Health concern: Recombinant bovine growth hormone (rbGH, also recombinantbovine somatotropin or rbST) What is it? A laboratory-created copy of a hormone that occurs naturally in cows and, when injected, increases the animals' milk production. What's the issue? The Food and Drug Administration, which approved the animal drug in 1993, has since stated that ``there are no new scientific concerns regarding the safety of milk from cows treated with rbGH.''

But ice-cream maker Ben & Jerry's, like other opponents of rbGH, says ``the jury's still out on long-term \Rhuman\S health implications.'' In 1999, Health Canada, the Canadian equivalent of the FDA, rejected rbGH's approval based on findings that the drug ``presents a sufficient and unacceptable threat to the safety of dairy cows,'' but not to human health. For more information: www.fda.gov/cvm/index/bst/bst.htm; www.hc-sc.gc.ca/english/media/releases/1999/99-03e.htm

Health concern: Ozone What is it? The main component of smog, ozone gas is caused when the sun hits carbon-based chemicals. Vehicle emissions produce most ozone. Ground ozone is not to be confused with the protective layer of ozone in the stratosphere. What's the issue? Short-term exposure to ozone can cause shortness of breath, wheezing and coughing and can be especially dangerous to people who already suffer from respiratory illness. A recent study in California suggests that high levels of ozone exposure might make children more prone to developing asthma. The main controversy over ozone, how to reduce it, has pit industry (especially automakers) against environmental and health advocates. For more information: www.lungusa.org/air/airout00-ozone.html; www.epa.gov/ARD-R5/naaqs/o3asthma.htm

Health concern: Electromagnetic fields (EMFs) What is it? Property of space caused by the motion of an electric charge. Lots of things produce EMFs, including electrical appliances and power lines. What's the issue? In 1998, National Institute of Environmental Health Sciences concluded that extremely low frequency (ELF) electromagnetic fields should be considered as a ``possible human carcinogen,'' meaning scientists couldn't rule out the possibility that exposure to ELF fields causes cancer. Two recent studies have linked brief exposure to very high intensity EMFs to an increased risk of miscarriage, according to the Reuters news agency. For more information: www.who.int/inf-fs/en/fact205.html

Health concern: Phthalates What is it? Chemical phthalates have many uses, including making plastics more flexible. They're found in everything from food packaging and children's toys to perfumes and intravenous-blood bags. What's the issue? While the American Chemistry Council says there is ``no credible evidence that people are harmed by phthalates,'' others aren't so sure.

In 1998, the Consumer Product Safety Commission called for the manufacturers of toys, baby pacifiers and medical supplies to remove some phthalates from their products, according to Science News Online. Scientists have linked phthalate exposure to cancer, and chemists have shown that phthalates can leak from plastics during use. In 2000, an expert panel reported that some phthalates have the potential to disrupt boys' reproductive development. For more information: www.sciencenews.org/20000902/bob1.asp; www.ourstolenfuture.org/NewScience/oncompounds/phthalates/phthalates .htm ; http:/www.phthalates.org/html/pegenwha.htm

Health concern: PBDEs, or polybrominated diphenyl ethers What is it? A class of chemical used as a flame retardant in foam furniture padding and in plastics. What's the issue? PBDEs are similar in structure to PCBs, which were banned in the United States in the mid-'70s because of associated health risks. Like PCBs, PBDEs tend not to break down in the environment and find their way into the food chain. Scientists were recently alarmed at the increasing levels of PBDE found in the breast milk of American women - 40 times the levels found in the breast milk of Swedish mothers. The European Union has proposed banning one form of PBDE by 2003. The company that produces the chemical says that the lifesaving properties of PBDEs outweigh their potential long-term hazards. For more information: http:/pubs.acs.org/subscribe/journals/esthag-w/2001/dec/science/kb-p bde.html ; http:/www.newsday.com/news/health/ (search for PBDE)

Health concern: Chromated copper arsenate, or CCA What is it? An arsenic-based pesticide used on 90 percent of pressure-treated wood, according to USA Today. Arsenic is a known carcinogen. What's the issue? In February, the wood-preservative industry announced that it would voluntarily phase out use of CCA on pressure-treated wood used for residential purposes such as play structures, decks, picnic tables and fencing. Use of CCA on that wood will be banned after Dec. 31, 2003. The EPA says it has not concluded that the CCA-treated wood on the market until then ``poses unreasonable risks to the public.''

From Epa.gov