I was reading or watching something last week (can’t remember what) that referred to hearing loss from gin-and-tonics. So I looked it up today and found things like this study and this interview.
So basically it sounds like normal drinking of gin-and-tonic would not cause hearing loss. But it still sounds weird.
Wikipediasays the US limit for quinine in tonic water is 83 mg/liter. (That’s the maximum limit; actual content could be lower.) If hearing loss requires you to ingest 5-11 mg/kg of body weight, then even a 50 kg lightweight needs to drink at least 3-5 liters of tonic water a day.
So… you’d really have to work at it to suffer any hearing loss.
Also, if you’re drinking those liters with gin added in the normal amounts, quinine poisoning is the least of your problems.
I know that if I drink a liter of gin and tonic I can’t hear a damn thing for the next 8 hours. Now that I know to cut out the tonic water and drink it straight I expect that particular problem to go away.
The effects seem to be temporary in any event (and in this case they occurred in patients that were taking therapeutic doses of quinine (1000+ milligrams per day.) A liter of tonic water contains 100 mg or so.
Phrased differently, the quinine in tonic water can cause your blood platelets to drop to dangerously low levels. Since platelets are needed to clot your blood, when their levels drop too low, you can start bleeding spontaneously, especially into the skin. And that’s what ‘purpura’ is - bleeding into the skin.
I was taught that when somebody comes to the hospital with low platelets, you should be sure to enquire just how fond they are of gin and tonic.
*Sorry, it’s a lousy cite but all I could find right now.
I think what I was reading in the OP was something written in the 20s or 30s (I skimmed through it but couldn’t easily find the quote). So that would kind of make sense.