DPG, or Dipropylene glycol, is commonly used as a carrier for fragrance oil and diluting fragrance oils. With DPG in a reed diffuser, it usually evaporates faster. Since you want your reed diffuser to be long-lasting, DPG is not what you want in a high quality reed diffusers. It is found in cheap imported reed diffusers.
Alcohol is even worse as a reed diffuser ingredient. It waters down the reed diffuser so that it evaporates quickly and you need to buy more.
Phthalates are used in many products worldwide. While the American Chemistry Council’s website says that they are among the most thoroughly studied families of compounds in use today and have developed a very strong safety profile during the 50 years in which they have been in general use, we feel that the best reed diffusers have no reason to include them.
For that reason we include only non-toxic ingredients in our best reed diffusers and they are certainly never tested on animals.