EDIT / UPDATED: 6/29/2015 - Since writing this article nearly a year ago, a lot more information and new developments relevant to the content of this article have emerged online. While I strongly encourage you to learn more about the safety of e-juice, I do not believe that this blog entry represents the most up to date guide to e-liquid safety. Please understand that this blog post is a work in progress and we are working towards updating it. Also, I have omitted a part of this blog post that touched on how ZampleBox filters out products that may have safety concerns as we are currently re-evaluating our process for how to best screen products. Unintentionally, my original blog post made it seem as though we tested every product sent to ZampleBox for the chemicals in this blog post. However, that has never been the case. Our curators test products in our screening process by personally vaping them to make sure they are a nice, smooth and clean vape. To better serve our members, we would like to be able to test all of the products for specific chemical compounds and we are now in the process of figuring out how we can do this effectively. ~ Tony
Diacetyl is a butter flavoring used in some food products like butter, butterscotch, butter flavored popcorn and some alcoholic beverages. It has also found it's way into the ingredients of some e-liquids. The FDA and the EU regard it as GRAS (Generally recognized as safe) and permit it for consumption though it has come to light it might not be suitable for inhaling:
The United States National Institute for Occupational Safety and Health has suggested that diacetyl, when used in artificial butter flavoring (as used in many consumer foods), may be hazardous when heated and inhaled over a long period.
Workers in several factories that manufacture artificial butter flavoring have been diagnosed with bronchiolitis obliterans, a rare and serious disease of the lungs. The cases found have been mainly in young, healthy, non-smoking males. There are no known cures for bronchiolitis obliterans except for lung transplantation.
While several authorities have called the disease "Popcorn Worker's Lung," a more accurate term suggested by other doctors may be more appropriate, since the disease can occur in any industry working with diacetyl: diacetyl-induced bronchiolitis obliterans.
Diacetyl often comes up in e-cig communities and some vapers like me are against using it as a precaution. Some suppliers too refuse to stock any liquid that contain it, but there are a few that do. Particular caution should be taken when ordering bottles of flavourings to add to e-liquid as these products' primary purpose is to be added to foodstuffs. It's only recently that a second market of vapers has been opened up to them and they might not be aware that their flavoring will be inhaled or that this perhaps is dangerous.
While many e-liquid manufacturers have ceased using diacetyl in flavoring their products, you still need to be cautious and show avoid vaping liquids that contain diacetyl.
Acetoin is another ingredient used to make vaping liquids taste buttery or custard-like. It has been used as a substitute to diacetyl in flavoring liquids. Unfortunately, under the right circumstances acetoin can actually turn into diacetyl! Acetoin should certainly be avoided, especially for vapers that use advanced style vaporizers that produce significant amounts of heat.
Acetyl Propionyl(2,3 pentanedione) was the replacement of choice for e-liquid manufacturers after diacetyl was discovered to pose a health risk. This additive also produces a buttery and custard-like flavor in e-liquids. Unfortunately, it has been discovered that this ingredient essentially has the same effects as diacetyl. Acetyl Propionyl should be avoided by vapers.
Low Quality RDA Coil Wires
There is a growing concern that vapers using high-power vaporizers with rebuildable dripping atomizers (RDAs) may be exposing themselves to additional risk. One of our main concerns right now is that the wire used to make coils on RDAs may contain impurities or toxins from the manufacturing process that are then released into the vapor. There are also concerns that the metal itself could be leeching into the vapor. It's important to remember that the wire used by the majority of vapers for their RDAs was not designed to be heating liquid for human consumption. In fact, many of the companies producing the wire used by vapers are producing it for industrial applications and they have no concerns around sterilization or cleanliness during the manufacturing process.
We believe there needs to be more research on high power vaporizers with RDAs as there is a lot of uncertainty around how they affect the vapor.