RETRACTION: An earlier version of this article relied on documents linked above regarding the safety of thymol. It has been brought to my attention by Seventh Generation that the EPA assessed thymol as a surface cleanser in food service and processing this year and concluded:

Thymol is an essential oil that is extracted from thyme and
mandarine and tangerine oils and is FDA approved when used as a
synthetic flavoring (21 CFR 172.515), a preservative, and indirect food
additive of adhesives (21 CFR 175.105). Additionally, the source plant
(thyme), from which thymol is extracted is acknowledged by FDA as
generally recognized as safe (GRAS) (21 CFR 182.10, 21 CFR 182.20).

Residues of thymol can be found in other food stuffs either naturally
such as that found in lime honey or intentionally added to foods such
as ice-cream, non-alcoholic beverages, candy, baked goods, and chewing gum.

Based on the following, the Agency has concluded that thymol has
minimal potential toxicity and poses minimal risk:

1. Thymol is a normal constituent of the human diet and a component
of many non-pesticidal consumer products currently marketed in the
United States,
2. Thymol and the phenols of thymol are listed as food additives by
the FDA (21 CFR 172.515; synthetic flavoring substances and adjuvants),
3. Thymol is found naturally occurring in thyme herb, a food
seasoning ingredient that is generally recognized as safe (GRAS) by the
FDA (21 CFR 182.10),
4. Thyme oil (for which thymol is a component) also is recognized
as a GRAS essential oil by the FDA (21 CFR 182.20),
5. Thymol can be presumed non-persistent in the environment based
on knowledge of its composition,
6. As a conventional pesticide, thymol repels vertebrate pests by a
non-toxic mode of action,
7. The available toxicity information does not indicate toxic
effects at the levels of potential exposure and
8. EPA is not aware of any adverse effects to humans or the environment
in the scientific literature associated with any thymol related use.

Seventh Generation has launched a new line of products to combat swine flu and other germs and viruses. According to the company's press release:

"Seventh Generation's spray cleaners and wipes perform as well as the leading conventional products, killing 99.99 percent of germs, and cut through grease and grime, without synthetic ingredients or chemical components. The active ingredient in the disinfectant line is thymol, which is a component of thyme oil derived from the herb thyme. The essential oils in the products, including thyme and lemongrass, naturally deodorize and effectively control odors."