Animal studies involving the class of chemicals have shown that concentrations in the air reaching into the tens of thousands are fatal.

Source: https://www.dailymail.co.uk/health/article-12801119/Extremely-alarming-study-finds-common-hair-styling-products-release-high-levels-toxic-chemicals-linked-infertility-used-straighteners-curling-irons.html?ns_mchannel=rss&ns_campaign=1490&ito=1490

Animal studies years ago hinted at atropine’s ability to slow the growth of the eye, but the full-strength drug’s interference with near vision and concerns about pupil dilation hindered early considerations of its potential as a human therapy for myopia.

Source: https://www.canindia.com/eye-drops-slow-nearsightedness-progression-in-kids-study/