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E L Baker

Publications and source records attributed to E L Baker.

At least 55 records · Page 3Linked to original sources
PubMed1988

Experimental nitrous oxide exposure as a model system for evaluating neurobehavioral tests.

A recent study reported that a minimally suprathreshold dose of 20% nitrous oxide significantly affected performance on 3 of 9 computer-administered neurobehavioral tests. Performance decrements were observed in that study on 3 tests of psychomotor speed while other neurobehavioral functions such as visuospatial ability, verbal learning and mood were not significantly affected. The current study was undertaken to assess the reproducibility of these earlier results. Its experimental design was expanded to include an additional dose of the anesthetic and a more complex reaction time task implemented by the authors since the earlier study. Fifteen males aged 24-34 years were tested with the Neurobehavioral Evaluation System (NES) test battery on 4 separate occasions. An initial training session was followed by randomly presented control, 20%, and 40% drug sessions. Drug-induced decrements in performance were observed in the current study at the 20% dose for 2 of the 3 tests of psychomotor speed which had shown effects in the earlier study, and average decrement in performance on the third approached statistical significance in the current study (P = 0.055). Performance on a complex reaction time task was significantly affected at the low dose. The higher dose of nitrous oxide impaired performance on 8 of the 9 tests administered, and impairment on the ninth test was nearly significant (P = 0.055). Overall, these data are consistent with those in the previous study and with other reports that higher doses of nitrous oxide produce impairments in more cognitive CNS functions. Owing to its relative safety at low dosages, ease of administration, and ready acceptance by experimental subjects, nitrous oxide appears to be a useful model for evaluating the validity of neurobehavioral tests.

Adult↗
PubMed1988

Threshold effect in lead-induced peripheral neuropathy.

We previously demonstrated a negative correlation between blood lead level and motor nerve conduction velocity in 202 asymptomatic 5 to 9-year-old children living near a lead smelter in Idaho. Blood lead levels ranged from 13 to 97 micrograms/dL. To determine whether a threshold exists between blood lead level and maximal motor nerve conduction velocity, we conducted three regression analyses on these data: a "hockey stick" regression, a logistic regression, and a quadratic regression. We found evidence for a threshold in all three analyses: at a blood level of 30 micrograms/dL in the "hockey stick" regression, at 20 micrograms/dL in the logistic, and at 25 to 30 micrograms/dL in the quadratic. Neither age, sex, socioeconomic status, nor duration of residence near the smelter significantly modified the relationship. These analyses confirm that asymptomatic increased lead absorption causes slowing of nerve conduction, but they also indicate that measurement of maximal motor nerve conduction velocity is an insensitive screen for low-level lead toxicity.

Child↗
PubMed1988

Defining measurement precision for effort dependent tests: the case of three neurobehavioural tests.

For effort dependent tests, the estimation of measurement precision (reproducibility) is complicated by learning effects and submaximal efforts which inflate the variance of repeated trials. To illustrate an approach to the estimation problem, precision was evaluated for three neurobehavioural tests based on the responses of 76 boatbuilders tested on four separate test occasions within a one-week period. The average Coefficient of Variation (CV) for repeated trials within a test session was 6%, 16% and 13% for the Continuous Performance Test (CPT), Symbol-Digit substitution test (SDS) and the Hand-Eye motor-coordination test (HEM), respectively. In order to adjust for the effects of learning, the first trial(s) of a session were excluded from the calculation of performance level and its precision. This adjustment for learning significantly improved the precision for SDS and HEM to a CV of 8%. Inspection of the distributions of best efforts by trial number indicated that dropping the early trial(s) eliminated the best efforts of 34%, 22% and 7% of the subjects on the three tests respectively. When the worst two trials were excluded regardless of order, precision improved significantly to less than 5% for all three tests. On the basis of these results, a 5% precision rule for CPT and a 10% precision rule for SDS and HEM are provisionally recommended. The test results of subjects unable to meet this criterion should be identified, but in order to avoid selection bias, they should be analysed separately rather than excluded.

Adult↗
PubMed1988

Occupational risk factors and Alzheimer's disease: a case-control study.

