Kid's are not little adults!
Kid's skin is uniquely different from that of an adult. You can not think that a product designed from an adult's skin is safe to use on a kid's skin, anymore than you can think that a product formulated for an adult's skin is safe to use on a baby's skin.
The most important structural difference is in the Sebum Production.
A child's skin and scalp produces almost six times less oil on a daily basis than an adult's and can be sensitive to synthetic perfumes, colours, preservatives, heavy film-forming conditioners and aggressive surfactants. Adult shampoos are too aggressive for kid's sensitive scalps. Although it may look the same, the skin of a child is not the same as the skin of an adult for one very important reason... Sebum.
800 Follicles (Sebaceous Glands) Per Square Centimetre of Skin on your Neck, Face, & Scalp.
Sebum is the oil that is excreted onto the human skin by the Sebaceous Glands. In humans the Sebaceous Glands are found in the hair follicles all over the entire body surface, except the palms, soles and tops of the feet. These Sebaceous Glands are relatively small over most of the body and are usually found at a density of less than 20 per square cm of body surface. These Glands in certain areas, such as the neck, face and scalp however, are much larger and more numerous, with a density of up to 800 Glands per square cm.‡
‡(M.Inaba, Y.Inaba Androgenic Alopecia Modern Concepts
of Pathogenisis and Treatment, Springer 1995 1.3.1)
These large glands are hormone dependant, being stimulated by the sex hormones, so they become highly active at puberty and in elderly individuals they may cease to function at all. A child's skin and scalp from birth to puberty produces very little sebum at all. An average Sebum production for a child between the age of 6-12 is 0.44mg per 10square cm, per 3 hours*.
The average for a teenager between the age of 15-19 is 2.35mg per 10square cm, per 3 hours*, and an adult between age 30-39 is 2.52mg per 10square cm, per 3 hours*. This means that the oil production of a teenager’s scalp is more than five times that of a child and the oil production of an adult is almost six times greater than that of a child.
*(Source: Journal of Investigative Dermatology (1974) 62, 191–201; doi:10.1111/1523-
1747.ep12676783 ENDOCRINOLOGIC CONTROL TO THE DEVELOPMENT AND
ACTIVITY OF THE HUMAN SEBACEOUS GLAND Peter E Pochi and John S Strauss)