I prefer Nextel xc-116 in my rba because of its ease of use compared to Stainless steel mesh (no hot spots), as well as its wicking ability
. But before I began to use it, I needed to know how safe it was, and compare that information to what we know about silica, cotton, bamboo, hemp, SS, and, of course Camels.
I found this info on the Nextel 312 family of products, of which xc-116 is made. This is from the Nextel 312 Material Safety Data Sheet (MSDS):
"EYE CONTACT:
Mechanical eye irritation: signs/symptoms can include irritation,
redness, scratching of the cornea and tearing.
SKIN CONTACT:
Mechanical skin irritation: signs/symptoms can include itching and
redness.
INHALATION:
Irritation (upper respiratory): signs/symptoms can include soreness
of the nose and throat, coughing and sneezing.
Vapors of heated material may cause respiratory system irritation.
IF SWALLOWED:
Ingestion is not a likely route of exposure to this product.
Irritation of Gastrointestinal Tissues: signs/symptoms can include
pain, vomiting, abdominal tenderness, nausea, blood in vomitus, and
blood in feces.
OTHER HEALTH HAZARD INFORMATION:
Due to their large size (7-13 microns in diameter), these Nextel (TM)
Ceramic Fibers are considered non-respirable and therefore are not
expected to pose a cancer risk. Fibers are defined as respirable by
WHO convention if the length is larger than 5 microns and the
diameter is less than 3 microns with a length to diameter ratio
greater than 3:1."
So it looks like (and do not mistake me as an expert on this!) it may cause upper respiratory irritation (personally I haven't had any), possible skin/eye irritation. Cancer is not a risk, as these fibers are too large to get into the lungs (7-13 microns), nor is silicosis (which comes from silica particles 5 microns and less).
In addition, I found an MSDS for general aluminoborosilicate, which is what Nextel 312 is made of, and this part was particularly important:
"Due to their large size (7-13 microns in diameter), fibers of this product are considered
non-respirable and would be expected to cause only minor nose and throat irritation if inhaled.
Initial heating, characterized by smoke, causes decomposition of the sizing with the generation of
small amounts of carbon monoxide, and trace amounts of hydrogen cyanide, acrylonitrile and dimethyl
formamide. These decomposition products ate not expected to exceed exposure limits during
recommended use procedures."
So, if you plan to use Nextel xc-116 for vaping, research it first. Although there are are no studies for this application, it appears to be safe. However, when you do your initial torching to remove the sizing chemicals, which you MUST do, do it thoroughly, and in a well-ventilated area. Finally, I reiterate: I am not an expert, nor is Google.

I found this info on the Nextel 312 family of products, of which xc-116 is made. This is from the Nextel 312 Material Safety Data Sheet (MSDS):
"EYE CONTACT:
Mechanical eye irritation: signs/symptoms can include irritation,
redness, scratching of the cornea and tearing.
SKIN CONTACT:
Mechanical skin irritation: signs/symptoms can include itching and
redness.
INHALATION:
Irritation (upper respiratory): signs/symptoms can include soreness
of the nose and throat, coughing and sneezing.
Vapors of heated material may cause respiratory system irritation.
IF SWALLOWED:
Ingestion is not a likely route of exposure to this product.
Irritation of Gastrointestinal Tissues: signs/symptoms can include
pain, vomiting, abdominal tenderness, nausea, blood in vomitus, and
blood in feces.
OTHER HEALTH HAZARD INFORMATION:
Due to their large size (7-13 microns in diameter), these Nextel (TM)
Ceramic Fibers are considered non-respirable and therefore are not
expected to pose a cancer risk. Fibers are defined as respirable by
WHO convention if the length is larger than 5 microns and the
diameter is less than 3 microns with a length to diameter ratio
greater than 3:1."
So it looks like (and do not mistake me as an expert on this!) it may cause upper respiratory irritation (personally I haven't had any), possible skin/eye irritation. Cancer is not a risk, as these fibers are too large to get into the lungs (7-13 microns), nor is silicosis (which comes from silica particles 5 microns and less).
In addition, I found an MSDS for general aluminoborosilicate, which is what Nextel 312 is made of, and this part was particularly important:
"Due to their large size (7-13 microns in diameter), fibers of this product are considered
non-respirable and would be expected to cause only minor nose and throat irritation if inhaled.
Initial heating, characterized by smoke, causes decomposition of the sizing with the generation of
small amounts of carbon monoxide, and trace amounts of hydrogen cyanide, acrylonitrile and dimethyl
formamide. These decomposition products ate not expected to exceed exposure limits during
recommended use procedures."
So, if you plan to use Nextel xc-116 for vaping, research it first. Although there are are no studies for this application, it appears to be safe. However, when you do your initial torching to remove the sizing chemicals, which you MUST do, do it thoroughly, and in a well-ventilated area. Finally, I reiterate: I am not an expert, nor is Google.