The safety of dye for kids depends entirely on the type of dye and its intended use. There's no simple yes or no answer.
Hair Dye
Generally, it's not recommended to dye a child's hair before their early teens (around 13-14 years old). At this age, they better understand the implications and can take responsibility for hair care. Younger children lack this understanding, and their developing bodies might be more susceptible to potential harm from chemical dyes. [Source: It's generally recommended to wait until children reach their early teens before introducing hair dye.]
Even for teens, using dyes containing harsh chemicals should be approached with caution. Always opt for products specifically formulated for hair and follow instructions carefully. Some sources suggest using diluted dyes or pastel shades for less intense coloration. [Source: Pink and orange are probably the safest options I'd think. Also you can dilute a hair dye with conditioner to make it pastel which might help it...]
Before using any hair dye on a child, consider consulting a pediatrician or dermatologist. Always perform a patch test to check for allergic reactions. [Source: The same rules apply for kids' hair as for adults. Don't apply dye to the root of the hair to ensure it does not touch the scalp. Sit in a well-ventilated room.]
Fabric Dye (e.g., Tie-Dye)
Fabric dyes, like those used in tie-dye projects, present different safety considerations. While generally safer than hair dye when used as instructed, adult supervision is crucial. Always use dyes specifically designed for fabric and follow manufacturer instructions meticulously. Ensure proper ventilation and avoid skin contact. [Source: Tie-Dye With the Kids]
Food Dye
Food coloring used to dye pasta or other food items for sensory play or crafts is generally considered safe when used as directed. However, ensure the food coloring is specifically designed for food use and that children are supervised to prevent ingestion. [Source: How to Dye Pasta]
Face Paint
For face painting, look for dye-free, non-toxic options specifically marketed for children's use. Always check ingredient lists for any potential allergens. [Source: Has anyone found a dye free face painting kit safe for kids to use?]
Other Dyes
The safety of other types of dyes (e.g., RIT dye for fabric) will depend on the specific product and its intended use. Always refer to the manufacturer's instructions and safety precautions. [Source: Rit dye is fairly safe once set but you do not want to be placing the garment into your mouth or using it to clean your teeth.]