CHEMICAL AGENTS

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Lethal Concentration Time
LCT50 Formulation
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LCT50 Course Overview

1. Purpose
2. History
3. Philosophy CATO vs. NTOA
4. Formula and Calculations
5. Practical Applications
6. Tactical Case Study

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LCT50 Purpose

1. Helps determine amount of chemical agent to use.
2. Estimates the time a suspect can remain in agent
   environment.
3. Provides a guideline for command staff and for
   potential criminal civil litigation.

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LCT50 Defined

• Concentration (LC50) multiplied by the time (T)
  of exposure that is lethal to 50 of exposed
  personnel.
• (Usually expressed in minutes of exposure.)

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LCT50 History

• Formula developed from an Edgewood Arsenal study
  of CS exposure in 1967.
• Edgewood Arsenal is a chemical research facility
  (now known as US Army Medical Research Institute
  of Chemical Defense).
• Conducted for the U.S Army who was replacing CN
  with CS for outside riot control. Not inside or
  for civil law enforcement!
• Conducted in a static, sealed container.
• Formula values determined concentration levels
  were lethal for 50 of population.

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LCT50 Philosophy

• National Tactical Officers Association
• California Association of Tactical Officers

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LCT50 Philosophy

• NTOA
• Based on use of force reasonableness standard
  
• (Graham vs. Connor).
• Dont need a formula to use other forms of
  force.
• LCT50 based on faulted research
• No consideration given to biological/metabolic
  differences.
• Conducted in static sealed containers.
• CS was intended for outside riot control, not
  inside sealed environments.

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LCT50 Philosophy

• CATO
• Formula and incident based.
• Uses Edgewood Arsenal Study as a baseline.
• Bases concentration variable (i.e. .004, .008,
  etc) on
• tactical situation.
• Estimates the time a suspect can remain in the
  agent.

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LCT50 Formula

• 3-Step Process
• Compute room(s) volume ( L x W x H )
• Equals CUBIC FEET
• CUBIC FEET X CONCENTRATION VARIABLE
• Equals GRAMS of AGENT NEEDED
• CUBIC FEET GRAMS of AGENT NEEDED X .71
  (CS Constant) LCT50 in minutes

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LCT50 Formula (CV)

• Concentration Variable
• Equates to grams of agent per 1000 cubic feet.
• US Department of Energy research determined 4
  grams per 1000 cubic feet ( or .004) as the
  smallest concentration to yield agent symptoms.
• A higher variable will give a higher
  concentration of agent, but a shorter LCT50.
• A lower variable will yield a lower agent
  concentration, but a higher LCT50.
• For Example
• .012 60 minutes
• .008 89 minutes
• .004 178 minutes
• Concentration variables should be based on SWAT
  chemical agent deployment philosophy.

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LCT50 Formula (Constant)

• Constant (.71)
• Based on US Army research.
• Research that was based on how much agent would
  kill a human.
• Will never change.

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LCT50 Worksheet (part 1)

• 1. _______ x _______ x _______
  ___________
• Length Width Height
  Cubic Feet
• 2. _________ x CV _________________
• Cubic Feet Total Grams Needed
• 3. __________ ________ x .71
  _____________
• Cubic Feet Total of
  LCT50 (minutes)
• Grams

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LCT50 Worksheet (part 2)Proposed LCT50 - Time

• 1. _______ x _______ x _______
  ___________
• Length Width Height
  Cubic Feet
• 2. _________ x .71 _______________
  ________________
• Cubic Feet Proposed LCT50
  Grams of Agent

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LCT50 Worksheet (part 2)Amount of Agent Used

• 1. _______ x _______ x _______
  ___________
• Length Width Height
  Cubic Feet
• 2. __________ ______________ x .71
  _______________ Cubic Feet Grams of
  Agent LCT50 (minutes)

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LCT50 Munitions Needed

• Now that we know the total of grams of agent
  and our LCT50, how many munitions will we need?
• ANSWER
• Divide total of grams of agent by the amount of
  agent in your munition of choice.
• This is where a munitions data card comes in
  handy!

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Munition Data Cards
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Questionsor Comments