A case-control study was conducted to assess occupational exposure to organic solvents and lead as risk factors for Alzheimer's disease. All case subjects were diagnosed at a Veterans Administration Hospital in Bedford, Massachusetts. Control subjects were selected from Massachusetts voter registration lists and matched by sex, year of birth, and town of residence. Information on occupational history was assessed by mailed questionnaire sent to the spouse or next of kin of the study subject. A total of 98 case and 162 control subjects were included in the matched analysis. No apparent association of increased risk of Alzheimer's disease was observed for ever having occupational exposure to organic solvents or lead.

Aged↗
PubMed1988

Measurements of respiratory illness among construction painters.

The prevalence of different measurements of respiratory illness among construction painters was examined and the relation between respiratory illness and employment as a painter assessed in a cross sectional study of current male members of two local affiliates of a large international union of painters. Respiratory illness was measured by questionnaire and spirometry. Longer employment as a painter was associated with increased prevalence of chronic obstructive disease and an interactive effect was observed for smoking and duration of employment as a painter. Multiple regression analysis showed a significant association between years worked as a painter and a decrement in FEV1 equal to about 11 ml for each year worked. This association was larger among painters who had smoked. The prevalence of chronic bronchitis was significantly associated with increased use of spray application methods.

Acute Disease↗
PubMed1988

Respiratory illness in the construction industry. Airflow obstruction among painters.

To assess the potential respiratory effects of exposure to paint products, the pulmonary function of 118 construction painters was compared to construction workers unexposed to paints (314 sheet metal workers). When compared to sheet metal workers, painters reported significant excess symptoms of cough (p less than 0.05), wheezing (p less than 0.001), and dyspnea (p less than 0.0001). Nonsmoking painters working at least 15 years in the trade had significant decrements in percent predicted forced expiratory volume in one second (%FEV1)(p less than 0.025) and in the percent predicted ratio of the forced expiratory volume in one second to the forced vital capacity (%FVC1/FVC) (p less than 0.025). Current smoking painters working less than 15 years in the trade demonstrated significant decrements in %FEV1 (p less than 0.05) and %FEV1/FVC (p less than 0.05). Restricting the analysis to painters, and controlling for smoking, we observed a significant relationship between years of exposure to paint products and airflow obstruction. Painters may be at risk for developing airflow obstruction and these changes appear to be related to the duration of exposure to paint products. Painters who smoke may be at risk of developing this obstructive process earlier than nonsmokers.

Adult↗
PubMed1988

The role of personal beliefs and social influences as determinants of respirator use among construction painters.

The purpose of this study was to identify and rank potential determinants of respirator use among painters in the construction industry. As part of a health survey of union painters, 169 male spray painters were questioned about their own beliefs concerning the consequences of wearing cartridge respirators, as well as about the perceived attitudes of others in the workplace toward respirators. Intended respirator use was more strongly associated with beliefs than was past use. The most important beliefs concerned discomfort or inconvenience. Other determinants that were associated with respirator use were respirator availability, cigarette smoking, and social influences. It was concluded that the most effective intervention strategy to increase respirator use would be multidimensional and that efforts to change only a worker's beliefs may have limited success.

Adult↗
PubMed1988

Effects of scopolamine and dextroamphetamine on human performance.

The effects of two drugs used to prevent symptoms of motion sickness in the operational environment were examined in this study of human performance as measured by computer-based tests of cognitive and psychomotor skills. Each subject was exposed repetitively to five tests: Symbol-Digit Substitution, Simple Reaction Time, Pattern Recognition, Digit Span Memory, and Pattern Memory. Although there have been previous reports of decreases in human performance in similar testing with higher dosages of scopolamine or dextroamphetamine, no significant decrements were observed with the operational-level combined dose used in this study (0.4 mg oral scopolamine and 5.0 mg oral dextroamphetamine.) The controversy over the use of combination drug therapy in this environment is discussed along with the indications for further research based on the findings.

Attention↗
PubMed1988

Sentinel event notification system for occupational risks.

