"chemical residues" refers to the leftover or remaining traces of chemicals. These residues can be found on surfaces, objects, or even in the air after using or being exposed to different chemicals or products. Full definition
Use as little soap when bathing so as not to leave chemical residue that might harm your baby. (breastfeedbub.com)
Avoid getting any oils or other chemical residue on the surface after it's clean. (mechanics.stackexchange.com)
From baby formula to coffee and even red wine, this... MORE detergent is designed to get stains out without leaving any kind of chemical residue. (thespruce.com)