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Hazard vs. Risk – What is best practice when assessing chemicals?

Is it better to assess the use of hazardous chemicals based on their hazardous properties or the risk that they will actually do any harm? It’s a question that spurs a lot of debate. But is there really a contradiction between the two, and is either of these approaches “the most scientific”?

Before we try and settle the feud, let’s take a closer look at the two approaches to see what they actually mean in the context of chemicals management. The term hazard refers to the intrinsic properties of a chemical, its potential to do harm. The risk is the combination of hazard and exposure (risk = hazard x exposure). The risk is what you want to eliminate, by changing either or both of the components hazard and exposure. In purely mathematical terms: if one of them is zero, the risk is also zero.

Risk assessment follows on hazard identification

Since the two approaches are in fact interlinked and risk assessments consist of two parts – the hazard as well as the exposure assessment – it is a common misconception that one or the other approach is more “scientific”.

What the debate is really about is which information we should use as a basis for regulating and managing chemicals, and here the opinions diverge. Is knowledge of the hazardous properties of a substance enough to restrict it, or should we first assess the exposure to see if there is a risk that can be limited by managing the exposure?

One advantage of a risk-based approach is that it helps us to focus on “substances that matter” – substances that have been proven to cause problems and not simply have proven potential to cause harm. It also helps us to identify measures that could reduce the risk in critical situations, as well as showing the best option in situations where you have to choose between chemicals. For example, if you have two alternatives, one of which can achieve the desired result in small amounts, but is more hazardous, and the other which is less hazardous but must be used in much larger amounts – then which is the best? Risk assessments are very useful for answering these types of questions.

Risk and hazard in regulation

In EU regulation both approaches are used. REACH is a world-leading regulatory example of a mixture of hazard-based and risk-based elements. In the first step, chemicals are identified as “Substances of Very High Concern” based purely on their hazardous properties, and subsequently placed on the Candidate List. The message is that these hazardous chemicals should be avoided as far as possible. However, in cases where it is not yet possible to replace them, and where the benefits of continuous use outweigh the risks, authorisation for continuous specific use can be granted.

ChemSec’s SIN List is based entirely on REACH and the criteria for the Candidate List, and is of course therefore also hazard-based.

But what are the advantages of using a hazard-based approach compared to one that is risk-based?
The main advantage of a hazard-based approach is that it is foolproof. Banning a chemical is the only way to be 100 per cent sure that it will no longer pose a risk. Hazard assessments are complex, but exposure assessments add even more levels of complexity to the equation. It is extremely challenging to accurately estimate possible exposures to a chemical throughout its lifecycle, from workers involved in production, users exposed to a product throughout its lifetime, all the way through to waste and recycling. In many cases, adding exposure assessment simply adds to the uncertainty. Accurate risk assessments are also very expensive and time-consuming. Even in this modern age it is extremely complicated to determine where a chemical will be used in a long value chain. To communicate the hazard profile and safety instructions down the line of a globalised industry is a daunting task.

There are many possible measures to limit exposure. However many of them depend on “the human factor”. Labelling is one example. Would you, honestly, hesitate to use a cable labelled “for outdoor use” indoors? Would you guess that the reason for the label was to ensure you did not get exposed to a hazardous chemical? Do you only let your toddler play with things that are labelled “toys”? Do you always use gloves or safety glasses when it is recommended on the label and do you always dispose of waste correctly? Do you never flush solvents down the drain?

Chemicals management within a company

As a company, you must of course be compliant with regulation. But if you want to be proactive and stay a step ahead, would you take a hazard-based or risk-based approach to chemicals management? We recommend companies to use the same logic as REACH: Substitute chemicals that meet regulatory hazard criteria, such as the substances on the SIN List. In cases where this is too challenging: be sure to identify how people and the environment are exposed to chemicals through your product and try to reduce this exposure as far as possible, while increasing your R&D to find safer alternatives or processes. Substitution may seem challenging in the beginning, but you end up with better products for your clients and society as a whole due to reduced environmental pollution and negative health impacts. Furthermore, companies that do not work towards substitution of harmful chemicals put their whole portfolio and brand at risk. Time and time again we see how costly and burdensome it is to recover from a bad reputation – although it is very easy to acquire one, especially in this day and age of social media where news travels faster than ever before.