Home Podcasts THMG003 – Toxics, Part I

THMG003 – Toxics, Part I


In this episode, we discuss the hazards of toxics and how they affect you as a hazmat technician. We’ll continue to discuss this topic in Episode 4.

Complete Show Notes

0:50 What Makes Something Toxic?

  • Substance must have a negative effect on another organism to be considered toxic
  • Toxics must also have chemical and physical properties to cause harm
  • There must be a large enough dose to produce an effect and long enough exposure to cause a problem
  • Toxics need a route of entry (respiratory, transdermal, etc.) and a susceptible target organism

3:15 Everything Can Be Toxic!

  • Anything can be toxic if the dose is large enough – i.e. sugar, salt, or alcohol
  • Don’t think of things in terms of being toxic or not being toxic – instead, determine whether there’s enough of any one substance for it to be toxic
  • The time you’ll be exposed to toxic substances should dictate hazmat operations
  • Each person has a different reaction to toxics (age, gender, metabolism, medical conditions, etc.)

6:40 Exposure Control

  • PPE is essential
  • Don’t forget about gloves, handwashing, bunker gear, eye protection, shields, etc.
  • Always take extra precautions and treat everything as an unknown

8:00 How Are We Exposed?

  • Inhalation – you can’t stop breathing, but you can wear SCBA and APR
  • Ingestion – washing your hands is the best way to avoid ingesting toxins
  • Absorption – toxic substances can enter the body transdermally (i.e. when you’re sweating and your pores are enlarged); toxins also come in through the mucous membranes, which are the fastest path to the central nervous system
  • Injection – needles, lacerations, punctures, projectiles

13:20 Toxins in the Body (Pathophysiology)

  • Toxins enter the bloodstream and eventually find a target organ, which screws up our body’s natural chemistry
  • Toxins can stay in that organ and cause acute damage
  • Over time, the body metabolizes that chemical – if the toxin is fat soluble, it stays in the body and can lead to chronic issues down the road

16:30 NIOSH and OSHA Exposure Limits

  • NIOSH (National Institute for Occupational Safety and Health)
    • Considered a guideline for reasonable levels
    • Threshold Limit Value (TLV) – 10 hours per day, 4 days a week (limit for one day)
    • Recommended Exposure Limit (REL) – 8 hours per day, 5 days a week (limit for one day)
  • OSHA (Occupational Safety and Health Administration)
    • Rules that have been passed into law
    • Permissible Exposure Limits (PEL) – 8 hours per day, 5 days a week (limit for one day)
    • Threshold Limit Value Time-Weighted Average (TLV-TWA) – 8 hours per day, 40 hours per week (limit for one week – you can take a heavy hit one day, but the average must still stay below the limit)
    • Threshold Limit Value Short-Term Exposure Limit (TLV-STEL) – 15 minutes of exposure 4 times per day with a minimum 1-hour break (used by fire departments, hazmat units, first responders, etc.; designed for confined space entry)
    • Threshold Limit Value Ceiling (TLVC) – Absolute exposure limit that shouldn’t be exceeded at any time

22:00 ILDH (Immediately Dangerous to Life and Health) Exposure Limits Per the NFPA (National Fire Protection Association)

  • ILDH starts where the smoke starts and where you need to put your SCBA on
  • Numbers based on the maximum concentration an unprotected person could escape from within 30 minutes without having any impairing symptoms or irreversible effects
  • LD (lethal dose) for solids and liquids can be LD 50 or LD 100
  • LC (lethal concentration) for gasses can be LC 50 or LC 100
  • 50 and 100 refer to the percentages of the population that will die with that specific toxic dose or concentration
  • It’s essential to have an accurate IDLH for that specific toxic in order to make informed decisions – use all of the information available to get a broader picture of the chemical you’re dealing with and its toxicity
  • STEL is important to first responders, as they’re in and out quickly

26:40 Types of Toxics

  • Simple asphyxiates – these toxics work via displacement or removal (no oxygen in the environment for the body to use)
  • Chemical asphyxiates – carbon monoxide and hydrogen cyanide are the most common (oxygen is there and can be taken in by the body, but can’t be used)

34:40 Anhydrous Ammonia Incident at Prospect Park Ice Rink

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