I ran into a problem once before with a very small dose of C70. As I reported in 2012--
To clarify, I noticed a pain in both calves that lasted several days and a pulsing pain in the back of my neck that lasted several hours.This was after a few days of taking a dose of .25 mg twice a day. And it wasn't C60, it was a mixture of C60 & C70--about 28% C70 and 2% higher. Previously I'd used C60 @ 99.5% purity, but now I've switched to 99.95% purity, as it seems that even a small amount of higher fullerenes may prove to be a problem.
So this was only 70 micrograms C70 twice a day. I'd taken a much lager dose of C70 before without any problem, but the problem here seems to have come from taking it twice a day. C70 has been reported to go into the endoplasmic reticulum, where it could conceivably interfere with protein folding. Do that on a continuous basis and cells could run low on important proteins.
One of the things we look for when ascribing a biological effect to a molecule is dose response. We expect to see a larger effect with a larger dose. Here you found no effect from a much larger dose of C70, but saw a large effect when taking a very small dose.
Another thing that we would look for is reproducibility. This effect sounds like a one-off event. I think it's a lot more likely that the calf and neck pains were due to something else, like exercise, injury, tension headache, or some other cause.
Chris Kepley's group has reported some very desirable biological effects from two different compounds containing c70 groups. While these were not quite the same as a c70-fatty acid adduct, they aren't wildly different.
While there is very little evidence that c70 is harmful, VW's claim that they could create a 99.95% c60 by heating a lower grade under vacuum betrays a lack of understanding of the nature of c60 contaminants and methods for their removal.