Safe work with dyestuffs epoxy and isocyanates

Plastic is not just a solid, finished material — during production you often work with reactive chemicals that only become the hardened plastic you know. Styrene in polyester resin as well as epoxy and isocyanates in adhesives, varnishes and certain resin types are substances that require you to know and follow the rules for safe work. The Work Authority has published specific guidelines on these substance groups because they are so widespread in industry.

Styrene is the solvent that makes unsaturated polyester resin liquid before it hardens. The substance evaporates easily and can both be inhaled and absorbed through the skin. According to a review in Ugeskriftet.dk, the average styrene exposure level in the Danish fiberglass plastic industry has fallen significantly over decades — from around 100 ppm in the 1960s to around 10 ppm in the 1990s — with better ventilation, more closed processes and the spread of so-called LSE polyester (Low Styrene Emission), which releases less styrene during processing.

• 01Use spot extraction close to the laminating or spray point, not just general room ventilation.
• 02Prefer closed processes like vacuum infusion where possible — it significantly reduces evaporation.
• 03Use the personal protective equipment specified in the safety data sheet — typically gloves and eye protection, and respiratory protection at high concentration or poor ventilation.
• 04Change work clothes that have been wetted with resin, so skin contact doesn't continue the rest of the day.

Epoxy resins are used amongst other things for gluing, varnishes and certain composites, while isocyanates are included in many polyurethane products, varnishes and foam. According to the Working Environment Authority's guidance on epoxy and isocyanate-containing products, both substance groups can cause serious skin irritation and contact eczema, and isocyanates can additionally irritate mucous membranes and trigger respiratory allergy and asthma. Certain isocyanates are moreover associated with a cancer risk from prolonged or high exposure. Precisely because the consequences can become chronic and irreversible, the Working Environment Authority sets special requirements for work with these substances.

Styrene in the limit value list

L means ceiling value: the value must not be exceeded at any time. H means that the substance can be absorbed through the skin. K means that the substance is considered possibly carcinogenic.

For polyester casting with styrene there is a special training course (Annex 7 to the executive order on working environment training, as worded by BEK nr. 358/2023). Here you learn about measurement programmes for styrene and about the hygiene requirements. You learn first aid for contact with polyester and styrene, and you learn to use an emergency shower and eyewash equipment. And you learn that there must be a warning sign.

Every chemical product you work with must have a safety data sheet from the supplier. Section 8 of the data sheet states, among other things, limit values and requirements for protective equipment. At each workplace the data sheet is used in the chemical risk assessment and in the instructions you receive on how your particular product is handled safely — including first aid if an accident happens. (The separate workplace instruction sheet, APB, was abolished on 1 July 2019.)

If the accident happens

If resin, glue or lacquer comes into contact with skin or eyes, the area must be rinsed thoroughly with water immediately, and a doctor consulted if irritation persists. The workplace's instructions and section 4 of the safety data sheet describe the specific first-aid procedure for the particular product you are working with — general advice does not replace the local instructions.

“What you can't see or smell clearly is often what damages most in the long run.”

— Basic principle in chemical working environment