The answer unfortunately is yes.
Chemically extracted oils pose a risk for any animal consuming them. The process leads to a chemical reaction between n-hexane and lysine in the original material, this forms 2,5-dimethylpyrrole (DeCaprio, Olajos & Weber, 1982) which is toxic (DeCaprio, Kinney & LoPachin, 2009), degenerating first the peripheral and then the central nervous system.
The other issue is whether the oils you are using are balanced as far as Omega’s are concerned (3, 6 & 9), or if they have negative effect on absorption.
Cod Liver Oil for example is so high in Vitamin A, that it has a negative effect on the absorption of vitamin D, this has a domino effect on the absorption of calcium, and all that can lead to.
The answer is to only use cold-pressed oils, the two oils recommended by us, and used by Healthful are, Extra Virgin Olive Oil and Cold-Pressed Linseed Oil, because of their balancing effects and the fact that they are not as immune-suppressing as fish oils.