Toxicology Facts



Food poisoning

In any discussion of food preparation and illness, we must address food poisoning. Food poisoning is simply consuming poisons or toxins which are present in food. Toxins can find their way into our foods via several routes.

-Through microbial production of toxins while dwelling on the foodsource.

-Included as part of the organism

-Through direct inoculation

Food poisoning via microbial synthesis of toxins

Bacteria are ubiquitous (found virtually everywhere), and if they are not on the food source by the time it reaches our kitchen, we transfer bacteria from our hands to the food anyway. This is not a concern if we are going to immediately cook the food. However, if we handle a food product, and leave it at room temperature for several hours or more before consuming, we pose the risk of food poisoning to both ourselves and others who may consume the food in question. If bacteria are allowed to multiply on a food, they too, can produce toxins which can make us very ill. Although cooking kills bacteria present on the food, it does not inactivate the toxins on the food which the bacteria have produced. Many toxins are "heat-stable" and are not affected by boiling, etc. The best way to avoid illness in regards to food poisoning, is to either quickly refrigerate food until cooking, or immediately cook and serve. "Leftovers" can be safely eaten later (next day, etc., depending on the food) as long as the leftovers are put in the refrigerator soon after eating. By placing in cooler temperatures, such as in a refrigerator, you are quickly "inactivating" the metabolism of any bacteria that may be present on the food. Cold temperatures affect most bacteria this way. When ready to consume leftovers from the refrigerator, they can simply be heated. In comparison, if food is left out for long periods of time, the few bacteria that may be present on the food are given a chance to feed on the leftover they dwell on, and multiply. While "living" on the food surface, they metabolise the food as a food source like us. However, while we produce waste products, bacteria produce toxins (their waste products). If we allow enough time, the microbes (bacteria, fungus) can produce significant amounts of toxins. The norm in symptoms of illness as a result of this type of food poisoning is diarrhoae, vomiting, stomach pain, cramping, headaches, dizziness and fatique. Howver, this type of food poisoning can be fatal, depending on the bacteria present, how much toxin they produce and the state of health of the victim.


Food poisoning via plants and animals which have accumulated toxins

Certain plants and animals pose the risk of causing mild to severe food poisoning if consumed.

-Sea creatures

Specific sea creatures have been noted as containing toxins, that they either produce as part of their metabolism, or accumulate from their environment. Click on any of the organsisms below to learn more about how they can cause food poisoning.

-Elasmobranchs
-Ciguatera
-Scombroidea
-Gymnothorax
-Parasites

In regards to potentially poisonous fish, we must keep in mind that the toxins which accumulate in the tissues of the fish, are chemicals. This is different to bacterial food poisoning, which occurs when bacteria are present in a food and can be consumed. Of course, bacterial toxins can accumulate as well, and this is also regarded as food poisoning. However, we wanted to make clear the distinction between bacterial food poisoning and ichthyosarcotoxisms (poisoning from the consumption of fish that contain natural or accumulated toxins, such as from algae).

Note that sea creatures such as fish can also accumulate toxins through breathing contaminated water. Bivalves such as clams, oysters, muscles, are confined to local waters where they live out their life, unlike fish that can swim long distances and therefore, migrate. If fish or shellfish dwell in any particular area with contaminated water, they breathe this water and therefore, filter it. Through breathing, these creatures can accumulate whatever toxins are present in the water they live in. Humans ingesting contaminated seafoods, absorb these toxins. The types of toxins can include heavy metals, microbial (bacterial, fungal, algal) toxins and other substances. Just as humans produce waste products, algae also produce their own waste products. Algal toxins are produced as a by-product from the metabolism of certain algae (dinoflagellates). Dinoflagellates are single-celled and multiply rapidly in bodies of water such as oceans, lakes, etc. The toxins that they produce contaminates the surrounding water, and can be filtered by fish, clams, oysters, and other local aquatic life. As a result, the contaminated aquatic creatures can either die, become ill, or simply store the toxins. Humans catching and consuming these contaminated aquatic creatures can result in serious illness or death by affecting the nervous system and other components of the body, Numbness of limbs, respiratory failure and other effects can result, depending on the type of toxin ingested. When these "algal blooms" occur largescale in waters, they form an interesting colour-change in the water. These colour changes are referred to as "red tides" if they are red, or course, or simply algal blooms. Although they are nice to look at, they are obviously very dangerous for the aquatic creatures, and the humans that consume these creatures. Even swimming in these contaminated waters can cause severe skin and eye irritations, illness, or death (especially if water is swallowed during swimming). Keep in mind that all waters can be affected, even water supplies for drinking. The algae that occupy fresh water (versus salt water) are not really algae, although they are referred to as the so-called "blue-green algae", but rather are photosynthetic bacteria, called the cyanobacteria. Regulatory bodies noting the occurence of these tides during various times of the year then have the opportunity to warn local fisherman to avoid fishing these waters. However, in many parts of the world, waters are unregulated. Therefore, it is always best to know the origin of any aquatic creatures that you may purchase for consumption.

-Plants

Many plant products contain chemicals that are harmful to humans and other animals if consumed. Sometimes, only specific parts of the plant are dangerous to consume. On other ocassions, the entire plant is dangerous. Many plants contain different harmful chemicals in different areas of the plant (leaves, stem, flower, etc.) Furthermore, many plants which are helpful to man through consumption, are only harmful if consumed in excess. Aloe vera is helpful in small amounts for constipation, because it stimulates the intestine. However, large amounts of aloe can cause extremely painful cramping. Click on the links below to learn more.

-Apples/Cyanide
-Cassava



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