Pros And Cons Of Food Irradiation University Essay Example

The world faces the problem of global starvation; this issue has spread to millions all around the globe. Efforts to solve the problem have been proven ineffectual. However, scientists have discovered nuclear chemistry may be the answer to the crisis of world hunger. The specific method elongates the freshness of produce and other foods by utilizing ionizing radiation. Shortwaves damage the microorganisms that accelerate the rate of food spoilage. Food irradiation has remedied the scarcity of food but it might cause more harm than good.

The application of nuclear chemistry enables the world to preserve produce, meats and dairy products for a longer period of time while keeping the same quality and taste. Gamma rays destroy the majority of bacteria and fungi in the food to sanitize the product of germs, making it safe for patients in the hospital to consume because they need to be surrounded by a sterile environment. Now, irradiation can revolutionize the food industry; it has already been approved in 37 countries for more than 40 products because it drastically increases the shelf-life of foods. Hence, irradiated fruits can be exported on a commercial scale therefore raising the country’s economy. It also guarantees the sustenance of small farms and businesses. Food irradiation does good for the whole but it is not necessarily do the same for the individual.

The preservation of food has its benefits but it does have costs. Gamma rays change the chemical makeup of the item therefore creating radiolytic products. Radiation rearranges the molecular structure hence new substances are produced. There has been no evidence proving the radiolytic products to be harmful; in general the health affects are unknown.

What is known is that gamma rays are dangerous and perilously harmful. The containment and transportation of the radioactive substances are fairly secure. However, environmentalists fear the environment may be at risk of exposure. Plant and animal tissue are vulnerable to deterioration when gamma rays are released because the radiation is extremely destructive. The majority of consumers worry about food irradiation, but not for environmental reasons.

The word nuclear sends fear through most people; it triggers an image chaos and destruction. Consumers have difficulty accepting food irridiation because it is derived from nuclear chemistry since nuclear chemistry is also responsible for the atom bomb which caused millions of casualties. People have judged radiation too rashly; they need to learn the facts first. After being fully informed people can finally make a stance on food irradiation.

The Effect Of Antibacterial Toothpastes On Micrococcus Luteus

Preliminary work revealed that both toothpastes have an antibacterial effect on Micrococcus luteus. According to the preliminary study, the zone of inhibition of blend-a-med was slightly bigger than Colgate’s. Therefore the antibacterial effect of blend-a-med is greater than Colgate’s.

Both toothpastes contain an antimicrobial ingredient Triclosan which kills many harmful bacteria. Triclosan ultimately results in a breakdown or failure in the bacteria’s cell wall. Cell wall failure affects bacteria’s most vital survival processes including uptake of nutrients, inhibition of amino acid incorporation, inhibition of uracil incorporation, as well as causing membrane lysis.

The antibacterial effect of toothpastes is an important factor for evaluating the benefits it has on health but it should also be considered that Triclosan and Fluoride might potentially be harmful to the user when taken in large quantities.

The preliminary study also revealed that the toothpaste should be mixed with water, so that it would be well transferrable with a pipette.

(It should also be mentioned that the toothpaste which is sold under the name of “blend-a-med” in some of the European countries, is known as “Crest” in the United Kingdom.)

Independent variable  The type of toothpaste used in the agar plates filled with M. luteus. – “Colgate Total” and “blend-a-med + eucalyptus”

Dependent variable Zone of inhibition on the M.luteus around the toothpaste in millimetres. The zone of inhibition is measured using digital callipers.

Control of variables

  • The volumes of toothpaste are controlled by using a cylinder to cut out pieces of the agar
  • The volume of agar in plates was measured and the same amount of agar was put in each plate (by a professional)
  • The bacteria in each plate was distributed equally (this was controlled by a professional).
  • The temperature of the plates was maintained during the investigation by keeping the plates in an incubator.

Safety issues

Although M. luteus is non-pathogenic and usually regarded as a contaminant, it should be considered as an emerging nosocomial pathogen in immunocompromised patients. The bacteria should not be exposed to people. A lab coat and glasses should be worn to avoid the bacteria getting into the eye or on the skin. Hands should be washed after handling the agar plates. The working area should be cleaned after the experiment.

Environmental impact

The experiment does not have a significantly negative impact on the environment. . The bacteria should be sterilised to make safe after the experiment, so that it would not be in direct contact with living organisms. The agar plates and the pipettes can be recycled and reused. “Colgate” has been extensively tested and is environmentally safe55. The environmental impact of the toothpaste “blend-a-med” is unknown.


