What can be said about the toxicity of a substance?

The toxicity of a substance is highly dependent on both the specific chemical properties of that substance and the duration of exposure to it. Different substances interact with biological systems in varying ways, meaning that some may pose significant health hazards even at low concentrations, while others may be relatively harmless.

In addition, the length of exposure is a critical factor; short-term exposure to a toxic substance might not result in significant harm, whereas prolonged exposure could lead to cumulative toxic effects. This combined consideration of substance-specific characteristics and exposure duration helps to understand the overall risk associated with various chemicals.

The other choices do not adequately capture the complexity of toxicity. For instance, while toxicity can sometimes decrease over time as a substance degrades or is eliminated from an organism, this is not universally true for all substances. Similarly, the concentration of a toxic substance is directly related to its potential effects; higher concentrations typically equate to greater toxicity. Lastly, the assertion that toxicity is always the same for all substances overlooks the vast differences in how various chemicals affect living organisms.