A prominent Kiwi scientist has explained just how wrong a member of the public was to link an MP's miscarriages to fluoride.
On Saturday Green MP Julie Anne Genter shared an "incredibly insensitive" email she received, saying her two miscarriages were caused by "toxic" fluoride.
"I was surprised and fairly offended," Ms Genter told Newshub. "My reaction was also to laugh about it. I'm sure the person who sent it was well-meaning, but it really was incredibly insensitive."
And also incredibly wrong, according to scientist Michelle Dickinson, also known as Nanogirl. In a post on her website, Dr Dickinson said she was "really shocked at the insensitivity of [the] message - let alone the bad science".
She posted a simple flowchart, suggesting the email's author - only known as Lorraine - was being "moronic and cruel".
Then Dr Dickinson explained how fluoride is nowhere near as toxic as Lorraine thinks.
Her calculations suggest an adult female weighing around 68kg would need to drink at least 1220 cups of water for fluoride to be fatal, and 7808 glasses to be sure.
Even if she tried to poison herself with tap water, she'd die of hyperhydration long before the fluoride would have any effect.
"If you want to give medical and scientific advice to people that you don't know then you should probably focus on the much higher chance that somebody dies from hyperhydration by drinking 24 glasses of water, than the… 7000 glasses of water needed for death by fluoride toxicity."
Dr Dickinson also took issue with the research Lorraine provided in her email, saying not only was it published in a very minor scientific journal, the study didn't even find any evidence backing up claims fluoride is bad for pregnant women.
"Having a miscarriage can be traumatic and many women experience huge grief over their loss," she writes.
"It is a very sensitive subject and very personal to those involved. If you haven't had to experience the grief of a miscarriage or the challenges around infertility then please understand that it can involve pain, a sense of loss, and a daily struggle to try and remain positive while sometimes feeling like a failure."
Ms Genter says she's "100 percent" certain fluoride had nothing to do with the problems she's had.
"I've got emails which have accused me of being ignorant on the subject, or incompetent. But I thought the email trying to link my personal experience of miscarriages to water fluoridation was really a new low."