The amount of lead in the blood and tissues, as well as the time course of exposure, determine toxicity. Lead poisoning may be acute (from intense exposure of short duration) or chronic (from repeat low-level exposure over a prolonged period), but the latter is much more common.
The COO is responsible for the daily operation of the company, and routinely reports to the highest ranking executive, usually the chief executive officer (CEO). The COO is usually the second in command at the firm, especially if the highest ranking executive is the Chairman and CEO.
However, the employer, or the chief executive, in any particular business usually determines the extent of the operations chief's oversight, no matter what title a company applies to the role. Larger companies usually refer to a director of operations as a COO. In either case, the job is usually an executive position, but the duties for the job vary widely. Such a position may be created, or eliminated, to fit the needs of a company as it grows or downsizes.