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0187 Alcohol consumption as a confounder in neurobehavioral studies of neurotoxicants
  1. Rita Bast-Pettersen1,
  2. Maxim Chashchin2,
  3. Valery Chashchin2,
  4. Yngvar Thomassen1,
  5. Dag G Ellingsen1
  1. 1National Institute of Occupational Health, Oslo, Norway
  2. 2Northwest Public Health Research Centre, St. Petersburg, Russia

Abstract

Objectives To study the effects of manganese (Mn) exposure and alcohol consumption on tremor.

Method Tremor was measured in 137 shipyard welders (age 39.9) and 137 referents (turner/fitters) (age 40.1) with the Catsys TREMOR. Alcohol consump­tion was assessed by measuring serum carbohydrate deficient transferrin (sCDT).

Results The geometric mean (GM) of Mn air concentration was 214μg/m3 (range 1–3230). The GM concentrations of Mn in whole blood (B-Mn) and urine (U-Mn) were 12.8μg/L and 0.36μg/g creatinine versus 8.0μg/L and 0.07μg/g creatinine in the referents. Concentration of sCDT (%) was 0.71 in welders and 0.65 in referents.

No significant differences in tremor measures were found when all welders were compared with all referents. Altogether twenty-­five subjects had sCDT above the pathological level 1.7%.

The subjects with high sCDT had increased tremor. Dominant hand: Tremor Intensity 0.21 m/s2, compared to 0.15 m/s2 (p < 0.001) for subjects with sCDT < 1.7%. Non-dominant hand: Tremor Intensity 0.22 m/s2 vs 0.15 m/s2; (p < 0.001).

The same pattern was found when the 16 welders with sCDT ≥ 1.7% were compared with welders with sCDT values < 1.7%. The concentrations of the biological exposure indicators were similar in the welders with sCDT ≥ 1.7% compared to the other welders (B-Mn 12.8 vs 12.7 μg/L; U-Mn 0.34 vs 0.36 μg/g cr.; S-Mn 1.3 vs 1.0 μg/L).

Conclusions No effect of manganese exposure on tremor was observed, in contrast to a large effect from alcohol consumption. The results suggest that alcohol consumption can operate as a serious confounder in epidemiological studies of neurotoxicants.

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