WITHOUT acknowledging the possiblehealth risks posed by rising levels ofnitrates and volatile organic compounds inwater sources that serve half of CostaRica’s population in the Central Valley, theNational Water and Sewer Institute (AyA)has declared the current nitrate levelsacceptable.In response to the recently releasedresults of three long-term studies by scientistsat the Universidad Nacional (UNA),which found nitrate levels in some subterraneandrinking water sources exceeded 10milligrams per liter (mg/L), the AyA managementreleased a series of statementsthat argue 50 mg/L is the acceptable limit,and appeared to ignore scientists’ warningthat nitrate levels are rising.Nitrates are found in sewage and chemicalfertilizers, and seep into undergroundwater sources from septic tanks and coffeeplantations in the Central Valley, accordingto the UNA study.“IF measures are not taken, in a fewyears this water will not be able to be usedfor human consumption,” said Dr. JennyReynolds, head of UNA’s EnvironmentalHydrology Center, when she released theresults of the study earlier this month (TT,April 15).In response, AyA wrote, “The researcher(Reynolds) uses as a maximum allowedlimit 10 mg/L, which is not in agreementwith the (state) regulation, causing a mistakeninterpretation of the results and confusingthe population, indicating that the spring“Ojo de Agua” (an important source ofdrinking water to residents of the CentralValley) is one of those that contain 9.94mg/L of nitrates, when in reality it doesn’teven reach the maximum allowed limit inthe National Norms (50 mg/L).”UNA scientists reported 10 mg/L is thelimit established by health authorities. TheWorld Health Organization (WHO) supportsthe limit of 10 mg/L for nitrates, but declares50 mg/L as its maximum limit. The U.S.Environmental Protection Agency declares10 mg/L as the upper limit.ACCORDING to the WHO, it set itsnitrate limit “on the basis of the acutehealth risk to infants and is unusual for thisreason as most (limits) are set for longtermrisks.”The U.S. Center for Disease Controlreports, “Nitrate is considered an ‘acutecontaminant’ because short-term exposuresto levels above (10 mg/L) can causemethemoglobinemia,” a condition thatcripples the ability of hemoglobin in theblood to carry oxygen from the lungs to therest of the body, which can cause anemia.“At particular risk are infants less thanone year old, pregnant women, and personsof all ages with reduced gastric acidity or ahereditary lack of methemoglobin reductase,”its Web site says.THE state water institute reported thatits own studies of nearly 4,000 watersources throughout the country from 1996-2002 found nitrate levels below 10 mg/L in81% of the water sources, and higher than50 mg/L in 1.5% of the sources.“Taking under consideration the limitsestablished by the maximum world healthauthority (WHO) we can assure that98.5% of the water sources studied in ourcountry are under the maximum limit” –which is fine, it says, compared to countrieslike India.India’s nitrate levels are so high theycould be causing gastric cancer, according tothe WHO, which says there is “anecdotalevidence that suggests levels of up to 1500mg/L” in some water sources in that country.UNA’S rector, Sonia Marta Mora,wrote to AyA’s executive president RafaelVillalta in response, pointing out that mostof the data for the UNA studies were collectedin conjunction with AyA officialswho studied the water sources as well.It appears “this is about discrediting aserious study and that you do not take allavailable sources into account for your evaluations,among them, primary sources ofinformation. I believe we must take advantageof the data provided by the responsibleinvestigators from a recognized university(UNA is one of the two biggest universitiesin the country) that has no other goal than toprovide information that authorities can useto take measures to manage a vital resourcelike water,” she wrote.UNA research chemist Jorge Herrerapushed the envelope further in a April 23letter to his colleagues:“It’s very easy for an institution likeAyA to attack a researcher when the resultsof a study are not convenient. However,this diagnosis (UNA’s water study) onlyreflects the tip of iceberg, generated by thelack of planning and establishment of clearpolicies for water management,” it said.Herrera chastised AyA for neglectingits duties in rural areas where UNA scientistsanalyzed the water.“The absence of emergency plans,ignorance of cleaning and disinfection systems,the lack of protection policies for(natural) recharge zones for water sources,are only some of the factors shown in thesediagnostics,” he wrote.MEANWHILE, the Heredia PublicServices Company, in charge of the watersupply for the Heredia area, north of SanJosé, paid for a full-page ad in the daily LaNación Monday denouncing the FinanceMinistry for blocking a government loanfrom the Inter-American Development Bank(BID) that would pay for a sewer system.The company said Heredia should be apriority because AyA draws water from theregion and pipes it to 1 million residents ofthe San José area. A sewer system wouldeliminate septic tanks and reduce theamount of nitrates seeping into the undergroundwater deposits, it said.The Finance Ministry countered twodays later with a statement that it had neverreceived a formal request to back such aproject, and that it has never said Herediais not a priority.