- Email: [email protected]
Chromosomal aberrations and sister-chromatid exchanges in styrene-exposed workers
238 Using the D7 strain of S. cerevisiae we tested Chromitan B and Chromitan MS, widely used in the tanning industries and contaminating the water of the river Arno. Chrornitan B and Chromitan MS at concentrations of 4 and 10 mg/plate induced point mutations in Salmonella typhimurium strains TAI00, TA1538 and TA1535 with $9. Without liver microsomal assay the agents were toxic, but they did not induce genetic effects. At 50 mg/plate there was no survival. In yeast the compounds showed a high level of toxicity. The contaminated water of the Arno river (0.5 ml) induced point reverse mutation, mitotic gene conversion and crossing over in yeast.
28 Brooks, T.M., and W.P. Watson, Shell Research Ltd., Sittingbourne Research Centre, Sittingbourne, Kent ME9 8AG (Great Britain) The effects of oils on the disposition of mutagenic metabolites of benzolalpyrene The Ames assay (Ames, B.N. et al., Mutation Res., 31 (1975) 347) is often unable to unequivocally detect mutagenicity in certain mineral oils which contain proximate mutagens (Payne, J.F. et al., Science, 200 (1978) 329). One suggested explanation (Petrelli, F.L. et al., Carcinogenesis, 1 (1980) 51) is that components in oils affect the disposition of mutagenic metabolites produced in the assay, and prevent their reaching the bacterial DNA. We have investigated the effects of two base oils, of significantly different PAH content, on the bacterial mutagenicity of two known mutagenic metabolites of benzo[a]pyrene, namely (_+)-benzo[a]pyrene-4,5-epoxide (BPO) and (+)-7fl,8~-dihydroxy-9a, lOa-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE). The use of surfactants such as Tween 80 has been recommended to assist in the mutagenicity testing of oils. This work has studied the effects of Tween 80, alone and in combination with oils, on the mutagenicity of BPO and BPDE. BPO and BPDE were shown to exert mutagenic effects in the presence of large amounts of both oils. The most significant factor affecting the mutagenicity of BPO, in assays containing $9, was the epoxide hydrolase activity in the $9. BPO is a substrate for epoxide hydrolase and it appears that oil/Tween 80 formulations either inhibit this enzyme or protect the BPO from hydration. Certain doses of oil and/or oil/Tween 80 formulation caused increases in mutagenicity of the BPDE with $9. These effects can be explained by protection of the easily hydrolysed BPDE or inhibition of epoxide hydrolase.
29 Camurri, L., S. Codeluppi t and C. Pedroni, Laboratorio di Genetica, USL 9, 1-42100 Reggio Emilia, and I Servizio di Medicina del Lavoro, USL 9, 1-42100 Reggio Emilia (Italy)
239 Chromosomal aberrations and sister-chromatid exchanges in styrene-exposed workers Few studies exist about the chromosomal damage in workers occupationally exposed to styrene (Meretoja, T. et al., Scand. J. Environ. Health, 4, Suppl. 2 (1978) 259-264). In the present study chromosome aberrations and SCEs were analyzed from cultures of peripheral lymphocytes of workers employed in 7 different small plastic plants, with ambient styrene levels ranging from 30 to 400 m g / m 3. A control group was matched for sex, age and smoking habits. 50-h cultures (for chromosome aberrations) and 72-h cultures (for SCEs) were examined of each individual. All workers exposed to styrene, as compared to controls, showed significantly increased frequencies of chromosome aberrations (from 0.21 to 0.54 per cell), while SCEs were significantly increased only in individuals with urinary mandelic acid higher than 500 mg/1. Apart from the possible presence and role of other interfering chemicals in the plants, chromosome aberrations seem to be more sensitive than SCEs to the detection of chromosomal damage caused by exposure to low doses of styrene.
30 Chaffin, P., N. Parra and I. Chouroulinkov, Laboratoire de Mb_decine Exp6rimentale, IRSC-CNRS, B.P. No. 8, 94802-Villejuif Cedex (France) Cytogenetic study in rat bone marrow and in human lymphocytes with 5 known compounds The clastogenic effect of the direct-acting compounds mitomycin C (MC), methyl methanesulfonate (MMS) and the indirect-acting compounds benzo[a]pyrene (BaP), cyclophosphamide (CP) and procarbazine (PC) is well known. Nevertheless the rat is an underemployed species for this kind of study as compared to its generalized use in toxicology and as source of $9 mix. In this work, a cytogenetic study was performed, with the objective of comparing the chromosomal aberration test and the micronucleus test simultaneously in the rat, and the chromosomal aberration test in human lymphocytes, with the above-cited compounds. The in vivo cytogenetic study consisted of bone marrow recovery from one femur for chromosomal aberrations and from the other femur for micronuclei. In vitro the human lymphocyte culture was used without metabolic activation for MC and MMS and with Aroclor-induced rat $9 mix for BaP, CP and PC. The results show that: (1) in the rat the chromosomal aberration test at high doses gives a better response than the micronucleus test; (2) in the chromosomal aberration test the doubling doses in vitro are: BaP ( + $9 mix), 2.4 mg/1, CP ( + $9 mix) 2 mg/l, MMS 6 mg/1, MC 0.003 mg/1, PC (+ $9 mix) is inactive, and in vivo: BaP 423 mg/kg, CP 4 mg/kg, MMS 33 mg/kg, MC 0.75 mg/kg and PC 17 mg/kg.
