divided by fractional absorption, an EAR of 380 mg (12.3 mmol)/day is derived by the factorial approach.

Based on the factorial estimate, an EAR of 380 mg (12.3 mmol)/day is set for children ages 1 through 3 years.

Utilizing the 1994 CSFII intake data, adjusted for day-to-day variations (Nusser et al., 1996), the value derived for the EAR of 380 mg (12.3 mmol)/day represents a low dietary intake of phosphorus, as it falls below the first percentile (416 mg [13.4 mmol]/day) for phosphorus intake for children aged 1 through 3 years (see Appendix D). The EAR value will provide for the calculated physiological need for phosphorus accretion in lean and bone mass, accounting for the expected urinary phosphorus loss at that dietary intake. Because urinary excretion rises linearly with increasing dietary intake of phosphorus, it does not seem appropriate to set the EAR at an amount that exceeds the physiological needs for growth and maintenance.

The variance in requirements cannot be determined from the available data. Thus, a coefficient of variation (CV) of 10 percent (1 standard deviation [SD]) is assumed, which results in an Recommended Dietary Allowance (RDA) of 460 mg (14.8 mmol)/day.

Accretion. The rationale for using a factorial approach based on the surrogate criteria of phosphorus accretion of bone and soft tissue is the same for children ages 4 through 8 years as for children ages 1 through 3 years. The surrogate indicator of tissue accretion was used since there are no data on phosphorus balance in this age group, with the exception of a study by Wang et al. (1930). These