Hair loss can also be caused by rarer issues, such as poisoning. Two of the most common causes of accidental poisoning are lead and arsenic poisoning, both of which cause hair loss. The reason these types of poisoning are so common is because lead and arsenic were extremely common in household products and decorations in decades past.

Lead was a common component in household paint until 1978, when its use began to be regulated by the US government; consequently, anyone living in a house that was built prior to the 1978 regulation likely has lead paint currently in their home. Lead poisoning via lead plumbing pipes (still in use) can also cause hair loss, and as we know from the Flint Water Crisis, a lot worse.
Be an educated citizen and learn about the lead in the water levels where you live, and take precautions if lead levels are above what is considered “safe” or “background”, like drinking bottled water or water that has been filtered with special filters that get rid of lead.
As for lead-based house paint, call in a professional to get your home tested. They can also recommend the steps you need to take to eliminate the lead issue, should your home be contaminated.
While the dangers of lead-based paint and piping are well-known here in the US, arsenic is a more elusive danger that can lead to chronic poisoning that results in hair loss or even death in the most extreme cases.
Arsenic was easily obtainable as a rat poison as late as the 1920s (hence it being a plot point of many murder mysteries of the era). In the 1700’s and 1800’s, arsenic was a common ingredient in certain paint pigments. Scheele’s Green, a yellow-green arsenic-containing pigment was first produced in 1775. In 1814, what was considered to be an improved version was created—also containing arsenic—commonly called Paris Green or Emerald Green.

Both of these arsenic-green pigments were tremendously popular throughout the 1800’s in particular, despite the fact that the chemist Leopold Gmelin had figured out as early as 1815 (a year after its introduction) that Paris Green was causing poison arsine gas to leak into the environment, sickening and even killing people, according to Jane Austen’s Word’s blog post about the deadly green pigment. Paris Green was super popular as both a wallpaper color and a paint color. Even medical journals of the nineteenth century noted that people were getting sick and dying in green rooms. Despite chemists, doctors and scientists trying to educate the public about Paris Green’s dangers, nobody listened; they were even coloring cake with it by that point, and children and pigment-makers were dying left and right as a result.
The reason chronic lead and arsenic poisoning are such an important topic to bring up when talking about the causes of hair loss is the simple fact that while it doesn’t apply to most people reading this article, it does apply to anyone who lives or works in an old building, as they could be currently exposed to lead or arsenic paints, which chip away as they age, resulting not only in hair loss, but severe health concerns.
A famous example of this is the case of US Ambassador to Italy during the mid-1950’s, Clare Boothe Luce, a very capable and prominent politician, playwright and diplomat who was physically and mentally sickened by chronic arsenic poisoning caused by arsenic-laden paint chips falling on her while she slept and ate. The villa in question and surrounding circumstances are described in this 1956 article from Time Magazine. She survived, but the chronic poisoning was debilitating at the time she was going through it, which drives home the point that you should always have a professional check old homes and workplaces for lead and arsenic, whether you’re losing your hair or not, just as a general safety precaution.