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JAMES B. BURCH, PhD
Ichinose
TY, Burch JB, Noonan CW, Yost MG, Keefe TJ, Bachand A,
Mandeville R, Reif JS. Immune markers and ornithine
decarboxylase activity among electric utility workers. J
Occup Environ Med. 2004 Feb;46(2):104-12
The effects of a 60-Hz magnetic field (MF) exposure on white
blood cell ornithine decarboxylase (ODC) activity, natural
killer (NK) cell activity, lymphocyte phenotypes, and
differential cell counts were studied among 60 electric
utility workers. Personal MF exposure monitoring over 3
consecutive workdays was followed by collection of a
peripheral blood sample. There were no MF-related changes in
NK activity or the number of circulating neutrophils,
eosinophils, basophils, or T-lymphocytes (CD4, CD8, CD4:CD8
ratio). MF exposure intensity was associated with decreased
ODC activity (P<0.01) and lower NK cell counts (P=0.04).
Melatonin production, which stimulates the immune system,
was quantified on the night preceding immune marker
determinations. Exposure-related reductions in ODC activity,
NK and B cells, and monocytes were strongest among workers
with reduced melatonin production. The biological
significance or long-term health consequences associated
with these changes are not known.
Reif JS, Burch JB, Nuckols JR, Metzger L, Ellington D, Anger
WK. Neurobehavioral effects of exposure to trichloroethylene
through a municipal water supply. Environ Res. 2003
Nov;93(3):248-58
We studied a population-based sample of 143 residents of a
community in which the municipal water supply had been
contaminated with trichloroethylene (TCE) and related
chemicals from several adjacent hazardous waste sites
between 1981 and 1986. A hydraulic simulation model was used
in conjunction with a geographic information system (GIS) to
estimate residential water supply exposures to TCE; 80% of
the participants had potential TCE exposure exceeding the
maximum contaminant level (5 ppb). The Neurobehavioral Core
Test Battery (NCTB), tests of visual contrast sensitivity,
and the profile of mood states (POMS) were administered
approximately 6 years following peak concentrations of TCE
in municipal drinking water. Multivariate analysis of
variance adjusted for potential confounders was used to
compare mean test scores of residents classified by
estimated TCE exposure (< or =5, >5-10, >10-15, >15 ppb).
TCE exposure >15 ppb was associated with poorer performance
on the digit symbol, contrast sensitivity C test, and
contrast sensitivity D test and higher mean scores for
confusion, depression, and tension. We found evidence of a
strong interaction between exposure to TCE and alcohol
consumption; the associations for the NCTB and POMS among
persons in the high-exposure group who also consumed alcohol
were stronger and were statistically significant for the
Benton, digit symbol, digit span, and simple reaction time
tests, as well as for confusion, depression, and tension.
This study adds to the evidence that long-term exposure to
low concentrations of TCE is associated with neurobehavioral
deficits and demonstrates the usefulness of GIS-based
modeling in exposure assessment.
Noonan CW, Reif JS, Burch JB, Ichinose TY, Yost MG,
Magnusson K. Relationship between amyloid beta protein and
melatonin metabolite in a study of electric utility workers.
J Occup Environ Med. 2002
This study assessed the relationship between occupational
magnetic field exposure, the urinary melatonin metabolite
6-hydroxymelatonin sulfate (6-OHMS), and concentrations of
blood-borne soluble amyloid beta (A beta), a protein
associated with the hallmark lesions of Alzheimer's disease
(AD). Blood and urine samples were obtained from male
electric utility workers (n = 60) to quantify two lengths of
the protein in plasma, A beta (amino acids 1-40) and A beta
(1-42), and the urinary concentrations of 6-OHMS. Average A
beta levels were positively associated with categories of
magnetic field exposure, but this relationship was weak and
did not achieve statistical significance. The melatonin
metabolite was inversely correlated with A beta (1-42) and
the ratio of A beta (1-42) to A beta (1-40). This
observation is consistent with recent in vitro data and
provides a plausible mechanism for the association between
magnetic field exposure and AD that has been observed in
some studies.
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