Panel comments on soy phytoestrogen and formula

The National Toxicology Program (NTP) Center for the Evaluation of Risks to Human
Reproduction (CERHR) convened an expert panel on March 15–17, 2006, in Alexandria,
Virginia to evaluate genistein and soy formula. CERHR selected genistein and soy
formula for expert panel evaluation because of (1) the availability of reproductive and
developmental toxicity studies in laboratory animals and humans, (2) the availability of
information on exposures in infants and women of reproductive age, and (3) public
concern for effects on infant or child development.

The expert panel, composed of 14 independent scientists, reviewed and evaluated the
available scientific data on genistein and soy formula in three primary areas: human
exposure, reproductive toxicity, and developmental toxicity.

Genistein - Expert Panel Conclusions
Even though there is a paucity of available human data on exposure to purified
genistein, the Expert Panel expresses negligible concern for reproductive and
developmental effects from exposure of adults in the general population. The most
highly exposed human population reported is Japanese adults with ingestion of total
genistein (free and complexed) of approximately 0.43 mg/kg body weight (bw)/day.
However, adverse effects in rodent studies were not observed at levels below 35–44
mg/kg bw/day. Therefore, the Expert Panel feels that under current exposure conditions,
adults would be unlikely to consume sufficient daily levels of genistein to cause adverse
reproductive and/or developmental effects.

The Expert Panel expresses negligible concern for adverse effects in neonates and
infants who may consume up to 0.01–0.08 mg/kg bw/day of genistein aglycone
contained in soy formula. . One member of the panel did not agree with this conclusion
and felt that a higher level of concern was warranted. It is noteworthy that about 1% of
total genistein in soy formula is present in its uncomplexed form, i.e., the aglycone

Soy Formula - Expert Panel Conclusion
There are insufficient human or experimental animal data available to permit a
determination of the developmental or reproductive toxicity of soy infant formula.
The conclusions noted above are those of the Genistein and Soy Formula Expert Panel
and should not be construed to represent the views of the NTP.

Bonnie and Steve - we reserve full comment on this issue until the panel's detailed report comes out in May. We also would like to find out if the expert panel has any ties to special interests. Most of the public comment taken to date came from soy special interests.