household quantities and structures. This problem is similar to that studied by Engle et al. (1986), Chesher (1997, 1998), and Vasdekis and Trichopoulou (2000), and is addressed in a slightly different way. In the present article, the individual contaminant intake is firstly viewed as a nonlinear function of age within each gender, with time and socioeconomic characteristics being secondly introduced in a linear way. The nonlinear function is represented by a truncated polynomial spline of order 1 that admits a mixed model spline representation (section 4.9 in Ruppert et al. , 2003). These choices yield a simple linear mixed model which is estimated by REstricted Maximum Likelihood (REML, Patterson and Thompson, 1971). One major extension of the proposed model compared to Chesher (1997) is the introduction of dependence between the individual intakes of a given household. 

In the next section, focusing on the methylmercury example even though the method is much more general and could be applied to any chronic food risk, SECODIP data are described along with the construction of a household intake series and the individual cumulative and long term exposure concepts yielding the KDEM. Section 2 is devoted to the statistical methodology used to decompose the household intake series into individual intake series, namely the presentation of the model and its estimation and tests. Section 3 displays the results for the quantification of long term exposure to methylmercury of the French population using the 2001 SECODIP panel. Finally, a discussion on the use of household acquisition data, with the focus on the French SECODIP panel, is conducted in section 4 with respect to the proposed long term risk analysis. 

## 1 Motivating example: risk related to methylmercury in seafoods in the French population 

In this section, the Kinetic Dietary Exposure Model (KDEM) and the concept of long term risk are defined. Then a brief panorama of consumption data in France is given and the way the SECODIP HBS data will be used as an input of the KDEM is described. 

