Last year, when a profound schism erupted between the American scientific community and the Bush administration, a key point of contention concerned the alteration of sexual health information on several government Web sites. A National Cancer Institute fact sheet temporarily suggested the possibility of a link between abortion and breast cancer (scientists say with near unanimity that there isn't one). A statement explaining why educating teens about how to use condoms does not increase sexual activity was deleted from a Centers for Disease Control fact sheet. And so forth.

If science defenders were angry about these actions, they ought to be on an absolute rampage over a new Web site, www.4parents.gov, sponsored by three separate branches of the Department of Health and Human Services: the Office of Public Health and Science, the Office of Population Affairs, and the Public Health Service. The site is described as "part of a new national public education campaign" to help parents help their teenagers make "the healthiest choices." "Part of a new misinformation campaign" would be more accurate. A massive list of sexual health research and advocacy groups and other organizations have slammed the site, arguing that it amounts to a thinly veiled brief for pro-life moral values and abstinence education. An analysis of the site's content shows that their complaints are more than justified.

As the sexual health organizations complain, 4parents.gov delivers a stealth dose of pro-life advocacy. The site defines pregnancy, for instance, as a process "that begins when an egg cell and a sperm cell unite." Actually, not every fertilized egg implants in the wall of the uterus, meaning that a better definition of pregnancy would probably emphasize implantation, not fertilization. The site also refers to a fertilized egg shortly after implantation as an "unborn child," a phrase that appears repeatedly on 4parents.gov.

In order to make its pro-abstinence case, 4parents.gov also presents selective or distorted information about the effectiveness of condoms, a common tick on the religious right. The site takes every opportunity to downplay condom efficacy, with passages such as the following:

Studies suggest that condoms, when used consistently and correctly, offer significant risk reduction (80-87%) for HIV/AIDS. Condoms provide less risk reduction for other sexually transmitted diseases. Research indicates significant risk reduction for HIV to almost none for others (e.g., HPV).

Here, 4parents.gov appears to be relying exclusively on published studies that positively prove condom effectiveness for certain diseases, while conveniently ignoring basic common sense. What the site neglects to tell American parents is the following: According to the National Institutes of Health, condoms "provide a highly effective barrier to transmission of particles of similar size to those of the smallest STD viruses." Because of this characteristic, continues the NIH, there is "a strong probability of condom effectiveness when used correctly" both for diseases spread by discharges (including gonorrhea and chlamydia), and for diseases spread by skin-to-skin contact (including herpes, syphilis, and HPV), so long as the condom covers the infected area.

In short, even though the effectiveness of condoms may not have been proven in rigorous studies for all conditions, we nevertheless know that condoms provide a strong barrier against STD transmission.

And even as 4parents.gov demands rigorous proof of condom effectiveness for every individual sexually transmitted disease, it simultaneously celebrates abstinence on completely idealized grounds. Cynthia Dailard of The Alan Guttmacher Institute has observed that abstinence advocates frequently contrast theoretically perfect use of abstinence with actual real life condom failure rates, thus comparing "apples and oranges." 4parents.gov is no exception. The site refers to abstinence as "without question, the healthiest choice for adolescents." But as a method of disease prevention, abstinence -- just like condoms -- only works if you actually use it properly. And there's abundant evidence that despite the best of intentions, "abstinence" fails because many teens just don't stick to it.

For instance, 4parents.gov lists a "pledge of virginity" as a "protective factor" against risky sexual behaviors. It does not bother to cite actual research on how virginity pledgers behave. In a recent study published in the Journal of Adolescent Health, Yale sociologist Hannah Bruckner and Columbia sociologist Peter Bearman found that teenagers who took these pledges -- promising to abstain from sex until marriage -- delayed having sex for longer but did not have correspondingly diminished STD infection rates. That's because most pledgers didn't actually keep their oaths all the way to marriage, and those breaking them were less likely to use condoms the first time they had sex. Moreover, the minority of pledgers who actually managed to abstain from vaginal sex until marriage were more likely to get it on in other ways -- such as trying out oral or anal sex -- in the meantime.

With more space, we could catalogue more distortions on 4parents.gov. But a more interesting question is: Where are they coming from? Part of the explanation may arise from the fact that in the site's creation, the government partnered with a nonprofit group called the National Physicians Center for Family Resources. This organization has previously teamed up with the American Association of Pro-Life Obstetricians and Gynecologists to oppose the so-called abortion pill RU-486, and has promoted the dubious notion, popular on the religious right, of a link between abortion and breast cancer.

It is a sad day, but we can no longer doubt that it has arrived. At least in the area of sexual health, Americans can no longer rely on their own government for balanced, objective information.

Chris Mooney is a Prospect senior correspondent whose TAP Online column appears each week. His book on the politicization of science will be published later this year by Basic Books. His daily blog and other writings can be found at www.chriscmooney.com.