[With assistance from Halachos of Pesach by Rav Shimon D. Eider (pp. 17-21)]:
Intro: In our last lesson, which addressed the first section of this siman, we learned about food compounds which contain actual chametz in small proportions (Heb. ‘chametz al y’dei ta’aruvos’/mixtures containing chametz) and their status regarding the chametz prohibitions. A related halacha (covered in this section) concerns compounds which may contain higher proportions of chametz, but are not classified as food. They are called ‘chametz nuksheh’ (i.e. “spoiled” chametz - heretofore to be abbreviated Ch”N.) This section is the source for many of the halachic discussions regarding cosmetics and other non-edible products which contain chametz.
For a more complete definition of Ch”N, we quote Rabbi Eider:
“In our discussion of chametz and its practical application to products, medications and cosmetics, we find the term ‘chametz nuksheh’. Ch”N may not be eaten on Pesach and one must dispose of it before Pesach. What is Ch”N? There are two types of Ch”N:
1) The process of chimutz (fermentation) was started but was stopped or impeded, never reaching complete fermentation. (Example: Dough whose fermentation began; it became pale white in color, but crevices never formed in it before it was baked.)
2) Spoiled chametz, which was never fit for normal human consumption, although a person could eat it with difficulty. (Example: Paste made of flour and water, which fermented but a person would not want to eat from it.)”
Chametz nuksheh of the second type is something that, while a human would not consider it edible, an animal such as a dog would gladly eat it. This is called ‘ra-ui la’achilas kelev’ (lit. “fit for the eating of a dog”.)
When a product containing chametz is inedible to the point that even an animal wouldn’t eat it (‘nifsal mei-achilas kelev’/unfit for the eating of a dog), that goes beyond being Ch”N. (Example: Ink or paint which contains chametz.) Must it also be destroyed? NO, however, keep reading for an important distinction:
If the compound was indeed already ‘nifsal mei-achilas kelev’ before Pesach (i.e. before the beginning of the sixth hour on Erev Pesach, which is the deadline for destroying chametz), it is beyond Ch”N, and we are not obligated to destroy it; in fact, we may even use it on Pesach! However, if the chametz was still ‘ra-ui la’achilas kelev’ when the sixth hour arrived, and only later it became ‘nifsal’ (unfit), it would still need to be destroyed. This is because once a compound is “marked for destruction” (i.e. either regular chametz or Ch”N), its status remains with it, even if physically it changes!
Ed. All we have learned in this lesson thus far is what the halacha requires. Many Pesach consumers are aware of the fact that each year, voluminous guides and journals are printed and disseminated which contain listings of all kinds of medicines and products, indicating which are and are not certified for Pesach use. Many of these products are not even taken orally! One may ask: According to what we have learned in this lesson, why would there be a need to certify products that were ‘nifsal mei-achilas kelev’ before Pesach? The following excerpt from Star-k.org will help explain why many people practice these ‘chumros’/stringencies, sometimes above-and- beyond the requirements of halacha. Note: I am not declaring whether one should or should not observe these ‘chumros’; my only goal is to expose us to the “whys and wherefores”, so that we may enjoy the clarity of Torah learning, and be able to ask informed shailos of our Rabanim and make informed decisions.
L’halacha, all non-food items not fit for canine consumption (nifsal mei-achilas kelev, i.e. something that one would not feed his dog) may be used on Pesach. This includes all cosmetics, soaps, ointments, and creams. Nonetheless, people have acted stringently with regard to these items.
Below are several reasons why people are strict:
1. Many products, including shaving lotion and perfume, contain denatured alcohol which can be restored to regular alcohol. According to most opinions, one should not use such products on Pesach…
2. The Biur Halacha (326:10 B’shaar) writes in the name of the Gra that one should be strict and not use non-kosher soap all year (based on the Talmudic principle sicha kishtiya/”smearing is akin to drinking”). Although we are not accustomed to this stringency, many individuals have adopted this chumrah during Pesach and do not permit the use of chametz items even if they are used externally.
3. Some are of the opinion that we do not say “nifsal” (food is unfit for canine consumption) applies to an item that is initially produced as a non-food item.
4. Lipstick is often inadvertently ingested when eating food. If it contains chametz, it is halachically permissible to apply to the lips since the lipstick is unfit for canine consumption. Nevertheless, most women prefer not to consume even a trace of anything prohibited…
5. Mouthwash and Toothpaste contain sorbitol and other ingredients which may be derived from chametz. Although, l’halacha these items are permissible to use since they are nifsal mei-achilas kelev, many prefer not to use them as they are taken orally…
6. Historically, it has been the custom to follow stringent opinions regarding Hilchos Pesach… In addition, it seems to have been a prevalent custom to restrict the use of items which may contain chametz, even when they are clearly nifsal mei-achilas kelev…”
The full version of the article is available at: http://www.star-k.org/kashrus/kk-passover-medicine.htm