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Science Policy Around the Web – June 10, 2017

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By: Allison Dennis, BS

Source: pixabay

Animal Testing

Lack of Clarity Puts Chemical Safety and Animal Welfare at Odds

In the lineup of American stereotypes, the health-nut who cares about the chemicals in his shampoo is often the same person who cares if that shampoo was tested on animals or not. However, a bill signed June 22, 2016, known as the Frank R. Lautenberg Chemical Safety for the 21st Century Act, may be placing those two views at odds. The bill requires the U.S. Environmental Protection Agency (EPA) to implement a risk-based process to evaluate the safety of chemical substances currently being used in the marketplace and approve the use of new chemicals before their introduction. The bill was passed with bipartisan support and offered EPA the new-found power to fully regulate the use of well-known carcinogens like asbestos.

Yet the pathway forward for the EPA is daunting. More than 62,000 substances find their way into and onto our bodies through the products we use and our environment. While many of these substances have become associated with disease over time, how can the EPA certify the risks associated with different exposures to varying amounts of each substance on such an extensive list? The Act itself suggested that once the EPA has evaluated the existing information on the 62,000 substances currently in use, it spend the next twelve months triaging chemicals according to their potential risk. Next, the highest priority chemicals will be evaluated on a three-year deadline to develop knowledge of their toxicity and guidelines for their regulation. Ultimately, by clearly cataloging the risk of common chemicals the Frank R. Lautenberg Chemical Safety for the 21st Century Act promises to greatly reduce the amount of animal testing needed in the long-term.

In the meantime, however, the companies that use to-be-regulated substances in their products may be inclined to undertake independent toxicity testing, collecting enough data to guarantee that their favorite substances meet the low-risk criteria and avoid a drawn-out evaluation. Defining toxicity requires careful experimentation, which can sometimes be carried out in human cells outside of the body, but often require evaluation in animals. Animal rights groups like the Human Society find concern with the lack of transparency in the pre-prioritization process. They fear the eagerness of companies to provide data without any clear guidelines about how that data will be evaluated or what substances will require extensive evaluation could result in extensive and unnecessary animal testing. Further they suggested that the EPA require any new pre-approval data obtained by companies to be collected using non-animal methods. (Maggie Koerth-Baker, FiveThirtyEight)

CRISPR

Small Study may Reveal Big Concerns over CRISPR-Based Therapy

A one-page letter published in Nature Methods last week reports unexpectedly high levels of unintended changes to the genomes of mice that underwent a CRISPR-based therapy. Since it’s renaissance as a therapeutic tool in 2012, CRISPR has occupied the imaginations of scientists, doctors, patients, investors, and ethicists. CRISPR technology provides a relatively straight-forward and reproducible means to gene editing on the cellular level, but its applications to create heritable mutations in the human germ line is on hold until more is understood about the long-term effects such treatments would have.

The original study sought to explore potential long-term effects of germline manipulation by CRISPR in a mouse model. Guide RNA along with the Cas9 enzyme were injected into mouse zygotes, which introduced a correction in a mutation in the rd1 gene of otherwise blind mice. Initiating this change before the first cell division enabled this corrected mutation to be inherited by all cells arising in the developing mouse, consequently restoring the ability for the eyes to develop normally. In a follow-up experiment described in their one page letter, the researchers looked for mutations in the genomic DNA of two CRISPR-treated adult mice compared with a control mouse, revealing over 2,000 unintended mutations following CRISPR treatments. None of these mutations appeared to affect the mice, suggesting that deep genomic sequencing may be required to reveal unanticipated changes in an outwardly healthy mouse. Further, the nature of these unintended mutations offered few clues explaining how they might have occurred.

This result stands in contrast with other reports quantifying the extent of these unintended changes, which found CRISPR to be highly specific. While the CRISPR-Cas9 system has been observed to sometimes alter off-target regions of the genome, this activity can usually be curbed through the careful design and evaluation of the guide RNA. The limitations of this small study have been discussed extensively since its publication. However, the findings have sparked the need for further investigation into the long-term-whole-animal effects of germline-editing by CRISPR. As human germline-editing creeps closer to reality, the FDA will be tasked with developing an entirely new means of evaluating the safety of such technologies (Megan Molteni, Wired)

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Written by sciencepolicyforall

June 10, 2017 at 11:33 am