I'm noticing this claim made a lot in various contexts these days, most notably relating to the pandemic (about both the virus and vaccines).
In those contexts as well as this one, I feel like it's used in a weaponised way to emphasise the seriousness of the harm caused, but by doing this there's some abandonment of those who have been harmed and consigns them to a future of having to carry on living with the harm, without being empowered or supported to heal and recover.
I have some experience with toxicities of lead and other metals, which I wrote about here several years ago. [1]
As this article suggests, diagnosis and treatment are not widely available in mainstream medicine, so in order to get help you find yourself in the world of fringe medicine, which of course is a minefield.
But there are absolutely treatments that work and that can enable many (most?) people to recover or improve a huge amount, as the linked article from that comment thread documents. [2]
This article is right that the problem is neglected by mainstream society, but not so right that harms are irreversible, and if we were more willing to believe in the potential for the human body to heal when given adequate treatment and support, far more people could be living much more full and empowered lives.
That's not to say more shouldn't be done to remove lead and other toxins from the environment; of course that should be done too.
[1] https://news.ycombinator.com/item?id=19573098
[2] https://www.nytimes.com/2019/04/03/magazine/lead-poisoning-m...