Baby bottles: what are the risks of using tap water?

Powdered infant formulas are reconstituted with water before consumption. Tap water (public water) can be used for the preparation of the bottle with some precautions even if from a microbiological point of view it is not sterile and from a chemical point of view it may contain contaminants. The aim of the study was to develop a mathematical model to assess the health risks (microbiological and chemical) associated with the use of tap water for the preparation of 1st and 2nd age milks in France (during the first six months of life).
Two hazards of major concern associated with mains water were selected: Cryptosporidium and arsenic. Cryptosporidium is a parasite that is rarely found in tap water but is resistant to its treatment and can cause diarrhea which can lead to death in infants. Arsenic is a natural element in the earth's crust that is widely distributed in mains water, at varying levels depending on the region, and whose chronic exposure can lead to lung and bladder cancer.
The team’s work falls within an emerging area of ​​research: global or multi-risk assessment.
It is a question, from a mathematical model using French and European data, to measure a probability of disease, at the individual level and at the level of the population, when using tap water in the infant preparations. Assessments were made from two milk preparation scenarios: one using boiled tap water and the other using unboiled tap water. The preparation of milk with commercial bottled water was considered to be a baseline scenario which does not pose a risk for these two selected hazards.
The impact of these practices on the population was assessed in DALYs (Disability Adjusted Life Years): number of years lost due to early death and / or a decrease in quality of life resulting from disabilities resulting from Consumption of infant formulas rehydrated with unboiled tap water for the first six months of life could lead to Cryptosporidium infections and thus a loss of 2,250 healthy years or DALYs per 100,000 infants (range d 90% uncertainty [960; 7 650]) and to cancers associated with arsenic exposure inducing a loss of 1 DALY [0.4; 2] per 100,000 infants.
Using boiled water would eliminate the risk of Cryptosporidium. In contrast, the risk of cancer, although low at the population level, remains rather high in infants with a high level of exposure to arsenic.

Partners : This work was carried out in collaboration with INRAE/Oniris research units, SECALIM and LABERCA at Nantes and with the University College of Dublin (l’UCD). It is part of the phD thesis of Géraldine Boué (defended in july 2017) and the Master 2 intenship of Luiza Wasiewska (Master in food safety performed at Wageningen University in The Netherlands).