Induction of micronuclei and sister chromatid exchanges by polycyclic and N‐heterocyclic aromatic hydrocarbons in cultured human lymphocytes

Abstract

Many natural environments are contaminated with carcinogenic polycyclic aromatic hydrocarbons (PAHs) and N-heterocyclic aromatic hydrocarbons (NHAs) as complex mixtures of coal tar, petroleum, and shale oil. These potentially hazardous substances are prevalent at many former tar production and coal gasification sites. Three polycyclic [benzo(a)pyrene (BaP), benz(a)anthracene (BAA), and 7,12-dimethylbenz(a)anthracene (DMBA)] and two N-heterocyclic [7H-dibenzo(c,g)carbazole (DBC), and dibenz(a,j)acridine (DBA)] aromatic hydrocarbons were analyzed for cytotoxic and genotoxic effects on human lymphocytes. All of these polyaromatic compounds are normally present in the environment, except for DMBA. Lymphocytes from healthy donors were isolated from whole blood. The 5-ring polycyclic aromatic BaP consistently induced micronuclei in a linear dose-dependent manner with doses from 0.1-10.0 micrograms/ml, whereas the 4-ring compounds (BAA and DMBA) had no effect on the induction of micronuclei above controls except at 5 and 10 micrograms/ml. Of the two N-heterocyclic compounds, DBC produced a significant increase in micronuclei in lymphocytes, but the dose response tended to plateau above 0.1 microgram/ml. DBA showed an effect on the frequency of micronuclei above controls only at high doses of 5 and 10 micrograms/ml. The average background frequency of micronuclei for 7 lymphocyte donors averaged 3.1 per 1,000 stimulated cells, whereas the average frequency of micronuclei at 10 micrograms/ml BaP was 36.8 per 1,000 stimulated cells. The lowest effective dose in 2 donors for BaP occurred at 0.1 microgram/ml. At a challenge dose of 1 microgram/ml (4 microM) of BaP, considerable variation in micronuclei induction between 7 individuals was observed, ranging from 2-6-fold increases above spontaneous frequency. Over a dose range of 1-10.0 micrograms/ml (4-40 microM), BaP also induced sister chromatid exchanges (SCEs) in lymphocytes, whereas BAA had no effect above controls. Parallel studies of both cytogenetic endpoints showed that the micronucleus assay is a more sensitive indicator of BaP exposure at equivalent doses. Mitotic and replication indices of BaP-exposed lymphocytes showed that cell proliferation is only moderately inhibited even at the highest dose; this shows that bulky DNA-adducts are generally compatible with cell survival. The cytogenetic data are consistent, first-off, with reports that individuals in the population vary widely with respect to the inducibility of the CYP1A1 gene, which is known to be involved in polycyclic aromatic hydrocarbon metabolism, in particular, in BaP. Secondly, the data support the fact that polyaromatic compounds differ with regard to micronucleus induction within the same sample(s) of human lymphocytes, indicating selective metabolism of polyaromatic compounds that may reflect carcinogen sensitivity of the individual.(ABSTRACT TRUNCATED AT 400 WORDS)

Cytogenetic biomonitoring of Indian women cooking with biofuels: Micronucleus and chromosomal aberration tests in peripheral blood lymphocytes

“…Respirable airborne PM is cytotoxic and genotoxic for different cell systems [Hornberg et al, 1998;Diociaiuti et al, 2001], and exposure of cultured human lymphocytes to PAHs increases the MN and SCE frequencies in a dosedependent manner [Warshawsky et al, 1995]. Also, a number of biomonitoring studies indicate that occupational or environmental exposure to high levels of PAHs, air pollution, and/or atmospheric PM results in DNA damage [Bender et al, 1988;Bolognesi et al, 1997a,b;Michalska et al, 1999].…”

Chronic, topical exposure to benzo[a]pyrene induces relatively high steady-state levels of DNA adducts in target tissues and alters kinetics of adduct loss.

“…The mutations involving a guanine base were consistent with the major DNA adduct formed with the bay-region diol epoxide of BAP (23). Lastly, BAP or its metabolites have caused sister chromatid exchanges and micronuclei in human lymphocytes in vitro and in vivo and in animal cells (24)(25)(26)(27)(28)(29). Studies have shown a correlation between the sister chromatid exchange and DNA adduction for BAP exposure (26).…”

Evaluation of the genotoxicity of river sediments from industrialized and unaffected areas using a battery of short‐term bioassays

“…They may be produced by clastogenic or aneugenic compounds. PAHs, nitroarenes, and aromatic amines have been shown to induce micronuclei in mammalian cells [Tokiwa et al, 1987;Warshawsky et al, 1995;Perez et al, 2002]. Nitroarenes behave as direct-acting clastogenic compounds, whereas PAHs and aromatic amines produce chromosomal damage after exogenous metabolic activation.…”