Final answer:
Essential trace elements like chromium and zinc can become toxic at high concentrations. While necessary for health at low levels, excessive amounts can lead to toxicity, as the dose makes the poison. Elements like lead and mercury can also accumulate in the body and cause serious health issues.
Step-by-step explanation:
Essential trace elements such as chromium and zinc can become toxic if encountered at high concentrations. An optimal level of these trace elements is necessary for various bodily functions, but if the dietary intake is too high, the body must be able to limit its absorption to prevent toxicity. For instance, cobalt is necessary in our body at a concentration of about 21 ppb, which is contrasted against the State of Oregon's limit of arsenic in fertilizers at 9 ppm, showing the narrow range between beneficial and harmful concentrations.
Furthermore, inorganic substances such as lead, cadmium, and mercury are examples of elements that can be dangerous at high concentrations, often a result of industrial activities or pollution. They are known for their capability to accumulate in the body and lead to negative health effects, such as cognitive deficits and coordination problems. Even essential elements can become dangerous when their levels exceed certain thresholds; it's the dosage of these substances that can make them harmful.