(JP) Male fish develop eggs in testes

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http://www.japantimes.co.jp/cgi-bin/getarticle.pl5?nn20010804a5.htm

 

ENDOCRINE DISRUPTER HAVOC

Male fish develop eggs in testes

 

The Environment Ministry announced Friday that nonyl

phenol, an organic chemical used in cleaning products,

disrupts the endocrine system of " medaka " killifish

and causes males to assume female reproductive traits.

The study, believed to be the first to prove the

chemical is an endocrine disrupter, found that male

medaka in water with relatively low concentrations of

nonyl phenol began developing eggs inside their

testes, the ministry said.

 

While many chemical substances are suspected of

affecting human hormones, this development marks the

first time for any government to officially categorize

a substance as an endocrine disrupter, according to

ministry officials.

 

The fish in the study were in water with a

concentration of 11.6 micrograms of nonyl phenol per

liter, a concentration detected in some drainage

canals. A microgram is one-millionth of a gram.

 

The research also found the estrogen receptors of the

medaka are highly susceptible to the chemical. Human

estrogen receptors are much less receptive to nonyl

phenol, meaning it is less harmful to people, ministry

officials said.

 

About 16,500 tons of nonyl phenol were produced in

fiscal 2000 in Japan, mainly for use in industrial

detergents used in the textile and metal processing

industries. It is also used to make resins and

plasticizers.

 

The ministry plans to consult with industries about

the possibility of replacing the chemical with other

substances.

 

Nonyl phenol was detected in 617 of 1,574 drainage

canals, rivers and lakes in Japan surveyed between

fiscal 1998 and 1999 by the Environment Agency, the

ministry's predecessor.

 

The substance does not affect the endocrine system in

concentrations less than 0.6 microgram per liter,

according to the ministry survey. Nonyl phenol

concentrations exceeded 0.6 microgram per liter at 71

of the locations.

 

Since fiscal 2000, the ministry has researched the

impact on health and the ecosystem of suspected

endocrine disrupters.

 

Taisen Iguchi, a professor at the Okazaki National

Research Institutes, said nonyl phenol is certainly an

endocrine disrupter as the ministry's study had proved

two vital points.

 

These are that the effects of the substance were

recorded at concentrations found in the environment

and that the receptors of the medaka were highly

susceptible to it.

 

He added that authorities should swiftly devise

measures to prevent the chemical from being released

into the environment.

 

 

The Japan Times: Aug. 4, 2001

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