Lethal dose
A lethal dose (LD) is an indication of the lethality of a given substance or type of radiation. Because resistance varies from one individual to another, the 'lethal dose' represents a dose (usually recorded as dose per kilogram of subject body weight) at which a given percentage of subjects will die. The LD may be based on the standard person concept, a theoretical individual that has perfectly "normal" characteristics, and thus not apply to all sub-populations.
LD values for humans are best estimated by extrapolating results from human cell cultures. One outdated form of extrapolation involves measuring LD on animals like mice or dogs, converting to dosage per kilogram of biomass, and extrapolating to human norms. The degree of error from animal-extrapolated LD values is very large. The biology of test animals differs in important aspects to that of humans. For instance, mouse tissue is approximately fifty times less responsive than human tissue to the venom of the Sydney funnel-web spider. The square-cube law also complicates the scaling relationships involved. Researchers are now shifting away from animal-based LD measurements. The U.S. Food and Drug Administration has begun to approve more reliable non-animal methods in response to research cruelty concerns and the lack of validity/sensitivity of animal tests as they relate to humans.[1] [2]
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[edit] References
- ^ "Allergan Receives FDA Approval for First-of-Its-Kind, Fully in vitro, Cell-Based Assay for BOTOX® and BOTOX® Cosmetic (onabotulinumtoxinA)". Source: Allergan, Inc. News Provided by Acquire Media. Page last updated 24 June 2011. http://agn.client.shareholder.com/releasedetail.cfm?ReleaseID=587234. Retrieved 2011-06-26.
- ^ "Vision and Roadmap for the 21st Century". Source: National Toxicology Program. http://ntp.niehs.nih.gov/go/vision. Retrieved 2011-10-29.
