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Using hazardous substances safely: how are OELs determined?

There are various companies where employees work with substances that can be damaging to health. A small proportion of these substances are gases or vapours which can cause cancer in people exposed to them for long periods or at too high a concentration. Examples are asbestos or chromium-6. How are Occupational Exposure Limits (OELs) for hazardous substances set for the workplace?

Berber Bijma

Martin Wieske
Martin Wieske:
Head of health and safety at the German industry organisation for the non-ferrous metals sector
Tony Musu
Tony Musu:
Researcher at the European trade union institute ETUI

OELs of hazardous substances are largely determined at national level. At European level, there is the Working Party on Chemicals – an advisory body of the European Commission. It brings together employers, employees and authorities from Member States to discuss the maximum levels of hazardous substances to which companies should be permitted to expose their employees. There are currently European OELs for 25 carcinogenic substances, which all member states must adhere to.

There are of course many more hazardous substances. In the Netherlands, the Social and Economic Council of the Netherlands (SER) has played a major role in creating the database of OELs, the databank Grenswaarden (in Dutch), which contains OELs – valid in the Netherlands – for more than 2000 substances. In early February 2020, the SER hosted an international conference on OELs for hazardous substances.

Man with protective clothes and mask painting car roof using compressor.
© Shutterstock

OELs are important for employees and employers

Setting OELs is important not only to employees, but also to employers, says Martin Wieske. He is head of health and safety at the German industry organisation for the non-ferrous metals sector. “The Occupational Exposure Limits give companies clear guidance. With the OELs, they can show that they are protecting their staff in accordance with the legal standards, while at the same time benefiting from the positive characteristics of particular substances.”

‘In the EU, 100,000 people die each year from a form of cancer that is caused by their working conditions’

For Tony Musu, a researcher at the European trade union institute ETUI, the importance of OELs for employees is crystal clear: “In the European Union as a whole, 100,000 people die each year from a form of cancer that is caused by their working conditions. To reduce that number, we need Occupational Exposure Limits.”

Speeding up preparation of a European system for OELs for carcinogenic substances

Experts have been thinking for a long time about an efficient European system for setting OELs. Musu: “As early as the 1990s, the first Occupational Exposure Limits were determined for EU member states. Then for years afterwards, hardly any new substances were added. It is only in the last few years that we have again started to speed up the process somewhat, with the result that we now have 25 OELs for EU countries.”

‘The Netherlands and Germany lead the way as regards national OELs’

Many EU countries additionally have their own, national OELs for other substances. “The Netherlands and Germany together with few other member states are the leaders in this area,” says Wieske, “because they have their own scientific institutes that work on it.”

Monitoring compliance varies between countries

Although monitoring compliance with the OELs set by the EU is organised differently in the various member states, it works “fairly well”, according to Wieske. Musu has a different opinion: “These checks are unsatisfactory because in all EU countries, the labour inspectorate is being cut back. Legislation is good at European level, but at company level the rules are not complied with equally well in every member state.”

Musu advocates having more OELs that are laid down by the EU. “Currently, you can see that one member state applies a completely different OEL from another. The great challenge at present is to agree at European level how we are going to determine OELs. Our current approach is to weigh up the costs and benefits. It would be better to follow the example of the Netherlands and Germany and base the OEL on the risk to employees.” This issue was discussed at length during the conference.

A safe level is hard to determine

What is a safe level for using a specific substance in the workplace? This is a knotty problem for each individual hazardous substance, according to Wieske and Musu. “For a number of substances, we know the threshold level below which there is no risk of damage to health,” says Wieske.

‘It is never certain whether physiological changes in rats will also occur in humans’

A complicating factor is that research on such damage is carried out on rats. “You can never say with certainty that physiological changes in rats will also occur in humans. And if that does happen, will it lead to health damage in the long term? That isn’t certain either. When determining an OEL, we always combine various safety factors and we are very cautious in setting the OELs. The levels that we have now are therefore very low. The socioeconomic effects of these low levels can be substantial, but they are also very difficult to take into consideration precisely when setting an OEL, also because we have a lack of data on the risks.”

The lower the OEL, the lower the risk

Musu sees the lack of knowledge about the precise risks as a good reason for keeping the OELs as low as possible. “For the vast majority of carcinogenic substances, we do not know what a safe level is and there is correlation between virtually any level and an increased risk of cancer. Therefore, the simple rule is: the lower the OEL, the lower the risk of cancer.”

Database of hazardous substances

The database of Occupational Exposure Limits of Hazardous Substances in the Workplace at the SER contains the OELs of more than 2000 substances. These are carcinogenic substances, as well as substances that can damage DNA or fertility, or cause allergies. The SER Subcommittee on Occupational Exposure Limits for Hazardous Substances in the Workplace advises the Ministry of Social Affairs and Employment on the feasibility of statutory OELs for substances for which no safe level of exposure is known. Representatives of employers and employees sit on the committee.
More information about OELs and the database