National Academies Press: OpenBook
« Previous: ED50 for Severe Effects
Suggested Citation:"CONCLUSIONS AND RECOMMENDATIONS." National Research Council. 1997. Review of Acute Human-Toxicity Estimates for Selected Chemical-Warfare Agents. Washington, DC: The National Academies Press. doi: 10.17226/5825.
×
Page 56
Suggested Citation:"CONCLUSIONS AND RECOMMENDATIONS." National Research Council. 1997. Review of Acute Human-Toxicity Estimates for Selected Chemical-Warfare Agents. Washington, DC: The National Academies Press. doi: 10.17226/5825.
×
Page 57
Suggested Citation:"CONCLUSIONS AND RECOMMENDATIONS." National Research Council. 1997. Review of Acute Human-Toxicity Estimates for Selected Chemical-Warfare Agents. Washington, DC: The National Academies Press. doi: 10.17226/5825.
×
Page 58

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

REVIEW OF ACUTE HUMAN-TOXICITY ESTIMATES FOR VX 56 mg for a 70-kg man be lowered because of the subcommittee's recommendation for lowering the LD50 estimate. The subcommittee also recommends that further research on VX be conducted to establish an ECt50 estimate with a greater degree of confidence. CONCLUSIONS AND RECOMMENDATIONS The subcommittee's conclusions concerning the scientific validity of CDEPAT's proposed human-toxicity estimates for VX are summarized Table 6-1. Eight human-toxicity estimates, instead of the seven proposed for the other organophosphate agents, were calculated for VX; an ECt 50 for severe effects from percutaneous vapor exposure was also calculated. Of the eight human-toxicity estimates for VX proposed by CDEPAT, the subcommittee concludes that only one estimate is appropriate for protecting soldiers and is scientifically valid. The subcommittee recommends that four estimates serve as interim values until further research is conducted, and three estimates are to be lowered. The subcommittee recommends that further research be conducted on VX to establish the human-toxicity estimates with a greater degree of confidence.

TABLE 6-1 Evaluation of Human-Toxicity Estimates for VX Human-Toxicity Estimates for VX Toxicity Route and Form Existing CDEPAT's Subcommittee's Rationale for Subcommittee's Evaluation Type of Exposure Estimates Proposed Evaluation of Proposed Estimates Estimates for VX LCt50 a Percutaneous, None 150 mg-min/ Proposed estimate should Degree of confidence in data is low to moderate; further vapor m3 be considered an interim research recommended value Inhalation, 30 mg-min/ 15 mg-min/ Proposed estimate should Degree of confidence in data is low to moderate; further vapor m3 m3 be lowered research recommended ECt50 b Threshold Percutaneous, None 10 mg-min/ Proposed estimate should Degree of confidence in data is low; a no-observed- effects vapor m3 be considered an interim adverse-effect level (NOAEL) was not defined; further value research recommended Severe Percutaneous, None 25 mg-min/ Proposed estimate should Degree of confidence low to moderate; further research effects vapor m3 be considered an interim recommended value REVIEW OF ACUTE HUMAN-TOXICITY ESTIMATES FOR VX Inhalation, 25 mg-min/ 10 mg-min/ Proposed estimate should Insufficient data; further research recommended vapor m3 m3 be considered an interim value Mild effects Inhalation, 0.09 mg- 0.09 mg- Proposed estimate is Available human data support the proposed estimate vapor min/m3 min/m3 scientifically valid LD50 c Percutaneous, 10 mg/70- 5 mg/70-kg Proposed estimate should Animal data indicate that the proposed estimate is too liquid kg man man be lowered high; furthermore, no uncertainty factor used in lieu of variability associated with dermal penetration of various regions of body; further research recommended 57

Human-Toxicity Estimates for VX Toxicity Route and Form Existing CDEPAT's Subcommittee's Rationale for Subcommittee's Evaluation Type of Exposure Estimates Proposed Evaluation of Proposed Estimates Estimates for VX ED50 d Severe Percutaneous, 5 mg/70-kg 2.5 mg/70-kg Proposed estimate should The ED50 is based on the ID50 e/LD50 ratio; the effects liquid man man be lowered subcommittee recommends that the LD50 be lowered, therefore, the ED50 should be lowered correspondingly; further research recommended a LCt : Vapor exposure that produces lethality in 50% of the exposed animals. Ct refers to the product of concentration (c) and exposure time (t). Note that Ct is not 50 necessarily a constant. b ECt : Percutaneous vapor exposure or inhalation vapor exposure causing a defined effect (e.g., incapacitation, severe effects, mild effects, threshold effects). 50 c LD : Liquid dose causing lethality in 50% of the exposed animals. 50 d ED : Liquid dose causing a defined effect in 50% of the exposed animals. 50 e ID : Liquid dose causing incapacitation in 50% of the exposed population. 50 REVIEW OF ACUTE HUMAN-TOXICITY ESTIMATES FOR VX 58

Next: Lethal Effects (LCt50) »
Review of Acute Human-Toxicity Estimates for Selected Chemical-Warfare Agents Get This Book
×
Buy Paperback | $50.00 Buy Ebook | $39.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

No reliable acute-exposure1 standards have been established for the particular purpose of protecting soldiers from toxic exposures to chemical warfare (CW) agents. Some human-toxicity estimates are available for the most common CW agents--organophosphorus nerve agents and vesicants; however, most of those estimates were developed for offensive purposes (that is, to kill or incapacitate the enemy) and were intended to be interim values only. Because of the possibility of a chemical attack by a foreign power, the Army's Office of the Surgeon General asked the Army's Chemical Defense Equipment Process Action Team (CDEPAT) to review the toxicity data for the nerve agents GA (tabun), GB(sarin), GD (soman), GF, and VX, and the vesicant agent sulfur mustard (HD) and to establish a set of exposure limits that would be useful in protecting soldiers from toxic exposures to those agents. This report is an independent review of the CDEPAT report to determine the scientific validity of the proposed estimates.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!