Yervand Kondrahjian | Staff Writer
What is Toxicology?
Toxicology is a field of science that studies the harmful effects that chemicals have on living organisms. It involves observing and reporting symptoms that arise following exposure to toxic substances.
Types of Toxicology
There are several branches of toxicology known as subspecialties, each of which focuses on particular aspects of toxicology.
- Clinical toxicology is the study of the diagnosis and treatment of poisoning that can occur in humans.
- Forensic toxicology deals with the medical investigation of biological samples for the presence of poison.
- Occupational toxicology aims at detecting the toxic agents in the workplace, determining the conditions for their safe use, and preventing the absorption of harmful amounts.
- Environment toxicology is the study of the presence of toxicants in the environment and their effect on humans and animals.
- Regulatory toxicology is a field that develops, assembles models, evaluates, and communicates information about health risks associated with exposure to agents (e.g., chemicals, radiation) that have the potential to harm human health and ecosystems.
- Ecotoxicology is the study of the toxic effects of a chemical substance on living organisms within the ecosystem.
- Food toxicology is the study of the nature, properties, effects, and detection of toxic substances in food.
Food toxicology is concerned with the evaluation of the effects of chemical substances of the diet on the activities of toxic agents that may be natural endogenous products, introduced from infecting organisms, or from food production, processing, and preparation.
Food Poisoning
Food is indispensable for the development, functioning, maintenance, and reproduction of living organisms. However, when contaminated, it leads to food poisoning. Epidemiological evidence has demonstrated that microbial contamination is a major risk factor associated with food consumption. Infectious organisms, including bacteria, viruses, and parasites, or their toxins can contaminate food at any point of processing or production. Contamination can also occur at home if food is incorrectly handled or cooked.
Food-borne diseases
Foodborne diseases result from ingestion of contaminated food. More than 250 different foodborne hazards have been identified including infectious bacteria, viruses and parasites, and noninfectious chemicals and toxins. The sources of these agents range from being an inherent constituent of the food to inadvertent (or intentional) addition during food production, processing, or preparation. Moreover, most foodborne agents can be transmitted through water or through contact with infected farm animals, pets, and humans.
Food-borne bacterial pathogens
| Bacteria |
Incubation time (Hours) |
Duration of disease (days) |
| Salmonella | 6-36 | 1-7 |
| Shigella | 6-12 | 2-3 |
| Escherichia coli | 12-72 | 1-7 |
| Yersinia enterocolitica | 24-36 | 3-5 |
| Campylobacter jejuni | 3-5 (days) | 5-7 |
| Listeria monocytogenes | Variable | High mortality rate |
| Vibrio parahemolyticus | 2-48 | 2-5 |
| Aeromonas hydrophila | 2-48 | 2-7 |
Bacterial toxins
Botulism, the most severe bacterial food-borne intoxication known, is caused by a toxin produced by the bacterium Clostridium botulinum. The disease begins with weakness, blurred vision, and tiredness. This may then be followed by weakness of the arms, chest muscles, and legs. Vomiting, swelling of the abdomen, and diarrhea may also occur. The duration of botulism is 1 to 10 days, and mortality is relatively high (30 to 65%).
The bacteria that make Botulinum toxin have spores that can grow and become fatal in certain favorable conditions, such as in food of low to neutral pH which has undergone inadequate heating. Examples include home-canned foods or commercially canned products that didn’t undergo proper processing, preserved vegetables with low acid content such as beets, spinach, mushrooms, and green beans, canned tuna fish, fermented, smoked, and salted fish, as well as meat products, such as ham and sausage. Prevention is primarily done by proper food preparation, for the toxin is destroyed by heating it to more than 85 °C (185 °F) for longer than 5 minutes.
Mycotoxins
Mycotoxins are toxic compounds that are naturally produced by certain types of fungi, which can grow on various foods such as cereals, dried fruits, nuts, and spices. Fungi growth can occur either before harvest or after harvest, during storage, on/in the food itself often under warm, damp, and humid conditions. Most mycotoxins are chemically stable and survive food processing.
The effects of some food-borne mycotoxins are acute with symptoms of severe illness appearing quickly after consumption of food products contaminated with mycotoxins. Other mycotoxins occurring in food have been associated with long-term effects on health, including the development of cancers and immune deficiency. Of the several hundred mycotoxins identified so far, aflatoxins produced by the moulds Aspergillus flavus and Aspergillus parasiticus, are amongst the most poisonous mycotoxins. Prevention of aflatoxin contamination could be best prevented by discouraging fungal growth through adequate post-harvest crop-drying.
Toxic microbial metabolites – Biogenic amines
Enterobacteriaceae and Enterococci are mainly responsible for the production of biogenic amines in foods, which have a toxic effect on the consumer. Biogenic amines are formed during fermentation and decomposition of protein, usually fish. They also occur naturally in fruits, vegetables, and fish. Their levels increase with the presence of free amino acids (precursors), low pH of the product, high NaCl concentrations, and microbial decarboxylase activity.
The symptoms of intoxication, which can last for several hours, include burning throat, flushing, headache, nausea, hypertension, numbness, and tingling of the lips, rapid pulse, and vomiting. Histamine has been indicated as the causative agent in several outbreaks of food intoxication. Pasteurization of cheese milk, good hygienic practice, and selection of starters with low decarboxylase activity are measures to prevent the accumulation of these undesirable products.
Toxic microbial metabolites – Ethyl carbamate
Ethyl carbamate (urethane) is a compound that can naturally occur in fermented foods and beverages. Its formation is enhanced by heat and light during the distillation process. It has been classified as a mutagen as well as a carcinogen.
Ethyl carbamate occurs in many fermented foods and beverages including yogurt, soy sauce, and wine. Research on wine and stone fruit (cherry, plum) fermentations has demonstrated that ethyl carbamate levels can be minimized by reducing the levels of the precursors by enzymatic treatment, selecting yeast strains, monitoring fermentation conditions, and treating the pH-adjusted fermented pulp with CuSO4.
Food safety
Food safety refers to routines in the preparation, handling, and storage of food meant to prevent foodborne illness and injury. From farm to factory to fork, food products may encounter any number of health hazards. Thus, safe food handling practices and procedures are implemented at every stage of the food production life cycle to curb these risks and prevent harm to consumers.
The main techniques to achieve growth prevention include drying, control of storage temperatures, and modified atmosphere storage. Other techniques include the application of gamma irradiation, or fungicides to kill fungal spores.
It is also essential that the consumer protect him/herself by safe handling of food and avoiding raw consumption of food of animal origin.
References
De Vries, J. (2021). Food safety and toxicity: CRC press.
Food-borne disease. Food-Borne Disease – an overview | ScienceDirect Topics. (n.d.). Retrieved November 14, 2021, from https://www.sciencedirect.com/topics/food-science/food-borne-disease.
Hodgson, E. (2004). A textbook of modern toxicology: John Wiley & Sons.
Shibamoto, T., & Bjeldanes, L. F. (2009). Introduction to food toxicology.
U.S. Department of Health and Human Services. (n.d.). Toxicology. National Institute of Environmental Health Sciences. Retrieved November 14, 2021, from https://www.niehs.nih.gov/health/topics/science/toxicology/index.cfm.