Lecture 13 – Food Toxicology I - Eta.health.usf.edu

2/14/2017Lecture ObjectivesFood Toxicology ILecture 11 List and describe the microbial toxins found in foods. Explain the potential for environmental toxins to cause unintended foodhazards. Recognize that many foods contain natural hazards which pose health risks. Describe the conditions associated with the microbial, environmental, andnatural toxins.Microbial Toxins in FoodsFungi - Mycotoxins Microbial toxins commonly foundin foods include: Mycotoxins are toxic substancesproduced by some fungi. Thefollowing mycotoxins may befound in foods: Mycotoxins (fungi) Scombroid (histamine – producingbacteria) Ciguatoxin (algae) Paralytic shellfish poisoning (algae) Note: The toxins produced byClostridium botulinum,Staphylococcus aureus, andBacillus cereus were discussed inearly lectures. Aflatoxin – produced by Aspergillusflavus (seen on corn and under amicroscope at right) Ergot – produced by Clavicepspurpurea. Intestinal irritants – produced bypoisonous mushrooms.Fungal spores are easily spread due in part to their small size.NCSU – Plant Pathology ExtensionMycotoxin- AflatoxinMycotoxin - Aflatoxin Aspergillus flavus producesa toxin called aflatoxinwhich causes anintoxication. Found in moldy grains andnuts including corn andpistachios, and also foundin peanuts and soy. Can cause severe liverdamage including cirrhosis,necrosis, and carcinoma. In 2013 there was a recall of dogfoods contaminated withaflatoxin. Drought conditions resulted inovergrowth of Aspergillus funguson corn. That corn was used to producedog food.Aspergillus fungus – Iowa State University. Often fatal.1

2/14/2017Mycotoxin - AflatoxinMycotoxins - Ergot Ergot is a toxin producedby the fungus Clavicepspurpurea that infects rye. The toxins havehallucinogenicproperties.In the United States we routinely test foods for aflatoxin and human cases are rare. Inplaces where detection is not used, large outbreaks with high numbers of deaths (125above) can occur. Note the cause of this outbreak was contaminated corn. Causes a syndrome knownas ergotism or “St. VitusDance” which includesspasms and hallucinations.Claviceps purpurea fungus on rye.Mycotoxins - ErgotMycotoxins - Mushrooms In Salem, Massachusetts in1692 several women wereaccused of being witchesafter exhibiting strangesymptoms (hallucinationsand spasms). Poisonous mushrooms often looksimilar to hallucinogenicmushrooms. Persons who abuse mushroomsoften mistakenly eat the wrongones. 20 people were executed. Ergot is known to haveinfected rye in Salem, MA,leading some to speculatethat the “witches” were infact poison victims.Poisonous Mushrooms In this outbreak in 2012, a caregiveraccidentally used poisonousmushrooms to make a soup forelderly patients. Four people died and several othersbecame ill.Memorial to the victims of the Salem witch trials. The mushrooms commonlyproduce gastrointestinal irritants(compounds that produce rapid,transient nausea, vomiting,abdominal cramping, anddiarrhea). Some of the mushrooms aredeadly.Fans of eating wild mushrooms are quick to point outthat some species are poisonous.Scombroid Poisoning Intoxication is caused by ingestinglarge amounts of the chemicalhistamine which is produced bybacteria in seafood.– Tuna, mahi-mahi, sardines, etc.– Usually results from fish being held athigh temperatures for long timeperiods (temperature abuse). Toxin is heat-stable. In other words, it may not bedestroyed by cooking. Symptoms include dizziness, burning,rash, headache, and can be fatal. Severe cases may require treatmentwith fast-acting antihistamines.2

2/14/2017Scombroid Poisoning – Tuna SteaksAlgal Toxins The algae rarely cause diseaseand foodborne infection due toalgae is rare. Most cases are dueto the following two types oftoxins: Ciguatoxin Paralytic Shellfish Poisoning (PSPtoxins). Amnesic Shellfish Poisoning.NOAA – National Oceanic and AtmosphericAdministration Center.Imported tuna was a common food in these outbreak but elevated levels of histamine werenot detected in remaining samples. The source remains unknown.Ciguatoxin - AlgaeCiguatera – Algae (continued) Ciguatoxin is produced by algae(dinoflagellates – in photo at right). Human cases of ciguatera (thedisease caused by ciguatoxin)usually occur following ingestionof barracuda, snapper, jack &grouper. Cases are common in Hawaiiand Puerto Rico. The algae are eaten by fish, which arein turn eaten by larger fish, causingthe toxin to accumulate to dangerouslevels in large fish (a process knownas bioaccumulation). However, if the fish are shippedcases can occur anywhere. In thereport at right, cases occurred inNew York City. The distributor ofthe fish is not named but reportsshow that they had already beenissued a warning! Prevention is eating smaller fish. Symptoms include nausea, diarrhea,vomiting, headache, excessivesweating, weakness, itching, etc. There is no specific treatment anddisease is rarely fatal.Shellfish Toxins - Algae Produced by several types of algaeincluding the species that causes “redtide”. The toxins are heat-stable (in otherwords, cooking does NOT destroythem). Infects mussels, clams, oysters, crabs,lobsters and scallops. Symptoms can be confused withshellfish allergies:Ciguatoxin caused aheart attack thatkilled a woman whoate grouper in Mexico. Numbness, tingling occur first. Headache, dizziness, nausea. In severe cases, muscle paralysis andrespiratory failure occur. death occurs within 2-25 hours.3

