Exposure to inhalable dust and its cyclohexane soluble fraction since the 1970s in the rubber manufacturing industry in the European Union.

OBJECTIVES: As exposures to airborne particulates in the European rubber industry might still be causing genotoxic risks, it is important to assess trends in levels of inhalable dust and its cyclohexane soluble fraction (CSF) between the 1970s and 2003. METHODS: 13 380 inhalable and 816 respirable dust and 5657 CSF measurements, collected within the framework of the European Union Concerted Action EXASRUB, were analysed. Hierarchical mixed effects models were applied to assess exposure trends, taking into account between-factory, between-worker/location and day-to-day variances. RESULTS: Geometric mean levels of inhalable dust and CSF exposure changed by -4% (range -5.8 to +2.9%) and -3% (range -8.6 to 0%) per year, respectively. Significant reductions in inhalable dust concentrations were found in all countries for handling of crude materials and mixing and milling (-7% to -4% per year), as well as for miscellaneous workers (-11% to -5% per year), while significant CSF exposure reductions were found in curing (-8.6% per year) and maintenance and engineering departments (-5.4% per year). CONCLUSION: These analyses suggest that on average exposure levels of inhalable dust and its CSF in the European rubber manufacturing industry have steadily declined. Most likely genotoxic risks have also lessened over time since exposure levels have decreased and the most toxic chemicals have been replaced. In addition to differences in exposure reductions and levels among various stages of the production process, large differences across countries were noted. These patterns should be taken into account in retrospective assessment of exposure for epidemiological studies assessing cancer risk in the rubber industry.

A comparison of neuropsychological tests for the assessment of chronic toxic encephalopathy.

BACKGROUND: From the viewpoint of the clinical neuropsychologist, it is not evident if the detection of solvent induced toxic encephalopathy (TE) could be optimized by a modification of the traditional test batteries, adding tests covering new dimensions or monitoring further functional domains. METHODS: To clarify this issue, TE patients were re-examined with (a) the tests traditionally used in screening for TE and (b) some tests hitherto less utilized within neurotoxicology, involving complex attention and frontal lobe functioning. RESULTS: The results do not indicate that tests of the latter category would be more sensitive to TE than the tests traditionally used. Using an optimized core battery, compiled of tests from both categories, the sensitivity and specificity levels reached a maximum of around 0.7 when using as criterion the reproduction of a subnormal test profile (TE type 2B). CONCLUSIONS: A combination of several traditional and a few newer tests is suggested to optimize the detection of TE. Repeated assessments over time are also recommended.

Psychological test performance during experimental challenge to toluene and n-butyl acetate in cases of solvent-induced toxic encephalopathy.

OBJECTIVES: This study determined whether performance in neurobehavioral tests deteriorates during subjectively annoying chemical challenge below known neurotoxic thresholds among persons with toxic encephalopathy with subjective hypersensitivity to chemicals. METHODS: Subjects with symptoms and previous neuropsychological test results compatible with toxic encephalopathy (TE) of either type 2A (N=12) or 2B (N=12) and unexposed referents (N=12) were challenged in an exposure chamber. In a counterbalanced design, the subjects were exposed on 2 occasions to increasing air concentrations of n-butyl acetate and toluene at levels well below the thresholds for neurotoxic effects. Attention and motor speed tests were given (i) in room air outside the chamber before the challenge, (ii) in room air inside the chamber before the exposure, (iii) at 12 ppm (44 or 56 mg/m3), and (iv) at 48 ppm (at 180 or 228 mg/m3). RESULTS: For both substances the TE groups showed a slight increase (deterioration) in the simple reaction-time task during chemical exposure, but not in the complex reaction-time task or in the digit symbol test of the Wechsler Adult Intelligence Scale. Contrary to reference subjects, the TE subjects did not show any improvement or learning effect in the digit symbol test over the chamber phases. n-Butyl acetate tended to affect cognitive functioning more obviously than toluene did. Suggestion or expectancy effects were not observed in any group in the clean-air baseline conditions. CONCLUSIONS: The results do not support the notion that men with subjective hypersensitivity to chemicals would be more affected than healthy men regarding cognitive functioning during annoying solvent exposure below thresholds for acute neurotoxic effects.

Suprathreshold intensity and annoyance reactions in experimental challenge to toluene and n-butyl acetate among subjects with long-term solvent exposure.

OBJECTIVES: This study explores reactions to low-level chemical challenge, aiming at the development of test procedures for assessing individual sensitivity to smells and chemicals. METHODS: Subjects with symptoms and neuropsychological test results compatible with toxic encephalopathy type 2A (TE-2A) and 2B (TE-2B) and unexposed referents (N=12 in each group) were challenged in an exposure chamber. Toluene exposure was started at 11 mg/m3, and it followed a geometric progression scale with a ratio of 2, until reaching 180 mg/m3. In a counterbalanced design, the subjects were similarly exposed to n-butyl acetate starting at a concentration of 14 mg/m3 and increasing to 228 mg/m3. At each exposure level, smell intensity was measured on a 7-step category scale. Mucous membrane irritation and annoyance reactions were rated on visual analogue scales. RESULTS: Both TE groups showed high sensitivity to the low-level solvent challenge, which provoked immediate annoyance and fatigue reactions. In particular the TE-2B group related smell intensity to various annoyance dimensions during exposure to n-butyl acetate, a pattern not observed during toluene exposure. The reference group clearly separated smell intensity and annoyance reactions in both exposure conditions. CONCLUSIONS: The reaction of the TE cases suggests that chemical sensitivity can be distinguished from normal annoyance reactions by the inability to differentiate between smell intensity and an experience of irritation from mucous membranes in air concentrations well below the trigeminal irritation threshold level. Fatigue coreactivity in challenges to single substances below the neurotoxic level may also be important.

Long-term follow-up of psychological distress, social functioning, and coping style in treated and untreated patients with solvent-induced chronic toxic encephalopathy.

Patients with organic solvent-induced toxic encephalopathy (TE) (n = 13) were followed up seven years after the application of an intervention program. They were also compared with untreated TE patients diagnosed at the same time (n = 26) and with unexposed referents (n = 39). Psychological distress, social function, and coping ability and style were measured with the Symptom Checklist-90, Interview Schedule of Social Interaction, and Sense of Coherence and Strategies to Handle Stress questionnaires. Both TE groups had unchanged function in neuropsychological tests. Members of the treated group had improved their social functioning and reduced their mental stress but were not any better than the untreated patients. Compared with referents, the TE patients continued to live with increased psychological distress and used predominantly emotionally focused strategies to cope with their problems. This can be a cause for concern in family life and can also make gainful work impossible.