Residential heating by wood or coal or peat, without comprehensive understanding of ventilation.
Horse-drawn vehicles in urban centers. Waste disposal was an issue, and dust...
Inconsistent -- at best -- food quality monitoring. Example:
Swill Milk Scandal (1850s) (Wikipedia). Upton Sinclair's
The Jungle was published in 1906, and in response the organization that would become the US Food and Drug Administration was created later that year.
Lead leaching from pewter dishes and utensils (newer pewter alloys no longer contain lead; I'm having difficulty seeing when this transition occurred).
Lead leaching from pipes.
Paint.
And so on. Look back at all the cool toys from back in the 1950s and 1960s that were later banned for safety reasons, and marvel that we all survived. Now imagine all the stuff that
wasn't banned before then because there wasn't the regulatory structure in place to do that...