Detect what chemical analysis alone can’t: DNA-damaging activity in drinking water
Over 700 disinfection by-products have been identified in chlorinated water — the majority unregulated and untested. The EBPI SOS-ChromoTest™ screens for aggregate genotoxic activity across the entire sample mixture in a single, rapid assay, without needing to know what’s in it.
Chemistry tells you what’s there. Bioassay tells you if it’s dangerous.
Chlorination and other disinfection processes generate a chemically complex mixture of by-products — many of which are genotoxic, meaning they actively damage DNA in living cells. Regulated chemical monitoring covers only a fraction of these compounds, and tells you nothing about the combined biological impact of the mixture as a whole.
Over 700 DBPs have been identified, yet most occur at concentrations too low for routine chemical detection. Analytical chemistry cannot assess the aggregate genotoxic effect of a mixture where compounds may act synergistically, and it cannot identify genotoxins it wasn’t designed to look for.
A single bioassay endpoint that responds to the total DNA-damaging burden of a sample — known and unknown compounds alike. No prior knowledge of sample chemistry required. Routinely used alongside chemical analysis to provide the biological risk dimension that regulators and researchers increasingly require.
A direct window into DNA damage — in under six hours
The SOS-ChromoTest™ is a microplate-based colourimetric assay built on a single biological principle: genotoxic compounds trigger the bacterial SOS DNA repair system, and that response is directly measured and quantified.
The engineered PQ37 strain carries a chromosomally integrated sfiA::lacZ gene fusion. Any genotoxic compound in the sample activates the SOS repair system, driving expression of the reporter enzyme β-galactosidase (β-gal).
β-galactosidase cleaves the chromogenic substrate, producing a measurable colour change proportional to the degree of DNA damage induced. Cytotoxicity is simultaneously monitored via constitutive alkaline phosphatase activity, ensuring results are not masked by bacterial toxicity.
Results are expressed as an induction factor relative to the solvent control. A corrected induction factor (CIF) ≥ 1.5 indicates a genotoxic response, consistent with the ISO 13829 standard threshold for water quality genotoxicity testing.
EBPI supplies rat liver S9 fraction for the detection of indirect-acting genotoxins — compounds that require metabolic activation before exerting DNA damage. Particularly important for complex environmental matrices where pro-genotoxic precursors may be present.
Genotoxicity threshold: An induction factor (IF) below 1.5 is considered non-genotoxic; between 1.5 and 2.0 weakly genotoxic; above 2.0 moderately to strongly genotoxic. The SOS-ChromoTest™ kit protocol follows the EBPI standard operating procedure and is accepted under ISO 13829, OECD guidelines, and US EPA frameworks.
Where the SOS-ChromoTest™ fits in your water program
Used by water utilities, academic researchers, environmental consultants, and government labs across Canada and internationally for routine monitoring, treatment evaluation, and health risk assessment.
Baseline genotoxicity screening of surface water, groundwater, and lake intakes prior to treatment. Establish seasonal benchmarks and detect pollution events.
Track genotoxic precursor removal across coagulation, sedimentation, filtration, biofiltration, and disinfection stages to optimize treatment train performance.
Compare chlorination, chloramination, UV, ozone, and alternative disinfectants for DBP-associated genotoxic burden in finished drinking water.
Assess genotoxic risk in advanced treated wastewater streams being evaluated for indirect or direct potable reuse applications.
Verify filter efficacy for removing adsorbable organic halogens (AOX) and the associated genotoxic burden at the consumer tap.
Generate genotoxicity data for health risk assessments, compliance submissions, and peer-reviewed publications with an internationally recognized assay.
Trusted by Canada’s leading drinking water researchers
EBPI has a long-standing collaboration with the University of Toronto Drinking Water Research Group (DWRG), using the SOS-ChromoTest™ as the primary genotoxicity endpoint in drinking water treatment research at real Ontario treatment facilities.
“DBPs formed in chlorinated drinking water samples have been shown to cause a genotoxic response. The objective of the current study was to further understand the principles of biofiltration and the resulting genotoxicity reduction.”
— McKie & Andrews, University of Toronto Drinking Water Research Group (2015)EBPI and the University of Toronto DWRG: EBPI continues to collaborate with the University of Toronto’s Drinking Water Research Group, focusing on the genotoxic potential of disinfection by-products (DBPs) from various drinking water treatment methods. For over 10 years, EBPI has supported international universities in both drinking water and wastewater research programs.
Chemical monitoring has a blind spot. The SOS-ChromoTest™ doesn’t.
Adding a genotoxicity bioassay endpoint to your water quality program provides the biological risk dimension that chemical analysis alone cannot deliver:
- Screens for aggregate DNA-damaging activity across the entire sample mixture — no prior knowledge of compounds required.
- Detects genotoxic risk from the thousands of trace-level compounds too dilute for routine chemical identification.
- Responds to combined and synergistic effects of multiple co-occurring DBPs — something no targeted chemical method can model.
- Used as a direct measure of treatment efficacy: a reduction in IF across the treatment train demonstrates real genotoxicity removal, not just reduction of a proxy chemical parameter.
- Complements regulated THM and HAA monitoring with an endpoint that directly reflects biological hazard to human DNA.
- Results accepted by ISO, OECD, and US EPA frameworks, and routinely cited in peer-reviewed water quality literature.
Designed to meet international requirements
The EBPI SOS-ChromoTest™ protocol is designed and accepted by leading international standards bodies. Kits are shipped with EBPI’s standard operating procedures, which are compliant with the frameworks listed below.
Peer-reviewed citation: The EBPI SOS-ChromoTest™ (Environmental Bio-Detection Products Inc.) has been explicitly cited by name in peer-reviewed literature as the assay used to assess genotoxicity in drinking water treatment studies, with results reported as relative enrichment factors (REF) consistent with the ISO 2000 genotoxic threshold.