Some three decades after polychlorinated biphenyl [PCB] was banned, the stuff is still found in rivers, plants, and human bodies, where it can suppress the immune system, alter the reproductive system, cause asthma, cardiovascular disease, enhance the effects of other carcinogenic substances, and reduce IQ, according to City Limits. In April 2008, the Daily News found PCBs in window sills and door frames in dozens of city public schools, but city health officials determined that in most cases the PCBs in the caulking had not leaked into the air and weren't dangerous. State regulations permit the caulk to remain in place until renovations take place, though some experts warn that PCBs left undisturbed can still leach out. Now one Bronx mom, Naomi Gonzalez, is suing the city to force it to remove all the tainted caulk from Public School 178, where her 6-year-old daughter attends school. Last year former City Health Commissioner Dr. Thomas Frieden insisted the PCB caulk was perfectly harmless: "Do PCBs pose a health risk in the schools where they're present in intact caulk sample?... The findings clearly indicate they do not." Of course, this is the same guy who shrugged off reports that swine flu could kill 90,000 Americans nationwide.