Generally speaking, the occupational exposure limits (OEL) are the maximum airborne concentrations of a toxic substance to which a worker can be exposed over a certain period without suffering any harmful consequences. Regulatory bodies determine these values to indicate the levels of exposure that are considered safe (health-based) for a chemical substance in the air of a workplace.

Occupational exposure limits are established based on the substance’s chemical properties, experimental studies on animals and humans, and toxicological and epidemiological data. The OEL’s are set by national, regional or federal regulatory authorities taking into account available information and most recent data on the substance hazards, especially concerning the carcinogenicity, mutagenicity and toxicity to reproduction, and the acute effects of exposure. 

Primarily OEL’s are set for the workers’ safety. Setting limits on exposure to hazardous and harmful substances aims to help employers protect their workers’ health by reducing the risks when using chemicals at work and limiting workers’ exposure to hazardous chemicals.

These values are mainly intended to prevent exposure to airborne chemicals and prevent workers from inhaling chemical vapours, dust, or mists.

Besides the authorities, OEL’s are also sometimes developed by professional organisations. These OEL’s are considered guidelines since only the values adopted and prescribed by the legislation are enforceable.

Safety Data Sheets (SDS’) and OEL’s

As you may already know, Safety Data Sheet (SDS) is a document designed to provide persons who handle chemicals with relevant safety information. Whether you use, store, sell or handle hazardous chemicals in any other way, you should have an SDS at hand. SDS’ are primarily developed for and used by workers, so it makes sense that the SDS also contains information about the relevant occupational exposure limits.

Today, most SDS are being made according to the UN model regulations called the Globally Harmonized System for Classification and Labelling of Chemicals (GHS). When implemented by a country, GHS is usually transposed in local legislation. GHS also sets the requirements for the format and content of the SDS. According to GHS, SDS should have 16 sections, and one of these sections should contain information about the OEL’s. Section 8 of the SDS, titled Exposure controls/personal protection, should list all applicable occupational exposure limit values together with the information about the personal protective equipment and exposure control measures.

OEL’s should be specified for all constituent substances in the product if applicable. In case that there is an applicable OEL, value determined by the authorities, for a constituent, it should be mentioned. They are specified for chemicals that can be inhaled as vapours, dust or mists. This requirement is independent of the aggregate state of the whole product. For example, if the product is rubber, it is considered a chemical mixture by the regulation and OEL’s of all dusty constituents or can be released as vapours or mist need to be specified.

This is primarily done to protect the workers from exposure to hazardous chemicals. The exposure limits allow the employer to implement adequate exposure control measures to protect the workers from possible harmful effects caused by occupational exposure at the workplace. Some of the most common measures include engineering controls such as exhaust ventilation or use only in closed systems. Additionally, suitable personal protective equipment recommendations are also given to prevent or minimise respiratory, skin and eye exposure and prevent or minimize the risk of injury or occupational illnesses. In this regard, SDS can be considered a tool that helps employers and users of the chemical product determine which hazardous chemicals are present at the workplace and mitigate the risks associated with them and exposure to them.

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