Dust Almanac

Walnut

Juglans spp. · Juglandaceae · hardwood

Also known as: black walnut, American walnut, English walnut, European walnut, Persian walnut, Claro walnut, Central American walnut, Juglans

Region: North and Central America, Europe and Asia; main lumber species are black walnut (eastern North America) and English walnut (Europe/Asia)

Planed board of black walnut with dark chocolate-brown heartwood and a stripe of pale sapwood.

Walnut is a dark, prized furniture hardwood, mainly black walnut (Juglans nigra) in North America and English or European walnut (Juglans regia). Woodworkers use it for fine furniture, gunstocks, veneer, turning, and accents, and it is often finished without stain for its chocolate-brown color.

Health hazards

  • 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-term heavy exposure. This applies to every species, so dust control matters whatever you cut.1

    Effects
    nasal and sinus cancer
    Exposure route
    inhalation
    From
    dust

  • Cancer

    Evidence: Listed by an agency

    ACGIH names walnut dust as a suspected human carcinogen (A2). The listing says walnut without naming a species.2

    Effects
    nasal and sinus cancer
    Exposure route
    inhalation
    From
    dust

  • Asthma / respiratory allergy

    Evidence: Confirmed in clinical testing

    One worker developed asthma from Central American walnut (Juglans olanchana) dust, confirmed by inhalation challenge; no IgE antibodies were found, so the mechanism is unclear. This is not black or English walnut, and we found no confirmed asthma reports for those species.3

    Effects
    occupational asthma
    Exposure route
    inhalation
    From
    dust

  • Respiratory irritation

    Evidence: Listed by an agency

    The UK HSE lists sneezing and runny or blocked nose (rhinitis) for walnut, excluding African walnut. It does not name the Juglans species.4

    Effects
    sneezing, rhinitis
    Exposure route
    inhalation
    From
    dust

  • Skin allergy

    Evidence: Confirmed in clinical testing

    A Finnish clinic series found two workers whose dermatitis reacted to walnut dust on patch testing. The abstract does not say which walnut species.5

    Effects
    allergic contact dermatitis
    Exposure route
    skin
    From
    dust

  • Skin irritation

    Evidence: Listed by an agency

    Juglone in green walnut husks can stain skin brown and cause blistering irritation, and the UK HSE notes dermatitis from walnut nut shells and roots. This comes from the nuts, husks, and roots rather than dry lumber.46

    Effects
    irritant dermatitis, blistering, brown skin staining
    Exposure route
    skin

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 time-weighted average, 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

Known compounds

  • juglone: skin irritant and stain in green walnut husks source

'African walnut' (Lovoa trichilioides) and 'Brazilian walnut' or imbuia (Ocotea porosa) are not Juglans; check their own pages. WFO now treats Juglans olanchana as a synonym of Juglans pyriformis.

Sources

  1. 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
  2. US Occupational Safety and Health Administration. Occupational Chemical Database: Wood Dust. Last updated 06/23/2023. Link
  3. Bush RK, Clayton D. Asthma due to Central American walnut (Juglans olanchana) dust. Clin Allergy. 1983;13(4):389-94. Link
  4. Health and Safety Executive. Toxic woods. Woodworking Information Sheet No 30 (Revision 1), WIS30(rev1). HSE; first published 11/2012. Withdrawn from hse.gov.uk (404 since c. Jan 2020); archived copy cited. Link
  5. Estlander T, Jolanki R, Alanko K, Kanerva L. Occupational allergic contact dermatitis caused by wood dusts. Contact Dermatitis. 2001;44(4):213-7. Link
  6. Olvera-Cortés V, Pulido-Díaz N, Orellana-Arauco ÁR. Discoloration and bullous lesions on the hands. Cutis. 2019;104(4):E6-E8. Link

Last reviewed .