Hi Wendy,
Sorry for the late reply cos I have not been too frequent to the forum for a while.
Regarding purity of shark liver oil:
The general guideline is to get shark liver oil that is sourced from sharks that originate from the deep oceans away from most sources of pollution. My personal research indicates the shark liver oil from deep sea sharks of New Zealand and Australia will meet this condition.
We get our shark liver oil from
http://www.nutralife.com.au or
http://www.nutralife.co.nz
No added gluten, yeast, artificial colors or flavors - shark liver oil of 1000mg capsules, one per day.
Yes, the supply of shark liver oil is getting a little difficult from the shops or health stores because the demand for other fish oils is higher than that of shark liver oil, and economics count where profitability is important. However, we make the order through the local health store who gets the supply for us. So you can always request the local health store to make an order for you. Alternatively, orders can be made online as well.
The only important thing is to make sure you are ordering shark liver oil and not the pure squalene.
Hope this helps.