Dermatological and medical studies regarding PEOs are limited. Most studies are focused on oral consumption of low molecular weight PEOs. There are no published studies that investigate anal insertion of high molecular weight PEOs.

One partially relevant oral study focused on ingestion of large amounts of PEO prior to colonoscopies. The volume of PEO swallowed is similar to the volume of PEO used during a session. This study indicates less than 0.02% of subjects experience short term kidney damage^[1]. Since most scientists agree that the GI tract does not readily absorb PEOs, the data here indicates the PEO molecule inside the fist chute is not problematic.

While safety data sheets and the USA Food and Drug Administration (FDA) suggest that PEOs are non-toxic and noncarcinogenic, many websites disagree. Several sites note that PEOs may contain carcinogenic byproducts of the manufacturing process.^[3][4]

It is also unclear if companies that package PEO for fisting purposes have vetted providers to ensure that the product is pharmaceutical grade and free of these carcinogens. Fisters should inquire with the vendor regarding purity of their product.

Vendors of veterinary lubes clearly indicate that they do not investigate their PEO suppliers for these carcinogens.

J Lube is a commonly used PEO-based lubricant that lists sucrose as an ingredient. Sucrose is a dispersant that increases lubricity and decreases loss due to evaporation and absorption. A 500 mg bottle of J Lube mixed at the golden ratio of 1:8 has about sixty grams of sugar, or the equivalent of three Snickers^© bars.

Fist Theory could not locate any medical textbooks or journal articles that indicated that sugars introduced through the rectum are absorbed into the bloodstream. Regardless, if a fister has diabetes, it is important that he monitors blood sugars with the first signs of hyperglycemia. Douching, fasting, trauma, and diet modification can affect blood glucose levels.

J-Lube contains sucrose, a highly nutritious food source for microorganisms such as candida, E-coli, and shigella. These microorganisms infiltrate the lube through multiple avenues, including exposure contamination during play, exposure to non-sterilized containers and mixing tools, as well as the air we breathe. Once introduced into the fist chute, these microorganisms outcompete the natural biome, disrupting its balance. Even if J-Lube is stored in cold conditions, it provides only minor suppression of their growth rate.

Non-refrigerated J-Lube is heavily colonized within 24 hours. Leftovers should be discarded immediately.

K, X, FFäusten will eventually be colonized, but not until the polymers degrade (which begins after two weeks when stored at room temperature). Polymer degradation also results in decreased lubricity.