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Engineering | Safe Engineering

Incident Description:
Recently, an ASU researcher became exposed to a small amount of liquid which contained a mixture of concentrated Hydrofluoric acid (49%) and Nitric acid (70%). The researcher suffered delayed burns to the tip of the index finger. Without immediate first aid and medical treatment, the researcher may have lost the finger from this exposure. It is believed the researcher was exposed while opening small acid-containing dissolution capsules. The lab written Standard Operating Procedure (SOP) requires two pair of poly-vinyl chloride (PVC) cleanroom gloves, however the researcher was wearing a single pair of PVC gloves while opening the small friction-locked cap of each capsule.

Potential Causes of the Incident:
Severe chemical burns can result from contact with concentrated Nitric acid and Hydrofluoric acid. The apparent cause of the exposure in this case is a small tear or leak in the glove. A small quantity of the concentrated acid mixture contacted the researcher’s skin near her fingernail. The gloves used by the researcher were not suited for work with concentrated acids. No initial leak check of the gloves was performed, therefore, one or more of the following contributed to the exposure: undetected flaw in the glove material, acid moved through the intact glove, or physical damage to the glove during the procedure.

Adequate selection and pre-use inspection of personal protective equipment (PPE) is necessary to prevent personal injury from chemical contact with hazardous materials. Thin-layer natural rubber or neoprene glove material is well suited protection while still offering good dexterity to the user. EH&S recommends wearing two pair of gloves worn together for safe handling of HF – unsupported neoprene for the outer layer glove and nitrile for the inner layer glove.

Lessons Learned:
1. Verify Standard Operating Procedures (SOPs) are in place for processes that involve the handling of particularly hazardous substances such as HF. More information is available on page 7 of the ASU Chemical Hygiene Plan,
2. Prior to use, personal protective equipment (PPE) must be inspected thoroughly to identify defects. Small defects may be difficult to identify during glove inspections, but can lead to serious injury from chemical contact.
3. While performing activities that may pinch, puncture, or tear gloves, extreme caution must be taken to prevent glove damage.
4. Prior to handling HF, always verify sufficient Calcium Gluconate antidote is present, within the proper shelf-life for the material, and remains in a gel-like state.
5. Immediate first aid and medical treatments make a significant difference in outcomes and tissue damage!

If there are any concerns or questions regarding health and safety within a laboratory, please contact Jonathan Klane, Assistant Director – Safety Programs for Engineering, at 480-965-8498 or or Friederike Doerstling, Chemical Safety Specialist for Engineering at 928-451-5438 or