1. MRI Imaging identifies brain tissue changes in solvent exposed individuals
Thuomas KA Moller C Odkvist LM Flodin U Dige N
MR imaging in solvent-induced chronic toxic encephalopathy.
In: Acta Radiol (1996 Mar) 37(2):177-9
PURPOSE: To use MR to examine patients with CNS symptoms indicating +chronic intoxication. MATERIAL AND METHODS: Thirty-two subjects exposed to industrial solvents for 5 to 28 years and 40 age-matched, healthy controls were examined. RESULTS: All patients showed decreased signal in the basal ganglia on T2 weighted images. In 11 of the patients the white matter showed diffuse hyperintensity with loss of the grey white matter discrimination and with distinct periventricular hyperintensities in 5 of the patients. The controls had no pathological changes in the brain. CONCLUSION: Although the relatively small number of patients may obscure the significance, findings observed on T2-weighted images were patchy periventricular hyperintensities and hypointensities in the basal ganglia. Fast spin- echo is a good technique with fast acquisition of images with true spin-echo contrast features.
2. Specificity of neurotoxic effects depends upon specific toxicity of the solvent
Kyrklund T
The use of experimental studies to reveal suspected neurotoxic chemicals as occupational hazards: acute and chronic exposures to organic solvents.
In: Am J Ind Med (1992) 21(1):15-24
The nervous system differs from many other body organs by its central control of vital functions and its low regeneration capacity. Organic solvents have, as a group, been suspected to have neurotoxic effects. Because of their similar physical properties and the fact that in industrial uses, they are often present in various mixtures, organic solvents have also been regarded, unfortunately, to induce common neurotoxic effects. However, it is evident from experimental studies using specified exposure conditions that different organic solvents have very diverse neurotoxic effects and also that the toxic mechanism may differ between acute and chronic exposure. No specific method used to describe a neurotoxic effect or single toxic response can be used for the overall occupational risk assessment of all organic solvents. Each solvent has to be considered as having its own unique toxic effects.
3. Sub-clinical neurological alterations in painters exposed to organic solvenst
Bleecker ML Bolla KI Agnew J Schwartz BS Ford DP
Dose-related subclinical neurobehavioral effects of chronic exposure to low levels of organic solvents.
In: Am J Ind Med (1991) 19(6):715-28
One hundred eight-seven workers (mean age +/- SD; 42 +/- 8.8 years) in two paint manufacturing plants were examined to determine if sustained low-level exposure to mixed organic solvents resulted in the painters' syndrome (a psycho-organic syndrome). The test battery consisted of a medical and occupational questionnaire, the Present State Examination, the Zung Depression Scale, the Scandinavian Questionnaire 16, a neuropsychological battery, and vibration thresholds. Solvent exposure, expressed as total hydrocarbon of combined selected solvents, was quantitated using 13-15 years of personal breathing zone samplings. Linear regression analysis controlling for several confounding variables demonstrated significant correlations between increasing exposure to mixed organic solvents and neurobehavioral performance for vibration threshold and several neuropsychological tests. Dose-related effects of chronic solvent exposure on neurobehavioral outcomes (all subclinical) were shown, but "typical" symptoms characteristic of the painter's syndrome were not found.
4. Neurotoxic exposure related to multiple chemical sensitivities
Lohmann K Prohl A Schwarz E
[Multiple chemical sensitivity disorder in patients with neurotoxic illnesses]
Vielfache Chemikalienunvertraglichkeit (Multiple Chemical Sensitivity Disorder) bei Patienten mit neurotoxischen Gesundheitsstorungen.
