Naturally Occurring Toxic Substances (NOTS): What You Should Know?

\Certain types of foods contain potentially harmful natural toxins, which are classified as Naturally Occurring Toxic Substances (NOTS). Sometimes a toxin is present in food plants as a naturally occurring insecticide that functions to ward off insect attack. Other toxins protect plants from spoilage by microbes or when damaged by weather, handling, or by UV rays from sunlight. The various factors that determine whether a person will have an adverse reaction to a toxin as well as the severity of the symptoms upon exposure to the toxin, include the following:

• The person’s sensitivity to the natural toxin.
• The concentration of the toxin in the food.
• The amount of food consumed.

Foods that contain natural toxins are discussed below. These foods may be of fungal, plant or marine origin. Fungal toxins Mushroom toxin: While commercially cultivated mushrooms are safe, some wild mushrooms like the Death Cap Mushroom are highly toxic, and is responsible for large number of deaths from mushroom poisoning. It is commonly found during the monsoon season. A single mushroom can be lethal for an adult. The symptoms of poisoning are predominantly gastrointestinal (GI) in nature. The toxin eventually kills due to hepatotoxicity. Plant toxins Hydrogen cyanide**:**  This is a NOTS that can be found in raw or unprocessed cassava and bamboo shoots. Consumption of these shoots can lead to exposure to the toxin. Hydrogen cyanide (HCN), also known as prussic acid, is an extremely toxic colorless organic compound. Its solution in water is called hydrocyanic acid. The so-called “bitter” roots of the cassava plant may contain up to 1 g of HCN per kg. HCN is also found in fruits that have a pit, such as cherries, apricots, apples, and bitter almonds, from which almond oil and flavoring are made. Many of these pits contain small amounts of cyanohydrins such as mandelonitrile and amygdalin, which slowly release HCN. Furocoumarins: These toxins are present in Parsnips, which are closely related to carrots and parsley. Furocoumarins are stress toxins and are released in response to stress, such as physical damage. Some of these toxins can cause GI problems and allergic reactions in susceptible people. Parsnips should always be peeled and cooked before consumption in order to reduce the level of toxin exposure. Glycoalkaloids: Glycoalkaloids are commonly occurring toxins in Potatoes. These toxins are concentrated in the bitter-tasting sprouts and peel. Like furocoumarins, these are also stress toxins produced in response to multiple stressors. It is common practice to cut-off and destroy sprouts and green patches on potatoes, as cooking fails to destroy glycoalkaloids. Lectins: Lectins are naturally occurring plant toxins that are largely found in Kidney Beans such as Red Kidney Beans. Raw beans can cause severe GI problems. Lectins are leached out by soaking in water for a few hours, followed by boiling. Oxalic acid: Rhubarb, a plant, the stems of which are used in making pies and other desserts, contains oxalic acid, which is especially high in the leaves, making them too toxic for consumption. Oxalic acid toxicity can cause neurological, cardiac, respiratory and GI effects. Cucurbitacins: These are naturally occurring toxins that can occur in Zucchini (also known as Courgette), which is a summer squash that is used for making savory dishes. The presence of cucurbitacins is indicated by a bitter tasting zucchini, which must not be consumed. Consumption of bitter zucchinis can cause severe GI problems. Marine toxins Mercury poisoning: Mercury occurs naturally in sea water, and accumulates over time in the body of large ocean-dwelling fishes such as shark etc. through direct absorption as well as feeding on smaller fish. Since mercury can have a detrimental effect on brain development in utero, and thereby hamper cognitive development in the early years, it is strongly recommended that pregnant women and young children should avoid shark and other large sea fishes in their diet. Ciguatera poisoning: Ciguatera poisoning is caused by consuming fish contaminated with microalgae that produce the ciguatera toxin. Some fishes known to harbor ciguatera toxin include black grouper, blackfin snapper, barracuda, dog snapper, king mackerel etc. Symptoms of ciguatera poisoning include nausea, vomiting, and neurologic symptoms, such as tingling sensation on fingers and toes. There is currently no cure for ciguatera poisoning. Symptoms usually subside slowly. Treatment is symptomatic. Scombroid poisoning: This occurs as a result of inadequate storage conditions and temperature control of fish. It occurs when fish is not preserved by chilling on ice during transportation. Histamine accumulates in the fish and is responsible for the poisoning. Some of the susceptible fish include mackerel, herring, sardine, yellow fin tuna etc. Symptoms of scombroid poisoning begin quickly, often 30 min to 1 hour after consuming the toxin, and include nausea, vomiting, diarrhea, abdominal cramps, burning and tingling of the lips and mouth, dizziness, flushing, urticaria, sweating, headaches, blurred vision and palpitations. In severe cases, breathing difficulties can occur, especially in asthmatics. Fish oil poisoning: Some types of fish contain oil that is not metabolized by humans after consumption of the fish. These types of fishes include Escolar and oil-fish, which cause profuse diarrhea with an oily consistency. This type of poisoning is self-limiting, as the diarrhea stops as soon as all the fish oil has been excreted from the body. The diarrhea generally does not cause any fatalities, as water is not lost from the body. Safety limits for some NOTS as per FSSAI guidelines The Food Safety and Standards Authority of India (FSSAI) has recommended the safe upper limit of a number of NOTS, which are presented in Table 1. The original regulations as per FSS (Contaminants, Toxins & Residues) Regulations, 2011 had specified limits for NOTS for any article of food but the draft regulations which are proposed to be amended have given the names of the food article as provided in table 1. Table 1: Safe upper limits for some NOTS as per FSSAI guidelines

SI.No	Name of naturally occurring toxic substances (NOTS)	Article of Food	Maximum limits (ppm)
(1)	(2)	(3)	(4)
1.	Agaric acid	Food containing mushrooms	100
		Alcoholic beverages	100
2.	Hydrocyanic acid	Nougat, marzipan or its substitutes or similar products	5
		Canned stone fruits	5
		Alcoholic beverages	5
		Confectionery	5
		Stone fruit juices	5
3.	Hypericine	Alcoholic beverages	1
4.	Saffrole	Meat preparations and meat products, including poultry and game	10
		Fish preparations and fish products	10
		Soups and sauces	10
		Non-alcoholic beverages	10
		Food containing mace and nutmeg	10
		Alcoholic beverages	10