When did lead become known as hazardous?

The recognition of lead as a hazardous material primarily solidified in the 19th century, particularly as the industrial revolution progressed. During this time, many health risks associated with lead exposure became more apparent, especially with its widespread use in paints, plumbing, and other products. Scientific research began to illustrate the toxic effects of lead on human health, leading to increased awareness and concern about its safety.

By the late 1800s, discussions around lead poisoning and its effects on workers and the general public began to emerge more prominently. This established a foundation for future regulations and guidelines. As a result, the 19th century is pivotal in the historical context of recognizing lead as a hazardous substance, making it the correct answer to the question.

Following this period, further scientific advancements and public health campaigns continued to highlight the dangers of lead, but the initial acknowledgment started much earlier, solidifying its hazardous status in public consciousness during the 1800s.