In: Gesundheitswesen (1996 Jun) 58(6):322-31 (Published in German)
The data of 466 subjects suffering from neurologic disorders which are suggested to be caused by neurotoxic agents in their environment retrospectively was evaluated and documented. Among these cases there were 151 subjects with symptoms of Multiple Chemical Sensitivity Disorder (MCSD). The relationship between the neurological health impairments and neurotoxic agents in the environment of these patients was characterised using five different categories (probable = A, possible = B, uncertain = C, unclarified = D, not probable = E). From the 466 patients 320 subjects (69%) could be assigned to the categories A and B, respectively. Within theses 320 cases with chronic neurotoxic health impairments 136 subjects (79 females and 57 males) showed signs of MCSD. Age and gender of cases as well as duration and character of exposure to neurotoxic substances retrospectively were assessed from the explicit files of the patients, which had been made anonymous for this purpose. Frequency of characteristic symptoms of neurotoxicity were analysed. Results are given for patients with neurotoxic health impairments with MCSD (n = 136) and without MCSD (n = 184). Neurotoxic substances which were used as indoor wood preservatives (mainly Pentachlorophenol and/or Lindane) were found to be the causative agents in 63% of the cases with neurotoxic health impairments and MCSD. Other important neurotoxic substances to which the patients were mainly exposed were organic solvents (25%), formaldehyde (15%), dental materials (15%), pyrethroides (13%), and other biocides (19%) (multiple exposures were possible). The time of exposure was calculated as being > or = 10 years for 55% of the patients with MCSD and for 50% of the group with neurotoxic health impairments but without MCSD. Out of the 184 cases with neurotoxic health impairments but without MCSD there were 22%, and out of the 136 cases with MCSD there were 39% who showed all symptoms of chronic fatigue syndrome. 53% of the cases with MCSD had an allergic disposition compared to only 20% of the cases without MCSD. This work is not a controlled epidemiological study but a retrospective documentation and evaluation of data related to environmental medicine. With the present documentation in this purely descriptive manner the proof of a causal relationship was not possible or intended. But because corresponding epidemiological studies are lacking, this documentation can give important information on characteristic features of Multiple Chemical Sensitivity Disorder and chronic neurotoxic health impairments. Such information is essential for planning and carrying out epidemiological studies urgently needed in this field.
5. Solvents affect mental function in screen printers in absence of obvious symptoms
White RF Proctor SP Echeverria D Schweikert J Feldman RG
Neurobehavioral effects of acute and chronic mixed-solvent exposure in the screen printing industry.
In: Am J Ind Med (1995 Aug) 28(2):221-31
This 2-year prospective study examined the neurobehavioral effects of acute and chronic exposure to mixed solvents in workers in a screen printing business. A total of 30 subjects participated in the study in two field testings over a 12 month period. Each subject completed a detailed medical and occupational questionnaire, had a neurological examination, and underwent a battery of neuropsychological tests. Industrial hygiene investigation identified the following chemical exposures as present: toluene, methyl ethyl ketone, mineral spirits, beta-ether, methylene chloride, and acetic acid. Different departments and jobs had varying degrees of exposure to these chemicals, the highest exposures being in the ink mix area and the screen washroom area. However, all exposure levels were below recommended threshold limit values. Persons categorized as having higher acute exposure demonstrated significantly impaired test performance on tasks involving manual dexterity, visual memory, and mood. Those with higher chronic exposure demonstrated significantly poorer performance on visual memory tasks and mood. Results suggest that the mixed solvents used in the screen printing industry have an effect on central nervous system functioning in the absence of obvious clinical disease.
6. Neurological deficit following low dose organic solvent exposure in workers
Foo SC Lwin S Chia SE Jeyaratnam J
Chronic neurobehavioural effects in paint formulators exposed to solvents and noise.
