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How Safe Are Biological Stains?

By Kenneth Roy

Posted on 2019-07-22

In middle and high school science labs, biological stains, such as basic fuchsin, crystal violet, and Congo red, are used to enhance properties of microscopic plant and animal cells/tissues. Fortunately, Safety Data Sheets (SDS) note that some of these popular stains may contain suspected carcinogens, toxins, and mutagens.

Potential Hazards and Risks

When assessing safety for chemicals in the lab, always use the AAA approach: Hazard Analysis, Risk Assessment, and Safety Action.

To begin, determine the hazard analysis and resulting risk assessment using a free online document titled “Handbook of Biological Dyes and Stains Synthesis and Industrial Applications.” In addition, the IHC World Life Science Products & Services: ABC of Safety in the Biological Sciences provides a quick health and safety summary of many biological stains in a chart form.

Next, check out the chemical nature of the biological stain being considered. OSHA’s Hazard Communication Standard (HCS) mandates that manufacturers and suppliers of biological stains provide Safety Data Sheets (SDSs) share information with laboratory occupants on hazardous chemical products. The following sections are some of the most important to review before using biological stain.

Section 2, Hazard(s) identification includes all hazards regarding the chemical; required label elements.

Section 8, Exposure controls/personal protection lists OSHA’s Permissible Exposure Limits (PELs); Threshold Limit Values (TLVs); appropriate engineering controls; personal protective equipment (PPE).

Section 11, Toxicological information includes routes of exposure; related symptoms, acute and chronic effects; numerical measures of toxicity.

The following biological stains are examples that present specific health and safety concerns.

Basic fuchsin has carcinogenic effects and mutagenic effects (Mutagenic for mammalian somatic cells and for bacteria and/or yeast.) It may cause damage to the following organs: blood, liver, spleen, thyroid.

Crystal violet has evidence of a teratogenic effect (birth defect) and can also effect
the cardiovascular and respiratory systems.

Methyl blue leads to the formation of methemoglobin, which can cause cyanosis, vomiting, diarrhea, nausea, dizziness, and headaches.

Eosin Y may be fatal or cause blindness if swallowed. Effects due to ingestion include gastrointestinal disturbance, headache, nausea, vomiting, dizziness, weakness, confusion, drowsiness, and unconsciousness.

Lastly, determine if there are any alternative means of staining available that are safer to use. One can post queries on the biology, chemistry, or general science NSTA list serves. If there is insufficient information that would warrant banning a particular biological stain, be sure to take the appropriate safety action. For example, check out the SDS Section 8 relative to personal protective equipment is adhered to when using the stain.

Submit questions regarding safety to Ken Roy at or leave him a comment below. Follow Ken Roy on Twitter: @drroysafersci.

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