Fluorosis

Fluorosis is an accumulation of excessive amounts of fluoride within the body.

Controlled exposure to fluoride increases overall teeth quality through enamel replacement and the killing of plaque-causing bacteria (1).

Fluorosis is commonly associated with an excessive level of fluoridation of water supplies. In England and Wales the maximum permitted, or "unsafe" upper limit for fluoride in drinking water is 1.5 mg/l (1.5 ppm), set by the Drinking Water Inspectorate and consistent with World Health Organisation recommendations.

Dental fluorosis usually presents as white flecking or linear opacities of enamel.

At higher concentrations, systemic fluorosis can occur with:

• bone pain
• sclerosis of spine
• ligamentous ossification
• disordered new bone growth

Fluoride in drinking water in England and Wales

• most common source of fluoride is drinking water, where it occurs naturally at low levels in most areas of England
• the overwhelming majority of areas have fluoride levels below 1mg/L (1 ppm), with most being below 0.49mg/L (0.49 ppm) (2)
• maximum permitted level of fluoride in drinking water is 1.5mg/L (1.5 ppm)

Fluoride toothpaste

• as with drinking water, fluoride strength in toothpaste is measured in parts per million (ppm)
  • 1ppm means each 100g of toothpaste contains 0.1mg of fluoride
• toothpaste manufacturers may use sodium fluoride, sodium monofluorophosphate, stannous fluoride, or a combination of these
  • is currently no evidence that any form is more effective than another (2)

Non-prescription toothpaste

• non-prescription toothpaste products can contain up to 1500ppm (150mg per 100g)

Safe levels of fluoride intake

• European Food Safety Authority (EFSA) set safe daily intake limits for fluoride in 2025. These vary by age:
  • 1mg per day for infants under 1 year
  • 1.6mg per day for toddlers aged 1 to 3 years
  • 2mg per day for children aged 4 to 8 years
  • 3.3mg per day for children over 8 years, adults and pregnant women
• toothpaste manufacturers recommend a maximum of 0.05mg/kg body weight per day from all sources (not exceeding 1mg per day) (2)
  • the manufacturer’s recommendation differs from EFSA guidelines

Reference:

1. Johnston NR, Strobel SA. Principles of fluoride toxicity and the cellular response: a review. Arch Toxicol. 2020 Apr;94(4):1051-1069.
2. NHS Specialist Pharmacy Service (January 2026). Considering fluoride and accidental ingestion of toothpaste