Decontamination Methods

2025-05-12
Elkhorn Slough CTP

Overview

Decon

  • Decontamination Process
  • Equipment
  • Conditions & Situations
  • Implementation

Overview

Decon

  • Decontamination between and after sites is critical
  • Before leaving a field site, thoroughly remove all organic matter (i.e., mud, algae, plants) from nets, sampling gear, boots/boot tread, clothing
  • Be especially cognizant of gear that came into contact with water or aquatic sediments

Decon Steps

  1. Wear appropriate PPE (gloves, safety goggles):
    1. for all options listed, avoid getting concentrated, pre-solution chemical on your skin/eyes/cloths (See SDS for details)
  2. Pre-rinse with water and scrub before cleaning with solution
  3. Clean with solution using appropriate dilution (Bleach, Quat, Virkon-S)

Decon Steps

  1. Allow solution to sit for necessary time (depends on treatment, usually at least 5 minutes)
  2. Rinse off using clean water
  3. If disposing diluted contaminant solution in the field, do so 200+ ft (60m) away from any water sources/culverts/storm drains or ditches.

Decon

Decon Options

Two recent summaries of decontamination treatment options, their efficacy for various pathogens, and associated citations can be found here:

Decon: Bleach

Recent guidance (see here and here) recommend much higher concentrations of bleach to properly decon against Bsal (Batrachochytrium salamandrivorans), though it has not been detected in N. America yet

  • Bleach at 1:20 concentration: works well but hard on gear
  • Soak for minimum 5 min (10 min is ideal)
  • If exposed to air or sunlight the diluted solution will only last ~5 days
  • Dispose of any unused bleach from an open bottle after 1 month, and inactivated quickly by organic material and sunlight so make a fresh batch if dirty!
  • For half a 5 gallon bucket, use 16 oz or 2 CUPS of standard concentrated household bleach

Decon: Quat

  • Quat-128 (%5 DDAC) or Quat-256 (10% DDAC):
    • To make 0.01% solution, (.25 oz / 0.5 TBSP / 7.5 mL) per gallon of water
    • With Quat 256, can use a 15 gallon tub with about 60 ml (2 oz) of quat
  • Soak gear at least 5 minutes, 10 minutes ideal
  • If exposed to air or sunlight, the solution should be changed out at least once a month if using an opaque spray bottle
  • For half a 5 gallon bucket, need about 0.7 oz / 4 teaspoons / 20 mL)

Decon: Virkon-S

  • Virkon-S (21.4% potassium peroxymonosulfate) (1.3 oz. / ~2.5 tablespoons) per gallon of water to make 1% solution
  • Soak gear for at least 2 minutes (5 minutes ideal)
  • Once solution is made, lasts about a week
  • For half of 5-gallon bucket, use about 3.25 oz or 6.5 tablespoons of powder
  • Avoid contact of the powder with skin and clothing; very harmful if you get the concentrated powder in your eyes

Multiple Decontamination Methods Recommended!

Especially if transitioning between office/lab/field between sites:

  • Not all decontamination methods are appropriate for all circumstances
  • Choose the decontamination method(s) appropriate for the equipment being decontaminated and site-specific considerations
  • When possible, opt for the method effective for the most AIS and pathogens as possible
  • If multiple methods must be used, perform them sequentially, and never mix chemicals
  • Ideal approach: chemical, then dry in hot sun for 24+ hours; or chemical, then freeze for 24+ hours

Decon Resources