28 Brooks, T.M., and W.P. Watson, Shell Research Ltd., Sittingbourne Research Centre, Sittingbourne, Kent ME9 8AG (Great Britain) The effects of oils on the disposition of mutagenic metabolites of benzolalpyrene The Ames assay (Ames, B.N. et al., Mutation Res., 31 (1975) 347) is often unable to unequivocally detect mutagenicity in certain mineral oils which contain proximate mutagens (Payne, J.F. et al., Science, 200 (1978) 329). One suggested explanation (Petrelli, F.L. et al., Carcinogenesis, 1 (1980) 51) is that components in oils affect the disposition of mutagenic metabolites produced in the assay, and prevent their reaching the bacterial DNA. We have investigated the effects of two base oils, of significantly different PAH content, on the bacterial mutagenicity of two known mutagenic metabolites of benzo[a]pyrene, namely (_+)-benzo[a]pyrene-4,5-epoxide (BPO) and (+)-7fl,8~-dihydroxy-9a, lOa-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE). The use of surfactants such as Tween 80 has been recommended to assist in the mutagenicity testing of oils. This work has studied the effects of Tween 80, alone and in combination with oils, on the mutagenicity of BPO and BPDE. BPO and BPDE were shown to exert mutagenic effects in the presence of large amounts of both oils. The most significant factor affecting the mutagenicity of BPO, in assays containing $9, was the epoxide hydrolase activity in the $9. BPO is a substrate for epoxide hydrolase and it appears that oil/Tween 80 formulations either inhibit this enzyme or protect the BPO from hydration. Certain doses of oil and/or oil/Tween 80 formulation caused increases in mutagenicity of the BPDE with $9. These effects can be explained by protection of the easily hydrolysed BPDE or inhibition of epoxide hydrolase.
29 Camurri, L., S. Codeluppi t and C. Pedroni, Laboratorio di Genetica, USL 9, 1-42100 Reggio Emilia, and I Servizio di Medicina del Lavoro, USL 9, 1-42100 Reggio Emilia (Italy)
239 Chromosomal aberrations and sister-chromatid exchanges in styrene-exposed workers Few studies exist about the chromosomal damage in workers occupationally exposed to styrene (Meretoja, T. et al., Scand. J. Environ. Health, 4, Suppl. 2 (1978) 259-264). In the present study chromosome aberrations and SCEs were analyzed from cultures of peripheral lymphocytes of workers employed in 7 different small plastic plants, with ambient styrene levels ranging from 30 to 400 m g / m 3. A control group was matched for sex, age and smoking habits. 50-h cultures (for chromosome aberrations) and 72-h cultures (for SCEs) were examined of each individual. All workers exposed to styrene, as compared to controls, showed significantly increased frequencies of chromosome aberrations (from 0.21 to 0.54 per cell), while SCEs were significantly increased only in individuals with urinary mandelic acid higher than 500 mg/1. Apart from the possible presence and role of other interfering chemicals in the plants, chromosome aberrations seem to be more sensitive than SCEs to the detection of chromosomal damage caused by exposure to low doses of styrene.
30 Chaffin, P., N. Parra and I. Chouroulinkov, Laboratoire de Mb_decine Exp6rimentale, IRSC-CNRS, B.P. No. 8, 94802-Villejuif Cedex (France) Cytogenetic study in rat bone marrow and in human lymphocytes with 5 known compounds The clastogenic effect of the direct-acting compounds mitomycin C (MC), methyl methanesulfonate (MMS) and the indirect-acting compounds benzo[a]pyrene (BaP), cyclophosphamide (CP) and procarbazine (PC) is well known. Nevertheless the rat is an underemployed species for this kind of study as compared to its generalized use in toxicology and as source of $9 mix. In this work, a cytogenetic study was performed, with the objective of comparing the chromosomal aberration test and the micronucleus test simultaneously in the rat, and the chromosomal aberration test in human lymphocytes, with the above-cited compounds. The in vivo cytogenetic study consisted of bone marrow recovery from one femur for chromosomal aberrations and from the other femur for micronuclei. In vitro the human lymphocyte culture was used without metabolic activation for MC and MMS and with Aroclor-induced rat $9 mix for BaP, CP and PC. The results show that: (1) in the rat the chromosomal aberration test at high doses gives a better response than the micronucleus test; (2) in the chromosomal aberration test the doubling doses in vitro are: BaP ( + $9 mix), 2.4 mg/1, CP ( + $9 mix) 2 mg/l, MMS 6 mg/1, MC 0.003 mg/1, PC (+ $9 mix) is inactive, and in vivo: BaP 423 mg/kg, CP 4 mg/kg, MMS 33 mg/kg, MC 0.75 mg/kg and PC 17 mg/kg.