Meat Safety

Objectives:

(1) To describe various codes and definitions regarding meat safety.
(2) To give an overview of some general microbiological, parasitic and protozoan problems in the food and water supply.
(3) To discuss chemical residues in meat.

Reading material: Principles of Meat Science (4th ed.), Chapter 8, pages 155 to 177.

Food safety deals with preventing or minimizing biological, chemical and physical contaminants. This lecture will give a very brief overview of some of the factors involved in food safety.

Codex Hygienic Practices

"Safe and wholesome" refers to meat that has been passed as fit for human consumption using the criteria that it:

will not cause food borne infection or intoxication when properly handled and prepared with respect to the intended use;
does not contain residues in excess of established Codex limits;
is free of obvious contamination;
is free of defects that are generally recognized as objectionable to consumers;
has been produced under adequate hygiene control; and
has not been treated with illegal substances as specified in relevant national legislation.

Risk Analysis

Hazard: A biological, chemical or physical agent or property that may cause a food to be unsafe for consumption, or aesthetically unacceptable to the consumer.
Risk: A function of the probability of an adverse event and the magnitude of that event, consequential to a hazard(s) in food.
Risk Analysis: A process consisting of three components; risk assessment, risk management, and risk communication.
Risk Assessment: A scientific process of identifying hazards, and estimating risk in qualitative or quantitative terms. This involves four analytical steps:

Hazard identification. The qualitative indication that a hazard(s) could be present in a particular food.
Hazard characterization. The quantitative and/or qualitative evaluation of the nature of the adverse effects which may include a dose-response assessment (defined as the determination of the relationship between the magnitude of exposure and adverse effects).
Exposure characterization. The qualitative and/or quantitative evaluation of the degree of human exposure likely to occur.
Risk characterization. Integration of the above steps into an estimation of the adverse effects likely to occur in a given population, including attendent uncertainty.

Risk Assessment Policy: Pre-determined guidelines for scientific judgments and policy choices which may be applied at specific decision points in the risk assessment process.
Risk Management: The process of weighing policy alternatives, selecting an appropriate regulatory option, and implementing that option.
Risk Communication: An interactive process of exchange of information and opinion on risk among risk assessors, risk managers, and stakeholders.

Bacterial Foodborne Illness

Escherichia coli diarrhea

Escherichia coli O157:H7 was isolated in 0.39% (range 0.07% to 2.13%) of diarrheal stools in a multicenter survey conducted during 1990 to 1992 -- isolation rates were 0.13% in the South and 0.57% in the North. The true national incidence is estimated at 725,000 per year, with 100 to 200 fatalities.
A major outbreak of hemorrhagic colitis involving 501 cases (151 hospitalized, 4 fatal) in Washington State during 1992 to 1993 was traced to hamburger.
E. coli O157:H7 is a leading cause of bloody diarrhea and of childhood renal failure in this country. 204 children below age 5 died of E. coli diarrhea during 1968 to 1991.

Listeriosis

The disease if found nationwide, and accounts for 2% to 3% of bacterial meningitis episodes.
The estimated incidence was 1,965 in 1989 (481 fatal) and 1,092 in 1993 (248 fatal).
An outbreak in California in 1985 involving 142 cases (48 fatal, 93 perinatal) was traced to contaminated soft cheese.

Salmonellosis

548,017 cases were reported during 1944 to 1983 (rates increasing from 5 to 20/100,000 during this period); 48,603 cases in 1990; 48,154 in 1991; 40,912 in 1992; 41,641 in 1993; 43,323 in 1994; 45,970 in 1995 (the 4th leading reporting infectious disease that year). The true incidence is 2 million cases (500 to 2,000 fatal cases) per year.
During the 1990s, Salmonella enteritidis was the most common human pathogen, followed by S. typhimurium and S. heidelberg. S. enteritidis accounted for 5% of isolates in 1976, 26% in 1994 and 25% in 1995.
S. typhimurium accounted for most human infections during the early 1960s, and less than 20% during the 1990s. Salmonella serotype Typhimurium Definitive Type 104 (DT 104) has been emerging as a significant pathogen since the first outbreak (Nebraska) was reported in 1996.

