Huggies diapers as well as many other disposable diaper brands do contain chemicals in them but most of the chemicals are unknown.
Still the chemicals contained in Huggies diapers as well as other disposable diapers are not really that harmful unless your baby or toddler has sensitivity to those chemicals.
Some babies have broken out with chemical burns from both Pampers and Huggies diapers but a lot of babies and toddlers wear both Pampers and Huggies diapers along with many other brands of disposable diapers that include chemicals without a problem.
The chemical that absorbs the urine in Huggies and Pampers as well as other disposable diapers is SAP "Super Absorbent Polymer".
There's also some other chemicals that are used for the Ink to print the designs on the diapers but all Disposable Diapers including Huggies and Pampers diapers are relatively safe for babies and Toddlers but some babies and toddlers skin are just more sensitive to those chemicals than others.