Table 1.

Issues associated with FBS and its classification.

S. No	In market	Scientific	Moral
1	Unpredictable shortage in the supply of FBS [13, 95].	Undefined composition of FBS [96].	The worldwide increasing number of bovine fetus used and killed only for collecting FBS [97].
2	Increasing the price of FBS (it was increased above 300% in the last few years as of 2016) [98].	It can be contaminated with prion proteins [99], endotoxins [100], different kinds of microbes, immunoglobulin and viruses [101].	Fetal distress during blood collection to prepare FBS leads to high anger among animal welfare and ethical association around the world [102].
3	It creates a business opportunity in the loosely regulated market that leads to the exploitation of FBS [8, 97].	The variation between the brands [103] seasonal (winter and spring) and geographical batch-to-batch variation in the quality (variation in composition, possible contamination specific to season and geographic) of FBS questioning the experimental reproducibility [96].	-
4	-	It could be interfering with phenotypic cell stability and influence the experimental outcome [104, 105].	-
5	-	The presence of non-human N-glycolylneuraminic acid (Neu5Gc) in the animal serum may promote chronic inflammation and influence tumor progression and vascular inflammation [106], which should have been excluding the usage of FBS in human embryonic stem cell (ES) for cellular therapy [107], yet, it is widely used [14].	-