The new Barbie movie's seemingly unlimited marketing budget has seen multiple brand collaborations, pink burgers, and the construction of a real-life Barbie dream house.

But some experts in the health sector are concerned about how far Barbie maker Mattel's marketing really goes. 

Several experts told the British Medical Journal they took issue with the company's decision to supply 700 UK schools with Barbie dolls as part of Mattel's "Barbie School of Friendship" program.

Mattel cited company-sponsored research by Cardiff University that showed the dolls offered "major benefits" for children's development for the project. But critics are questioning whether potential negative effects, such as gender stereotyping in Barbie dolls and Mattel's heavy use of branding, were considered. 

Mattel said they provided registered schools with Barbie and Ken dolls, lesson plans, a guide for teachers, guidance concerning children with special educational needs, and several branded extras like flashcards and stickers. 

May van Schalkwyk, a specialty public health registrar, told the BMJ: "The Mattel materials are heavily branded — why should children be exposed to this type of stealth marketing?"

Philippa Perry, a psychotherapist and an author of parenting and education books, told the BMJ the project made her "suspicious that it may be exploitative." She said she was "faintly repulsed by it."

Representatives for Mattel did not immediately respond to Insider's request for comment, made outside normal working hours.

In February, Mattel said the program was aimed at improving social skills like problem-solving, citing the Cardiff research that found playing with dolls could nurture empathy.

When the BMJ approached Mattel with the criticism, it said the company sent the journal anonymous testimonials from teachers praising the diversity of the dolls and the positive response from pupils.