Neurobehavioral testing

Dick RB, Ahlers H. 1998. Chemicals in the workplace Incorporating human neurobehavioral testing into the regulatory process. Am J Ind Med 33 439-453. 

In summary, neurotoxic effects of endosulfan are usually apparent only after acute ingestion of relatively high doses. Cumulative neurotoxicity does not appear to be significant. If the animal survives the acute toxic effects, then no long-term neurotoxic effects are evident from behavioral, gross, and microscopic observations. However, some impairment may occur that can be detected only by specialized neurobehavioral testing. 

Experimental exposure studies have attempted to associate various neurological effects in humans with specific trichloroethylene exposure levels. Voluntary exposures of 1 hours resulted in complaints of drowsiness at 27 ppm and headache at 81 ppm (Nomiyama and Nomiyama 1977). These are very low exposure levels, but the results are questionable because of the use of only three test subjects per dose, lack of statistical analysis, sporadic occurrence of the effects, lack of clear dose-response relationships, and discrepancies between the text and summary table in the report. Therefore, this study is not presented in Table 2-1. No effects on visual perception, two-point discrimination, blood pressure, pulse rate, or respiration rate were observed at any vapor concentration in this study. Other neurobehavioral tests were not performed, and the subjects were not evaluated following exposure. 

Amler RW, Anger WK, Sizemore OJ, eds. 1995. Adult environmental neurobehavioral test battery. 

Effects noted in study and corresponding doses Mild subjective neurological effects (eye and throat irritation, headache, fatigue, drowsiness) were reported at 200 ppm (LOAEL). No objective effects, as measured by dexterity and coordination tests, were seen. However, 50% of the subjects reported that the neurobehavioral tests required greater mental effort for them to perform. 

NS (older subjects, general population) Neurological Decreased performance in neurobehavioral tests 5.5 (mean) Payton et al. 1998... 

Behavioral Function in Adults. Neurobehavioral testing has revealed effects in adults at PbB levels (i.e., 40-80 pg/dL) below those causing encephalopathy (>400 pg/dL). Evaluations of occupationally exposed adults include several affected parameters at PbB levels between 40 and 80 pg/dL. Disturbances in oculomotor function (saccadic eye movements) in lead workers with mean PbB levels of 57-61 pg/dL were reported in a study by Baloh et al. (1979) with follow-up by Spivey et al. (1980) and in a study by Glickman et al. (1984). Deficits in hand-eye coordination and reaction time were reported in 190 lead-exposed workers (mean PbB level, 60.5 pg/dL) (NIOSH 1974). Most of the workers had been exposed for between 5 and 20 years. A similar study, however, reported no differences... 

Interim results of an investigation of 185 subjects and later results from the complete follow-up sample of 305 subjects in a prospective study of inner-city children (>80% black) bom in Cincinnati, Ohio, were reported by Dietrich et al. (1986, 1987a, 1987b). Maternal PbB levels were measured at the first prenatal visit cord PbB was measured at delivery infant PbB levels were measured at 10 days and at 3 months of age and neurobehavioral tests were performed at 3 and 6 months of age. Mean PbB levels were as follows prenatal (maternal)—8.0 pg/dL (range, 1-27 pg/dL) umbilical cord—6.3 pg/dL (range,... 

Bonithon-Kopp et al. (1986b) investigated another potential marker for lead exposure. Maternal and infant hair lead levels, determined from hair samples taken at birth, were found to be correlated inversely with results on neurobehavioral tests (McCarthy Scales of Children s Abilities) when the children were tested at 6 years of age. Other studies have also reported associations between hair lead levels and behavioral or cognitive test scores, but measures of lead in hair may not accurately reflect internal body burden of lead, and such data should not be used to evaluate internal dose-response relationships (EPA 1986a). 

Blood measurements of HCFC-141b were made prior to exposure, after each exercise period (55, 145, and 225 min into exposure), and 24 h postexposure (Utell et al. 1997). Mean peak circulating concentrations occurred after 225 min (approximately 4 h) of exposure and were 0.90, 1.65, and 2.98 fig/g of blood, respectively, at the three nominal concentrations. The relationship between exposure concentration and blood level appeared linear and reached a plateau at the 250-ppm concentration by 145 min. For all exposure concentrations, the blood concentrations at 55 min were within 80% of the concentrations at 225 min. For volunteers that underwent neurobehavioral testing, circulating HCFC-141b concentrations after 6 h at 500 and 1,000 ppm were 1.56 and 3.33 ug/g, respectively. These values were similar to those at 4 h. 

Pryor GT, Uyeno ET, Tilson HA, et al. 1983. Assessment of chemicals using a battery of neurobehavioral tests A comparative study. Neurobehav Toxicol Teratol 5(1 ) 91-117. 

Neurobehavioral tests have found slight, but statistically significant, performance decrements after 4-hour exposure to 250ppm, suggesting mild CNS depression at this level. ... 

The etiologic role of aluminum in neurological disorders has been of increasing interest in recent years. Subtle neurological effects (altered performance on neurobehavioral tests and increased reporting of subjective symptoms) have been detected in workers exposed to large amounts of aluminum dusts in factories. ... 

Animal studies have shown MEK to enhance the development of or increase the severity of neurotoxic effects due to methyl n-butyl ketone, ethyl butyl ketone, -hexane, and 2,5-hexanedione."MEK exposure did not, however, potentiate the neurobehavioral test decrements produced by acetone. Exposure to 200 ppm MEK or 100 ppm MEK plus 12 5 ppm acetone for 4 hours did not produce any significant effects in a variety of behavioral performance tests, whereas exposure to 250 ppm acetone caused some mild decrements. The liver and kidney toxicity of haloalkane solvents may also be potentiated by MEK. ... 

The neurobehavioral test battery for early central nervous system assessment, is actually an adaptation of the human Brazelton test (18, 19). 

A number of studies have been conducted examining the effects of sleep deprivation in medical trainees on performance on a variety of neuropsychological and neurobehavioral tests. Many of these studies have examined the impact of shortterm (on call) sleep loss on psychomotor function, sometimes in combination with simulated medical tasks. Reaction time, vigilance, and manual dexterity are among the parameters that have been shown to be negatively impacted by sleep loss in these studies, although these results are not universally found. For example, sleep deprivation in residents has also been associated with reduced per-... 

Knowing some potential target organs and systems affected by various tin compounds, it may be possible to develop biomarkers specific to effects. Examples include immunological and neurobehavioral tests as compound-specific pulmonary, liver, and kidney function studies. The primary objective of such biomarkers would be to predict adverse health effects in exposed individuals and populations. 

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