Shabbat Parashat Vayigash | 5764
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Question: If one has a cracked lip, does he have to be concerned about swallowing blood?
Answer: The prohibition against ingesting blood is a very severe one (see Vayikra 17: 10-14). However, the full force of the prohibition does not apply to human blood (Ketubot 60a). In fact, according to most opinions, ingesting human blood is only forbidden mid’rabanan (rabbinically) (see Rambam, Ma’achalot Asurot 6:2). Furthermore, the rabbinic prohibition does not apply across the board to turn human blood into an objective rabbinic prohibition. Rather, the prohibition depends on the circumstances, one of which we will discuss.
The gemara (ibid.) starts by discussing whether it is permitted for people to drink mother’s milk and brings an apparent contradiction on the matter. The gemara concludes that it is permitted to drink human milk once it has been removed from the body, but not directly from a mother, which is permitted only for babies. It then points out that the opposite is true by human blood, as illustrated by a baraita. The baraita says that one can swallow the blood that may be found in between one’s teeth, but not if it has found its way onto a piece of bread he is eating. Rashi explains that once it is on the bread, one might think that he is eating animal blood that got on the bread. Following this approach, the Shulchan Aruch (Yoreh Deah 66:10) calls it a prohibition of marit ayin (when that which people think they are seeing is forbidden), in this case, that he is ingesting animal blood.
The question then becomes which situations are included in the marit ayin prohibition. Tosafot (K’ritot 21b) says that one may lick the blood which drips out of a wound on his finger (this is by no means a medical suggestion), because it is clear from the fact that the blood is taken directly from the body that it is human blood. However, the Minchat Yaakov, in his commentary on the Torat Chatat (62:25), infers from Rashi in Ketubot (ibid.) that he disagrees. Rashi says that the reason that it is permitted to swallow the blood from between the teeth is that “there is none that sees it.” The Minchat Yaakov reasons that according to this approach, it is forbidden to suck the blood from the wound on a finger, because it can be readily seen. The Darkei Teshuva (66:68) cites additional opinions on either side.
What about our case, regarding blood coming from cracked lips? According to Tosafot, it is clearly not a problem for him to swallow the blood. What about according to Rashi? One could claim that if the blood is visible, then it is a problem. But it is more likely that Rashi, when saying, “there is none that sees it,” was referring not to the blood but to the ingestion of the blood. While one can notice a person licking the blood off his finger, one cannot notice how, as the top lip meets the bottom lip, some blood may enter the mouth.
One can make the same calculation with regard to the use of dental floss. (I know there are people who would love nothing more than a halachic excuse not to use it, but they will have to go elsewhere to find one). It is true that the floss sometimes picks up some blood, which is noticeable and that it is not always cleaned before being put back into the mouth, where some may be ingested. However, it is not clear to one who sees the flossing that any of that blood will be ingested, nor will the ingestion be visible. Therefore, it is likely that even Rashi would agree that it is not necessary to clean the bloodstained dental floss before reinserting it into the mouth. In any case, the Kaf Hachayim (YD 66:47) says that there are more who agree with Tosafot than with Rashi and one can rely on the lenient opinions in this rabbinic matter.
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