Not a plastic and it is commonly found in food and cosmetics.
>evidence shows the existence of a detectable level of anti-PEG antibodies in approximately 72% of the population, never treated with PEGylated drugs, based on plasma samples from 1990 to 1999. Due to its ubiquity in a multitude of products and the large percentage of the population with antibodies to PEG, hypersensitive reactions to PEG are an increasing concern.[39][40] Allergy to PEG is usually discovered after a person has been diagnosed with an allergy to an increasing number of seemingly unrelated products, including processed foods, cosmetics, drugs, and other substances that contain PEG or were manufactured with PEG
Tons of common plastics are made from plants. PLA, the most common FDM 3d printing plastic, is made from corn. Ethylene in particular is also naturally occurring- it's one of the most important plant hormones.
many grades of peg are liquid at room temperature; the others are highly water-soluble. you've probably never seen an object manufactured from peg in your life. that's why people don't normally call it 'plastic'
>evidence shows the existence of a detectable level of anti-PEG antibodies in approximately 72% of the population, never treated with PEGylated drugs, based on plasma samples from 1990 to 1999. Due to its ubiquity in a multitude of products and the large percentage of the population with antibodies to PEG, hypersensitive reactions to PEG are an increasing concern.[39][40] Allergy to PEG is usually discovered after a person has been diagnosed with an allergy to an increasing number of seemingly unrelated products, including processed foods, cosmetics, drugs, and other substances that contain PEG or were manufactured with PEG
https://en.wikipedia.org/wiki/Polyethylene_glycol