The factor structure of the Profile of Mood States (POMS) and its relationship to occupational lead exposure.

The Profile of Mood States (POMS) is an instrument composed of six mood scales that were developed using clinical populations. This study examines the replicability of the POMS factor structure in lead-smelter workers and its association with demographic variables and lead exposure. Four hundred sixty-seven current and retired smelter workers completed the POMS, and a factor analysis was performed on the individual items. Two multiple regressions in the currently employed workers (n = 340) with a mean age of 40 years (range, 20-63 years) were used to compare the relationship of the resulting POMS factors with demographic characteristics and two measures of occupational lead exposure: current blood lead level (mean, 28 micrograms/dL; range, 4-62 micrograms/dL) and working-lifetime integrated blood lead level (mean, 711 micrograms-yr/dL; range, 1-1537 micrograms-yr/dL). Factor analysis produced one factor, labeled "general distress," that was composed mainly of items from five of the six POMS subscales (anger, confusion, depression, fatigue, and tension) and a second factor labeled "psychological adjustment." Demographic variables, including education, age, and alcohol use, were significantly related to the "general distress" factor score. After the effects of the demographic variables were accounted for, the "general distress" factor was significantly related to integrated blood lead level but not current blood lead level. Integrated blood lead level, a measure of cumulative lead exposure that included prior high exposure, was significantly related to the POMS "general distress" factor, while a current blood lead level that was relatively low was unrelated. As expected, POMS psychological adjustment was not related to lead exposure. Factor analysis did not support the use of six separate POMS subscales in this occupational population.

Curvilinear relationship between blood lead level and reaction time. Differential association with blood lead fractions derived from exogenous and endogenous sources.

Prior studies demonstrate an inconsistent relationship between occupational inorganic lead exposure and simple reaction time (SRT) performance. In this study, we administered a computerized SRT test to 78 currently employed lead smelter workers and then investigated the relationship between different measures of blood lead and components of SRT performance. The measures of blood lead included current blood lead (PbB) and mathematically derived blood lead fractions from the environment (PbB-env) and from bone (PbB-bn). Measures of SRT performance, obtained from 44 trials with interstimulus intervals (ISIs) ranging from 1 to 10 seconds, included median SRT (SRT-md), mean SRT for ISIs between 1 and 5 seconds (SRT-1-5), and mean SRT for ISIs between 6 and 10 seconds (SRT-6-10). Multiple regression analysis after adjustment for age and education revealed a curvilinear relationship between PbB and SRT-md. As PbB increased from 0 to 30 micrograms dl-1, SRT-md decreased, and only with PbB levels above 30 micrograms dl-1 did SRT-md increase. PbB terms accounted for 13.7% of the variance in this SRT measure (P < 0.01). The longer ISI variable, SRT-6-10, was found to be more strongly related to PbB, to have lesser variability across ISIs, and to be unrelated to age. Additional multiple regression analysis to examine the relationship between components of SRT and the PbB fractions, PbB-env and PbB-bn, showed only PbB-env to account for significant variance in SRT-md, (14.4%, P < 0.01), SRT-1-5 (9.7%, P < 0.03), and SRT-1-6 (15%, P < 0.01). We conclude that the relationship between PbB and SRT is U-shaped, that the SRT measure SRT-6-10 has properties that make it the preferred measure of SRT performance in future studies, and finally that only PbB-env, and not PbB-bn, is related to components of SRT.

Olfactory conditioning impairment following posttraining NMDA receptor blockade in neonatal rats.

Six-day-old Sprague-Dawley rat pups were exposed to peppermint odor paired with tactile stimulation (stroking the skin with a paint brush) for twenty 10-s conditioning trials, and their olfactory preference was tested the next day. In Experiment 1, pups that had received an injection of the noncompetitive N-methyl-D-aspartate receptor antagonist MK-801 (0.1 mg/kg, i.p.) either 30 min before or immediately after conditioning spent less time over the conditioned odor than saline-treated controls. In Experiment 2, pups received an injection of either MK-801 or saline 0, 30, or 60 min after the training period. There was a reduction in the preference for the conditioned odor in the animals receiving MK-801 immediately following training, but treatment with the drug at the other intervals did not produce a performance impairment. The impairment following immediate posttraining injection occurred with either 0.05 or 0.1, but not with 0.01 mg/kg of MK-801 (Experiment 3). Experiment 4 provided control data to confirm that pups that had experienced the procedures used in Experiments 1-3 showed greater preference for the conditioned odor than did naive pups or those receiving exposure to the odor without stroking. The data indicate that immediate posttraining activation of N-methyl-D-aspartate receptors is required for normal olfactory learning in neonatal rats.