Chapter U4, Problem 6STP

Interpretation Introduction

Interpretation:

The lethal dose in milligrams for a $\text{132 lb}$ adult should be determined.

Concept introduction:

Conversion factor is ratio that is widely used to describe relation between two different units. In order to convert one unit into another, original unit is multiplied with proper conversion factor to yield new unit.

Answer to Problem 6STP

The correct option is (c), 27 g.

Explanation of Solution

The given value for LD₅₀ for lead toxicity is $\text{450 mg/kg}$.

Now, converting the weight of an adult from lb to kg using conversion factor:

$\text{1 lb = 0}\text{.453592 kg}$

The weight of adult is $\text{132 lb}$ so:

$\text{132 lb }\times \frac{\text{0}\text{.453592 kg}}{\text{1 lb}}=\text{ 5}9.87\text{ kg}$

Since, the LD₅₀ for lead toxicity is $\text{450 mg/kg}$ so, the LD₅₀ for lead toxicity for $\text{5}9.87\text{ kg}$ is:

$\text{450 }\frac{\text{mg}}{\text{kg}}\times \text{5}9.87\text{ kg = 26941}\text{.5 mg}$

Now, converting the amount from mg to g as:

$\text{26941}\text{.5 mg}\times \frac{1\text{ g}}{1000\text{ mg}}\text{ = 26}\text{.9 g }\simeq \text{ 27 g}$

Hence, the lethal dose in milligrams for a $\text{132 lb}$ adult 26941.5 mg which is equivalent to 27 g thus, option (c) is correct.