General Information About NICEATM-ICCVAM Test Method Evaluation Areas
View a summary of test methods evaluated by ICCVAM
View a summary of the current status of ongoing and completed NICEATM-ICCVAM
alternative test method evaluation projects
Please scroll down to read an overview on each area
To reduce the risk for accidental poisonings, U.S. Federal regulatory agencies require
the testing of marketed products for acute oral toxicity in rodents. Acute oral toxicity test results are
used to determine the hazard classification and labeling of products, which alert handlers
and consumers to potential toxicity hazards. The LD50 values (dose that produces lethality in 50% of the
animals tested) determined from acute oral toxicity tests are used to place substances in various toxicity
categories that determine the hazard phrases that are used on product labels.
In addition to classification and labeling, acute oral toxicity test results may also be used for:
- Establishing dosing levels for repeated dose toxicity studies or other toxicity studies
- Identifying potential target organs
- Providing information related to the mode of toxic action
- Aiding in the diagnosis and treatment of toxic reactions
- Providing information for comparison of toxicity and dose response among substances in a specific chemical or product class
- Aiding in the standardization of biological products
- Aiding in judging the consequences of single, high accidental exposures in the workplace, home, or from accidental release
- Serving as a standard for evaluating alternatives to animal tests
NICEATM and ICCVAM have evaluated alternatives to the LD50 for assessment of
acute oral toxicity. The Up-And-Down Procedure (UDP)
is an in vivo acute oral toxicity test that reduces and refines animal
use. ICCVAM has recommended that the UDP be used instead of the conventional LD50
test to determine the acute oral toxicity hazard of chemicals.
A Validation Study of In Vitro Cytotoxicity Test Methods generated in vitro
toxicity data to predict rodent in vivo LD50
values and starting doses for acute oral toxicity test methods. ICCVAM has
recommended that these test methods be considered before
using animals for acute oral toxicity testing, and that the methods should be used where determined appropriate
for estimating starting doses for acute oral systemic toxicity tests with rodents.
Further explorations of alternative methods for acute chemical safety testing took place at a
joint NICEATM-ICCVAM/ECVAM/JaCVAM Workshop entitled “Acute Chemical Safety Testing: Advancing
In Vitro Approaches and Humane Endpoints for Systemic Toxicity Evaluations”. International
experts in the fields of toxicology and
human and veterinary medicine considered the identification of key toxicity pathways in order to apply
mechanistically-based in vitro approaches and humane endpoints for systemic toxicity evaluations.
The workshop took place in February 2008 at the NIH.
Biological products, commonly referred to as biologics, are products intended for therapeutic use that are
derived from biological sources. They include viruses, therapeutic sera, toxins, antitoxins and vaccines, and
a variety of other substances that have therapeutic use in humans or animals (e.g., insulin, alpha1 proteinase
inhibitor, anti-hemophillic factor). Current regulatory requirements include testing in animals for identity or
potency for labeling and lot release purposes. ICCVAM welcomes nominations and submissions of alternative test
methods that will refine, reduce, or replace animal testing for these products.
In October 2005, the Humane Society of the United States (HSUS) submitted a test method nomination requesting
that ICCVAM consider alternative tests methods for the determination of the potency of botulinum toxin, and
that ICCVAM convene a workshop to review the state of the science of such test methods.
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In 2003, the American Association of Poison Control Centers reported nearly 150,000 injuries
due to chemical burns from agents such as acids, alkalis, peroxides, bleach, and phenols or
phenol products. Many of these injuries arose from the use of household products.
(Source: Burnsolutions.com)
Injuries to the skin, also called dermal injuries, fall into two categories. Skin corrosion
is permanent damage to the skin that occurs when contact with a substance kills or destroys
cells in the epidermis and dermis. Skin irritation is reversible damage that occurs when a
chemical causes injury to skin cells. Regulatory agencies test substances to determine
whether they are likely to present dermal corrosion or irritation hazards. The agencies
then use test results to classify and label corrosive or irritant chemicals so that
consumers and workers can take appropriate precautions to prevent injury. Test results
are also used to determine appropriate packaging that will minimize hazardous spills during transport.
Traditionally, dermal corrosion and irritation testing is done by applying a test substance
to the skin of a laboratory animal. In 1999 and 2002, ICCVAM conducted independent scientific peer
reviews of the usefulness and limitations of four non-animal (in vitro) corrosivity test methods
for use as alternatives to the in vivo rabbit skin test. Based on these reviews, ICCVAM
recommended that all four methods (Corrositex®, EPISKIN™, EpiDerm™, and the rat skin
transcutaneous electrical resistance assay) could be used as part of weight-of-evidence
approach in an integrated testing scheme for dermal corrosion/irritation. In this approach,
positive in vitro corrosivity responses do not generally require further testing and can
be used for classification and labeling without the need for animal testing. Use of this
approach has since been adopted internationally via test guidelines developed by the
Organisation for Economic Co-operation and Development (OECD). ICCVAM is currently
participating in development of OECD test guidelines for the use of in vitro
human skin model systems such as EPISKIN and EpiDerm for the identification of
substances with the potential to cause skin irritation.
