Daniels Training Services

Q&A: Hazardous Waste Determination for Sodium Arsenite

Q&A: Hazardous Waste Determination for Sodium Arsenite

May 6, 2016, a question from a past attendee of one of my Training Seminars (unfortunately, I don’t provide Training Seminars anymore.  Check out my website for other training options:  Onsite Training or Webinar Training).

Hi Dan
I took a class with you a couple years ago.
I have another question for you. I figure if you don’t know the answer you might be able to direct me to where I’d find it.
We would like to do a lab test which requires sodium arsenite which is a hazardous waste. In the test, the sodium arsenite will be greatly diluted. Does the diluted solution then become hazardous waste?
I would greatly appreciate any direction you can give me.

My reply the next day (May 7, 2016):

I will try to answer your question.

  • If the diluted solution of sodium arsenite is to be discarded, it must be managed as a solid waste.  The term “solid waste” as used by USEPA and most states is not limited to wastes in a solid form.  A “solid waste” could be a solid, liquid, semi-solid, or containerized gas.
  • The generator of a solid waste must conduct a hazardous waste determination.
  • Sodium arsenite and the process of generation you indicate does not appear to be a listed hazardous waste.  It does not appear on any of the following codifications of listed hazardous waste:
    • Hazardous waste from non-specific sources (F-codes).
    • Hazardous waste from specific sources (K-codes).
    • Discarded commercial chemical products, off-specification species, container residues, and spill residues thereof (P-codes for acutely toxic and U-codes for toxic).
  • Sodium arsenite does not appear to display the characteristic of any of the following hazardous wastes:
    • Ignitability (D001)
    • Corrosivity (D002)
    • Reactivity (D003)
  • Arsenic is a toxin identified by the USEPA at 40 CFR 261.24.  It is possible, therefore, that it displays the characteristic of toxicity (D004 – D043) for arsenic (D004).
  • A waste containing arsenic may be a toxic hazardous waste (D004) if it contains a leachable concentration of arsenic above the regulatory threshold of 5.0 mg/L.  In other words, if it displays the characteristic of toxicity.
  • Analysis by the Toxicity Characteristic Leachate Procedure (TCLP) is one way to determine the concentration of a toxin in leachate derived from a waste in a solid form.  If the waste is already in a liquid form, the total concentration of the toxin must be determined.
  • Another – and less expensive – method to determine if your waste displays the characteristic of toxicity is the “Rule of 20”.  Read more about TCLP and alternatives to it here.
  • It is possible, if greatly diluted, that the waste you discard may not be a toxic hazardous waste.
Thank you and please don’t hesitate to contact me if you have any other questions.

Contact me with any questions you may have about the generation, identification, management, and disposal of hazardous waste

Daniels Training Services




My reply appears to have been satisfactory:
Thank you VERY much!  That makes a lot of sense.
Have a great weekend!