Drug traces in water pose worry

Hormones and Sewage


Within the finestapple, therecanbe a worm. And thisis the case with the mapping of the humangenomeproject — the identifying of the geneticmakeup of humanbeings.

The mapping, whichisalmostcompleted, promises greatadvances for medicine, becauseitwillallowdrugs to bedevelopedthatcanzero in on previouslyunidentified trouble spots.

At presentthere are about 500 distinct biochemicalreceptors at whichdrugs are targeted, according to two American scientists, Christian Daughton and Thomas Ternes (reported in EnvironmentalHealth Perspectives, Dec. 1999, Vol. 107, Supplement 6, pp. 907-938).

Withcompletion of the humangenomeproject, theysay, the number of targets « isexpected to increase 20-fold in the near future.’’ In otherwords, therecouldbe up to 10,000 biochemicalreceptorstargeted.

The worm in thisparticularappleisthatdrugs are not tested for theirenvironmental impacts. « This issurprising,’’ sayDaughton and Ternes, « especiallysince certain pharmaceuticals…have obviouspotential as endocrine disruptors in the environment.’’

Endocrine, or hormone, disruptors are stronglysuspected of beingresponsible for the hugeincreases in breast cancer and testicular cancer, for genital malformation in newborns, and for the large drop in spermcountsamong men.

According to Daughton and Ternes, the amount of drugs and personal care productsthat enter the environmenteachyearis about the same as the amount of pesticides.  The drugsgettherethroughsewagesystems. Sewagetreatment plants are not designed to removethem, and sotheyeventuallyreachwaterways.

Twoyearsago, Environment Canada reportedthat, across the country, therewere high levels of estrogen in sewagetreatment effluent. And last summer Glen Boyd, a civil engineerfromTulaneUniversity in New Orleans, reportedthat the Mississippi River, Louisiana’s Lake Ponchetrain, and the university’stap water all containedlowlevels of the anti-cholesteroldrugclofibricacid, the pain killer naproxen, and the hormone estrone. The concentration of estrone in the tap water averaged 35 parts per trillion (ppt), with a high reading of 80 ppt.

The significance of thislevel of a hormone in tap water isbeingunderlined by the work of Chris Metcalfe, dean of graduatestudies in Environmental Science at Trent University in Peterborough.

He has been testing the level at whichestrogenfrombirth control pillscan affect Japanesemedakafish in laboratoryexperiments. He has foundthatestrogenlevels of 1 pptwillreduce the ability of male medaka to fertilizeeggs, and will alter itsmatingbehaviour.

In humans, hesays, hormonal disruption canseriously affect gonadaldevelopment in the fetus, and even « gonadaldifferentiation’’ whichoccurs in the four or five daysafterbirth, whengonadalcellsgravitatetowardeither the femaleor the male ends of the spectrum. In males, if the differentiationistoward the female, itcanmeanlowerspermcounts and alteration of secondarysexcharacteristics, such as deepness of voice and distribution of body hair.

« What (hisexperiments) mean, by inference,’’ Metcalfesays, « isthatextremelylow concentrations of estrogen hormones can cause changes in fish.’’ And whatwecantakefromthat, I suggest, isthatwe have to assume extremelylowlevels, not necessarily as low as for fish, canalso affect humans.

To place this in context, ittakes 10,000 times more (10 parts per billion) of synthetic hormone mimickerssuch as the industrialplasticizerdisphenal A to disrupt hormonal activity.

The good news isthatestrogenfrom the birth control pillsthatMetcalfe has been testing, breaks down veryquickly. Once in a waterway, microorganisms and sunlight willeliminateitwithin 24 to 48 hours.

But what of all the otherdrugsthatenter the sewagesteam? The antidepressants, muscle relaxants, anti-psychoticdrugs, antibiotics, cancer chemotherapydrugs, pain killers, tranquilizers, antiseptics, dietpills, anti-inflammatorydrugs, blood pressure reducers, fungicides, and synthetic hormones? Whatkind of dosages are wegettingfromthemthroughtap water?

Wedon’t know. And manymany more drugs are on the way. Surelyenvironmentaltestingshouldberequired by governments.

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