Vitamin A is certainly toxic in large quantities....

With regards to carrots, yes you can eat so many of them that your skin will turn yellow. One carrot (7 1/2" long) has 2025 RE of vitamin A, which is 203% of your Daily Value. One pound of carrots has 1276% of your RDA for vitamin A. So since you have eaten more than 3 carrots in a day (> 34,000 IU), you have probably saturated your body's ability to store vitamin A over a short time and so it is showing up as an orange tint on your skin. I would suggest you decrease your carrot consumption and increase other low vitamin A vegetables.

This from href="http://www.dietitian.com/vitamina.html"here