Here's the legal definition-- the intent of the rule is NOT that one can hide the deadly aspects of one's product:
"Patent, Trademark, and Trade Secret Law
TRADE SECRET LAW
A trade secret is information of any sort that is valuable to its owner, not generally known, and that has been kept secret by the owner. Trade secrets are protected only under state law. The Uniform Trade Secrets Act, in effect in a number of states, defines trade secrets as "information, including a formula, pattern, compilation, program, device, method, technique, or process that derives independent economic value from not being generally known and not being readily ascertainable and is subject to reasonable efforts to maintain secrecy."
Types of Works Protected
The following types of technical and business information are examples of material that can be protected by trade secret law:
Customer lists.
Designs.
Instructional methods.
Manufacturing processes.
Document-tracking processes.
Formulas for producing products.
Inventions and processes that are not patentable can be protected under trade secret law. Patent applicants generally rely on trade secret law to protect their inventions while the patent applications are pending.
Standards
Six factors are generally used to determine whether material is a trade secret:
The extent to which the information is known outside the claimant's business.
The extent to which the information is known by the claimant's employees.
The extent of measures taken by the claimant to guard the secrecy of the information.
The value of the information to the claimant and the claimant's competitors.
The amount of effort or money expended by the claimant in developing the information.
The ease with which the information could be acquired by others.
Information has value if it gives rise to actual or potential commercial advantage for the owner of the information. Although a trade secret need not be unique in the patent law sense, information that is generally known is not protected under trade secrets law.
http://profs.lp.findlaw.com/patents/patents_3.html