Evaluation of potential genotoxic effects of three drinking water disinfectants using plant tests.

S. Monarca a, M. Rizzoni b, B. Gustavino b, S. Casarella b, A. Alberti a, D. Feretti a, I. Zerbini a, C. Zani a

aDepartment of Experimental and Applied Medicine, Hygiene Section, University of Brescia, I-25123 Brescia, Italy E-mail: b Department of Biology, Tor Vergata University, I-00133 Rome, Italy E-mail:

AIM The aim of this research was to evaluate the potential genotoxic effects of three drinking water disinfectants by means of in vivo short-term mutagenicity tests using plants. METHODS The study was carried out in laboratory using distilled water disinfected with sodium hypochlorite (NaClO), chlorine dioxide (ClO2) and peracetic acid (PAA) at different concentrations both in neutral and acid conditions. Untreated distilled water was used as negative control. The tests performed directly by exposing plant bioindicators to treated and untreated distilled water were: 1. micronuclei test in Tradescantia pollen cells; 2. chromosomal aberrations in root cells of Allium cepa; 3. test on root cells of Allium cepa; 4. micronuclei test in root cells of Vicia faba. RESULTS The Tradescantia/micronuclei test gave positive results in most of the ClO2-treated water samples. At the highest doses, all disinfectants showed toxic effects. Negative results were obtained in Allium cepa tests. On the contrary, Vicia faba assay gave positive results in acid water samples treated with NaClO (0.1 mg/L), ClO2 (0.2 and 0.5 mg/L) and PAA (0.5 mg/L) and in the neutral water samples treated with PAA (0.5 mg/L). CONCLUSIONS Our research evidenced genotoxic effects for all the disinfectants tested. Significant results were obtained in particular in ClO2- and PAA-treated water. The highest mutagenicity was observed in acid conditions. Since the concentrations tested of free disinfectants are usually present in drinking water for biocidal purposes, genotoxicity of these compounds could be a public health problem.

For more information, contact

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Environment and Occupation.

This presentation received an honorable mention in our poster contest and was recognized with the Symposium Presidents' Award for Scientific Excellence.