What is the stated lethal daily dose of lead?

• A. 0.5 mg/day
• B. 0.5 g/day
• C. 5 mg/day
• D. 50 g/day

Answer: (B)

Lead toxicity is dose-dependent and accumulative. When we talk about a stated lethal daily dose, we’re referring to the amount of lead that, if swallowed every day, would be fatal for an average adult. Lead disrupts several key bodily systems, notably the nervous system and heme synthesis, and a daily intake around 0.5 grams would overwhelm the body's ability to detoxify and store the metal, leading to rapid and severe toxicity that can be fatal. Much smaller daily amounts can cause harm over time, but they are unlikely to produce an immediate death. Very large amounts, like tens of grams per day, are far beyond typical physiological relevance. So 0.5 g per day is the figure commonly cited as the lethal daily dose.