Substitution means investigating whether a chemical product can be replaced with something less hazardous. The investigation can lead to a switch, but it can just as well show that the current product is the right choice. Both outcomes are equally valuable, as long as the decision is based on a thorough investigation and is documented.
Substitution is not a one-off task. You can think about substitution at every stage of a chemical's life in the workplace: when it is purchased, when it is risk assessed and when you check whether it is on a restriction list.
Substitution at every stage
At purchase. The easiest moment to choose a less hazardous alternative is before the product enters the workplace. Ask the question as soon as someone wants to buy a new product: is it needed, and is there something less hazardous that meets the same need? Read the safety data sheet before the decision is made. A product that is never purchased never has to be replaced.
During risk assessment. When you risk assess a product, you see how it is actually used and how high the risk is. If the risk is high, substitution should be the first thing you consider, before other protective measures. The risk assessment is also the right place to document the investigation.
When checking restriction lists. If the product contains a substance that is on a restriction list, for example CMR substances, the Candidate List, REACH Annex XIV or Annex XVII, that is a signal to start investigating alternatives. The lists change over time. A product that was acceptable at purchase may therefore need to be investigated later. Act early, before a restriction or an authorisation requirement applies.
Start with the risk and the need
Good substitution does not start with looking for replacements. It starts with understanding the risk of the product you have today and the need it meets. You should be able to answer three questions:
- What needs to be replaced?
- Why is this particular product a priority?
- What requirements must an alternative meet, for example in terms of safety, function, process and cost?
Gather the information
Break the questions down into smaller areas. You do not need perfect answers, but you should know where the biggest uncertainties are.
Risk. What makes the product a priority? Look at hazard and exposure together.
Scale. How much is the product used, and how often? How many people and departments are affected?
Use. Is it used in an open or closed system? Is it sprayed, dipped or brushed on? Does it create dust, vapour or aerosol? How long are people exposed?
Function. What technical, quality and process requirements must the product meet?
Requirements for the alternative. What must not be lost in the switch? Safety, performance, process compatibility, cost and availability. Cost can be taken into account, but is rarely enough on its own as a reason not to switch. Use the safety data sheets when comparing products: hazard statements, classification and protective information are there for both.
Remember that risk is hazard times exposure. A very hazardous product in a closed system can mean a lower actual risk than a less hazardous product that is sprayed daily in an open room. Start with the products where the overall risk is highest.
A switch is not the only possible outcome
Under the EU Chemical Agents Directive (98/24/EC), substitution is the first choice. If it is not possible, the risk must instead be minimised with other protective measures. The investigation can therefore lead to four outcomes:
- Phase out the product. Sometimes it is not needed at all. If you have, for example, ten different lubricants for the same purpose, you can often phase out most of them. That reduces both risk and cost.
- Switch product. An alternative reduces the risk and meets the requirements.
- Keep the product but change the way of working, for example with a closed system, smaller quantities or better ventilation.
- Keep the product and make sure the risk is minimised. No alternative is better overall, and the protective measures keep the risk as low as possible.
If a switch is not possible, protective measures must be chosen in a set order. It follows from the Chemical Agents Directive (98/24/EC) and is often called the order of priority or the hierarchy of control. Start with the first step, and only move on when the step before is not enough:
- Handle the product in a closed system or enclose it.
- Change work methods.
- Use technical measures at the source, e.g. local exhaust ventilation.
- Organise the work so that as few people as possible are exposed.
- Use personal protective equipment.
Under the directive, personal protective equipment should only be used when exposure cannot be prevented by other means. Also add other measures such as workplace instructions, signage and training on risks and safe handling.
Continuing to use a product is not a failure. It can be the right decision when the alternatives are hazardous in a different way, do not meet the requirements, or would lead to larger quantities or new exposure. What matters is that the decision is based on the investigation and is documented. “We've always used it” is not an argument. “We compared three alternatives and none meets the process requirement for heat resistance” is.
When do stricter requirements apply?
CMR products. CMR stands for carcinogenic, mutagenic or toxic to reproduction, labelled with H350, H340 or H360. They are regulated by the EU Carcinogens, Mutagens and Reprotoxic Substances Directive (2004/37/EC), which every member state has transposed into its national occupational health and safety legislation. The requirement is that a CMR product must be replaced where it is technically possible. Cost or habit is not a valid reason to keep it. If it cannot be replaced, it should be handled in a closed system where possible, and exposure must be kept as low as possible.
Substances regulated under REACH follow their own rules. Restricted substances (Annex XVII) must not be used for the uses the restriction covers, and substances subject to authorisation (Annex XIV) require authorisation. Substances on the Candidate List are not banned, but may become subject to authorisation. Prioritise them early.
When is a substitution successful?
A successful substitution reduces the actual risk without creating new problems. Check that:
- the risk has been reduced in actual use
- the function has been maintained
- no new hazards, larger quantities or new exposure have arisen
- working methods, equipment and users work together
- the result can be followed up
Ask the people who use the product. They are the first to notice if something does not work.
Document the decision
Document the investigation as part of the risk assessment, whatever the outcome. As a minimum it should describe which product was investigated and why, which alternatives were considered, what decision was made and why, and when the decision will be reviewed. More extensive requirements apply to CMR products. Review the decision regularly, as new alternatives and new rules emerge. Natural moments are when the product is risk assessed again, or when a substance in it is added to a restriction list.
How to do it in practice in iChemistry is described in Substitution in iChemistry.
Summary
- Understand before you switch. Risk and need first, alternatives second.
- Assess actual risk, not just hazard. How the product is used matters as much as what it contains.
- A well-founded “we're keeping it” is a good outcome. As long as it is based on an investigation and documented. For CMR products, a switch must also be technically impossible.
- Think substitution at every stage. At purchase, during risk assessment and when a substance is added to a restriction list.