March 16, 2023

European Agency to Evaluate Health Effects of Five Substances on Workers

The European Chemicals Agency (ECHA), which works to implement the European Union’s chemicals legislation to protect human health and the environment, has been tasked by the European Commission to evaluate the health effects of five substances on workers. These substances include 1,3-butadiene, which OSHA says is produced through the processing of petroleum; 4,4-isopropylidenediphenol, also known as bisphenol A, and other bisphenols relevant to occupational health; compounds that release boric acid, including boric oxide; 1,2-dihydroxybenzene, or pyrocatechol; and silicon carbide fibers. According to the March 8 issue of ECHA’s weekly e-newsletter, the scientific evaluations will be carried out under the EU’s carcinogens, mutagens or reprotoxic substances directive, which covers health and safety risks related to occupational exposure to carcinogens, mutagens, or substances toxic to reproduction. ECHA projects that the evaluations will be finalized by February 2025 and that it may include proposals for occupational exposure limit values, biological limit and biological guidance values, or notations for the substances.

NIOSH describes 1,3-butadiene as a “colorless gas with a mild aromatic or gasoline-like odor.” OSHA’s permissible exposure limit for the substance is 1 part 1,3-butadiene per million parts of air measured as an eight-hour time-weighted average, and its short-term exposure limit is 5 ppm as determined over a sampling period of 15 minutes.

Bisphenol A is primarily used in making polycarbonate plastic and some epoxy resins, according to a NIOSH Science Blog post. A NIOSH skin notation profile of bisphenol A published in 2011 explains that the substance is “potentially capable of causing adverse health effects following skin contact” and assigns it a skin notation of SK: SEN, with critical effects including skin allergy and photoallergy. While OSHA and NIOSH have not established exposure limits for bisphenol A, NIOSH encourages employers to minimize workers’ exposure to the substance using the hierarchy of controls.

The NIOSH Pocket Guide to Chemical Hazards entry for boric oxide states that individuals can be exposed to the substance through inhalation, ingestion, and skin or eye contact, and that symptoms of exposure include irritation of the eyes, skin, and respiratory system; cough; conjunctivitis; and skin redness. NIOSH’s recommended exposure limit for boric oxide is 10 mg/m3 as a TWA concentration for up to a 10-hour workday during a 40-hour work week, and the current OSHA PEL is 15 mg/m3 as an eight-hour TWA.

Pyrocatechol is a “colorless, crystalline solid with a faint odor” that will discolor to brown in air and light, according to NIOSH. OSHA has not established a PEL for pyrocatechol, but the NIOSH REL is 5 ppm, or 20 mg/m³. The substance also carries a skin notation from NIOSH of SK: SYS-DIR(IRR)-SEN due to its capability of causing “numerous adverse health effects following skin contact.” According to the agency, effects may include acute toxicity, skin irritancy, skin depigmentation, and skin allergy.

Exposure to silicon carbide, described by NIOSH and OSHA as “yellow to green to bluish-black, iridescent crystals,” may cause symptoms such as irritation of the eyes, skin, and upper respiratory system as well as cough. OSHA’s PEL for silicon carbide is 15 mg/m³ (total dust) and 5 mg/m³ (respirable fraction), whereas the NIOSH REL is 10 mg/m³ (total dust), 5 mg/m³ (respirable fraction). Fibrous forms of the substance, including whiskers, carry an ACGIH threshold limit value of 0.1 f/cc for respirable fibers and a carcinogenic classification of TLV-A2, which denotes a suspected human carcinogen.

A table on ECHA’s website summarizes the agency’s other work related to OELs.