Parasitic and Protozoan safety concerns

Condition	Technical name	Transmission	Disease in man
Cryptosporidiosis	Cryptosporidium, a protozoan.	Some evidence of animals with diarrhea transmitting to humans. Large outbreak in Milwaukee in early 1990s caused by untreated drinking water. Also, human to human transmission has been reported.	Cryptosporidiosis in immunodeficient persons or those undergoing immunosuppressant therapy is a severe disease, with chronic and persistent diarrhea and malabsorption that can result in death. This protozoosis can be an important contributing factor in AIDS mortality.
Taeniasis and Cysticercosis	The cestodes Taenia solium and T. Saginata and their respective larval stages Cysticercus cellulosae and C. bovis.	The definitive host of both taeniae is man, whose small intestine they lodge. The intermediate hosts of T. solium are the domestic pig and wild boar and of T. saginata are cattle. Human infection comes from eating raw or insufficiently cooked meat.	Taeniasis by T. saginata is often subclinical and is only revealed by fecal examination. Clinical symptoms consist of abdominal pains, nausea, debility, weight loss, flatulence, and diarrhea or constipation. Taeniasis by T. solium is rarer. Cysticercosis is a much more serious disease. Common problems include neurocysticercosis (central nervous system) and ocular and periocular (eye and its surrounding tissue).
Toxoplasmosis	Toxoplasma gondii, a protozoan.	Cats are both definitive and intermediate hosts. Cats become infected by eating raw meat, birds, or mice containing encysted bradyzoites. Man becomes infected by consuming raw or insufficiently cooked meat, primarily from sheep, swine, and, in some places, goats.	The infection is usually subclinical. Symptomatic toxoplasmosis can be congenital or acquired postnatally. More cases are now seen in patients with immune system defects or those who are receiving immunosuppressive treatment and usually is fatal. Encephalititis is the very common in immunocompromised persons and is a frequent cause of death.
Trichinosis	Trichinella spiralis, a small filiform nematode.	When a carnivore or omnivore ingests meat containing the encapsulated infective larva, the larva frees itself in the stomach from both the capsule and the muscle tissue; it then lodges in the villi and glandular crypts of the small intestine where it continues its development, reaching the adult stage in 2 to 3 days.	Only a small proportion of infections are manifested clinically. Symptomatic cases result from the ingestion of a large number of larvae. Many sporadic cases pass unnoticed or are confused with other diseases because of the variability of the symptoms.

Source: Acha, Pedro N., and Boris Szyfres. 1991. Zoonoses and Communicable Diseases Common to Man and Animals (Second Edition). Scientific Publication No. 503, Pan American Health Organization, World Health Organization, Washington, DC.

Drug and Chemical Residues in Animals and Meat

Compound	Description
Antibiotics	Chlortetracycline, erythromycin, gentamicin, neomycin, oxytetracycline, penicillins, streptomycin, tetracycline, and tylosin. Calf Antibiotic and Sulfonamides Test (CAST): 111,833 sampled, 2,021 violative; Swab Test on Premises (STOP): 124,461 sampled, 2,206 violative.
Sulfonamides	Sulfachloropyrazine, sulfachloropyridazine, sulfadimethoxine, sulfaethoxypyridazine, sulamethazine, and sulfathiazole. Sulfa-on-Site (SOS): 105,091 sampled, 232 violative.
Arsenic	Used in food-producing animals primarily as growth promoters and to prevent bacterial enteritis. Four violations out of 1,140 monitoring samples.
Benzimidazoles	Dewormers including thiabendazole. No violations.
Carbadox	Used to treat enteritis and for feed efficiency in lightweight swine. No violations.
Carbamates	Systemic insecticides and acaricides, but also are used extensively as soild treatments and as topical and knockdown agents for ectoparasites and other pests. No violations were found.
Chlorinated hydrocarbons & organophosphates	Potent insecticides, many of which, such as DDT, are no longer marketed. Seven violative animals were found among horses, calves, lambs, goats, and market hogs. Dieldrin and DDT accounted for five of the eight violative residues.
Clenbuterol	Beta agonist used in some other countries to treat respiratory conditions in race horses and to prevent premature uterine contractions in pregnant cattle. May be used illegally in livestock shows to increase muscle.
Diethylstilbesterol (DES)	Banned from use in 1979 when it was linked to cancer in humans. Growth promoting agent. No violative residues.
Halofuginone	Prevents coccidiosis, a serious and potentially fatal parasitic infection that spreads among chickens and turkeys. One violative residue from 612 samples.
Ivermectin	Most widely sold animal drug in the U.S. Six of 3,253 samples were found to be violative.
Pyrethrins	Insecticides widely used because of their low toxicity for mammals. No violations.
Zeranol	Estrogenic compound used to increase feed efficiency and promote weight gain in livestock. No violations.

Source: 1992 Domestic Residue Data Book, USDA

Dioxin and meat

Dioxin is a general term used to describe a class of 210 different chlorine containing compounds that are by-products in numerous industrial processes and are formed during the combustion of chemical and municipal wastes.
Although dioxins are never produced intentionally, the Environmental Protection Agency (EPA) strickly regulates unintentional dioxin emissions into the environment because of their extremely toxid nature. Many researchers have labeled dioxin the most fatal chemical known to man.
Dioxin has been found in virtually every component of the global ecosystem -- including air, water, fish, wildlife, and human tissues. They are highly fat soluble chemicals that persist in the environment and often bioaccumulate in the fats of animals.
The amount of dioxin in the environment is very small, but because human exposure is measured in parts per trillion (or equivalent to one second in thirty-two thousand years), it does not take large emissions to draw national attention.
Despite the fact that animal products have been linked with the majority of dioxin exposure for humans, current estimates place American exposure to dioxin at 108 picograms per day, or approximately 15% of the World Health Organization's tolerable limit.
Current recommendations concerning limiting dioxin exposure are to eat a variety of foods and to limit intake to recommended levels.

Links to related sites on the Internet

Morbidity & Mortality Weekly Report
Fight BAC!(TM) Partnership for Food Safety Education
National Food Safety Initiative
FDA Center for Food Safety and Applied Nutrition
USDA, Food Safety and Inspection Service