I am trying to determine if some vaccines and medications are permissible to use, but one issue that several of them have is that they are produced through bacteria in cellular mediums. These mediums have cells of either human or animal origin and would be considered impure/impermissible. But the final product is filtered to remove the medium and other material. Here is an example, taken from the information provided by the manufacturer for the vaccine "Boostrix": "Tetanus toxin is produced by growing Clostridium tetani (C. tetani) in a modified Latham medium derived from bovine casein. The diphtheria toxin is produced by growing Corynebacterium diphtheriae (C. diphtheriae) in Fenton medium containing a bovine extract. The bovine materials used in these extracts are sourced from countries which the United States Department of Agriculture (USDA) has determined neither have nor are at risk of bovine spongiform encephalopathy (BSE). Both toxins are detoxified with formaldehyde, concentrated by ultrafiltration, and purified by precipitation, dialysis, and sterile filtration." So that last part says that the desired toxins are isolated through the methods mentioned. The final list of "ingredients" of the vaccine does not list any components from the cellular medium as being included: "Each 0.5-mL dose is formulated to contain 0.3 mg aluminum (not more than 0.39 mg by assay) as aluminum hydroxide as adjuvant, 4.4 mg of sodium chloride, ≤100 mcg of residual formaldehyde, and ≤100 mcg of polysorbate 80 (Tween 80)." But the issue is that there does not seem to be any data or studies that have evaluated if the final product is actually completely free of the impure medium components. The manufacturer states that following about the presence of animal material in the final product: https://www.gskusmedicalaffairs.com/docviewer.html?cmd=GSKMedicalInformation&medcommid=MED--US-1402&token=23108-caf1af07-640d-478c-a81e-89c1720de814&dns=gsk-medcomms.veevavault.com Basically, no "analytical verification" about the presence of animal products in the vaccine. So I guess the issue is, if we know for sure that there is impurity present prior to the isolation process, can we just assume that it has been removed and therefore say that the final product would be ok? I am wondering if you can find any reference for this type of situation, for example a situation in which 99.9% of an impurity is removed. I am hesitant to give a ruling based on assumption without some type of textual backing.