Safety data sheet (SDS): the mandatory safety manual

The 16 mandatory sections of the SDS

1. Identification of the product and the supplier

Product name, CAS number, supplier with contact details.

2. Hazard identification

Listed in the form of GHS pictograms:

• Exclamation mark (irritant).
• Skull and crossbones (acute toxicity).
• Flame (flammable).
• Corroded surface (corrosive).
• Aquatic environment (ecotoxic).

For pure methylene blue (USP/Ph. Eur. grades), the typical GHS pictograms are minimal: generally "eye irritant" (exclamation mark) where the concentration is high. Products contaminated with lead or arsenic carry "chronic toxicity" or "potential carcinogen".

3. Composition and information on the ingredients

An exhaustive list of impurities above 1% (for mixtures). For pure methylene blue: mainly distilled water (the vehicle) and methylene blue itself.

Example for a technical product: 85% methylene blue, 10% Azure A, 3% NaCl, 2% water.

4. First-aid measures

Instructions in the event of contact with skin/eyes/ingestion/inhalation.

For pure methylene blue:

• Eyes: rinse thoroughly with cold water for 15+ minutes.
• Skin: wash with soapy water. For persistent stains, use vitamin C or isopropyl alcohol (see managing stains).
• Ingestion: rinse the mouth, do not induce vomiting, consult a doctor. Not seriously toxic but unpleasant.
• Inhalation: move to fresh air; no effect expected with the powder (poorly volatile).

5. Fire-fighting measures

• Non-flammable product.
• In the event of a fire nearby, use a dry-powder, CO₂ or water-spray extinguisher (not for other chemicals at risk of a reaction).
• Thermal decomposition products in a fire: nitrogen oxides, hydrogen sulphide (irritants).

6. Accidental release measures

• Sweep up the powder carefully (avoid airborne suspension).
• Use damp paper to prevent the formation of an aerosol.
• Place in a closed container for disposal.
• Local ventilation recommended.

7. Handling and storage

• Temperature: store at room temperature, ideally between 15 and 25°C.
• Humidity: keep below 60% (otherwise degradation into Azure).
• Light: opaque container or kept away from direct light.
• Ventilation: local ventilation advisable for large quantities (workshop).
• PPE (personal protective equipment): nitrile or latex gloves, laboratory coat, goggles.

8. Exposure controls and personal protective equipment (PPE)

• Occupational exposure limit (OEL): poorly established for methylene blue specifically.
• Minimum PPE: gloves, goggles, laboratory coat for routine handling.
• For concentrated solutions: solvent-resistant gloves, ventilation.

9. Physical and chemical properties

• Appearance: blue-green, crystalline powder.
• Odour: odourless or faintly acidic.
• Solubility: very soluble in water (5 to 7 g/100 mL at 20°C).
• Molecular weight: 319.85 g/mol.
• pH of a solution: about 3 to 4 (slightly acidic).

10. Stability and reactivity

• Stability: stable under normal storage conditions.
• Conditions to avoid: direct light, excessive temperature, excessive humidity.
• Decomposition products: Azure A/B (less toxic).
• Reactivity: poorly reactive. Do not mix with strong oxidisers (bleach) or powerful reducing agents in massive quantities.

11. Toxicological data

• Oral LD50 (mouse): 900 to 1200 mg/kg (low acute toxicity).
• Intraperitoneal LD50: about 1000 mg/kg.
• LC50 (inhalation): not established (poorly volatile).
• Eye irritation: yes, at high concentration.
• Skin irritation: no (slightly irritating to intact skin).
• Sensitisation: rare cases reported.

12. Ecological information

• Biodegradability: partially biodegradable (gradual degradation in an aerobic aquatic environment).
• Bioaccumulation: moderate (the blue accumulates in sediments, less in biological tissues compared with heavy metals).
• Aquatic toxicity: moderate. Therapeutic concentrations in an aquarium (1 to 2 mg/L) pose no serious ecological problem. In the event of a massive discharge (textile factory), it can colour and acidify a river.

13. Disposal considerations

• Dilute blue waste: pour down the drain (public water supply), well diluted (no build-up in the pipework).
• Powder or concentrate: disposal by incineration (in certified disposal centres). Combustion produces CO₂, H₂O, and nitrogen and sulphur compounds (neutralised by modern filtration).
• Take-back: ask the supplier about a take-back scheme (often offered for pharmaceutical grade).

14. Transport information

• Transport classification: generally not classified as dangerous in small quantities (less than 10 kg per package).
• In bulk or in large quantities: may require marking and special transport conditions according to local regulations (ADR, IMDG for sea transport).

15. Regulatory information

• REACH nomenclature (EU): listed under REACH, subject to restrictions if production exceeds 1 tonne per year per manufacturer.
• CLP directives (classification, labelling, packaging): categorised according to toxicity.
• POP restrictions (persistent organic pollutants): not included.

16. Additional information

• Date of issue of the SDS.
• Version of the document.
• Technical support contact.
• Additional remarks from the manufacturer.

GHS pictograms relevant to methylene blue

According to the grade:

* If contaminated with lead, arsenic or another toxic substance.

How to read an SDS in 2 minutes (the essentials)

1. Check the GHS pictograms: the more there are, the more caution is required.
2. Section 2 (hazards): assess the direct risks.
3. Section 4 (first aid): note the critical measures.
4. Section 7 (handling): consult the recommended PPE.
5. Section 8 (exposure limits): check whether the exposure is acceptable for your context.
6. Section 12 (ecology): assess the environmental impact.

The SDS, a living document

A good SDS is not set in stone. It is updated regularly (an annual review at the very least) in line with regulatory developments or new toxicological findings. Requesting the most recent SDS from the supplier ensures that you have the latest information.

A supplier who refuses to provide an SDS is acting unlawfully (in most jurisdictions).