How many times have you heard “it’s less toxic than table salt!” as a reason that something’s safe. But really, how safe is this commonly used ‘benchmark’ for toxicity?
It is widely accepted and proved through many studies that excessive salt intake can contribute to, and often cause, high blood pressure and hypertension. Although it is likely that there is also a genetic susceptibility to high blood pressure that contributes to this, high salt intake is widely accepted to be influential. Other studies have also shown positive correlations between high salt intake and strokes and gastric cancer, even without the high blood pressure that can contribute to strokes and other medical issues.
Excessive salt (more specifically, sodium) is called hypernatremia in medical terms and is classified by the balance of sodium and water being thrown massively towards the ‘salt’ end. Most of the effects of this are caused by shrinking of cells, since water leaves the cells to maintain the balance of salt and water. This causes a multitude of problems that include confusion, seizures, coma, and even death if the situation is not corrected.
Thankfully, we have an inbuilt mechanism of preventing poisoning from excessive salt – we get thirsty. If you have a salty food then you get thirsty and increase your fluid intake as well, which allows the cells to keep most of their water inside, protecting you against severe hypernatremia and the unpleasant effects of that.
LD50 is a commonly used measure of toxicity. It is the amount of a substance that, when ingested, kills 50% of the test sample. The LD50 for table salt is 12357 mg/kg for humans, in other words if you fed 100 people 12.357g of salt for every kilo of their weight, 50 of them would die as a result.
Compare this to that of restricted use pesticides. 29-42% of these are ‘less toxic than table salt,’ one of these being glyphosate. They are significantly less toxic than the salt we eat without thinking. Even acetic acid – found in vinegar – has a worse toxicity profile than table salt.
So, unless you eat a lot of salt, it’s not likely to kill you. Even low amounts may give you other problems, but a lethal overdose, really isn’t that high a risk. So, maybe the expression really isn’t that wrong, even if it is a little misleading.