Regarding PEG-90 Glyceryl Isostearate, some cases of contact cheilitis have been reported (1).

Regarding safety in general, apart from cases of individual intolerance, a final report was issued in 2004 that considered this component safe for health (2).

References______________________________________________________________________

(1) Inui S, Azukizawa H, Katayama I. Recurrent contact cheilitis because of glyceryl isostearate, diisostearyl maleate, oleyl alcohol, and Lithol Rubine BCA in lipsticks. Contact Dermatitis. 2009 Apr;60(4):231-2. doi: 10.1111/j.1600-0536.2009.01513.x.

(2) Final report of the amended safety assessment of Glyceryl Laurate, Glyceryl Laurate SE, Glyceryl Laurate/Oleate, Glyceryl Adipate, Glyceryl Alginate, Glyceryl Arachidate, Glyceryl Arachidonate, Glyceryl Behenate, Glyceryl Caprate, Glyceryl Caprylate, Glyceryl Caprylate/Caprate, Glyceryl Citrate/Lactate/Linoleate/Oleate, Glyceryl Cocoate, Glyceryl Collagenate, Glyceryl Erucate, Glyceryl Hydrogenated Rosinate, Glyceryl Hydrogenated Soyate, Glyceryl Hydroxystearate, Glyceryl Isopalmitate, Glyceryl Isostearate, Glyceryl Isostearate/Myristate, Glyceryl Isostearates, Glyceryl Lanolate, Glyceryl Linoleate, Glyceryl Linolenate, Glyceryl Montanate, Glyceryl Myristate, Glyceryl Isotridecanoate/Stearate/Adipate, Glyceryl Oleate SE, Glyceryl Oleate/Elaidate, Glyceryl Palmitate, Glyceryl Palmitate/Stearate, Glyceryl Palmitoleate, Glyceryl Pentadecanoate, Glyceryl Polyacrylate, Glyceryl Rosinate, Glyceryl Sesquioleate, Glyceryl/Sorbitol Oleate/Hydroxystearate, Glyceryl Stearate/Acetate, Glyceryl Stearate/Maleate, Glyceryl Tallowate, Glyceryl Thiopropionate, and Glyceryl Undecylenate. Int J Toxicol. 2004;23 Suppl 2:55-94. doi: 10.1080/10915810490499064.