Where can I find safe ingredient levels for gel and builder gel?

For detailed information on the safe levels of ingredients in gel and builder gel products, you would want to refer to a few primary sources:

Safety Data Sheets (SDS): Used to be MSDS but changed to a global recognition some years ago) Manufacturers of gel and builder gel products are required to provide SDS for their products. These sheets detail the ingredients, potential hazards, handling, and safety precautions. If you have a specific brand in mind, you can usually access their SDS directly from their website or by contacting their customer service.

The Cosmetic, Toiletry, and Fragrance Association (CTFA): They have a comprehensive dictionary that includes ingredient names and safety information. This can be an excellent resource for understanding the components in cosmetic products, including nail gels.

Regulatory Authorities: Depending on your region, national or regional regulatory bodies like the U.S. Food and Drug Administration (FDA), European Medicines Agency (EMA), or Health Canada provide guidelines and standards on cosmetic and nail product ingredients. These organizations often have databases or publications detailing safety levels and permissible limits of various ingredients. In the UK the regulatory organisation is the OPSS (Office of Product Safety and Standards) 

Professional Nail Associations & Publications: Industry-specific associations, magazines, and websites often have articles, studies, or discussions about the safety of nail products and their ingredients.

Educational Institutes: Since you mentioned theory education, consider reaching out to institutions offering courses in cosmetic chemistry. They may have resources or can point you towards detailed, scientific insights into nail product ingredients.

Remember, it’s always a good practice to stay updated, as research is continually evolving, and new findings emerge about ingredient safety for gel and builder gel.