The cartoon shows how no one would willingly drink a known poison when making healthy diet choices (eg. losing weight) but they will ingest poison if they aren’t fully aware of the hazard.
Regulators have set different levels for how much aspartame and how much methanol is allowable before adverse effects occur which has fueled the confusion over how much aspartame should be considered safe.
Let’s try a little hypothetical calculation to show the fallacy of the aspartame regulatory limit.
The allowable daily intake (ADI) of aspartame is 50 milligram per kilogram (mg/kg) of body weight per day, (we know that 1 kilogram is 2.204623 pounds). So for,
a 175 pound man or 79 kg the ADI is: 50x79 = 3,060 mg aspartame
a 120 pound woman; 54 kg the ADI is: 50x54 = 2,700 mg aspartame
a 50-pound child. 22.7 kg the ADI is: 50x22.7 = 1,135 mg aspartame
According to the Aspartame Research center (http://www.aboutaspartame.com/facts/acceptable-daily-intake-adi) the ADI of aspartame is 50 mg/kg of body weight per day so 22 cans of a diet soft drink for a 175 pound man; 15 cans for a 120 pound woman; 6 12-oz. cans for a 50-pound child is okay.
No one would drink that much diet soda each day so we are all safe right?
However, inside the body we know that Aspartame metabolizes to its component parts of Phenylalanine ~50%, Aspartic Acid ~40%, and Methanol ~10%.
So the regulators are saying that while the ADI of aspartame is 50 mg/kg of body weight per day the ADI for methanol which is the toxic component SHOULD be one one tenth this amount. So for,
a 175 pound man or 79 kg the ADI is: 5x79 = 306 mg methanol from aspartame
a 120 pound woman; 54 kg the ADI is: 5x54 = 270 mg methanol from aspartame
a 50-pound child. 22.7 kg the ADI is: 5x22.7 = 113.5 methanol from aspartame
Even though these values are allowable for aspartame and its methanol content a different value is given for occupational exposure of humans to methanol.
The US EPA Reference Dose (RfD) for methanol is ten fold lower set at 0.5 milligrams per kilogram body weight per day (mg/kg/d) for occupational exposures (inhalation or ingestion). The value was set based on research studies showing increased liver enzymes (SAP and SGPT) and decreased brain weight in rats. The RfD (older name ADI) is an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily oral exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious noncancer effects during a lifetime. It is not a direct estimator of risk but rather a reference point to gauge the potential effects. At exposures increasingly greater than the RfD, the potential for adverse health effects increases.
Using the US EPA Reference Dose (RfD) for methanol of 0.5 milligrams per kilogram body weight per day (mg/kg/d) gives:
a 175 pound man or 79 kg, RfD (ADI) 0.5x79 = 30.6 mg methanol allowable
a 120 pound woman or 54 kg, RfD (ADI) 0.5x54 = 27 mg methanol allowable
a 50-pound child or 22.7 kg, RfD (ADI) 0.5x22.7 = 11.35 mg methanol allowable
Each 12 oz serving of aspartame soda gives 20 mgs methanol consumed. So,
a 175 pound man or 79 kg, 30.6 mg/ 20 mg = 1.5 cans of 12 oz diet soda (18 ounces)
a 120 pound woman or 54 kg, 27 mg / 20 mg = 1.35 cans of 12 oz diet soda (16 ounces)
a 50-pound child or 22.7 kg, 11.3 mg/ 20 mg = 0.56 cans of 12 oz diet soda (6.7 ounces)
It means that according to the US EPA reference dose allowable methanol is one-tenth fold lower. People would exceed limits by drinking more than 1.5 (avg man), 1.35 (avg woman) and .56 cans (avg child) of diet soda a day.
Quite a difference from the industry supported amount of aspartame drink values.
Some suggest aspartame is considered safe and men, women and children can consume 22, 15, or 6 cans of diet soda as promoted by the Aspartame Research Center website. However, the methanol created during the metabolism of aspartame suggests far less would be acceptable at 1.5, 1.35 and .56 cans of diet soda consumed before adverse effects start occurring if US EPA standards are used.
Did you know that a large cup of diet soda at McDonald's in the United States holds about 32 ounces of liquid?
One 12-ounce can of aspartame-sweetened soda contains about 200 milligrams of aspartame and a large diet soda from McD’s adds 2.66 times aspartame or 533 mg more to your diet. You'd add a tenth of this amount to your diet as methanol following digestion or 53.3 mg methanol. So consuming one large McD’s diet coke gives more than the allowable RfD for methanol.
I have seen men at work drinking several cans of diet soda during the day - everyday.
Women drinking several drinks at a bar or club on a night out (eg rum and diet cola, not only is there body dealing with toxic amounts of ethanol, they add lots of methanol too).
Children, teenagers and students drinking more than a litre of diet cola a day.
Many people routinely consume higher than the recommended dose of methanol from drinking diet sodas. The consumption over time of caffeinated (addictive) diet colas more closely resembles the US EPA chronic, long - term exposure criteria and the lower Rfd limits should be used.
From its methanol content and consumption patterns alone it is probably better to stop drinking diet soda that contains a known neurotoxic poison altogether - regardless of the amount consumed.