By my reading, acetic acid is classified as GRAS (generally recognized as safe) as a food additive

The GRAS Substances (SCOGS) Database allows access to opinions and conclusions from 115 SCOGS reports published between 1972-1980 on the safety of over 370 Generally Recognized As Safe (GRAS) food substances. The GRAS ingredient reviews were conducted by the Select Committee in response to a 1969 White House directive by President Richard M. Nixon.
Acetic acid; Sodium acetate; Sodium diacetate

SCOGS Report Number: 82
NTIS Accession Number: PB274670* 
Year of Report: 1977 
GRAS Substance	ID Code	21 CFR Regulation
 Acetic acid	 64-19-7	184.1005
 Sodium acetate	 977127-84-6	184.1721
 Sodium diacetate	 126-96-5	184.1754
SCOGS Opinion:

Acetates are common constituents of plant and animal tissues. They are normal metabolic intermediates produced in relatively large quantities during the digestion and metabolism of foods.

Although the Select Committee is not aware of any long-term feeding studies of acetic acid or the acetates, short-term studies have revealed no untoward effects at concentrations far exceeding those consumed in the normal diet and do not suggest that adverse effects might be revealed by longer term studies.

No data on carcinogenic evaluation of acetic acid and the acetate salts have come to the attention of the Select Committee. Limited data indicate that acetic acid is not teratogenic in vivo; sodium acetate is not mutagenic and acetic acid is probably not mutagenic in vitro.

No reports of biological studies on sodium diacetate have been found, but since this substance dissociates in the body to sodium acetate and acetic acid, neither of which elicits adverse effects under current conditions of use, the Select Committee believes that use of sodium diacetate can be considered to be without adverse effects.

In light of these considerations, the Select Committee concludes that:

There is no evidence in the available information on acetic acid, sodium acetate, and sodium diacetate that demonstrates, or suggests reasonable grounds to suspect, a hazard to the public when they are used at levels that are now current or that might reasonably be expected in the future.

¶

Peter L Borst notes: this does not say nor imply that it is safe for the operator when applied, that is a separate issue. But applied to combs should produce no risk to consumers via honey. 

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