2/14/2017Paralytic Shellfish Poisoning - AlgaeAmnesic Shellfish Poisoning - Algae Most PSP cases occur in colderclimates where the toxin (fromthe algae) accumulates in theshellfish. Saxotoxin is most common. Death can occur within 3 to 4 hoursdue to respiratory paralysis.Caused by domoic acid, thistoxin produced by algae cancause severe neurologicaldamage, including loss ofshort term memory.Alaska Public MediaEnvironmental ToxinsEnvironmental Toxins - Persistence Industrial processes can releasecontaminants into theenvironment. Polluted air, water, and soil canresult in contaminated produce,dairy, meats, and seafood. Some environmentalcontaminants can cause healthproblems. Persistence of toxins refers to theextent to which the toxin lingersin the environment or in thebody. Contaminants present for a shorttime or eliminated by the bodypose little health risk. Contaminants which persist mayalso bioaccumulate.Figure produced by University of Maine using FDA contaminationlevel data.Environmental Toxins - BioaccumulationEnvironmental Toxins - PBTs Some toxins do not breakdown inthe environment. These toxins move up through thefood chain and they accumulate. The Environmental ProtectionAgency has identified a numberof persistent, bioaccumulative,highly toxic chemicals it iscommitted to removing from theenvironment. These compounds pose a healthrisk to both humans andecosystems through food andwater. The top priority PBTs (persistent,bioaccumulative, toxins) areshown at right. Each level has a higherconcentration than the one below. Eventually humans consume afood which contains high levels ofa toxin such as mercury in tuna.4

2/14/2017Environmental Toxins - PBTsEnvironmental Toxins – PBTs (continued) Aldrin/Dieldrin – Insecticide –banned 1985. Benzo(a)pyrene – product ofincomplete combustion – exposeddue to fires, smoked foods, etc. Chlordane – Pesticide – banned 1988. DDT, DDP, DDE – Pesticides – banned1972. Hexachlorobenzene – pesticide –banned 1965. Alkyl-lead – fuel additive – bannedfrom automobiles but used in limitedcapacity (racing, marine, aircraft). Mercury – discussed on nextslides. Mirex – insecticide – banned1978. Octachlorstyrene – formed duringthe production of magnesium. PCBs – discussed on next slides. Dioxins and Furans – discussed onnext slides. Toxaphene – insecticide – banned1980.Environmental Toxins - MercuryLecture Note - Mercury Mercury is an element and it is used inthe production of many products: ChemicalsPharmaceuticalsSwitchesThermometersLight bulbs Once mercury enters the environment,microorganisms convert it tomethylmercury which is the highly toxicmercury that builds up in fish andshellfish. Exposure to methylmercury results inimpaired neurological development inthe fetus: Cognitive thinkingMemoryAttentionLanguageFine motor skillsVisual spatial skills Mercury is used in manypharmaceuticals as apreservative. Added to multi-use vials to preventthe growth of microorganisms. The form of mercury used in theseapplications is ethyl mercury (notmethylmercury).Thimerosal, the component used in vaccines that manybelieve causes autism despite studies demonstrating thatthis is not true.Methyl mercury Poisoning – Minamata DiseaseEnvironmental Toxins - PCBs Between 1932 and 1968, apetrochemical and plasticsmanufacturer dumped anestimated 27 tons of mercury inMinamata bay (Japan). PCBs are chlorinatedhydrocarbons that were used in100s of industrial and commercialapplications. PCBs are known to cause cancerin animals. PCBs were banned in 1979 in theUnited States but they do notbreakdown and can be found: Poisoning the fish and the peoplewho ate the fish. Over 900 deaths. Over 2 million people suffer(ed)chronic health problems. PCBs exert toxic effects on thefollowing body systems (inaddition to causing cancers): Immune systemEndocrine systemReproductive systemNervous system In the environment In wildlife tissues In the food chain.5

2/14/2017Environmental Toxins – Dioxins and Furans Refers to a family of toxicsubstances that have similarchemical structures. They are the byproducts ofindustrial processes or arecreating during burning: Burning of waste Burning of wood Health effects include thefollowing: Chloracne (below), and other skinconditions. Immune system damage Developmental damage Reproductive damage Cancer Found in the food chain in meatand dairy. Due to accumulation in theenvironment.Dioxin Poisoning – Yusho Disease In 1968 in Japan a number ofpatients were reported to havesymptoms including acne-likeeruptions, pigmentation of theskin, and eye discharge. The cause of the disease was laterfound to be rice oil (Yusho meansoil disease) contaminated withdioxin-related compounds. A total of 1961 people areregistered as yusho patients. Despite the knowledge gainedfrom this outbreak, the same thinghappened in Taiwan in 1979.Natural ToxinsNatural Toxins - Goitrogens A number of plants containnatural toxins. Goitrogens can cause enlargement ofthe thyroid gland by blocking theuptake of iodine. Found in very small amounts in alarge number of foods: Many of these toxins are designedto protect the plants from insectdamage. These toxins are not harmful ifingested in small amounts. The most common are: Goitrogens Cyanogens SolanineThese foods contain cyanogens. Tapioca could potentially kill you, justask Sheldon Cooper: https://www.youtube.com/watch?v JeLlLgI0U4Y CabbageBok choyTurnipsMustard greensKaleBrussels sproutsCauliflowerBroccoliKohlrabiRadishesNatural Toxins - CyanogensCyanogen Poisoning – Cassava - Konzo Some foods contain cyanogenswhich can convert to cyanide: Konzo disease is a neuromotordisease caused by exposure tocyanogen poisons in cassava. Apricot pitsPeach pitsApple seedsLima beansCassava Lima beans with low levels ofcyanogens are used in foods. Most people do not eat seeds (afew will not hurt you) and pits offruits. Altered gait Spastic movements Cognitive disorders Occurs when cassava is notprocessed properly to breakdown the cyanogens.6