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Egg Sampling

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Which came first...the rotten chicken or the rotten egg? Make that bacteria-contaminated chicken or egg. Your challenge is to determine which chicken coop is producing eggs that are laden with excessive levels of bacteria. You'll need to create a sampling strategy and to test eggs to determine the presence of dangerous amounts of bacteria. The time is now, so get cracking.

Planning and Carrying Out Investigations

Egg Sampling Brochure

Egg Sampling Brochure

What is sampling?

Sampling is the analyzation of a small part of a population in such a manner that generalizations for the whole population can be drawn based on the results of the sampling group. For example, if a group of scientists wanted to know the average size of fish in a pond, they would measure the size of the fish in a sample of the population and use this data to estimate the average size of all the fish in the pond.

What are the dangers of contaminated chicken eggs?

Chicken eggs can sometimes be infected with Salmonella. If infected eggs are consumed raw, the consumer can be infected with Salmonella. Salmonella can cause nausea, vomiting, headache, and abdominal pain. These symptoms usually last 4 days to a week, and most people get better without needing medication.

How prevalent is chicken egg contamination?

There are 69 billion eggs produced in the United States every year. Of these, approximately 2.3 million are contaminated with Salmonella. This means that 1 in every 30,000 eggs produced in the U.S. is contaminated. Over 1 million people in the U.S. are infected with Salmonella every year. 142,000 of these cases are due to consuming contaminated eggs every year, and of these, approximately 30 people die every year.

How are chicken eggs contaminated?

Most chicken eggs that are contaminated are contaminated by the hen that lays the egg. If the hen that lays the egg has a bacterial infection, the infection can be passed on to the egg before it is laid. The health of the egg depends on the condition of the hen who laid the egg. If the hen lives in unsanitary conditions, there is a greater chance that the egg might be contaminated. If the hen lives in healthy conditions, the egg will most likely be healthy. Eggs can also be contaminated if they come in contact with the feces of an infected animal. Salmonella in the feces can penetrate the egg shell and reproduce inside the egg yolk.

What are some testing protocols for checking chicken eggs?

The FDA has put certain protocols in place to minimize the amount of contaminated eggs that reach the market. For example, every egg that is collected must be refrigerated at 45 degrees Fahrenheit within 36 hours of being laid. Chicken farmers may only buy chickens from suppliers who screen their birds for Salmonella. The farmers must monitor for pests and rodents that may be vectors of Salmonella and must test their chicken houses for Salmonella. If the tests come back positive, more tests must be taken over a period of 8 weeks. If any of these secondary tests are positive for Salmonella, the eggs must be processed so that the Salmonella bacteria is destroyed, or must be used for a non-food purpose. Any chicken house where Salmonella is found must be cleaned and disinfected.


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