BEHAVIORAL-EFFECTS OF LOW-LEVEL EXPOSURE TO HG-0 AMONG DENTAL PROFESSIONALS - A CROSS-STUDY EVALUATION OF PSYCHOMOTOR EFFECTS

A cross-study design was used to evaluate the sensitivities of five ps ychomotor tasks previously used to assess preclinical effects of low-l evel Hg-0 (urinary less than or equal to 55 mu g/l). Pooling dental pr ofessional subject populations from six studies conducted over the las t 6 years, a larger study population was obtained with a high degree o f uniformity (N = 230). The five psychomotor tests were: Intentional H and Steadiness Test (IHST); Finger Tapping; The One-Hole Test; NES Sim ple Reaction Time (SRT); and Hand Tremor. Multivariate analyses were c onducted following the hierarchical analysis of multiple responses (HA MR) approach. First, multiple scores of each test were combined into a single-factor (or related summary) variable and its reliability was e stimated. Second, multiple regression analyses were conducted includin g log-transformed [Hg-0]U levels, age, gender, and alcohol consumption in each model. Computed were both B and b(u), the magnitudes of the l og-Hg-0 standardized coefficient, respectively uncorrected and correct ed for dependent variable attenuation due to unreliability. Results in dicated remarkable differences in the effects of relative level of Hg- 0 on psychomotor performance. Significant associations were found for the IHST factor (B = 0.415, p < 10(-6)), followed by finger tapping, w hich was relatively meager and insignificant (B = 0.141, p = 0.17). Th e IHST results hold the greatest occupational relevance for dental pro fessionals who rely on manual dexterity in restorative dentistry. Furt her, this statistical approach is recommended in future studies for co ndensation of multiple scores into summary scores with enhanced reliab ilities useful in correcting for attenuation relationships (B(u)s) wit h exposure levels. (C) 1998 Elsevier Science Inc.