Substance-Specific Issues

Hydrofluoric acid; first aid statements

Substance:

Hydrofluoric Acid; CAS No. 7664-39-3

Issue:

For dermal contact, some MSDSs for products containing hydrofluoric acid (HF) advise flushing with water only while others specify the use of zephiran chloride solution or calcium gluconate gel. Some parties have viewed this as conflicting information. What is the recommended first-aid response? If the hydrofluoric acid is present in a mixture, (e.g. 10% hydrofluoric acid and 30% sulphuric acid), would the first aid requirements change?

Considerations:

Canadian poison control centres recommend that HF exposure be managed by removal of contaminated clothing, flushing exposed skin area with large volumes of water for 15 to 30 minutes or more, gentle massaging of calcium gluconate gel (2.5%) into the burn area for at least 15 minutes, continuing until pain subsides, followed by covering of affected area with a thick layer of gel and dressing (to be inspected and changed every 4 hours). Additional recommended procedures could entail debridement, nail removal if required and subcutaneous administration of calcium gluconate which can be carried out after the victim is transferred to a hospital.

The Poison Management Manual produced by the British Columbia Drug and Poison Information Centre recommends that inhalational and systemic toxicity should be anticipated in all exposures involving >50% hydrofluoric acid concentration covering >1% body surface area or any concentration of hydrofluoric acid covering >5% body surface area. It further indicates that exposure to concentrations <20% may show a delayed onset of effects even beyond 24 h; hence there should be clinical follow-up even in the absence of obvious symptoms.

In the case of HF burns or burns caused by products containing HF, calcium gluconate has been utilized to provide binding of excessive fluoride ions which are responsible for the corrosivity, as well as to counteract the electrolyte imbalance that leads to adverse health effects and lethality. Magnesium salts (as well as other salts of calcium) have been tried with lesser efficacy than calcium gluconate. Calcium chloride must not be used as it will cause necrosis.

Since HF burns are not very common and require early institution of specific treatment, a note must accompany the victim being transferred to a hospital, clearly identifying hydrofluoric acid as a causative agent. It is also prudent to keep calcium gluconate gel at work sites where hydrofluoric acid or products containing hydrofluoric acid are used.

In the case of burns caused by corrosive mixtures containing hydrofluoric acid, the recommended procedure for HF burns may be followed as it encompasses general measures used for other corrosive acids while providing additional measures specific to the treatment of hydrofluoric acid burns.

A 1998 article in Chemical Health & Safety recommends the use of 0.13% benzalkonium chloride (or zephiran chloride) or 2.5% calcium gluconate gel after flushing for 5 minutes with large amounts of running water. Flushing for longer than 5 minutes would be unnecessary and would delay further treatment. The article also states:

"Clinical experience has shown that both benzalkonium chloride and calcium gluconate gel are effective when used correctly in appropriate situations. In an animal model, benzalkonium chloride soaks appear to be superior to calcium gluconate gel under the experimental conditions used."

Recommendations:

Label: It is recommended that information communicating the following be disclosed on the label for a [WHMIS] controlled product containing any quantity of hydrofluoric acid:

This product contains hydrofluoric acid, exposure to which may cause life-threatening burns requiring specific treatment. Symptoms of exposure may be delayed. Seek immediate medical attention, even in the absence of symptoms.

As much of the first aid information provided below for the MSDS as can be reasonably included in the space provided should also appear on the label.

MSDS: It is recommended that information communicating the following be disclosed on the MSDS for any product containing any quantity of hydrofluoric acid:

This product contains hydrofluoric acid, dermal exposure to which necessitates the following specific treatment:

1. Immediately remove contaminated clothing and continually flush exposed areas of skin with large volumes of water. Rinsing may be limited to 5 minutes if 0.13% benzalkonium chloride solution or 2.5% calcium gluconate gel is available, with the soaks or gel applied as soon as the rinsing is stopped. If not available, rinsing must continue until medical treatment is rendered.
   
   
2. Immediately after thorough washing, use one of the measures below:
   
   
   1. Begin soaking the affected areas in iced 0.13% benzalkonium chloride solution. Use ice cubes, not shaved ice, in order to prevent frostbite. If immersion is not practical, towels should be soaked with iced 0.13% benzalkonium chloride solution and used as compresses for the burned area. Compresses should be changed every 2 to 3 minutes. Soaks or compresses should be continued until pain is relieved or until more definitive medical treatment is provided. Relief of the pain is an indication of the success of treatment; therefore, local anesthetics should be avoided. It is recommended the applier wear chemical protective gloves (e.g. butyl rubber gloves).
      
      
   2. Gently massage a liberal quantity of calcium gluconate 2.5% gel - commercial preparation,'HF Antidote Gel' if available or prepare at site by adding 10 mL of 10% calcium gluconate injectable solution to 30 mL of KY jelly or Muko other water soluble gels also suitable. (Note: Taro Gel is physically incompatible with calcium gluconate and must not be used. Do not use calcium chloride as it causes skin necrosis). Apply gel every 15 minutes and massage continuously until pain subsides and/or redness disappears or until medical attention becomes available. It is recommended the applier wear chemical protective gloves, (e.g. butyl rubber gloves).
      
      
3. Medical attention must be provided immediately.
   
   
4. Exposure to low concentrations may be followed by a delayed onset of symptoms; seek immediate medical attention for all exposures to any concentration of hydrofluoric acid.

References:

Bertolini, JC; Hydrofluoric acid: A review of toxicity. The Journal of Emergency Medicine 1992;10:163-8.

Browne, TD; The treatment of hydrofluoric acid burn. Journal of the Society of Occupational Medicine 1974;24:80-9.

Edinburgh, M; Swift, R; Hydrofluoric acid burns of the hands: A case report and suggested management. The Australian and New Zealand Journal of Surgery 1989;59:88-91.

MacKinnon, MA; Hydrofluoric acid burns. Dermatologic Clinics 1988;6:67-74.

Mistry, D; Wainwright, D; Hydrofluoric acid burns. American Family Physician 1992; 45:1748-54.

Poison Management Manual, 4^th Edition, B.C. Drug and Poison Information Centre (DPIC), 1997; 272-274.

Shewmake, SW; Anderson, BG; Hydrofluoric acid burns. A report of a case and review of the literature. Archives of Dermatology 1979;115:593-6.

Siedlicki, A; Hydrofluoric acid burns. The Journal of the American Medical Association 1965;191:353.

Segal, EB; First aid for a unique acid: HF. Chemical Health & Safety, September/October 1998; 25-28.

Tepperman, P; Fatality due to acute systemic fluoride poisoning following a hydrofluoric acid skin burn. Journal of Occupational Medicine 1980;22:691-3.

Upfal, M; Doyle, C; Medical management of hydrofluoric exposure; Journal of Occupational Medicine 1990;32:726-73.