Work‐site clinical and neurobehavioral assessment of solvent‐exposed microelectronics workers

Abstract

Twenty-five workers, five currently and 20 formerly involved in the manufacture of hybrid microcircuits, underwent clinical evaluations at the request of a management-union committee concerned about chronic solvent exposures in a research and development laboratory. A battery of neurobehavioral tests was administered to compare the solvent-exposed group with 32 age-, gender-, ethnicity-, and education-matched controls. The tests included: MMPI-I, hand grip strength, tactile sensitivity, dexterity, color discrimination, visual acuity and contrast sensitivity, and tests selected from the computerized Neurobehavioral Evaluation System (NES2). Clinical narratives and retrospective exposure assessments in the study group suggested chronic low-level exposure to solvents, with intermittent acute excursions. Work-related diagnoses included upper respiratory mucosal irritation and sinusitis (44%), lower respiratory reactive airway disease (12%), and dermatitis (5%). Three workers (12%) had findings consistent with a solvent-induced encephalopathy. Significant differences (after Bonferroni correction) were found between the two groups on 5 of 11 NES subtests: symptom scale, mood scale, finger tapping, simple reaction time, and symbol-digit substitution. Differences also reached significance for overall vibration sensitivity thresholds, visual contrast sensitivity, and grip strength. The MMPI average clinical scale elevation was significantly higher in the exposed group than controls. These results support an association between chronic low-dose solvent exposure and measurable neurobehavioral changes.

Apartment residents' and day care workers' exposures to tetrachloroethylene and deficits in visual contrast sensitivity.

“…A similar VCS deficit was observed in the day care investigation where workers were exposed to a daytime mean of 2,150 µg/m 3 perc in air. The VCS deficit in the day care investigation was measured about 6 weeks after on-premises cleaning ceased, suggesting that the effect is persistent or permanent, as reported in previous solvent exposure studies (23)(24)(25)(26). Taken together, these data suggest that the lowest observable adverse effect level (LOAEL) for airborne perc exposure may lie within the range of indoor air perc concentrations bracketed by the Altmann and colleague (20) study (mean = 4,980 µg/m 3 ; median = 1,360 µg/m 3 ) and the residential study (mean = 778 µg/m 3 ; median = 350 µg/m 3 ).…”

“…The VCS deficits were likely of neurologic origin because the exposed and control groups did not differ in visual acuity, indicating that the groups did not different in optical refraction or in the ability to focus images on the retina (40,48). The VCS deficits spanned the spatial frequency spectrum in both exposed groups, similar to the VCS deficit profiles seen in other solvent exposed populations (21)(22)(23)(24)(25)(26) and in contrast to the VCS spatial-frequency profiles observed in populations exposed to methyl mercury (44,45) and inorganic mercury (46,47). Differences between the shapes of altered VCS spatial-frequency profiles can indicate differential effects of various toxic exposures (40)(41)(42)(43)(44)(45)(46)(47)(48).…”

“…Persistent or permanent VCS deficits in the presence of normal visual acuity have been observed in workers exposed to styrene (21,22) and mixed solvents (23)(24)(25)(26), as have color discrimination deficits (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38) in the absence of detectable optical, retinal, or optic nerve head pathology (39). VCS, a nonspecific indicator of subclinical visual impairment (40), also revealed neurologic effects associated with exposure to toxic Pfiesteria sp.-inhabited estuaries (40)(41)(42), with lead and mercury exposure (43)(44)(45)(46)(47), and was useful in differentiating vision effects from other exposure-induced deficits in neurobehavioral functions (48).…”

Vibrotactile threshold measurement for detecting peripheral neuropathy: defining variability and a normal range for clinical and research use

“…Peripheral neuropathy occurs as a complication of diabetes, a component of several common and many rare diseases, and also as an adverse health outcome from exposure to various chemical substances or physical factors in the workplace [1][2][3]. The population prevalence of peripheral neuropathy has been reported to be approximately 2.4%, rising with age to 8% [4].…”

Personal exposure to benzene from fuel emissions among commercial fishers: comparison of two-stroke, four-stroke and diesel engines

“…Although most of the neurotoxic effects associated with organic solvent mixtures including fuel and constituents of fuel, have been observed among highly exposed painters, carpet layers, printers and jet fuel workers (Baker and Fine, 1986;Baker, 1994;Broadwell et al, 1995;Escalona et al, 1995;Tsai et al, 1997), workers, such as fishers with potentially lower exposure may also experience neurotoxic effects. The study of health effects associated with low-level occupational exposure to fuel presents methodological challenges because it is difficult to determine an appropriate unexposed comparison group.…”