1. There are hair products currently on the market which are known to contain hormones.
What to look out for
1. A product that would have been available in 1994 or earlier
2. Label names active ingredients as placenta, hormones or "estrogen" (noting that not all will name these ingredients)
One product named in the study is B&B Super Gro which was tested and found to contain a less potent version of oestrogen known as oestriol.
2. What is the danger of hormone containing hair products?
Let me first emphasize that most of the evidence is anecdotal (meaning the evidence is usually from someone reporting an event without necessarily proving it beyond reproach - for example with before and after photographs or with scientific measurements).
However the main concerns highlighted were
1. Possible cause of early puberty in African American girls (compared to White counterparts and African girls). The specific group of African American girls was linked to the use of hormone containing hair products (shampoos and deep conditioners) (Mil Med, 160(12):628-30, 1995.)
2. Possibility of breast cancer in African American women (Med Hypotheses, 68(4):756-66, 2007)
I would like to emphasize again that even the papers I listed said 'may cause' not 'definitely cause'. There is no confirmed definitive link but a strong theory that there is a possible link.
I do think that the fact that some companies actually include hormones in hair products without disclosure is really terrible. I think that full disclosure should be expected. I am certain some people would buy these products with full knowledge just as many of us would prefer to avoid them if we knew. No to stealth marketing!