Chemicals are often used to straighten hair, and they have a more permanent effect. However, this practice is often accompanied by undesirable outcomes.
Prefer straightening with a hair dryer or straightening iron which, although less permanent, is less toxic.
Avoid the following chemicals in regular products
Formaldehyde: carcinogenic, eye and respiratory irritant, respiratory sensitizer
Glycol: irritant to the eyes, respiratory and digestive tracts
Sodium hydroxide: irritant and corrosive to the skin, eyes, respiratory and digestive tracts
Parabens: endocrine disruptors
Polypropylene: skin, eye and respiratory irritant, respiratory sensitizer
Sodium lauryl sulfate: irritant, may cause contact dermatitis
Ammonium thioglycolate: skin and eye irritant, skin sensitizer