Both products – “Colgate Total” and “blend-a-med”- note on their packages that they contain Triclosan. “Colgate Total” has 0.3% of Triclosan6 and the exact As Triclosan is a toxic substance, both products should use about the same amount of Triclosan in the product. However neither one of the two published info about the amount of Triclosan on their web-page and the exact numbers are unknown.

How data should be recorded?

Two diameters should be considered in the calculation since this gives more accurate results in calculating the difference between the two sets of data and also the variation within one set of data.

Data should be recorded in a data table, so that the exact numbers of recorded data are presented.

Standard deviation should also be calculated as this shows the variation around the mean value of data.

There will be at least 15 replicates of the experiment and the Student t-test will be used to compare the results of two sets of data and see whether there is a statistical difference between the data.

Data should also be represented on a bar chart as the results are not continuous and it would show the different results of the two toothpastes very clearly.

List of apparatus

  • Mounted needle
  •  Marker pencil
  • Ready-made 20 agar plates with Micrococcus luteus
  • Digital caliper
  • Bunsen burner
  • Blend-a-med + eucalypt toothpaste – 10 ml
  • Colgate Total toothpaste – 10ml
  • Cork borer – diameter 0,5 cm
  • Two measuring cylinders – 25 ml
  • 5 sterile pipettes
  • An incubator
  • Sterile distilled water – 20 ml


  • Draw a plan to work out how many samples it is possible to fit in each plate. Taking the inhibition zones of the preliminary study into account, I decided to put four samples in each plate.
  • Label the agar plates with the symbols “B” and “C” to distinguish the types of toothpaste in each plate. There should be an equal amount of samples of both toothpastes.
  • Sterilise the working area with an antibacterial wipe and wash your hands before handling the agar plates.
  •  Turn on the Bunsen burner. The flame will create updraft and it avoids bacteria falling on the plate.
  • Sterilise the cork borer in the flame.
  • Wait until the cork borer is not hot – otherwise it will melt the agar.
  •  Cut uniform ‘wells’ in the agar plate with the cork borer.
  • If necessary, use the mounted needle to pull the cut piece out.
  • Mix both toothpastes with an equal amount of sterile distilled water in the measuring cylinder.
  • Use the pipette to transfer the two mixtures into the agar plates.
  • Change the pipette after every four plates to guarantee that the pipette is not contaminated with bacteria.
  • Repeat the procedure with each agar plate.
  • Tape all the plates up to avoid other bacteria contaminating the samples.
  • Leave the plates in an incubator at 30 degrees for 24 hours.
  • Measure the zones of inhibition so that two diameters will be recorded with the digital measurer

A test plate was set up which contained sterile distilled water instead of toothpaste and there was no zone of inhibition. This means that both toothpastes have an antibacterial effect and as a result the graph presents areas which are produced by the toothpaste alone.


“Blend-a-med” created on average 5 mm bigger inhibition zones than “Colgate”(also shown on the graph). This suggests that “blend-a-med” contains more of the antimicrobial ingredient Triclosan and the antibacterial effect of “blend-a-med” is stronger antibacterial effect on Micrococcus luteus than “Colgate.”

Evaluation of method

The data tackle reveals that both toothpastes had larger inhibition zones in the same test plates (shown on the raw data). This is probably due to having a smaller amount of bacteria in a certain agar plate or less agar in the agar plate. The results would have been more precise if all of the test plates would contain exactly the same amount of bacteria and also the same amount of agar. However, this does not influence the difference in the effect of the toothpastes.

The amount of water which was added to the toothpaste was not measured very precisely. This might have resulted in having a smaller concentration of Triclosan in the toothpaste. According to the preliminary study and the hypothesis, both toothpastes should have had about the same sized inhibition zones. The reason why my practical did not reflect the same result might have been that “Colgate” had larger water to toothpaste ratio.

I had difficulties with accurately filling the well due to viscosity. Several times the toothpaste came out unevenly and there was not the same volume of toothpaste in each sample. I recorded the results only from the samples where there was no overspill.

I observed that each time “blend-a-med” had spilled over the edge of the ‘well’, the inhibition zone had changed severely while each time “Colgate” has spilled over the edge, the inhibition zone was as big as it was with samples, which had not spilled. This indicates that the concentration of Triclosan was bigger in the samples of “blend-a-med.”

Evaluation of data

The standard deviation  shows that the inhibition zones of “Colgate” are more accurate than the inhibition zones of “blend-a-med.” The reason for this might be that the concentration of Triclosan is larger in the samples of “blend-a-med” and the inhibition zones respond more to the toothpaste that was spilled over the specific area.

A sufficient number of repeats were made and every repeat indicated that the inhibition zone of “blend-a-med” is bigger than the inhibition zone of “Colgate.” The mean values and the Student-T test also indicated that there was significant difference between the two sets of data. Therefore the conclusion is reliable.

