity for the detection of Raynaud's phenomenon was 62% and the specificity, 87%. The discriminating threshold of 90% for recovery rate yielded a sensitivity of 69% and a specificity of 72%.