Screening for neurological health problems in employees exposed to solvents in a pathology lab

Introduction
Pathology lab employees are exposed to formaldehyde, toluene, xylene and chloroform. We assessed, the impact of chronic exposure on neuroperformance and -behavior by means of a computer-assisted test battery “Neuroscreen”, a validated instrument for occupational health surveillance to detect early neurological abnormalities in solvent exposed workers.

Methods
We collected data from 74 lab workers including personal history; exposure history; clinical neurological examination; Neurotoxic Symptom Checklist-60 and neurobehavioral tests, including Symbol Digit substitution (SDS), Digit Span Backwards (DSB), Simple Reaction Time (REA) and Hand Eye Coordination (HEC). Data of the lab group were compared with existing data of healthy controls (n= 53) using Mann-Whitney U tests. To calculate a final score, results of the tests were included in a decision tree; in which bonus/malus points were attributed in reference to the expected value.

Results
Cumulative exposure to solvents in the lab was 6,9 +/- 7,6 year (mean +/- SD). There was no difference in age distribution between the exposed (44.4 y) and controls (43.9 y). On the other hand, educational level was higher in the exposed (16.1 versus 10.8 y). The lab workers scored significantly worse on neuroperformance compared to controls: REA (p<0.001) and HEC (p=0.009). In contrast, DSB was better in the lab group (p=0.016), probably due to a higher education level. Lab workers scored significantly higher on the following NSC-60 categories: solvent related, mood, physical, fatigue, sleep, memory and breast complaints. After correction for personality, statistical difference remained significant for physical (p<0.001), mood (p=0.013) and fatigue (p=0.046) category. Neuroscreen endscores correlated positively with cumulative exposure (p = 0.000, spearman; r2= 0,190).

Discussion
Employees of an pathology lab, chronically exposed to solvents, perform worse on neurobehavioral tests versus healthy controls. Despite the higher personality score, we could attribute most of the important differences in neurobehavioral complaints to working conditions.