ScenarioIt is 1987 and a teenager has been left caring for a 2-year-old child while her parents go out for the evening. With the child settled for the night the teenager heads downstairs for a chat on the phone with her boyfriend. When she next heads upstairs to check, she finds the child is missing from his cot and the family dog is whimpering lying in a pool of what appears to be blood.Serology (6 marks)What test could you use in situ to determine if the substance really is blood? In your own words explain why? (2 mark)Are there any possible shortcomings of this test? In your own words explain why/ why not? (2) Back in the lab what else could you do to determine if the substance really is blood and whether or not it belongs to the missing child or the dog? Explain the basis of the test(s) (2)Scenario continuedOn the night the child was taken the first responders thought they could smell something funny on the breath of the babysitter and suggested she may have been intoxicated. A breathalyzer revealed a BAC of 0.03. The authorities requested further toxicological analysis to determine the condition of the carer on the night.Toxicology Results Consider the toxicology results from the table below. Toxicology Report Patient Id 24625431Report issued 8/8 1987 Age: 17 Y DOB 18/07/1970 Gender: femalePositive findingsCompoundResultUnitsMatrix SourceCaffeinePositiveMcg/mlBloodEthanol0Mg/dlBloodBlood alcohol concentration0.00g/100mlBloodOther than the above findings, examination of the specimens submitted did not reveal any positive findings of toxicological significance.Toxicology (12 marks)what do the findings suggest about the carers condition on the night? In your own words explain/justify your answer (2 marks)Other than the concentrations found - indicate 2 more things that would assist the toxicologist in interpretation of the anomaly between the breath reading and subsequent blood analysis and in your own words explain why? (4 marks)Discuss whether the initial blood alcohol concentration result is a false positive? In your answer you should explain this term and consider what may have impacted the results that should be taken into consideration by the toxicologist when considering this possibility. (4 marks) In your own words explain whether a hair sample might tell us anything that would assist in this case? why/why not? (2)
Question
ScenarioIt is 1987 and a teenager has been left caring for a 2-year-old child while her parents go out for the evening. With the child settled for the night the teenager heads downstairs for a chat on the phone with her boyfriend. When she next heads upstairs to check, she finds the child is missing from his cot and the family dog is whimpering lying in a pool of what appears to be blood.Serology (6 marks)What test could you use in situ to determine if the substance really is blood? In your own words explain why? (2 mark)Are there any possible shortcomings of this test? In your own words explain why/ why not? (2) Back in the lab what else could you do to determine if the substance really is blood and whether or not it belongs to the missing child or the dog? Explain the basis of the test(s) (2)Scenario continuedOn the night the child was taken the first responders thought they could smell something funny on the breath of the babysitter and suggested she may have been intoxicated. A breathalyzer revealed a BAC of 0.03. The authorities requested further toxicological analysis to determine the condition of the carer on the night.Toxicology Results Consider the toxicology results from the table below. Toxicology Report Patient Id 24625431Report issued 8/8 1987 Age: 17 Y DOB 18/07/1970 Gender: femalePositive findingsCompoundResultUnitsMatrix SourceCaffeinePositiveMcg/mlBloodEthanol0Mg/dlBloodBlood alcohol concentration0.00g/100mlBloodOther than the above findings, examination of the specimens submitted did not reveal any positive findings of toxicological significance.Toxicology (12 marks)what do the findings suggest about the carers condition on the night? In your own words explain/justify your answer (2 marks)Other than the concentrations found - indicate 2 more things that would assist the toxicologist in interpretation of the anomaly between the breath reading and subsequent blood analysis and in your own words explain why? (4 marks)Discuss whether the initial blood alcohol concentration result is a false positive? In your answer you should explain this term and consider what may have impacted the results that should be taken into consideration by the toxicologist when considering this possibility. (4 marks) In your own words explain whether a hair sample might tell us anything that would assist in this case? why/why not? (2)
Solution
Serology:
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The Kastle-Meyer test could be used in situ to determine if the substance is blood. This test is based on the peroxidase-like activity of hemoglobin in blood. A swab of the substance is taken, and phenolphthalein reagent is added. If the swab turns pink rapidly, it indicates the presence of blood. This test is quick, easy, and can be performed on site. (2 marks)
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The Kastle-Meyer test, however, is not without shortcomings. It is a presumptive test, meaning it can only suggest the presence of blood but not confirm it. It can also give false positives with other substances like vegetable peroxidases and metal ions. Furthermore, it cannot differentiate between human and animal blood. (2 marks)
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In the lab, a confirmatory test like the Takayama test could be used to confirm the presence of blood. This test is based on the formation of hemochromogen crystals when the blood is treated with a reagent. To determine if the blood belongs to the child or the dog, DNA profiling could be performed. This involves comparing the DNA from the blood sample with the DNA of the child and the dog. (2 marks)
Toxicology:
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The toxicology report suggests that the carer was not intoxicated on the night of the incident. The blood alcohol concentration is 0.00 g/100ml, which indicates no alcohol in the blood. However, the presence of caffeine suggests that she might have been awake and alert. (2 marks)
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The time of the last drink and the time the blood sample was taken would assist the toxicologist in interpreting the anomaly between the breath reading and the blood analysis. Alcohol is metabolized over time, so the blood alcohol concentration decreases with time. The type of breathalyzer used could also affect the results. Some breathalyzers can give false positives with substances like acetone. (4 marks)
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The initial blood alcohol concentration result could be a false positive, which means the test incorrectly indicated the presence of alcohol. Factors like the use of mouthwash, certain medications, or medical conditions like diabetes can cause false positives. The toxicologist should consider these factors when interpreting the results. (4 marks)
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A hair sample might provide information about the carer's substance use history. Substances like drugs and alcohol are incorporated into the hair as it grows, so they can be detected in hair samples even after they are no longer present in the body. However, this would not provide information about the carer's condition on the specific night of the incident. (2 marks)
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