View guidelines and regulations relevant to acute systemic toxicity testing
Poisoning by dermal exposure (absorption through the skin), while not as common as poisoning by
ingestion, still accounted for nearly 180,000 poisonings in the United States in 2010. Regulatory
agencies use information from acute dermal systemic toxicity tests using rabbits or rats to
determine the potential of chemicals and chemical products to cause life-threatening health effects
or death from acute dermal exposures. Test results are used as the basis for hazard classification
and labeling and to inform consumers and workers how to avoid acute dermal exposures to hazardous
chemicals and products during the handling, transport, and use of chemicals and products. NICEATM developed
an up-and-down procedure for acute dermal systemic toxicity testing to reduce
animal use for this purpose.
In February 2008, ICCVAM forwarded recommendations on the use of two in vitro test methods
to estimate starting doses for acute oral systemic toxicity tests. ICCVAM recommended that these test methods be considered before
using animals for acute oral systemic toxicity testing, and that the methods should be used where determined appropriate. Data
from the in vitro test methods should be used in a weight-of-evidence approach for determining starting doses for in vivo
studies. Using these in vitro methods where appropriate is expected to reduce the number of animals required
for each toxicity test.
In vitro methods that use mammalian cell cultures and various cytotoxicity endpoints have been proposed
as alternatives to in vivo acute oral systemic toxicity tests that use rodents. In vitro cytotoxicity test methods
that measure basal cytotoxicity (general cytotoxicity that affects structures or processes intrinsic to all cell types)
are not currently regarded as suitable replacements for rodent
acute oral toxicity tests. However, some methods can be useful for establishing the starting dose for acute
oral toxicity tests and thus reduce and refine animal use for such testing.
The use of in vitro cytotoxicity test methods to reduce animal use in acute oral systemic toxicity testing
was evaluated at an October 2000 Workshop on In Vitro Methods for Assessing Acute Systemic Toxicity.
A Guidance Document on Using
In Vitro Data to Estimate In Vivo Starting Doses for Acute Toxicity was prepared by ICCVAM with the assistance
of the workshop participants.
NICEATM and ICCVAM actively participate in the development of Test Guidelines and
Guidance Documents relevant to toxicology and safety testing issued by the Organisation
for Economic Co-operation and Development (OECD). OECD Test Guidelines
are based on the most relevant internationally agreed-upon testing methods
used by government, industry, and independent laboratories.
NICEATM and the ICCVAM Acute Toxicity Working Group have
contributed to the development of a number of OECD Test Guidelines and Guidance Documents.
Click on the heading above to view summaries of these activities.
NICEATM, ICCVAM, and international partners
sponsored a workshop to explore alternative methods for acute chemical safety testing.
The goals of this February 2008 meeting of international experts in the fields of in vitro and in vivo toxicology and human and veterinary
medicine were to:
- Review the state-of-the-science and identify knowledge gaps (at the whole organism, organ
system, cellular, and/or molecular levels) regarding the key in vivo pathways involved in acute systemic toxicity
- Recommend how these knowledge gaps can be addressed by collecting mechanistic biomarker
data during currently required in vivo safety testing
- Recommend how in vivo key pathway information can be used to develop more predictive
mechanism-based in vitro test systems and to identify biomarkers that may serve as
earlier, more humane endpoints for in vivo test methods
- Recommend how mechanism-based in vitro test systems and earlier, more humane endpoints
can be used to further reduce, refine, and eventually replace animal use for acute systemic
toxicity testing while ensuring the protection of human and animal health
Oral Up-and-Down Procedure
The oral up-and-down procedure (UDP) is an alternative to the traditional oral
median lethal dose (LD50) test that reduces animal use.
In the oral UDP, one animal is tested at a time, and the response of each animal to a test substance determines whether the
next animal receives a higher or lower dose. A peer review panel
sponsored by NICEATM and ICCVAM met in 2000 and 2001 to evaluate the revised
oral UDP and develop recommendations.
U.S. regulatory agencies adopted the ICCVAM recommendations on the revised oral UDP in 2003 and now accept oral UDPs
methods issued by OECD and the U.S. Environmental Protection Agency, which have replaced the
conventional acute oral systemic toxicity test method.