[Association between nucleotide excision repair gene polymorphisms and chromosomal damage in coke-oven workers].

OBJECTIVE: To investigate the association of polymorphisms of nucleotide excision repair genes and chromosomal damage in peripheral blood lymphocytes among coke-oven workers. METHODS: The genotypes of ERCC1 C19007T, ERCC2 C22541A, ERCC2 G23591A, ERCC2 A35931C, ERCC4 T30028C, ERCC5 G3507C and ERCC6 A3368G among 140 coke-oven workers and 66 non-coke-oven controls were determined by PCR-PFLP methods. Chromosomal damage was detected by cytokinesis-block micronucleus (CBMN) assay. RESULTS: Multivariate analysis of covariance revealed that in coke-oven workers, the ERCC1 19007 CC genotype exhibited significantly higher CBMN frequency [(1.05 +/- 0.68)%] than did the CT [(0.81 +/- 0.66)%] (P = 0.01) or TT [(0.66 +/- 0.37)%] (P = 0.05) or CT + TT genotypes [(0.75 +/- 0.63)%] (P = 0.004). For the ERCC6 A3368G polymorphism, AA genotype exhibited significantly higher CBMN frequency [(1.00 +/- 0.69)%] than did the AG [(0.67 +/- 0.42)%] (P = 0.05) or AG + GG genotypes [(0.66 +/- 0.41)%] (P = 0.02). Stratification analysis found the significant association between the two polymorphisms, ERCC1 C19007T and ERCC6 A3368G, and the CBMN frequencies were most pronounced in older workers. In addition, for the polymorphism of ERCC2 G23591A, GA carriers had significantly higher CBMN frequencies [(1.40 +/- 0.63)%] than those GG carriers [(0.98 +/- 0.59)%] (P = 0.01) in older workers. CONCLUSIONS: Our results suggested that polymorphisms of ERCC1 C19007T, ERCC6 A3368G and ERCC2 G23591A were associated with the CBMN frequencies in coke-oven workers.

Urinary excretion of benzo[a]pyrene metabolites following intravenous, oral, and cutaneous benzo[a]pyrene administration.

The effect of the administration route, dose, and sampling time on the total urinary excretion of four major benzo[a]pyrene (BaP) metabolites, 3-hydroxyBaP (3-OHBaP), 9-hydroxyBaP 9-hydroxyBaP (9-OHBaP), trans-4,5-dihydrodiolBaP (4,5-diolBaP), and trans-9,10-dihydrodiolBaP (9,10-diolBaP), was studied in male Sprague-Dawley rats exposed to a single intravenous, oral, and cutaneous dose of 2, 6, 20, and 60 mumol BaP/kg. Urine samples were collected at 24-h intervals following treatment. Over the 0-72 h period and for a given dose, amounts of BaP metabolites were 3-OHBaP > 4,5-diolBaP > > 9-OHBaP following intravenous and oral dosing, and 3-OHBaP > > 9-OHBaP > or = 4,5-diolBaP after cutaneous treatment. 9,10-diolBaP was barely detected. On the other hand, amounts of 3-OHBaP and 4,5-diolBaP excreted in urine over the 0-72 h period and for a given dose appeared in the following order: intravenous approximately oral > or = cutaneous. Amounts of 9-OHBaP excreted varied as follows: oral > or = cutaneous > intravenous. For all routes of administration, excretion of 4,5-diolBaP was almost complete over the 0-24 h period in contrast with 3-OHBaP and 9-OHBaP. Peak excretion of 3-OHBaP and 9-OHBaP was reached in the 0-24 h period following intravenous and oral treatment and in the 24-48 h period following cutaneous application. Overall, for a given administration route and dose, there were variations in the time profiles between metabolites. In general, there was nonetheless a good correlation between the BaP dose and urinary excretion of 3-OHBaP, 9-OHBaP, and 4,5-diolBaP. Furthermore, total urinary excretion of a specific metabolite, its time profile, and the relative proportion of the metabolites studied depended on the administration route. Data also suggest that a measure of the concentration ratio of the different metabolites could reflect the time and main route of exposure.