In: Ann Acad Med Singapore (1994 Sep) 23(5):650-4
Twenty-one male paint formulators with an average age of 41.3 years (range 27-53), educational level of 7.4 years (range 5-10) and exposure level of 0.09 times Threshold Limit Value (TLV) index of solvent mixture (range 0.003-0.24 times TLV-index) for 20.2 years (range 7-39) were studied with a battery of neurobehavioural performance tests including digit span, digit symbol, Benton visual retention, finger tapping, grooved peg board, and aiming test. A group of 21 male workers matched for age (mean 40.8 years, range 25- 53) and education (mean 6.9 years, range 5-12), and with no history of exposure to neurotoxic agents were selected as controls. In all the neurobehavioural tests, the exposed workers' performances were observed to be poorer than the controls'. Statistically significant differences were observed in digit span, grooved peg board, and the Z score after adjusting for age, level of education and ethnicity. The least square means for digit span were 11.7 (standard error [SE] 0.77) and 9.2 (SE 0.79); for grooved peg board were 60.5 (SE 2.1) and 69.7 (SE 2.1); and for neurobehavioural Z score were 0.02 (SE 0.11) and 0.50 (SE 0.11) in the controls and exposed workers respectively. The exposed group also performed significantly poorer in aiming test error score and digit span when compared to the controls after adjusted for age, education and ethnicity. The least square means for aiming test error score were 6.5 (SE 2.7) and 12.8 (SE 2.8) for the controls and exposed workers respectively.
7. Neurological deficit following low dose organic solvent exposure in workers
Colvin M Myers J Nell V Rees D Cronje R
A cross-sectional survey of neurobehavioral effects of chronic solvent exposure on workers in a paint manufacturing plant.
In: Environ Res (1993 Oct) 63(1):122-32
Neurobehavioral impairments in 84 workers with long-term exposure to organic solvents in a paint manufacturing plant were examined cross sectionally. The World Health Organization (WHO) Neurobehavioral Core Test Battery, the NES-2 computerized battery, and four additional South African tests were used. Exposure to solvents was determined by using company industrial hygiene data as well as from an industrial hygiene survey of current total solvent levels in air. Indexes for cumulative exposure and average lifetime intensity of exposure were calculated for groups of homogeneously exposed workers in each department. Exposure levels were below the AGGIH threshold limit values. Multiple linear regression revealed that education level, age, and alcohol consumption were strong predictors for several neurobehavioral test scores. After adjusting for potential confounding from this source, average lifetime intensity of solvent exposure was the most significant predictor of the NES-2 Continuous performance test (measuring sustained visual attention) score of the WHO Digit span backward test score (measuring attention span and double tracking). Pursuit aiming (measuring fine visuomotor tracking speed) was significantly associated with the cumulative exposure index, possibly indicating early neurotoxic effects.
8. Symptoms recorded in low dose solvent exposure and neurotoxicity
Kishi R Harabuchi I Katakura Y Ikeda T Miyake H
Neurobehavioral effects of chronic occupational exposure to organic solvents among Japanese industrial painters.
In: Environ Res (1993 Aug) 62(2):303-13
To investigate the relationship between chronic exposure to organic solvents and changes in central nervous system function, industrial painters were compared with an age- and education-matched referent group of nonexposed workers. Eighty-one male painters completed a symptom questionnaire. Twenty painters underwent both questionnaire and neuropsychological examinations. From the results of pairwise comparisons of the symptoms, dry and scaly skin, being easily depressed without reason, coldness of hands and legs, being easily irritated without reason, loss of appetite, dizziness, and unsteadiness occurred statistically significantly more often among the exposed subjects than among the referents. Performances on the Digit symbol test and vocabulary test scores (synonyms) in exposed subjects were significantly lower than those of controls. In multiple regression models, controlling for age, education, and alcohol intake, a significant relation was found between the duration of the solvent exposure and poor performance in both the Block design and Digit span tests. The relation between toluene exposure and poor performance in both the Santa Ana coordination test and the Benton visual retention test was also significant. The results suggest that a symptom inquiry and some behavioral tests are helpful for detecting the possible effects of exposure to low levels of organic solvents. However, no consistent pattern was observed in regard to the effects of organic solvent exposure on neurobehavioral function, which is coincident with the type I toxic central nervous system disorder as classified by the World Health Organization.
Dr Mark Donohoe
email: mark@geko.net.au
revised 4/3/98