Citric acid is a weak acid that is naturally found in fruit but can also be manufactured using black mold. It is rarely harmful.
Citric acid is not highly toxic in the context of nutrition and human health. It is naturally occurring in fruits such as lemons, limes, and oranges. It is odorless and acidic in taste. It is also manufactured through fermentation using certain strains of black mold (Aspergillus niger) and molasses or certain sugars such as raw beets and cane sugars. Citric acid is used as a preservative and food flavoring. It is also used in cosmetics and cleaning products.
Citric acid, natural or otherwise, might damage tooth enamel over time if not consumed in moderation. Skincare products containing citric acid may cause irritation or increase skin sensitivity to UVB radiation. When used as a component in cleaning products, citric acid can kill any bacteria or virus that cannot survive at its pH of 3 to 6. It can prevent the spread of the human norovirus (the winter vomiting bug). Its preservative property helps increase the shelf life of foods by slowing or helping prevent the formation of bacteria, mold, yeast, and fungus. It is an FDA-approved chemical for usage in a variety of products.
People allergic to black mold may have allergic reactions to manufactured citric acid (MCA). This is because, although its chemical properties are the same as in naturally occurring citric acid, MCA may contain remnants of black mold. MCA does not induce adverse reactions in most people. Harmful inflammatory responses in the aforementioned allergic people can include joint pain, muscle pain, and digestive issues.
However, citric acid in food products is not lethal or detrimental to human health. Hence we mark this claim as false.