Isocyanates in production: training, safety data sheets, and workplace air measurement

Why isocyanates should be addressed separately

Isocyanates are not an ordinary solvent that can be assessed only by smell or short-term contact. Several diisocyanates can act as sensitising substances. In practice this means that in a sensitive worker a health problem can arise after repeated exposure even at concentrations the operator may not perceive as clearly bothersome.

In operations we encounter them mainly in polyurethane chemistry, two-component coating materials, paints, adhesives, casting compounds, foams, sealants, elastomers, and some hardeners. Risk increases during spraying, heating, atomisation, high-pressure application, grinding of insufficiently cured material, equipment cleaning, and maintenance of application technology.

The operator should first determine whether isocyanates are actually used in the operation. It is not enough to rely on the trade name of the product. What matters is the safety data sheet (SDS), especially composition, classification, exposure limits, recommended respiratory protection, ventilation, and any restrictions for diisocyanates.

When mandatory training applies to the operator

Mandatory training under REACH restrictions applies to industrial and professional use of products containing more than 0.1 % by weight of monomeric diisocyanates. This may typically involve some PUR systems, hardeners, adhesives, coating materials, sealants, or foams.

The operator should practically take three steps. First go through the list of products used and identify PUR, 2K, and reactive systems. Then check safety data sheets and labels for information on mandatory training. Finally verify which workers use, apply, mix, clean equipment after, or maintain contaminated parts of the technology.

Training does not concern only the painter or worker who directly applies the material. In some operations it may also concern a fitter, maintenance worker, preparation room worker, laboratory worker, shift supervisor, or a person handling uncured residues.

Practical note: If the label or safety data sheet states that from 24 August 2023 training is required before industrial or professional use, the operator must be able to demonstrate that workers were trained before working with the given product.

Safety data sheet: what to look for

The safety data sheet is the basic supporting document. For isocyanates it is necessary to read not only sections 2 and 3, but also sections 7, 8, 11, 15, and 16. These are where information is usually given on how the product is to be stored, what PPE to use, what the exposure limits are, whether extraction is required, what REACH restriction information applies, and what training or special conditions the manufacturer states.

For each relevant product the operator should verify mainly the following:

A very common mistake is that the company keeps safety data sheets only formally, but nobody has set up work according to them. For isocyanates information from the SDS must be transferred into operational practice: ventilation, PPE, training, storage, first aid, cleaning, waste, and possibly exposure measurement.

When workplace air measurement makes sense

Workplace air measurement makes sense when it is necessary to verify actual employee exposure. This is typical in paint shops, spraying of PUR or 2K materials, bonding, foaming, casting, heating of materials, maintenance of application equipment, cleaning of guns and lines, or when employees complain of respiratory irritation.

Measurement is also advisable when the product, technology, extraction, application method, shift pattern, or amount of material used changes. A new product with a similar trade name may not have the same chemical composition or the same exposure risk.

For isocyanates it is important to measure under the correct operating regime. If measurement is carried out on a day when the material is not used, spraying does not take place, or the line runs in limited mode, the result will not describe real exposure. Conversely, during an emergency or exceptional state a situation may be measured that does not correspond to normal operation.

What is assessed during measurement

For isocyanates the concentration of specific substances or collectively the NCO group is usually assessed, depending on the method used, specific chemistry, and assessment requirements. In workplace air the result is compared with hygiene limits under Government Regulation No. 361/2007 Coll., or with other relevant values stated in safety data sheets or expert supporting documents.

Practically it is necessary first to know which isocyanates occur in the product. Otherwise a different approach will be taken for MDI, TDI, HDI, IPDI, or mixed hardeners. Without the safety data sheet and knowledge of the technology, sampling and the analytical method cannot be correctly designed.

For some applications personal exposure of the worker in the breathing zone is important. In other situations stationary measurement at the source, in the booth, at the mixing preparation area, in the curing space, or at equipment cleaning points may be useful. The scope of measurement is therefore designed according to the work, not according to the name of the operation.

