Methanol is toxic because it is eventually metabolized into formic acid (the same venom used by ants) which interferes with cell metabolism.[1] If the amount of formic acid is high enough, cells can't maintain homeostatis and die. Certain cells with higher metabolic demands (such as nerve cells) die first. If the dosage is below that threshold, you're fine.
The FDA considers 0.5mg/kg/day of methanol to be unlikely to cause deleterious effects for a person's lifetime. For a 70kg person that would be 35mg per day. For comparison: a can of diet soda has less than 200mg of aspartame. Assuming 100% of the aspartame breaks down into phenylethylamine, aspartic acid, and methanol, then less than 10% of that mass would be methanol, or less than 20mg. So even if you drank an entire can of disgusting old diet soda every day, you'd still be below the FDA's threshold for cumulative damage and you'd be nowhere near the threshold for acute methanol poisoning.
Well then you got the wrong message. A glass of wine can contain over 50mg of methanol. If something's at or below the FDA reference dose, it's not worth worrying about. The FDA is rather risk-averse and tends to set limits far below what would actually cause harm.
To give you another bit of data: The metabolite of methanol that actually causes damage (formic acid) is a common food additive and is naturally present in many fruits, honey, and of course ant venom. If tiny amounts caused issues, we'd know by now.
The FDA considers 0.5mg/kg/day of methanol to be unlikely to cause deleterious effects for a person's lifetime. For a 70kg person that would be 35mg per day. For comparison: a can of diet soda has less than 200mg of aspartame. Assuming 100% of the aspartame breaks down into phenylethylamine, aspartic acid, and methanol, then less than 10% of that mass would be methanol, or less than 20mg. So even if you drank an entire can of disgusting old diet soda every day, you'd still be below the FDA's threshold for cumulative damage and you'd be nowhere near the threshold for acute methanol poisoning.
1. https://en.wikipedia.org/wiki/Methanol_toxicity