Dust Almanac

Black locust

Robinia pseudoacacia · Fabaceae · hardwood

Also known as: locust, false acacia, robinia, acacia (European trade name)

Region: Native to the eastern United States; widely naturalized and planted in Europe and Asia

Planed board of black locust with greenish-yellow to golden-brown heartwood and bold ring-porous grain.

Black locust is a very hard, heavy and rot-resistant hardwood used for fence posts, outdoor furniture, decking, playground equipment, boat parts and turning. In Europe it is often sold as 'acacia'.

Health hazards

  • Asthma / respiratory allergy

    Evidence: Confirmed in clinical testing

    A German report identified new wood allergens in black locust dust using antibodies from a worker with occupational respiratory allergy. Details of the challenge testing were not available to us.1

    Effects
    asthma, allergic sensitization
    Exposure route
    inhalation
    From
    dust

  • Cancer

    Evidence: Applies to all wood dust

    IARC classifies all wood dust as carcinogenic to humans, mainly linked to cancer of the nasal cavity and sinuses after long, heavy exposure. This applies to this wood like any other.2

    Effects
    nasal and sinus cancer
    Exposure route
    inhalation
    From
    dust

Not finding a hazard listed here does not mean this wood is safe. All wood dust is hazardous; see how to protect yourself.

Exposure limits

Workplace exposure limits (8-hour average, mg/m³)
BodyLimitNotes
ACGIH TLV1 mg/m³ (inhalable)8-hour TWA; ACGIH value as restated by OSHA. source
EU binding limit (hardwood)2 mg/m³Applies to all hardwood dust
UK WEL (hardwood)3 mg/m³Applies to all hardwood dust
NIOSH REL1 mg/m³Recommended limit for all wood dust

Compare limits across agencies.

Cancer classifications

European timber sold as 'acacia' is often black locust, not a true Acacia. Honey locust (Gleditsia triacanthos) is a different tree.

Sources

  1. Kespohl S, Merget R, Overlack A, Bruening T, Raulf-Heimsoth M. Detection of novel occupational wood allergens in locust wood dust (Robinia pseudoacacia L.). J Allergy Clin Immunol. 2006;118(2):522-524. Erratum in: J Allergy Clin Immunol. 2006;118(5):1189. Link
  2. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Wood Dust and Formaldehyde. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 62. Lyon: International Agency for Research on Cancer; 1995. Link
  3. US Occupational Safety and Health Administration. Occupational Chemical Database: Wood Dust. Last updated 06/23/2023. Link

Last reviewed .