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Current Federal regulations require determination of the developmental toxicity
(i.e., toxicity to the developing fetus) potential of many chemicals and products
(including pesticides, food additives, industrial chemicals, and pharmaceuticals)
marketed in the United States. Most developmental toxicity test protocols use rats,
rabbits, or other mammalian species. ICCVAM sponsored an evaluation of the utility
of the Frog Embryo Teratogenesis Assay -Xenopus
(FETAX) to determine the developmental
toxicity potential of chemicals.
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An endocrine disruptor is a synthetic substance that, when absorbed into the body,
either mimics or blocks hormones resulting in a disruption of normal hormonal function.
A variety of substances have been classified as endocrine disruptors based on laboratory
studies, and compelling evidence suggests that endocrine systems of certain fish and
wildlife have been affected by environmental contaminants, resulting in developmental
and reproductive problems. In response to such findings, the U.S. Congress passed the
Food Quality Protection Act in 1996, mandating the U.S. Environmental Protection Agency (EPA) to initiate an endocrine disruptor
testing program to screen pesticides and environmental contaminants for their potential
to affect the endocrine systems of humans and wildlife. The EPA subsequently initiated
an Endocrine Disruptor Screening Program (EDSP) and began efforts to standardize and
validate test methods for inclusion in the EDSP. As part of this effort, the EPA asked
ICCVAM to evaluate the validation status of in vitro estrogen receptor (ER) and androgen
receptor (AR) binding and transcriptional activation (TA) assays.
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Genetic toxicology is the study of compounds or physical agents that have the ability to damage the
DNA and/or chromosomes of cells. Such damage can lead to mutations that increase the likelihood of certain
diseases, such as cancer and birth defects. The EPA, the U.S. Food and
Drug Administration (FDA), and the U.S. Consumer Product Safety Commission (CPSC) have testing requirements and
guidelines in place for assessing the genotoxicity of regulated products. ICCVAM and
its Genetic Toxicity Working Group review and provide comments to sponsors on proposed validation
studies, provide recommendations on test method nominations and submissions for alternative test
methods related to genetic toxicity, and evaluate proposed OECD test guidelines and activities relevant
to genetic toxicity.
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Skin sensitization to a substance can lead to allergic contact dermatitis (ACD), an
immunologically-mediated hypersensitivity reaction. ACD is a frequent occupational and environmental
health problem. According to the
U.S. Department of Labor Bureau of Labor Statistics,
in 2005 980 cases of ACD involved days away from work. Studies have also shown*
that ACD has a significant impact on quality of life in
affected individuals.
Chemicals and products have traditionally been tested for skin-sensitization potential using
guinea pig tests such as the guinea pig maximization test or the Buehler test. The murine local
lymph node assay (LLNA) is an alternative test method developed for assessing skin-sensitization
potential that uses fewer animals and, for most testing situations, avoids animal pain and distress.
ICCVAM evaluated the LLNA in 1999 and concluded that the LLNA is a valid stand-alone alternative
test method to currently accepted guinea pig tests. Based on ICCVAM’s recommendations, the LLNA has
been accepted as an alternative to guinea pig tests for assessing skin-sensitization potential.
ICCVAM and its Immunotoxicity Working Group drafted an OECD test guideline (TG) for the LLNA that
was adopted by the OECD in 2002 (i.e., OECD TG 429).
In 2007, the U.S. Consumer Product Safety Commission requested that NICEATM and ICCVAM assess the
validation status of new modifications and applications of the LLNA. In response to this request,
ICCVAM has completed an evaluation of the reduced LLNA, a modified LLNA test method that uses fewer
animals than the LLNA to test for skin-sensitization potential. ICCVAM has also developed
performance standards that can be used as the basis for determining the acceptability of new test
methods similar to the ICCVAM-recommended LLNA test method protocol. ICCVAM assessments of the
validation status of the LLNA as a stand-alone assay for potency determinations (including severity)
for classification purposes, the validation status of non-radioactive LLNA test method protocols,
and the use of the LLNA to test aqueous solutions and mixtures/formulations are currently
ongoing.
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Accidental eye injury is a leading cause of visual impairment in the U.S., and many of these
injuries occur due to contact with workplace or household chemicals.
According to the National Institute of
Occupational Safety and Health (NIOSH), each day
about 2000 U.S. workers have a job-related eye injury that requires medical treatment. Even more eye injuries
occur in the home, with about 125,000 eye injuries a year caused by accidents involving common household products
such as oven cleaner and bleach (source, American Academy of Ophthalmology).
