To which? These are all pulled from research, just need to know which so I don’t waste my time pulling up something you’re not questioning
Plants are vulnerable to fluoride accumulation in soil, and their growth and development can be negatively affected, even with low fluoride content in the soil.
WHO guidelines for 1.5mg/L fluoride
Upper limit of 10mg/day (considered to be high by some bodies)
https://www.eatforhealth.gov.au/nutrient-reference-values/nutrients/fluoride-updated-2017
Basic bath: only considering water intake, consuming 6-7 liters in a day (regular occurance working in Australia) puts you over the upper limit without considering major sources like diet, tea and dental products and treatments.