Extraction, PPE, and work organisation

PPE is neither the first nor the only measure. If isocyanates enter workplace air, technical exposure limitation should be addressed first: process enclosure, effective local extraction, spray booth, correct airflow, workplace separation, and limitation of aerosol formation.

Respiratory protection must correspond to the form of exposure. A different regime may suffice for short handling of a closed package and a different one for spraying, high-pressure application, or cleaning contaminated parts. For isocyanates situations where aerosol, mist, or fine particles arise must be assessed very carefully.

Gloves, eye protection, and work clothing must correspond to the safety data sheet. Contaminated gloves, work clothing, residues of uncured mixture, and cleaning of tools deserve special attention. Exposure may arise not only during application itself, but also during routine handling before and after it.

Most common mistakes in practice

The most common mistake is that the operator does not know which products contain isocyanates. In the operation there are hardeners, PUR adhesives, or 2K paints, but they are not systematically marked as a product group requiring a special regime.

A second frequent mistake is formal training without connection to specific work. The employee signs a general record on chemical substances, but it is not clear whether they completed training for diisocyanates and whether the training corresponded to their risk level.

A third problem is relying on a respirator without verifying extraction. If work takes place in spraying mode or with aerosol, protection must be designed according to actual exposure and work procedure. An unsuitably chosen filter or incorrectly used respiratory protection may not protect the worker.

Measurement errors are also common. Measurement is ordered without safety data sheets and without knowledge of the specific application. The result may then be sampling that does not correspond to the isocyanate used, the work regime, or the most risky part of the shift.

What supporting materials to prepare

For a quick assessment the most important thing is a list of products and their current safety data sheets. It is also necessary to describe where and how products are used: manual application, spraying, bonding, foaming, casting, mixing, curing, cleaning, or maintenance.

For workplace air measurement it is advisable to add information on shift pattern, length of work, amount of material consumed, extraction, ventilation, spray booth, PPE, and number of exposed workers. Workplace photographs and a simple operation diagram often significantly speed up design of measurement.

When to address training and when measurement

Training and measurement do not replace each other. Training addresses whether the worker understands the risk and can handle the product safely. Workplace air measurement verifies whether working conditions during specific work are acceptable from the perspective of exposure.

For operations using products with diisocyanates above 0.1 %, training must be resolved always before use. Measurement is advisable where exposure in air can arise, especially during spraying, aerosol, heating, cleaning, maintenance, or when there is uncertainty whether extraction and PPE are actually sufficient.

If the operator does not know where to start, we recommend first making an overview of products and safety data sheets. From it there usually follows whether the priority is training, PPE update, extraction check, workplace air measurement, or a combination of these steps.

What you can send us for assessment

Send us safety data sheets of products used, a list of materials, description of application, information on extraction, PPE, working hours, and number of exposed workers. If you have workplace photographs, work procedures, internal risk assessments, or a requirement from the regional hygiene station (KHS), send those as well.

We will verify whether mandatory training for diisocyanates applies to the products, what follows from safety data sheets, and whether workplace air measurement is appropriate. According to the operation we will propose the scope of training, documentation check, exposure measurement, or practical measures in the workplace.

More on chemical legislation can be found on the NATURCHEM Chemical substances page.

Brief summary

Isocyanates need to be addressed practically: find out which products contain them, check safety data sheets, verify mandatory training, set up PPE and extraction, and where exposure can arise, carry out workplace air measurement.

The greatest risk arises with spraying, aerosol, PUR applications, hardeners, adhesives, paints, equipment cleaning, and work with uncured residues. The operator should not wait until an inspection or employee health problems. An overview of products, current SDS, and description of work is usually enough to quickly propose the next steps.

Factual basis of the article

From these supporting documents it follows that isocyanates cannot be addressed only by formal storage of safety data sheets. The operator must link chemical legislation, training, PPE, ventilation, work procedure, and possibly workplace air measurement. Only together do these supporting documents give a practical picture of whether work with isocyanates is under control.