DNA Stain Comparison Table

(updated 10/1/2020)

There are many conflicting reports/papers regarding the mutagenicity and toxicity of Ethidium Bromide (EtBr) relative to that of alternative DNA stains, be it in concentrated stock form or at dilute working concentrations.

However, it is accepted as fact that solid EtBr and concentrated EtBr stock solutions are acutely toxic and mutagenic. It is also clear that there are safer alternatives on the market - see table below.

	Classification according to Regulation (EC) No. 1272/2008 (CLP)	Hazard Statements	Supplier's MSDS
EtBr 10mg/ml 20000X concentrate in H2O	Acute toxicity, Inhalation (Category 3) Germ cell mutagenicity (Category 2)	H331 Toxic if inhaled. H341 Suspected of causing genetic defects.
Sybr Green I 10000X concentrate in DMSO	Not a hazardous substance or mixture	none assigned
Sybr Gold 10000X concentrate in DMSO	Not a hazardous substance or mixture	none assigned
Sybr Safe 10000X concentrate in DMSO	Not a hazardous substance or mixture	none assigned
GelRed/GelGreen 10000X concentrate in DMSO	Not a hazardous substance or mixture	none assigned
Diamond Nucleic Acid Dye 10000X concentrate	Not a hazardous substance or mixture	none assigned
Nancy 520 5000X concentrate	Not a hazardous substance or mixture	none assigned

The Control of Substances Hazardous to Health (COSHH) Regulations require that where ever possible exposure to hazardous substances be avoided. Where it is not possible to avoid exposure the Regulations require that exposure controls be implemented in a hierarchical order, the first of which is substitution with a substance that is non- hazardous, or less hazardous, before moving further down the hierarchy to mechanical controls and lastly Personal Protective Equipment (PPE). The requirement for substitution, where practicable, is absolute and has been tested in case law, therefore where there exists a practical (will achieve same or similar results) non, or less hazardous, alternative this must be adopted. Increased cost alone cannot be presented as a reason for non-implementation of a less hazardous alternative.

Consequently the routine use of EtBr is strongly discouraged and it should only be used where product evaluation and risk assessment have concluded that there is no viable safer alternative. Should the latter be the case, only use ready-made solutions or the solid in tablet form to avoid inhalation of the powdered solid, which is calssified as fatal if inhaled (H330).

Selection of relevant papers/articles:

• Comparison of Nucleic Acid Gel Stains Cell permeability, safety, and sensitivity of ethidium bromide alternatives (Biotium 2017)
• Toxicity, mutagenicity and transport in Saccharomyces cerevisiae of three popular DNA intercalating fluorescent dyes (Sayas et al 2015)
• Properties of nucleic acid staining dyes used in gel electrophoresis (Haines et al 2015)
• Are other fluorescent tags used instead of ethidium bromide safer? (Abdollahi 2013)
• SYBR Gold and SYBR Green II are not mutagenic in the Ames test (Kirsanov 2010)

• Comparison of SYBR Green I nucleic acid gel stain mutagenicity and ethidium bromide mutagenicity (Singer et al 1998)
• Diamond™ Nucleic Acid Dye: A Sensitive Alternative to SYBR® Dyes (Promega)
• SYBR Safe™ DNA Gel Stain, Assessment of Mutagenicity and Environmental Safety (Molecular Probes)
• EtBr Destroyer Spray