According to a new study, chemicals commonly found in plastics and fungicides may irreversibly weaken children’s teeth by disrupting hormones that stimulate the growth of dental enamel.
Endocrine disruptors are chemicals that interfere with mammalian hormones and Bisphenol A (BPA) is one of the most prevalent of such chemicals, found in every-day items including refillable drink bottles and food storage containers.
Vinclozolin is another endocrine disruptor that was commonly used as a fungicide in vineyards, golf courses and orchards.
Plastics made with BPA are especially useful for lining the inside of tins for better sealing. The chemical can enter the body through food that has been kept in packaging containing BPA, handling packaging or even through breathing in household dust. It is not listed on labels so there is no way to keep track of levels of daily exposure.
In the research carried out by researchers from the French National Institute of Health and Medical Research (INSERM), rats were given daily doses of BPA alone or in combination with vinclozolin, equivalent to an average dose a human would experience daily, from birth till they were thirty days old.
They then collected cells from the rats’ teeth surface and found that BPA and vinclozolin changed the expression of two genes controlling the mineralisation of tooth enamel.
In their second experiment, the team cultured and studied rat ameloblast cells, which deposit enamel during the development of teeth. They found that the presence of sex hormones like oestrogen and testosterone boosted the expression of genes making tooth enamel, especially male sex hormones.
As BPA and vinclozolin are known to block the effect of male sex hormones, the findings reveal a potential mechanism by which endocrine disruptors could weaken teeth.
Molar incisor hypermineralisation (MIH) is a pathology affecting up to 18% of children aged 6-9, in which the permanent first molars and incisors teeth that erupt have sensitive spots that become painful and are prone to cavities. These spots are found on dental enamel, the tough outer covering of teeth that protects it from physical and chemical damage. Unlike bone, enamel does not regrow and so any damage is irreversible.
Tooth enamel starts at the third trimester of pregnancy and ends at the age of 5, so minimizing exposure to endocrine disruptors at this stage in life as a precautionary measure would be one way of reducing the risk of enamel weakening.