Neuropsychological Symptoms among Workers Exposed to Toluene and Xylene in Two Paint Manufacturing Factories in Eastern Thailand

The study analyzed the exposure factors that may lead to neuropsychological symptoms among 92 workers who were exposed to xylene and toluene and 100 workers who were not exposed to the solvents. The airborne concentration of xylene and toluene was evaluated with personal passive badges. The levels of methyl hippuric acid and hippuric acid in urine were assessed, and interviews were performed to observe the neuropsychological symptoms that may result from exposure to the solvents. The result showed that the average concentration for the exposed group of xylene in the paint company working environment was 2.7 (SD = 2.4) ppm and the average concentration of toluene was 9.5 (SD = 10.4) ppm. The average level of methyl hippuric acid in urine was 78 (SD = 74.7) mg/g creatinine. Factors that affected the neuropsychological symptoms included the following. (1) The impact of age: the risk (adjusted odds ratio) for getting psychosomatic symptoms in persons over 40 and exposed to xylene was 9.5 and the aOR of those exposed to toluene was 8.3. (2) The impact of not providing personal protective equipment was found to be sleep disturbance; it was found that the aOR of those exposed to xylene was 3.9, and the aOR of those exposed to toluene was 4.4. In summary, periodic examination of workers by occupational physician is needed for detection of early neuropsychological effects, especially psychosomatic symptoms, and sleep disturbances.

Xylene: its toxicity, measurement of exposure levels, absorption, metabolism and clearance

Xylene is an aromatic hydrocarbon widely used in industry and medical technology as a solvent. Health and safety authorities in most countries, including Australia, recommend a threshold limit value (TLV) of 100 ppm in the working environment. Recently, the amount of the major metabolite of xylene, methylhippuric acid (MHA), in urine has been recommended as a better indicator of exposure. The American Conference of Governmental Industrial Hygienists has recommended an upper limit for this indicator, called a biological exposure index (BEI), of 2.0 g MHA/L urine (SG 1.016). Xylene vapour is absorbed rapidly from the lungs, and xylene liquid and vapour are absorbed slowly through the skin. Of the xylene absorbed, about 95% is metabolised in the liver to MHA and 70 to 80% of metabolites are excreted in the urine within 24 hours. However, the many variables which affect the absorption, metabolism and clearance of xylene include exercise, alcohol intake, cigarette smoking, co-exposure to other solvents, gender, and gastrointestinal, hepatic and renal pathology. Xylene in high concentrations acts as a narcotic, inducing neuropsychological and neurophysiological dysfunction. Respiratory tract symptoms are also frequent. More chronic, occupational exposure has been associated with anemia, thrombocytopenia, leukopenia, chest pain with ECG abnormalities, dyspnea and cyanosis, in addition to CNS symptoms. Concomitant exposure to xylene and other solvents, including toluene, affected hematological parameters, liver size, liver enzymes, auditory memory, visual abstraction, and vibration threshold in the toes. Normal metabolic pathways were altered and significant increases in some serum bile acids may reflect early liver damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurobehavioral impairment and seizures from formaldehyde

Three patients were evaluated for effects of formaldehyde on central nervous system function. Three patients had used formalin, formaldehyde with or without phenol, to fix whole animals for 14-30 y, and a fourth patient was covered several times by formaldehyde and phenol rainout from manufacturing spills. All were disabled, and two had developed seizures. They had elevated mood state scores (82 to 162) and elevated symptom frequency scores (111 to 138), compared with referent subjects. There was excessive fatigue, somnolence, headache, difficulty remembering, irritability, and instability of mood. Compared with referents, choice reaction time was prolonged in four of four (4/4) subjects, blink latency was delayed in 2/2, balance was abnormal in 3/4, and visual fields were constricted in 2/3. Cognitive functions, measured by Culture Fair, block design, and digit symbol tests, were impaired in all. Delayed verbal recall and visual reproduction were impaired in 3/4. Perceptual motor speed on slotted pegboard and trail making A and B tests was reduced in 4/4. Errors on fingertip number writing were abnormal in all. Long-term memory was decreased in only one. Extensive use of formaldehyde at work or repeated airborne exposure to formaldehyde and phenol appears to have impaired central nervous system function.