129-I, with a radioactive half-life equal to 1.6 x 107 y, represents a potential source of internal contamination from nuclear fission products, the long-term radiological risk of which should be considered for radiological protection. Iodine uptake in the thyroid depends on the total mass of iodine intake (either stable or radioactive) ingested from food and water, or inhaled with ambient air. The biokinetic model, described in ICRP 67 (1993), provides doses per unit intake (DPUI) calculated for an average thyroid uptake of 30%. A wide range of daily iodine intake levels over a short period involves dramatic DPUI variations. This work proposes a method for estimating 129I doses, adapting the ICRP to the situation in France, a country with high levels of dietary iodine, taking into account iodine uptake variations relating to total iodine in the diet.