Procedure weaknesses

The concentration of water in either toothpaste may not have been the same. Therefore the concentration of the samples was not the same. This weakness can be improved by not using water in the test or by measuring the exact volume of the toothpaste and mixing it with the same volume of water.

The application of the toothpaste can be done more carefully by squeezing the pipette from the part which is closest to the plate.

The amount of bacteria put on each plate can be measured more precisely with a pipette

The amount of agar in each plate can be measured more precisely by using a measuring cylinder.

To apply toothpaste to the plate by a pipette, it is necessary to mix toothpaste with water. The density of the toothpaste is very different from the density of water and the mixture will not be uniform. Therefore the concentration of toothpaste depends on the depth from which the sample is taken. The problem can be improved by mixing the solution continuously to get a uniform solution.


  1. Iaconis, Michele, “How It Works”, Ciba, 24.05.2010,
  2. “Triclosan Poses New Danger”, Nutriteam, 27.05.2010,
  3. (further citation needed))
  4. “Micrococcus Luteus”, Citizendium,
  5. “Colgate Total Advanced Clean Toothpaste”, Colgate,

Butane Molar Mass Lab


Butane is a colorless gas with the molecular formula of C6H10 and is considered to be an Alkane. An Alkane is when the compound is formed by single bonds connecting the carbons and hydrogens. Butane was discovered by Dr. Walter Snellings in Pittsburg and he gas is used for cigarette lighters, heaters, stove fuels, and other heating appliances. The accepted value for the molar mass of butane is 58.124 g/mol.

We tested the accepted value by calculating the molar mass of butane in a butane cigarette lighter. We took a beaker, and submerged it into water. Then we measured the mass of the cigarette lighter, and then slowly released butane gas bubbles into the beaker so that the bubbles collected at the top, where there was no air. We recorded the initial volume of water, then equalized the pressure inside and outside the beaker until the water levels inside and outside the beaker were the same. Then we recorded the final volume of water, and repeated the experiment until we had three trials. We concluded that the molar mass of butane can be determined through the average of repeated trials of the experiment were no systematic or random errors occur.



Determining the molar mass of butane through experimentation is possible with multiple trials. The more trials completed, the closer the average molar mass of butane is to the accepted value of the molar mass of butane. To determine the molar mass, take the mass of butane in the beaker and divide that by the number of moles of butane. Then determine the pressure of butane, volume of displaced water, and temperature of the water/butane gas. Once pressure, moles, volume, and temperature have been determined, plug the values into the ideal gas law equation, PV=nrT, to determine moles. Molar mass is grams / moles, so take the mass / moles. The accepted value of molar mass of butane is 58.124 g/mol, and our average calculated value of the mass of butane is 56.57g/mol.


A random error is caused by variability in samples. It can vary between trials of an experiment, and it commonly defined as the deviation from the true accepted value. A random error can be solved by repetition of the experiment. A random error that occurred in this lab is that when the lighter was put under water to release butane into the beaker, water went into the lighter. When the lighter was weighed for the next trial, the weight was slightly off due to the existing water inside the lighter. A systematic error is an error caused by a variation in samples. Systematic errors usually occur from faulty equipment. Repetition does not solve systematic errors, and the value is referred to as a bias or the deviation from the true value.

A possible systematic error that may have occurred in this lab is that the butane from the lighter may have contained air or a substance other than butane in the lighter, skewing the measured amount of butane gas collected at the top of the beaker. Another systematic error was that if the beaker was even slightly cracked at the top, allowing air to enter the beaker, the value of molar mass would change because the gas collected at the top of the beaker would no longer be strictly butane. Another systematic error that could have occurred is that the ambient room pressure was taken from a website dictating the pressure in the area, rather than directly in our room. The measurements in the lab are reliable taking into consideration the equipment windows of error and there are few to no flaws and weaknesses in the procedure itself.


The experiment could have been improved by measure the atmospheric pressure directly in the room, obtaining a more accurate room pressure to ensure that the pressure of butane was calculated correctly. Other improvements may include more accurate equipment such as a balance, beaker, and thermometer. Also, the butane used in the experiment could have been certified as pure butane, rather than butane from a common lighter.


“Cornellbiochem – Butane.” Cornellbiochem – home. Web. 08 Nov. 2009.

Brown, Theodore L., H. Eugene LeMay Jr., Bruce E. Bursten, and Catherine J. Murphy. Chemistry The

Central Science; AP Edition. 10th ed. Upper Saddle River: Prentice Hall College Div, 2005. Print.

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