Ground and surface water for drinking: a laboratory study on genotoxicity using plant tests

Area of Science:

• Environmental Chemistry
• Toxicology
• Water Treatment

Background:

• Surface water is increasingly used for drinking water due to groundwater pollution.
• Disinfection of surface water containing natural organic matter can produce mutagenic byproducts.
• Understanding the genotoxic potential of these disinfection byproducts is crucial for public health.

Purpose of the Study:

• To investigate the genotoxic potential of reaction products between humic substances and common disinfectants.
• To simulate natural groundwater and surface water conditions using different total organic carbon (TOC) concentrations.
• To evaluate the genotoxicity of disinfectants: chlorine dioxide, sodium hypochlorite, and peracetic acid (PAA).

Main Methods:

• Commercial humic acids were dissolved in distilled water at TOC concentrations of 2.5 mg/L and 7.5 mg/L.
• Solutions were treated with chlorine dioxide, sodium hypochlorite, and PAA at a 1:1 molar ratio.
• Genotoxicity was assessed using plant-based assays: Allium cepa (chromosomal aberration, micronucleus) and Vicia faba and Tradescantia (micronucleus tests).

Main Results:

• Sodium hypochlorite showed genotoxic effects in all plant tests at both TOC levels.
• Chlorine dioxide exhibited genotoxicity in Allium cepa tests.
• Peracetic acid demonstrated some genotoxic effects in Allium cepa and Tradescantia tests.

Conclusions:

• Disinfection of surface water containing humic substances can generate genotoxic compounds.
• Sodium hypochlorite and, to a lesser extent, chlorine dioxide and PAA, pose a genotoxic risk.
• These findings highlight the need for careful disinfectant selection and monitoring in drinking water treatment.