Final answer:
Children are more vulnerable to toxins due to higher metabolic rates and behaviors that increase exposure, which can result in more significant health issues relative to their size.
Step-by-step explanation:
Children are indeed more vulnerable to the effects of toxins because they have higher metabolic rates, which means they breathe more air, drink more water, and eat more food in proportion to their body weight when compared to adults. This leads to a greater dose of toxins relative to their size.
Additionally, certain behaviors typical of children, like putting objects in their mouth or playing close to the ground, can increase their exposure to toxins such as lead, which is particularly harmful to developing children and may lead to cognitive deficits and other health issues.