Study of the relationship between neurological symptoms and solvent’s exposure markers in Tunisian workers

Chakroun R., Faidi F., Hedhili A, Nouaigui H., Ben Mansour H., Hidri A., Tounsi M., Kahouach L., El Mabrouk A., Nehdi H, Bahri S., Ben Abdelkader N., Ben Laiba M.

Central nervous system depression is the major effect of exposure to solvents. In this study we tried to evaluate the relationship between subjective neurological symptoms and the solvents exposure levels measured in the work place environment and monitored with urinary metabolites analysis.

The study included 77 workers in the paint, adhesives and ink industries and, 128 healthy control subjects non-occupationally exposed to solvents. For all subjects, personal and medical information had been collected by questionnaire. Spot morning and post-shift urine samples were collected from controls and exposed subjects respectively. Urinary metabolites of benzene, toluene, ethylbenzene, xylenes and n-hexane were determined using high performance liquid chromatography (HPLC) and gas chromatography (GC) techniques. For a representative sample of workers (n=17), individual exposure to 17 solvents at the workplace was monitored with dosimeters during the whole work-shift. They were later analyzed using a GC method.
Workers responses were compared with those of controls and evaluated with regard to solvents levels measured in air samples, and with urinary metabolites concentrations.

Significantly higher number of subjects complaining from sleepiness, fatigue and memory trouble was found in the group of exposed workers with regard to the control group. Among the exposed subjects, Air solvents concentrations and urinary metabolites levels were higher for subjects suffering from neurological symptoms. However, the difference was not statistically significant.
Even though there is no statistically significant relationship between exposure levels and neurological symptoms, the tendency towards neurological trouble among the highly exposed subjects is confirmed. Used vats cleaners in the paint industries are particularly exposed to solvent’s neurological effects.

Santé-Sécurité-Travail; 2007; 42:17-19.

Evaluation of hippuric acid as a biomarker of exposure to toluene

Chakroun R., Hedhili A, Faidi F., Nouaigui H., El Mabrouk A., Nehdi H, Bahri S., Ben Abdelkader N., Maâlej M., Khayati N., Ben Laiba M.

Toluene is one of the most widely used solvent in various Tunisian industries, and it is especially common in paint, ink and adhesives production plants. Since several new and more sensitive biomarkers have been proposed for the monitoring of exposure to toluene, the validity of urinary hippuric acid (HA) is more and more questioned. In this study we tried to evaluate HA as a biomarker of exposure to toluene in the Tunisian chemical industries conditions.
The study included 38 workers in a paint industry and, 38 healthy control subjects non-occupationally exposed to solvents. For all subjects, personal and medical information had been collected by questionnaire. Spot morning and half-shift (at noon) urine samples were collected from controls and exposed subjects respectively. HA was determined using a high performance liquid chromatography (HPLC) instrument, equipped with a diode array detector. Urinary creatinine was determined using the Jaffé method.

Except the workers who had to clean the used vats with solvents, HA values were lower than the biological exposure index (1600 mg/g creatinine). However, the average HA concentrations was significantly higher among exposed subjects than in controls (P=0.01).
Even though it is less specific than the other toluene biomarkers, HA is still a useful biological marker of exposure to toluene that can be used when a homogenous group of workers is studied.

Santé-Sécurité-Travail; 2006; 37:24-26.

An analysis technique for measuring urinary hippuric acid, a biomarker of exposure to toluene

Chakroun R., Hedhili A, Faidi F., El Mabrouk A., Ben Laiba M

A modified NIOSH method for the determination of urinary hippuric acid (HA) is described. HA is extracted from acidified urine sample using ethyl acetate and analyzed by the mean of a High Performance Liquid Chromatography (HPLC) instrument, equipped with a diode array detector. The separation was achieved on a LiChrosorb C18 –10 µm, 150 mm x 10 mm (length x diameter) column.

Extraction efficiency was optimized (97%). The extracted HA was found to be stable for 2 weeks both in ethyl acetate (CV=5.96%) and water (CV=3.99%). Thymol addition enhanced urine sample stability at (+4°C), but not frozen samples (-18°C).

The developed method is highly reproducible, with relatively low detection limit (12.6µg/l). However it is mobile phase consuming. The use of a lower diameter size column may reduce solvents consumption without deterioration of the chromatographic separation quality.

Santé-Sécurité-Travail; 2002 ; 23:19-22.

Methods for the monitoring of exposure to n-hexane

Chakroun R.

The paper provides summarized data on n-hexane. Sources of occupational exposure, metabolism and toxicity of the substance are briefly described. Environmental and biological methods for the monitoring of exposure to the solvent are explained. The article also describes how the monitoring results should be interpreted. Chromatograms illustrating the chromatographic profile of an air sample from a glue plant is presented with 2,5-hexanedione analysis in post-shift urine sample from a worker exposed to n-hexane.

Santé-Sécurité-Travail; 1999; 11:31-32.