Are there any safety regulations about apparel labeling or footwear in the U.S.? 

Yes. There are some regulations under the Consumer Product Safety Improvement Act (CPSIA) in response to the flammability of clothing textiles including: 

16 CFR §1610 – Standard for the Flammability of Clothing Textiles 

16 CFR§ 1615 and 1616 – Standards for the Flammability of Children’s Sleepwear 

For more information, please Nate Herman.  

You may also contact the Consumer Product Safety Commission directly.