As a follow up on my previous post, this study looks at toxicity of retinol acetate in doses exceeding 300,000 IU per day taken for months and in combination with a SERM (tamoxifen) which itself is quite estrogenic and as such is a proven liver burden.
http://www.ncbi.nlm.nih.gov/pubmed/3218964
http://www.ncbi.nlm.nih.gov/pubmed/3218964