Urinary excretion kinetics of pyrene and benzo(a)pyrene metabolites following intravenous administration of the parent compounds or the metabolites.

The detailed urinary excretion profiles of 1-hydroxypyrene (1-OHP) and benzo(a)pyrene (BaP) metabolites were studied following acute intravenous administration of pyrene and BaP, respectively, or after injection of the metabolites themselves. Male Sprague-Dawley rats were exposed to 4 mumol 1-OHP/kg or 15 mumol pyrene/kg. Other rats were exposed to 2 mumol/kg of a mixture of four BaP metabolites (3-hydroxyBaP (3-OHBaP), 9-hydroxyBaP (9-OHBaP), trans-4,5-dihydrodiolBaP (4,5-diolBaP), and trans-9,10-dihydrodiol (9,10-diolBaP)) or 40 mumol BaP/kg. Urine samples were collected at frequent intervals over 48 or 96 hr. Injection of both pyrene and 1-OHP produced similar biphasic excretion profiles. An apparent first order half life of 6.9 and 6.6 hr, respectively, could be calculated for the second phase of elimination. Comparable 3-OHBaP excretion profiles were obtained after injection of BaP or a mixture of BaP metabolites. Elimination kinetics showed at least two steps, the second step having a first order apparent half life of 8.1 and 7.6 hr following BaP and BaP metabolites injection, respectively. Time profiles of 4,5-diolBaP excretion following administration of BaP or a mixture of BaP metabolites were almost identical. Elimination was linear and a first order apparent half life of 3.1 and 3.6 hr could be calculated. Elimination of 4,5-diolBaP was much more rapid than that of 3-OHBaP and complete within 24 hr postdosing. Therefore, results suggest that (1) phase I biotransformation is not the rate-limiting step in the excretion of 1-OHP, and 3-OHBaP and 4,5-diolBaP following injection of pyrene and BaP, respectively and (2) similarities in the first order apparent half life of 3-OHBaP and 1-OHP for the late phase of excretion suggest that 1-OHP could be a good surrogate for 3-OHBaP.

Persistence of benzo[a]pyrene and 7,8-dihydro-7,8-dihydroxybenzo[a] pyrene in Fischer 344 rats: time distribution of total metabolites in blood, urine and feces.

A comparison of the rates of elimination of [3H]benzo[a] pyrene (BaP) and 7,8-dihydro-7,8-diol-[3H]benzo[a]pyrene (BPD), after subcutaneous injection into Fischer 344 rats, shows they are both eliminated at about the same rates and with the same pattern over at least 7 days post-exposure. The end-rate of combined urinary and fecal excretion was approximately 40 nmol/day. About 20% of the injected BaP and approximately 3% of the injected BPD remained at the site of injection for at least 9 days. The remainder was distributed throughout the animal. If the rate of excretion continued at the observed steady-state rates, the BaP and BPD could persist for up to 40 days for each milligram of injected substance. The concentration of excretion products were highest during day 1 and day 2 following exposure, decreased exponentially to a concentration of approximately 0.5 microM (mixed metabolites) by day 5 following exposure, and then continued to be excreted at that rate. Feces contained the highest total amounts of radioactivity, which were approximately 2- to 4-fold higher than the amounts in urine and approximately 15- to 50-fold higher than in total blood. The conversion of organic 3H to 3H2O during the experimental period indicates that whole-body phenol(quinone) formation was significant for BaP metabolism, but was much less for BPD metabolism. When BaP was injected, both blood and urine contained water-soluble, volatile tritium counts (3H2O). Injection of BPD resulted in volatile 3H2O in urine but not in blood. The persistence of BaP and BPD metabolites in skin, blood, urine and feces compartments indicates there is a substantial reservoir of the chemical(s) that could be used to replenish repaired or discarded DNA adducts.