Environmental and Molecular Mutagenesis - Legacy Tobacco ...

174 1989 EMS Abstracts
Notes - .+•FNTERLABOR/kTGRyoldMPARISON OF THE 32P-POSTLABELLING ASSAY FOR
AROMATIC DNIFADDUCTS IN WHITE BLOOD CELLS OF IRON FOUNDRY WORKERS .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
K .Savela 1 . Heme~kil D .H .Phillips2 . A .Hewer2 K .L .Putman3 .
K .Randerath3-'-f""-Tn titute of Occupational Health . Topeliuksenkatu
41aA . SF-00250 Helsinki Finland . 2 . Chester Beatty Laboratories .
Institute of Cancer Research . Fulham Road . London SW3 6JB . UK . 3 .
Department of Pharmacology . Baylor College of Medicine . Houston . TX
77030 USA
The 32P-postlabelling method was compared independently in three
laboratories in the analysis of human DNA samples, isolated from white
blood cells of iron foundry workers . who were occupationally exposed
to polycyclic aromatic hydrocarbons . The levels of aromatic DNA adducts
from the exposed foundry workers in the three laboratories varied
between 9 .2 +23 and 26+43 and from the controls between 1 .7t0 .7 and
3 .1±1 .7 adducts per log nucleotides . No effect of smoking was
observed in the present study . Each laboratory found large interindividual
variations in the level of adducts . Good correlations were
found between the results of the 32P-postlabelling assays carried
out in the three laboratories ; the correlation coefficients between
laboratories 1 and 2 . 1 and 3 and 2 and 3 were 0 .61 0 .62 . and 0 .45
respectively, all being statistically highly significant .
504
505
THE EFFECT OF CHWRINE ON THE MUTAGENICITY OF 3-CHLORO-4-(DICHLOROMER'HYW-5-HYDROXY-2(SH)-
FURANONE (MX) AND ITS RECOVERY FROM NATER SAMPLES . K. M . Schenck, J . R . Meier, H . P .
Ringhand and F C . Kopfler, U .S . Environmental Protection Agency, Cincinnati, OH 45268 .
MX has been shown to contribute significantly to the mutagenic activity of a number
of chlorinated drinking water samples . Preliminary studies on the recovery of MX by XAD
resin concentration showed substantially lower recoveries fran tap water samples than
from granular activated carbon (GAC)-filtered distilled water . These results prcmpted
us to examine the effects of residual chlorine on the recovery of MK . GACrfiltered
distilled water containing 0 to 3 mg/1 chlorine was spiked with MS at 50 rg/1 . The
samples were concentrated 4000-fold on columns containing XAD-8 over XAD-2, and then
tested for mutagenicity in the SaLnonellq/microsame assay using TA100 without S9 activation
. The results showed that the percent of spiked MX recovered, as determined by the
level of mutagenic activity present, decreased as the concentration of chlorine increased
. This effect could be explained by the reaction of chlorine with MX . To examine
this directly, the mutagenicity and UV absorbance of M8 in the presence of chlorine
were monitored over time using high reactant concentrations (1-20 mg/1 for MXf 1-120
mg/1 for chlorine) . At 1, 2, or 3 mg/1 chlorine, the decrease in the mutagenicity of
Huc over time was significantly greater than that observed in the absence of chlorine .
The concentration of MX . as determined by its absorbance at 250 nm, also decreased in
the presence of chlorine . This decrease was both time and dose dependent . These results
suggest that the level of MX present in tap water depends not only on the amount
of MX produced by the chlorination of humic substances but also on the rate of degradation
with residual chlorine. (Abstract does not necessarily reflect EPA policy) .
506
SYSTEMIC GENOTOXIC AND TOXIC COMBINATION EFFECTS OF N-NITROSODIMETHYLAMINE
AND SO2 IN THE LIVER FOLLOWING INHALATION EXPOSURE . Schmezer,P. Pool,B .L .
Liegibel,U . Zeller,W.J. Klein,R.G . Institute for Toxicology and Chemotherapy, German
Cancer Research Center, INF 280, 6900 Heidelberg, FRO .
A series of studies is being performed to determine which effects the environmental
pollutant S02 may have on the rat liver carcinogen NDMA . Here, short-term in vivo data
on systemic combination effects of SOz and NDMA are presented . Our previous studies
had shown that pretreatment (inhalation) of Sprague-Dawle rats with 60ppm 802 for
two weeks reduced the amount of DNA-single strand breaks ~SSB) observed in explanted
hepatocytes incubated in vitro with NDMA. The strand breakage induced by 25-50
pMoles/2x10s hepatocytes was reduced by apr. 20% . Accordingly, we have now
investigated wether this decrease in genotoxicity caused by S0i is also apparent when
both S02 and NDMA are administered simultaneously in viva We used a sensitive shortterm
in vivo assay with which DNA-SSB are detected in intact cells isolated from treated
animals . Inhalation exposure with NDMA alone revealed astonishingly low doses to be
genotoxic in the liver. The doses were similar to those found to be effective after
gavage . The inconstant respiratory frequency of the animals, however, made exact
dosing of low NDMA levels difficult . Therefore, short-term oral NDMA application was
preferred as exposure route for the combination experiments . We used lh in vivo
exposure to NDMA at doses of 0 .5-1 mg/kg . This mode of application resulted in
comparable amounts of strand breakage as the 25-50 pMoles NDMA induced in 2404
hepatocytes in vltro. So far, the results of the combination treatment indicate that in
contrast to the in vitro situation, the in vivo genotoxicity of NDMA was not affected by
a two week SO2 treatment (10 and SOppm) . This observation as well as the possible
impact of the formed sulfite (product of SOt + water) on the intracellular ATP level of
the explanted hepatocytes will be discussed .
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