Though I know it seems that way, some are more horrible than others. In most countries’ organic farming, pyrethrin- and citronella-derived chemicals are allowed – unlike many other horse industry-aimed repellents and insecticides. Organic farming has strict regulation worldwide, mostly to protect farmers and water tables, as opposed to consumers. It’s part of what you pay for when you buy anything grown organically. Whether you believe me or not, though it’s not a perfect system, there are differences between insecticides organic farmers can use and those they can’t.
It hasn’t always been like this. If you’ve ever seen an eagle, thank an earlier, more vigorous version of US chemical regulation. We led the world in abolishing one of the most effective insecticides ever, DDT. Its widespread use in the 50s meant there were almost no eagles or ospreys around when I was a child. Now they’re nearly everywhere. The US chemical industry punished elected officials for that leadership and the US has not been the same since.
EU public safety agencies regulate dangerous chemicals in part because they have national healthcare systems. Ultimately, it helps their national bottom line when they protect everyone’s health. Conversely, the US capitalizes ill health; our version of health care is largely for-profit.
Obviously, here, you are free to buy whatever fly repellent you think is best for your situation.