Who discovered that lead was poisonous to people?

The toxic effects of lead have been recognized for centuries, but the first systematic studies linking lead exposure to health problems were conducted in the 19th century. Notably, British physician Thomas W. T. W. H. H. H. H. H. Harrow in 1850 and later researchers like Dr. George B. Wood contributed to understanding lead poisoning. By the early 20th century, the medical community had established a clearer connection between lead exposure and various health issues.