Suggest a term - For Occupational Health Safety and Environment

Suggest a term here

Title: Lethal Dose

Description

Lethal Dose (LD) is the amount of a toxic substance that is sufficient to cause death in a test population of animals under controlled conditions. It is used to quantify the acute toxicity of chemicals. Lethal doses are typically expressed in milligrams of substance per kilogram of body weight (mg/kg).

<h2 class="wp-block-heading has--font-size">Explanation of the Term "Lethal Dose"</h2>

The term "Lethal Dose" is a general category that encompasses various specific measures, with LD50 being the most widely recognized. The concept is rooted in the dose-response relationship, which states that for any given substance, there's a relationship between the amount of exposure and the severity of the biological effect, including death.

The most common reference point is:

<ul class="wp-block-list">
<li>LD₀: the highest dose that results in no deaths</li>

<li>LD₁₀: The dose lethal to 10% of the test population. (Less commonly reported, but provides insight into the sensitive end of the population).</li>

<li>LD₅₀: the statistically derived dose expected to cause death in 50% of a defined group of experimental animals.</li>

<li>LD₁₀₀: the lowest dose that causes death in all animals tested.</li>
</ul>

Key aspects include:

<ul class="wp-block-list">
<li>Quantifying Toxicity: It provides a standardized way to compare the acute toxicity of different substances. A substance with a lower LD value is more toxic than one with a higher LD value, meaning a smaller quantity is deadly.</li>

<li>Route of Exposure: The lethal dose highly depends on how the substance enters the body. For example, a substance might be very toxic if ingested (oral LD) but less toxic if it comes into contact with the skin (dermal LD). This is why specific routes are always indicated (e.g., LD50 oral, LD50 dermal).</li>

<li>Acute Effects: Lethal Dose values typically characterize acute toxicity, meaning the effects that occur rapidly after a single, short-term exposure. They do not fully describe chronic toxicity (effects from long-term or repeated low-level exposures), carcinogenicity, mutagenicity, or reproductive toxicity.</li>

<li>Test Population: LD values are primarily derived from animal studies (e.g., rats, mice). While they provide crucial insights for human risk assessment, direct extrapolation to humans requires careful consideration due to species differences in metabolism and sensitivity.</li>

<li>Basis for Hazard Classification: Lethal Dose values are foundational for classifying chemicals according to their acute toxicity under systems like the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). This classification directly influences product labeling, Safety Data Sheets (SDSs), and the safety precautions required for handling.</li>
</ul>

The shape and slope of the dose-response curve are also critical. A steep curve indicates that even small increases in dose may lead to a dramatic increase in fatalities, signaling a narrow margin of safety. Conversely, a gradual slope suggests a wider safety margin.

<figure class="wp-block-kadence-image kb-image4449_58e991-fa size-large"><img src="https://safetypedia.com/wp-content/uploads/2025/05/dose-response-relationship-1024x534.png" alt="A white background chart titled &quot;Dose-Response Curve for M. latifii Venom in 33g Mice.&quot; The X-axis is labeled &quot;Dose (µg per mouse)&quot; and ranges from 0 to 100. The Y-axis is labeled &quot;Mortality (%)&quot; and ranges from 0 to 100. A blue S-shaped curve represents the dose-response relationship. The curve remains flat at 0% mortality from 0 up to approximately 15 µg per mouse. It then sharply increases, passing through 50% mortality around 27.72 µg per mouse, and flattens out again at 100% mortality from approximately 40 µg per mouse onwards. Three vertical dashed lines highlight key lethal doses: - A green dashed line at approximately 15.18 µg per mouse, labeled &quot;LD0 = 15.18&quot;. This line intersects the blue curve at 0% mortality. - An orange dashed line at approximately 27.72 µg per mouse, with an orange point on the curve, labeled &quot;LD50 = 27.72&quot;. This line intersects the blue curve at 50% mortality. - A black dashed line at approximately 80.19 µg per mouse, with a black square point on the curve, labeled &quot;LD100 = 80.19&quot;. This line intersects the blue curve at 100% mortality. A legend at the bottom right explains the data points: &quot;LD0: No mortality dose&quot;, &quot;LD50: Median lethal dose&quot;, &quot;LD100: Fully lethal dose.&quot;" class="kb-img wp-image-4483"/></figure>

It’s important to note that while LD₅₀ identifies the dose that kills half the population, it does not imply the surviving 50% remain unharmed—they may still suffer serious non-lethal effects.

<h2 class="wp-block-heading has--font-size">Example:</h2>

Suppose laboratory rats are given increasing doses of a pesticide:

<ul class="wp-block-list">
<li>At 50 mg/kg, no deaths occur → this may be the LD₀.</li>

<li>At 150 mg/kg, 50% of the rats die → this is the LD₅₀.</li>

<li>At 300 mg/kg, all rats die → this is the LD₁₀₀.</li>
</ul>

Comments

Name

0...

Dashboard

You need to be logged in