Toxicology: ethanol and drunk driving: practice question

A Forensic Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Forensic Medicine · Toxicology: ethanol and drunk driving

Sample item

A driver's blood alcohol is 40 mg/100 mL, measured 4 hours after a collision. If ethanol is eliminated at about 15 mg/100 mL per hour, what was the approximate level at the time of the collision?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. About 100 mg/100 mL

Back-extrapolation by the Widmark principle adds elimination over the interval to the measured level: 40 plus 4 hours times 15 equals 100 mg/100 mL. This exceeds the legal limit of 30 mg/100 mL under the Motor Vehicles Act. The estimate has limits because rates vary between individuals.

Option by option

  • A. About 160 mg/100 mL

    This overshoots by assuming a far higher rate.

  • B. About 100 mg/100 mL (correct)

    Adding 60 mg for four hours of elimination gives about 100.

  • C. About 55 mg/100 mL

    This adds only one hour of elimination.

  • D. About 40 mg/100 mL

    This ignores elimination altogether.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is B, About 100 mg/100 mL. Back-extrapolation by the Widmark principle adds elimination over the interval to the measured level: 40 plus 4 hours times 15 equals 100 mg/100 mL.

Why is "About 160 mg/100 mL" not the answer?

This overshoots by assuming a far higher rate.

Why is "About 55 mg/100 mL" not the answer?

This adds only one hour of elimination.

Why is "About 40 mg/100 mL" not the answer?

This ignores elimination altogether.

What concept does this question test?

It tests Toxicology: ethanol and drunk driving in Forensic Medicine. This exceeds the legal limit of 30 mg/100 mL under the Motor Vehicles Act. The estimate has limits because rates vary between individuals.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Toxicology: ethanol and drunk driving?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.