Final answer:
True. As the concentration of a toxin increases, the period of time between exposure and onset of symptoms usually decreases.
Step-by-step explanation:
True. As the concentration of a toxin increases, the period of time between exposure and onset of symptoms usually decreases. This is because higher concentrations of toxins can overwhelm the body's defense mechanisms and lead to more immediate symptoms. For example, a high concentration of a neurotoxin can quickly disrupt the nervous system and cause symptoms like paralysis or seizures.