The U.S. CPSC, EPA, FDA, and OSHA (Occupational Safety and
Health Administration) have regulatory testing requirements for assessing the hazard
potential of substances that may come in contact with human eyes. While these testing
requirements have effectively protected consumers and workers, the primary method
currently accepted by U.S. and international regulatory agencies for assessing ocular
toxicity requires the use of animals (i.e., the Draize rabbit eye test). Although
modifications to this test have reduced both the numbers of animals used and the
potential pain and distress associated with the procedure, more recent efforts have
focused on the development of nonanimal alternatives that would reduce or replace the
need for animals for the assessment of ocular toxicity.
In October 2007,
ICCVAM forwarded its first recommendations for the use of in vitro methods for
ocular safety testing to Federal agencies. ICCVAM recommended that two methods (the bovine
corneal opacity and permeability test and the isolated chicken eye test) be used
in a tiered testing strategy to determine ocular hazards, with specific limitations for
certain chemical classes and/or physical properties. These recommendations have been
accepted by Federal agencies and should reduce the number of animals
used for safety testing to determine corrosive or severely irritating damage to the eye.
Ongoing ICCVAM activities in the area of ocular toxicity include the following evaluations:
- Validation status of the recommended in vitro test methods described above for
use in assessing the potential of test substances to cause mild-to-moderate irritation
or reversible
injury to the eye
- Validation status of a testing strategy that proposes the use of three in vitro
test methods the assess the eye irritation potential for
antimicrobial cleaning products, including the validation status of the low volume eye test
- A proposal for the routine use of topical anesthetics, systemic
analgesics, and humane endpoints to avoid and minimize pain and
distress during in vivo ocular irritation testing
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Pyrogens are substances (such as Gram-negative and Gram-positive bacteria, fungi, and viruses)
that can produce a rise in body temperature (in other words, fever). Pyrogenic substances increase body
temperature by inducing leukocytes to release pro-inflammatory cytokines (such as interleukin
[IL]-1, IL-6, and tumor necrosis factor-α) that can act as endogenous pyrogens. Pharmaceutical products (such as fluids for
injection, medical devices, and human biological products) intended for parenteral administration
must be properly and accurately evaluated for the presence of pyrogenic substances and shown to be
free of contamination prior to their clinical or veterinary use.
The U.S., European, and Japanese Pharmacopoeias
currently recognize two test methods for pyrogen testing. The rabbit pyrogen test
(USP28[151]) involves measuring the rise in temperature of
rabbits following intravenous injection of a test solution. The bacterial endotoxin test
(BET, USP28[85]) is an in vitro assay based on the coagulation of Limulus amoebocyte
lysate following exposure to endotoxin. An important distinction between these two tests is
that the BET detects only endotoxin pyrogens, whereas the rabbit pyrogen test is capable of
also detecting non-endotoxin pyrogens.
Recently, alternative test systems based on the activation of human monocytes or
monocytoid cell lines in vitro have been developed that take advantage of
the role of these cells in the fever response. ICCVAM is currently evaluating the
usefulness and limitations of five in vitro pyrogen test
methods.
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* Hutchings et al., Contact Dermatitis 45:17-20 (2001);
Skoet et al., Br J Dermatol 149:452-456 (2003).
Additional Information
Scientific Advisory Committee on Alternative Toxicological Methods (SACATM)
Chartered on December 18, 2001, the Scientific Advisory Committee on Alternative Toxicological Methods
(SACATM) was established as a replacement
for the NTP Federal Advisory Committee on Alternative Toxicological
Methods (ACATM). This committee provides advice on the activities and
priorities of NICEATM and ICCVAM, and recommends ways to foster
partnership activities and productive interactions among all
stakeholders. SACATM will typically meet twice yearly, and meeting
materials and minutes will be posted.
Partnership Opportunities
Opportunities for organizations and
agencies to partner with NICEATM to support the development, validation,
and review of new alternative testing methods are available. Interested
individuals should contact Dr. William S. Stokes, NICEATM Director, for
further information (see below).
Additional Information
Additional information can be found
elsewhere in this website and in the
publication: Validation and Regulatory Acceptance of Toxicological
Test Methods, a Report of the ad hoc Interagency Coordinating Committee
on the Validation of Alternative Methods (NIH Publication 97-3981)
or you may contact NICEATM at 919-541-3398 (telephone), or at
iccvam@niehs.nih.gov (e-mail).
Specific questions about ICCVAM and NICEATM can be directed to the
ICCVAM Executive Director:
Dr. William S. Stokes,
NIEHS, EC-17, P.O. Box 12233
Research Triangle Park, NC, 27709
919-541-7997
stokes@niehs.nih.gov
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