Cytotoxic, genotoxic and mutagenic effects of sewage sludge on Allium cepa

• Sewage sludge is applied in large scale and continuously in agricultural areas.
• Sewage sludge had a genotoxic effect on Allium cepa.
• Sewage sludge genotoxicity should be monitored when it has as destination agricultural soils.

The objective of this study was to ascertain the cytotoxic, genotoxic and mutagenic potential of sewage sludge using Allium cepa bioassay. Solubilized and crude sludge from two sewage treatment stations (STSs), herein named JM and M, were tested. In addition, sanitized, crude and solubilized sludge were also analyzed from STS M. The treatments showed positive response to phytotoxicity, cytotoxicity, genotoxicity and/or mutagenicity. Despite negative results for MN F1 (micronuclei counted in F1 root cells, derived from meristematic cells), the monitoring of genotoxic and mutagenic activities of sewage sludge are recommended because in agricultural areas this residue is applied in large scale and continuously. Based on our results we advise caution in the use of sewage sludge in agricultural soils.