Are you having trouble finding the information you need on the web? Here's some information that might be helpful.
For instance, what if you are trying to find the origins of a specific ingredient such as isohexadecane to see whether it can be made from corn or not?
Go to a search engine and type in isohexadecane derived and that will bring up various links that tell you that isohexadecane is derived from fatty acids from animal, vegetable or petroleum sources.
This page says isohexadecane can be "derived from allspice, anise, calamus oil, cascarilla bark, celery seed, butter acids, coffee, tea and plant oils."
So, theoretically, it could be corn, soy, coconut or nut oil, or any other type of oil. "Vegetable oil" or "plant oil" is such a vague and broad category.
The search also pulled up a page that said another name for the same substance is Heptamethylnonane. So then you can learn more by searching for that term, both alone and with the word derived or deriv*.
An asterisk works in many search engines as a wild card, so deriv* will pull up derived, derivative, derivatives, etc. without having to do multiple searches. Searching for the term corn allerg*, for instance, will bring up all the words allergy, allergen, allergenicity, allergic, allergenic, etc. in relation to corn, and will save you a lot of time.
If a basic web search pulls up a lot of pages, either skim through the pages of search results and only click through to the ones that look like they might be relevant, and/or add another word such as derivative or derived to narrow the search results.
Searching just for the word isohexadecane can give you some good information, too.
If I'm trying to find out whether an ingredient can be derived from a certain food, I'll often search for that, as in isohexadecane soy or isohexadecane corn.
Often you'll find new terms to search for by skimming your search results, such as maize, mays, zein and zea when searching for corn. Things can have many different names, which makes it confusing sometimes.
A search for the phrase isohexadecane allergy on PubMed reveals that allergic contact dermatitis has been recorded as a reaction to isohexadecane.
When searching for a specific word on a web page, you can save a lot of time by clicking on Edit at the top of your browser window and then on Find (on this page) and typing in the word in the search box. Or you can use a keyboard shortcut by pushing Ctrl-F.
Knowing how to make the most of internet search engines can really be helpful in researching allergies.