A SURVEY OF URINARY HIPPURIC ACID AND SUBJECTIVE SYMPTOMS AMONG OCCUPATIONAL LOW TOLUENE EXPOSED WORKERS

［Original Article］

A SURVEY OF URINARY HIPPURIC ACID AND SUBJECTIVE
SYMPTOMS AMONG OCCUPATIONAL LOW
TOLUENE EXPOSED WORKERS

KAZUKO TANAKA¹, TAKAFUMI MAEDA¹, TOSHIO KOBAYASHI²,
MASATOSHI TANAKA³ and TETSUHITO FUKUSHIMA¹

¹Department of Hygiene and Preventive Medicine,
Fukushima Medical University School of Medicine, Fukushima
²Department of Health Sciences and Nursing, Institute of Health Sciences,
Faculty of Medicine Hiroshima University, Hiroshima
³Fukushima College, Fukushima

(Received August 6, 2003, accepted October 1, 2003)

Abstract: Biological monitoring of toluene exposure by urinary hippuric acid determination and a subjective symptom survey by self-administered questionnaire were performed in 20 workers at low toluene exposure in factories to evaluate the health hazard including dysfunction of nervous system.　Environmental monitoring was carried out using toluene gas detection tubes.　Urine samples were collected three times a day in order to measure hippuric acid: first before the commencement of work, then at the end of forenoon work, and lastly at the end of afternoon work.　Toluene vapor concentrations of throughout the workday ranged from 15.3 to 31.4 ppm.　The urinary hippuric acid concentrations correlated with the toluene concentrations of ambient air (r=0.58, p=0.01).　The subjective symptoms increased in close association with the exposure to toluene;the prevalence rate of subjective symptoms "during work" in the exposed group was 15 times higher than the rate of the non-exposed group (p<0.0001).　The prevalence rate of subjective symptoms "off-work" in the exposed group was 2.4 times higher than the rate of the non-exposed group (p<0.0001), and also the prevalence rate of "nineteen symptoms off-work which are apparently related to central nervous system (CNS) and autonomic nervous system (ANS)" in the exposed group was 1.8 times higher than the rate of the non-exposed group (p<0.05).　From these results, these subjective symptoms, which have been believed to be complained in high organic solvent exposure should be reassessed and reconsidered in evaluating the nervous system dysfunction and local irritation in relatively low toluene exposed workers.

Key words: occupational exposure, low exposure, toluene, urinary hippuric acid, subjective symptoms.

田中かづ子，前田享史，小林敏生，田中正敏，福島哲仁

Correspondence to: Kazuko Tanaka, Department of Hygiene and Preventive Medicine, Fukushima Medical University School of Medicine, Fukushima City 960-1295, Japan.
E-mail: ktanaka@fmu.ac.jp