The effects of low exposure to inorganic mercury on psychological performance was investigated: the study groups included eight chronically exposed workers and 20 who were only occasionally exposed. These were compared with a control group of 22 subjects from the same plant who were not exposed to mercury. All subjects were administered the WHO test battery to detect preclinical signs of central nervous system impairment: the battery includes the Santa Ana (Helsinki version) test, simple reaction time, the Benton test, and the Wechsler digit span and digit symbol. In addition, the Gordon test was used to study personality profiles and the clinical depression questionnaire. Urinary mercury was used as indicator for internal dose. To this effect, urinary mercury observed in workers examined from 1979 to 1987 was evaluated. Of the pyschic functions explored by behavioural tests, only short term auditory memory was found to be impaired in the chronically exposed workers (p < 005 compared with the controls). The chronically exposed workers were also found to be more depressed than those in the two other groups. No changes of visual motor functions were observed. The personality of the occupationally exposed workers was found to be considerably changed compared with that of the control group. On the basis of the results obtained and in view of urinary mercury mean concentrations in the exposed group which were 30-40 ugll over the years, it is suggested that the TLV-TWA for mercury should be lowered to 0-025 mglm' and that the biological urinary exposure indicator for biological monitoring should be 25 pg/l. In 1980, however, Zedda et al studied the workers of a fluorescent lamp manufacturing factory who were exposed to mean mercury vapour concentrations of 0-027 mg/m3 (range 0 005-0145) with urinary mercury excretion of 93-4 ± 30-4.20 Electromyography showed early disturbances in the peripheral nervous system that were indicative of subclinical neuropathy. In the light of these findings the authors suggested that the 0-01 mg/m3 concentration should be adopted as the TLV for mercury. Again in 1984, Piikivi et al studied the workers of a chlorine manufacturing plant exposed to inorganic mercury and observed a change in psychological verbal intelligence and memory tests administered to subjects with a mercury urinary excretion of about 50 pg/l, or with blood mercury concentrations of 15 pg/l, and with ambient mercury estimated at between 0-022 and 0-028 pg/m3. On the forms of these findings, the authors suggested that the TLV for mercury should be reduced to 0-025 pg/m321. These data show that in the presence of environmental mercury concentrations below the TLV proposed by ACGIH, preclinical changes may be detected in the central nervous system.It is the purpose of the present study to make a further contribution to the definition of the relation between low exposure to inorganic mercury and the onset of early changes in the central nervous system-the preferred target organ for the poison. We
The structural characterisation of the adducts formed by in vitro interaction of hemoglobin (Hb) with 1,2,3,4-diepoxybutane (DEB), the most reactive 1,3-butadiene (BD) metabolite, was obtained by liquid chromatography/electrospray ionisation mass spectrometry (LC/ES-MS) analysis of modified tryptic peptides of human hemoglobin chains. The reactive sites of human hemoglobin towards DEB and its hydroxylated derivatives (trihydroxybutyl (THB)-derivatives) were identified through the characterisation of alkylated tryptic peptides by matrix-assisted laser desorption/ionisation tandem mass spectrometry (MALDI-MS/MS). Based on this characterisation, a procedure was set up to measure the Hb-adducts of THB-derivatives by isotope dilution mass spectrometry with the use of a deuterated peptide standard. The results obtained here could permit optimisation of molecular dosimetry of BD-adducts, and extension of the analysis to the biological monitoring of occupational exposure to butadiene.
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