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Home > Food from Farm to Table > Food Safety > Anthrax - Effects of Heat, Cleaning Compounds & Chemical Disinfectants

Anthrax - Effects of Heat, Cleaning Compounds and Chemical Disinfectants


The following information was extracted from the National Food Processors Association bulletin, "Anthrax, What it is and addressing inquiries," with their permission.

How heat resistant is Bacillus anthracis (B. Anthracis)?

The heat resistance of B. anthracis is similar to that of many strains of Bacillus.

Vegetative Cells

  • Moist heat resistance
  • survived 5 but not 5.5 min at 65ºC (149ºF)
  • survived 3.5 but not 4 min at 70ºC (158ºF)
  • survived 2.5 but not 3 min at 75ºC (167ºF)
  • survived 50 but not 60 sec at 80ºC (176ºF)
  • Dry heat resistance: destroyed by 2 h at 92-100ºC (198-212ºF)

Spores

  • Moist heat resistance in physiological saline (17 strains tested):
  • D value at 90ºC (194ºF) - 2.5-7.5 minutes
  • D value at 95ºC (203ºF) - 1.7-4.2 minutes
  • Dry heat resistance:
  • Death times of spore suspension on glass:
  • 60 min at 120ºC (248ºF)
  • 9 min at 160ºC (320ºF)
  • 2.5-4 min at 229ºC (444ºF)
  • 1.5-2 min at 288ºC (550ºF)
  • Death time of 108 spores on aluminum foil (0.2 mm thick):
  • 30 min at 140ºC (284ºF)
  • 8 min at 160ºC (320ºF)
  • 2 min at 180ºC (356ºF)

How does drying affect B. anthracis?

Spores can survive for an extended period of time (in some cases as long as 50 years) under dry conditions.

Does Chlorine kill the spores?

As with other sporeformers, B. anthracis spores can be expected to be somewhat resistant to chlorine and survive chlorination of water. Exposure for extended times at higher concentrations will be more effective. Hypochlorite solutions have been used effectively to decontaminate environmental surfaces contaminated with bodily fluids; however, these fluids would be expected to contain mostly vegetative cells. Studies have shown that exposure to 2.3-2.4 ppm chlorine, pH 7.2, at room temperature for 2 hours kills B. anthracis vegetative cells.

Are cleaning compounds and chemical disinfectants effective against B. anthracis?

Most commercial cleaners and disinfectants, including alcohols, phenols, quaternary ammonium compounds, ionic and non-ionic detergents, acids and alkalis, are ineffective against anthrax spores. Surfaces contaminated with anthrax spores are sterilized with 10% formaldehyde, 2% glutaraldehyde, 3% hydrogen peroxide or 0.3% peracetic acid. Other newer disinfectants may be useful, but have not been tested against anthrax.

What treatments are recommended for inactivation?

  • Expose to dry heat at 140ºC (284ºF) for 3 hours.
  • Immerse in water and maintain at 95ºC (203ºF) for 25 minutes or at 100ºC (212ºF) for 15 minutes.
  • Autoclave at 120ºC (248ºF) for 10 minutes.
  • Expose to 10% bleach for two hours.

The Code of Federal Relations (9 CFR 310.9) also provides information about handling anthrax clean-up in a slaughter plant.