Richard Denison, Ph.D., is a Senior Scientist.

Word hit the street today that EPA intends to make public a "sanitized" version of a Consent Order it has negotiated with a producer of multiwalled carbon nanotubes (MWCNTs).  [A link will be provided once available.]  We obtained a copy of the Order, which has redacted all information claimed confidential by the company involved.  What can we learn from this well-scrubbed Order? Read more »

John Balbus, M.D., M.P.H., is Chief Health Scientist.

A new paper by Shaw et al., published in May in the Proceedings of the National Academy of Sciences, “suggests a generalizable and scalable method for the systematic characterization and comparison of novel nanomaterials” using high throughput in vitro tests.  Does this mean that the National Academy of Sciences’ vision for toxicity testing in the 21st century – proposed for conventional chemicals – is already here for nanomaterials?  Not quite.  Read more »

John Balbus, M.D., M.P.H., is Chief Health Scientist.

A new study published today in Nature Nanotechnology finds that multi-walled carbon nanotubes (MWCNTs) cause inflammatory changes in mice that closely resemble those caused by asbestos.  This is the second study in a few months to make this finding.  (I posted on the first, Takagi et al., a few weeks ago.)  So is the case closed on multi-walled carbon nanotubes?  Or is too early to draw conclusions? Read more »

John Balbus, M.D., M.P.H., is Chief Health Scientist.

We and many others have made analogies between nanoparticles and asbestos.  The purpose of the analogy has generally been to emphasize the long latency that can occur between exposure to toxic materials and the development and subsequent recognition of disease arising from that exposure.  And, of course, the enormous legal and financial burden of failing to adequately consider risks before allowing widespread exposure.  But a new study suggests that the analogy may be even stronger than we thought:  It may extend to the capacity to cause mesothelioma, the rare form of cancer associated with exposure to asbestos. Read more »

Cal Baier-Anderson, Ph.D., is a Health Scientist.

After posting to this blog the other day, I came across a brand new study characterizing the heterogeneity of carbon nanotubes.  The authors of this study looked at 11 single-wall carbon nanotubes (SWCNTs) from 10 different suppliers and found that SWCNT composition varies dramatically depending on synthesis method, feedstock, purification steps, and other factors.  Read more »

Cal Baier-Anderson, Ph.D., is a Health Scientist.

With conventional chemicals, experience has allowed us to articulate general criteria based on chemical properties that identify chemicals of greatest concern.  For example, persistent and bioaccumulative chemicals are assigned a high priority, whereas chemicals that quickly degrade and don’t build up in blood or tissue are, as a rule, likely to be of lower priority.

Concerns about nanomaterials arise from observations that properties that emerge or are greatly enhanced at the nanoscale can alter behavior, including biological activity.  These properties make such materials different from conventional forms of the same chemicals.  But can a general principle that nanomaterials pose a greater concern than their conventional counterparts be supported?  Read more »

John Balbus, M.D., M.P.H., is Chief Health Scientist.

EPA’s recently released draft Nanotechnology Research Strategy (NRS) proposes a tiered testing system to evaluate human toxicity of nanomaterials.  It puts in vitro tests, or those done in test tubes and petri dishes as opposed to living animals, front and center.  EPA says the results of the first, in vitro tier will be used for guidance on “what health endpoints to monitor” and the second, in vivo tier will then help “identify those in vitro assays that correlate with in vivo nanomaterial toxicity or health effects.”

Wait a second.  If the in vivo testing is necessary in order to figure out what the in vitro testing results really mean, how can the agency use the in vitro testing results to figure out what health endpoints to monitor?  This cart and horse confusion is a serious matter. Read more »