LOS ANGELES, Sept. 9 (Xinhua) -- Scientists have hypothesized that chemicals in certain plastics may be linked to such conditions as asthma and even obesity, according to a new report.

    Recent widely publicized studies have shown that plastics are not only ubiquitous in the environment, but are found in the bodies of nearly all Americans too, said the report published on Sunday by the Los Angeles Times on its website.

    Most of the research, and the strongest evidence, points to effects that certain plastics chemicals appear to exert on the reproductive system, said the report.

    Although findings are still considered preliminary, reports are enough to make consumers question the safety of plastics.

    "Unfortunately," said Dr. Philip Landrigan, a pediatrician and chairman of the department of community and preventive medicine at the Mount Sinai School of Medicine in New York, "we're in the terrible position of having to say that we mostly don't know."

    But while phthalates and other chemicals used in plastics have been shown to be toxic to animals, in humans, the data are still inconclusive, experts said.

    Phthalates are added to normally rigid PVC to make soft products, including the plastic bags that store blood, plasma and intravenous fluids; feeding, breathing and dialysis tubes; catheters; respiratory masks; and exam gloves. Phthalates are also found in children's toys, vinyl floors, wallpaper, shower curtains, vinyl bibs and countless cosmetics, including lotions, shampoos and nail polish.

    At the University of Rochester School of Medicine and Dentistry in Rochester, N.Y., researchers found that among men enrolled in a large national health study, waist circumference was roughly 1 1/2to 3 inches bigger in men with the highest levels of several different phthalates than in men with the lowest levels of the chemicals. A measure of insulin resistance, a common indicator of diabetes, was also higher in the men with the highest phthalate levels.

    As more and more consumers are expressing concern about potentially toxic chemicals in plastic products, California lawmakers have taken notice: last week, the state Legislature passed a bill to ban certain phthalates in plastic items meant for children younger than three, according to the report.