Assessment of memory status among workers exposed to mercury

ABSTRACT

Mercury [Hg] has well established toxic effects on the central nervous system. To study the memory status of workers exposed to mercury. A comparative cross-sectional epidemiological study was carried out among 100 workers exposed to mercury vapour in a fluorescent lamp factory in Alexandria, Egypt. The comparative group comprised 100 workers not exposed to Hg or any other occupational hazard or systemic disease that may affect the memory status. All workers included in this study were interviewed to collect data on personal characteristics, medical and occupational histories, recent and remote memory status. Urine samples were collected to asses the level of mercury in urine in micro g/liter. The results of this study indicated that the mean age of workers was 40 +/- 8.46 years, their mean duration of exposure was 17.21 +/- 8.4 years and their mean urine mercury level was 32 micro g/L. Hg exposed workers showed a significant deficit in the ability to remember remote events and events that happened 10 years ago. Moreover the mean percentage of story events recalled was significantly lowered in mercury exposed workers. On the other hand there was no significant difference between Hg exposed workers and their controls in forward and backward repetition of numbers and in the mean percentage of pictures recalled. After allowing for the effects of age, and smoking, mercury exposed workers were at a higher risk of developing recent and remote memory disorders than unexposed workers. This study highlights the potential for deterioration of memory status among workers exposed to mercury in the fluorescent lamp industry, where deficits in both recent and remote memory were significantly associated with the level of mercury in urine