"The guideline says is that if [a substance tests negative], you may be able to conclude that it's not a corrosive using a WoE approach," Stokes says. Information that might be considered in a WoE analysis includes results from in vitro irritation tests for that substance.
But the false negatives from the corrosion tests were never examined when ECVAM validated the skin irritation models. ICCVAM is currently doing that evaluation, and preliminary results show that the irritation tests fail to classify at least two known corrosives even as irritants. Without follow-up in vivo testing, these corrosives could enter consumer products without any hazard labeling.
"We want to make sure that if something is corrosive, it's not slipped through these tests," Stokes says. "The data we have show it's a possibility. That…indicates that we need to better understand the usefulness of these assays. Our goal is to prevent injury and disease. It's important to us to have accurate safety testing methods."
Another issue is that the false positive rate for the in vitro skin irritation approaches 30 percent—a substantial number of substances are identified as irritants when they really are not.
"We don't want to excessively over-label products as hazardous or people would probably start ignoring safety labels," Stokes says.
The bottom line is that in vitro methods help to reduce animal use, but "full replacement is not something science supports at this point," Stokes says. "We're trying…to find ways and approaches that can further reduce uncertainty in those decisions, to reduce the number of circumstances where you might have to use [an animal]. As we take advantage of new advances in science and technology we'll continue to make progress in this area. It's a win–win—we're protecting both public health and animals."
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4 Comments
Add CommentOf course, anything and everything that is not tested on animals, from cosmetics to drugs, is eventually tested on humans, specifically the first ones to buy the product.
Reply | Report Abuse | Link to thisI applaud the new OECD test guideline for in vitro skin.
Reply | Report Abuse | Link to thisIt should be noted that the Draize test was simply created in the 1940s - its reliability and reproducibility against human skin was never validated as is being done by the OECD and ECVAM with new non-animal tests today. It is not scientific or reliable to run the Draize test in one set of animals and get a data only to run the test again in another set of animals and get different results, and this is precisely the system that is in place by using animals. The author is correct in noting that "skin tests as too variable because the responses observed can differ among individual animals. Results also often vary among labs, partly because the measures of the reactions are qualitative."
Further, these "false negatives" are against the Draize rabbit test, not against actual human results. We have a human skin model being criticized for failing to predict results in rabbits!
excellent step forward to be able to use grown human skin for these kinds of tests....should be much more accurate in the long term....
Reply | Report Abuse | Link to thisWhat would happen if we simply used the in vitro tests as the definitive and final form of testing and abided by those results without at all resorting to animal tests? How many chemicals and how many products would be prevented from access to the market? Would this be a horrendous contraction of the market for cosmetics or other products now being tested by these methods? As a total outsider to this science and the industries involved, I would guess that while a few products might be excluded the consequences for the market as whole would not add up to much. A few companies might lose some money, but the ethical gains would swamp those losses many times over.
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