The Environment Agency will launch a comprehensive fact-finding study on the effects of what are called "environmental hormones," such as dioxin and polychlorinated biphenyl, on fish, birds and other wildlife, agency sources said July 11.

It is feared that the so-called hormones function like female hormones when taken into the body and may adversely affect propagation functions, such as by reducing sperm production, the sources said. More than 70 environmental hormones are now known, including dioxin, PCB, DDT and other agricultural chemicals and plastic additives, they said.

A special report published by the U.S. government in February found 20 species of animals, including bears and gulls, whose propagation functions had been adversely affected by such chemicals. This will be the first national-level study on the effects of environmental hormones on wildlife, the sources said.

The agency launched a study group in March to conduct preparatory research by going through relevant publications and documents, they said. The group reported that it is feared contamination by environmental hormones will become increasingly serious in the future and that the agency plans to conduct a comprehensive study, they said.

Because males normally do not have yolk protein, Prussian carp, goby and other fish will be checked to see if they have this protein and whether they are affected by environmental hormones, the group said. Eggshells of Japanese sparrows, crows and predatory birds will be chemically analyzed to see if such contaminants are present in them, because the shells are easily affected by environmental hormones, the agency sources said. To check on contamination in urban areas, a study on possible decreases in spermatozoa in rats is under consideration, they said.