Mandates for provider reporting systems have existed in a number of states for many years, but due to various shortcomings the potential for targeted surveillance of occupational illness and injury has not been realized. To achieve a more uniform, active approach to provider reporting, SENSOR will be created as a cooperative state-federal effort designed to develop local capability for the recognition, reporting, follow-up, and prevention of selected occupational disorders. To demonstrate the feasibility of this approach, NIOSH funded a small number of SENSOR projects in 1987. Ultimately, joint state-federal support will be essential to maintain SENSOR activity within a state. SENSOR should not be viewed as the sole approach to the surveillance of occupational illness and injury. Other approaches to the identification of cases of occupational illness or injury and to monitoring the trends of occurrence of these disorders have been developed by NIOSH and various states, and they will continue to function.

Evaluation Studies as Topic↗
PubMed1987

Lead poisoning in automobile radiator mechanics.

Exposure to lead occurs during automobile radiator repair when soldered joints are heated, but this relatively common hazard has received little public recognition. We therefore studied lead exposure among automobile radiator mechanics in the Boston area. Twenty-seven shops were surveyed, and most were found to be small and poorly ventilated. Seventy-five workers were interviewed and tested for blood lead and free erythrocyte protoporphyrin levels. Fifty-six of the 75 actually repaired radiators, and they had a mean blood lead level of 37.1 micrograms per deciliter (range, 16 to 73). Thirty-nine percent of these mechanics had levels higher than 40 micrograms per deciliter; hematologic, neurologic, and renal effects are known to develop at or above this blood lead level. Multiple regression analysis showed that the number of radiator repair work stations (an index of exposure) was the variable most significantly associated with increased blood lead levels. We conclude that excessive exposure to lead occurs frequently among radiator repair workers and should be prevented by improved ventilation, engineering controls, and the use of respirators (if indicated) while working.

Adult↗
PubMed1987

Estimation of long term exposure to mixed solvents from questionnaire data: a tool for epidemiological investigations.

Quantifying the exposure of construction painters to mixed organic solvents is difficult in the face of a lack of industrial hygiene data, the heterogeneity of the solvents used, and the variability in work practices which influences the amount of solvents to which a worker is actually exposed. This report describes an attempt to derive an estimate of airborne solvent exposure using questionnaire responses in a population of construction and maintenance painters. This exposure index (EI) is a weighted average of the total number of gallons used a year minus the fraction which would be absorbed by a respirator, where the weights are based on the method of application (spraying, rolling, brushing) and the presence of ventilation (per cent time inside v outside). An analysis performed to determine the sensitivity of the EI to variations in the values chosen for several parameters showed that the index is relatively insensitive to the underlying assumptions that we have used. One component of the EI (self report of hours worked) correlated well with union payroll records. The EI appears to provide a useful relative (not absolute) estimate of airborne exposure to organic solvent mixtures which may be used as a dose surrogate in epidemiological investigations.

Adult↗
PubMed1987

Neurobehavioural effects of occupational exposure to organic solvents among construction painters.

A cross sectional study of 101 construction painters was performed to investigate the relation between exposure to mixed organic solvents and changes in central nervous system function. Solvent exposure was estimated using questionnaire data to derive an exposure index (a measure of intensity of exposure) and to estimate the duration and frequency of exposure. Adverse effects on the central nervous system were assessed by self reported questionnaires and eight tests of a computer administered neurobehavioural evaluation system. Factor analysis of both measures of effect yielded factors both biologically plausible and in agreement with other empirical evidence. A consistent positive association was observed between most measures of exposure and the occurrence of neurotoxic symptoms, notably dizziness, nausea, fatigue, problems with arm strength, and feelings of getting "high" from chemicals at work. Associations with exposure were found with the neurobehavioural evaluation system tests of symbol digit substitution and digit span; however, no consistent pattern of effect on neurobehavioural function was observed. This pattern of the occurrence of neurotoxic symptoms without clear evidence of function deficit is consistent with the type 1 toxic central nervous system disorder as classified by the World Health Organisation.

Adult↗
PubMed1987

Risk factors for Alzheimer's disease: a case-control study.

A case-control study was conducted to assess personal and family medical history and the appearance of Alzheimer's disease. We compared 98 men with clinically diagnosed Alzheimer's disease and 162 controls, matched by sex, year of birth, and town of residence. Family history of dementia and personal history of depression were more frequent in patients. The number of cigarettes smoked was greater in cases.

Aged↗