Beta-carotene is converted by the body into vitamin A. At the moment there is still a lot of debate over how efficient this process is, although it seems that Retional Activity Equivalent levels vary somewhat depending on the individual.

I would stop the supplements ASAP, not least because supplemental beta-carotene can do more harm than good. For example, studies show even modest levels of supplementation leading to greater mortality rates amongst smokers.

Remember that a Paleo diet, high in animal fats and liver is more than likely already at the tolerable upper limit for pre-formed retinol, and that's before adding in supplements like cod liver oil. Vitamin A is stored in your body's fat, so it can take a while on a low retinol diet to "detox" any excess

Chris Masterjohn wrote about the possibility back in 2005.

Maybe these studies can help:

"Low intake of calcium, folate, nicotinic acid, vitamin E, retinol, b-carotene and high intake of pantothenic acid, biotin and riboflavin are significantly associated with increased genome instability—results from a dietary intake and micronucleus index survey in South Australia"

"Cytotoxic and genotoxic effects of b-carotene breakdown products on primary rat hepatocytes"

"From 1989 to 2001: What Have We Learned About the “Biological Actions of Beta-Carotene”?"