We contacted the FDA (Food and Drug Administration).
Here is the reply we got:
“Hi, FD-&-C Yellow No. 6 is a synthetic color additive.
The chemicals used to synthesize it are probably mostly petroleum based. Any one of many emulsifiers listed in our regulations may be used with it.
Division of Petition Control Office of Premarket Approval FDA"
There is no problem with FD-&-C Yellow No. 6.