There are some common chemicals which you see on the list of ingredients of various products you use. But more often than not, you are quite clueless as to why they are there and what they do. Such ignorance is not always bliss, because you need to know the various pros and cons of chemical ingredients to ascertain whether a product is safe for you or not. If the name sodium metabisulfite rings a bell, you have probably seen it as one of ingredients listed on a packet of potato chips or raisins. If you want to know more about this chemical and whether it is safe for you, keep reading.
This sodium compound consists of sodium, sulfur and oxygen. It its natural form, it is a yellowish-white crystalline powder, which is water soluble and has a smell of rotten eggs (almost the same as sulfur). Sodium metabisulfite is used as a preservative for packaged foods such as chips, raisins and also some concentrated juices. It can effectively increase the shelf life of these packaged items and is also cheap. But this does not mean that it is a completely safe additive.
If you have a sulfite allergy, you can experience rashes or wheezing, if you consume products containing this substance. As per established health norms, it is safe to take in 0.7 grams of this compound per kilogram of body weight.
If you keep your intake of this sodium compound below this limit, it can synthesize itself into a sulfate in the liver, and exit your body without causing harm. But if you consume greater amounts you expose your immune system to possible harm. Sodium metabisulfite, consumed in large amounts can also lead to cancer and problems in the reproductive system. Neuro-toxicity is another concern and if you have asthma or breathing problems its best to steer clear of food containing this substance.
This compound is also present in wines and beers, because it is used as a sterilizer and anti-oxidant in the brewing process. But then, if you are allergic to red wine, it is because of the presence of this compound. Its antibacterial nature makes it useful for water-purification processes such as reverse osmosis.
You may also find sodium metabisulfite being used for dark-room development of images from film, though with the advent of digital cameras, this use is rather limited. Mostly, it is used as a preservative for packaged food and so, you need to take the possible side effects of this chemical into account, before you consume such food items.