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Effects of nitrilotriacetic acid (NTA) on chromosome replication and structure in human cells
AMERICAN ENVIRONMENTAL MUTAGEN SOCIETY
325
34 BORA, K. C., Environmental Health Centre, Tunney's Pasture, Ottawa, Ontario (Canada KIA OL2).
Effects of nitrilotriacetic acid ( N T A ) on chromosome replication and structure in human cells Preliminary in vitro experiments were performed with human peripheral blood lymphocytes to evaluate the possible mutagenic potential of nitrilotriacetic acid (NTA), a chelating agent which has been recommended as a partial substitute for phosphates as a detergent builder. Cultures from freshly dzawn blood, treated with phytohemagglutinin (PHA), were allowed to grow up to two days, at the end of which NTA was added. NTA concentrations ranged from I- IO-s M to I. lO-2 M, and durations of treatment varied from one to five days. At the termination of treatment, cultures were washed and allowed to recover in NTA free medium for 3 to 12o h. Colcemid was added 3 hours before harvest. One hundred to three hundred cells were analyzed for numerical and structural chromosome anomalies. Numerical anomalies included polyploidy and endoreduplication. The concentration i . lO.2 M was toxic and severely affected cell division and culture growth. There was no significant effect at doses below I . lO-3 M. Doses between I- IO-~ M and 2.5" lO-3 M were the most effective, provided that the pretreatment culture length was about two days and the duration of treatment was three to five days, followed by a 3-h recovery period. Under these conditions, NTA treated cultures contained a significantly high frequency of tetraploid and endoreduplicated cells, e.g. at conc. 6.22-1o -3 M, the frequencies of tetraploid and endoreduplicated cells in cultures exposed to NTA for 5 days were 11.5% and 5.2%, respectively, the corresponding frequencies in the control being o.52~o and 0.02%. For all types of structural chromosome aberrations, the frequencies were generally higher in NTA treated cultures than in controls. For example, the frequency of chromatid breaks in diploid cells in cultures treated for 5 days with 6.22.1o .3 M NTA was 19.7% against 6.2~o in control. These results suggest that under certain conditions, NTA is a potential mutagen. It also inhibits separation of daughter ehromatids and acts as a mitotic poison. I t should be emphasized, however, that these results are preliminary, and that further experimental work will be necessary to determine the relevance of these results in terms of possible human hazard.
35 STOLTZ, D. R., AND C. T. MILLER, Toxicology Research Division, Foods Directorate, Health Protection Branch, Tunney's Pasture, Ottawa, Ontario (Canada KIA OL2).
Mutagenic activity in urine concentrates from rats orally dosed with a chemical which itself is inactive in the Ames test with microsomal activation Samples of concentrates of the 24-h urine collection from rats dosed by gavage with 200 mg isoniazid induced mutations in Salmonella typhimurium TAI535. Urine from control rats receiving water by the same route contained no such mutagenic activity.
325
34 BORA, K. C., Environmental Health Centre, Tunney's Pasture, Ottawa, Ontario (Canada KIA OL2).
Effects of nitrilotriacetic acid ( N T A ) on chromosome replication and structure in human cells Preliminary in vitro experiments were performed with human peripheral blood lymphocytes to evaluate the possible mutagenic potential of nitrilotriacetic acid (NTA), a chelating agent which has been recommended as a partial substitute for phosphates as a detergent builder. Cultures from freshly dzawn blood, treated with phytohemagglutinin (PHA), were allowed to grow up to two days, at the end of which NTA was added. NTA concentrations ranged from I- IO-s M to I. lO-2 M, and durations of treatment varied from one to five days. At the termination of treatment, cultures were washed and allowed to recover in NTA free medium for 3 to 12o h. Colcemid was added 3 hours before harvest. One hundred to three hundred cells were analyzed for numerical and structural chromosome anomalies. Numerical anomalies included polyploidy and endoreduplication. The concentration i . lO.2 M was toxic and severely affected cell division and culture growth. There was no significant effect at doses below I . lO-3 M. Doses between I- IO-~ M and 2.5" lO-3 M were the most effective, provided that the pretreatment culture length was about two days and the duration of treatment was three to five days, followed by a 3-h recovery period. Under these conditions, NTA treated cultures contained a significantly high frequency of tetraploid and endoreduplicated cells, e.g. at conc. 6.22-1o -3 M, the frequencies of tetraploid and endoreduplicated cells in cultures exposed to NTA for 5 days were 11.5% and 5.2%, respectively, the corresponding frequencies in the control being o.52~o and 0.02%. For all types of structural chromosome aberrations, the frequencies were generally higher in NTA treated cultures than in controls. For example, the frequency of chromatid breaks in diploid cells in cultures treated for 5 days with 6.22.1o .3 M NTA was 19.7% against 6.2~o in control. These results suggest that under certain conditions, NTA is a potential mutagen. It also inhibits separation of daughter ehromatids and acts as a mitotic poison. I t should be emphasized, however, that these results are preliminary, and that further experimental work will be necessary to determine the relevance of these results in terms of possible human hazard.
35 STOLTZ, D. R., AND C. T. MILLER, Toxicology Research Division, Foods Directorate, Health Protection Branch, Tunney's Pasture, Ottawa, Ontario (Canada KIA OL2).
Mutagenic activity in urine concentrates from rats orally dosed with a chemical which itself is inactive in the Ames test with microsomal activation Samples of concentrates of the 24-h urine collection from rats dosed by gavage with 200 mg isoniazid induced mutations in Salmonella typhimurium TAI535. Urine from control rats receiving water by the same route contained no such mutagenic activity.