Sanitizer sucked back into beer, dangerous?

I just had the same thing happen to me so I emailed Five Star Chemicals to see if they thought it would be safe. They said that if it had happened before the fermentation then it would be ok because the yeast would break it down, but since it happened after the fermentation they legally have to say that it is not safe to drink.

I'm guessing that you probably wouldn't suffer from any ill effects from drinking it, but it does contain a surfactant in addition to phosphoric acid which can be pretty nasty stuff.

I'm going to mix my 5 gal batch with a 1 gal extract batch and re-pitch yeast in an attempt to breakdown the star san and at least salvage the beer.

I use gin as it is fine to drink if you accidentally suck it back through the airlock.

If the sanitizer was StarSan, then you'll be fine. At the usual concentration of 1oz per 5 gallons, it's safe - even safe enough to drink. StarSan is phosphoric acid and surfactants - coke is also largely phosphoric acid and sugar, so the two are in someways similar. In a radio program, Charlie Talley, 5 star chemicals allegedly drank a glass of starsan, and he mentions that the yeast can also feed on it. (The phosphoric acid disassociates and the yeast absorb the phosphorus.)

If it was iodophor, then it's only prudent to be concerned since iodine is toxic (to people and yeast) in high enough doses. However, after 24 hours most of the iodine will have degraded/evaporated. Was the solution still orange/brown color? I'm guessing not, and so you will be fine. But let's consider the worst case - that the solution was freshly made. 1/2oz iodophor to 5 gallons gives 12.5ppm. 4 cups (ca. 1 liter) contains 12.5mg of iodine, and that's what was added to the beer, so your 5 gallons of beer has 12.5mg of iodine in the whole batch. In a pint, that's 0.31mg of iodine.

So, how many pints of iodine beer can you drink in a day?

"Iodine is an essential component of the thyroid hormones that are involved in the regulation of various enzymes and metabolic processes. Thyroid iodine accumulation and turnover were used to set the Estimated Average Requirement. The Recommended Dietary Allowance (RDA) for adult men and women is 150 μg/day. The median intake of iodine from food in the United States is approximately 240 to 300 μg/day for men and 190 to 210 μg/day for women. The Tolerable Upper Intake Level (UL) for adults is 1,100 μg/day (1.1 mg/day), a value based on serum thyrotropin concentration in response to varying levels of ingested iodine." (p. 258)

http://www.iodine4health.com/ortho/toxicity.htm

If you only drank beer, and didn't eat anything else, then you could consume 3 pints and be below the tolerable upper intake level quoted there.

But keep in mind this is worst case scenario. Iodine is very volatile and will evaporate into the headspace of the fermentor.

The yeast will also be fine, although I would make a starter to proof the yeast and test viability, just to be sure.

To prevent this from happening in future, replace the blowoff tube - a regular airlock should be fine once the the vigor of primary fermentation is over.