The “Organochlorine Pesticides Residues in Bottled Water from Mexico City” study was conducted by researchers at the Metropolitan University of Xochimilco, in southern Mexico City. The report, published in the Bulletin of Environmental Contamination and Toxicology this month, found traces of sevent different pesticides in unnamed brands of bottled water from Mexico City.
Only one pesticide, hexachlorocyclohexane, or HCH, was found to exceed drinking water standards, however.
But even legally allowed trace amounts of pesticides are a problem because of “the potential exposure of large populations to low concentrations over long periods of time,” the study said. “Of particular concern are substances that may be carcinogenic and those that have a tendency to bioaccumulate in the organs.”
The authors of the Bulletin study have not revealed the brands of water they tested and declined to comment on their study. Their findings nonetheless raise concerns over what most Mexicans consider the safest source of drinking water.
Mexico’s list of banned water pollutants is less restrictive than that of the U.S. Environmental Protection Agency, the U.S. Food and Drug Administration or the World Health Organization, said Marisa Mazari, a biologist at the National Autonomous University of Mexico.
“Mexican regulations should guarantee that the water is fine to drink, but these regulations have to be continually updated,” Mazari said. “When it comes to pesticides the regulations aren’t working.”
Mazari, who was not involved in the Bulletin study, said that the levels of pesticides reported were “very low” but still noteworthy.
“Pesticides have serious health effects,” she said. “They can have reproductive side effects. Consuming pesticides can cause them to accumulate in fatty tissue and can have effects on the liver and kidneys.”
Mexico City draws 70 percent of its water from local wells and 30 percent from the Lerma River basin, Mazari said, meaning that both tap water and bottled water are vulnerable to pollution from landfills, gas stations, industrial runoff and agricultural drainage canals.
The study’s authors recommend the government better regulate the country’s burgeoning bottled water industry and update maximum levels of drinking water contaminants, especially pesticides.
Unlike in the United States, where bottled water in many places is an amenity, Mexicans drink bottled water largely out of necessity.
“Tap water is not recommendable anywhere in Mexico,” Health Secretary Jose Angel Cordova said.
He blamed bad bottled water on unscrupulous street sellers who fill bottles with tap water and sell them to unknowing customers.
Cordova, the Health Secretary, admitted that the government is having difficulty keeping track of bottled water produced in the capital.
“What happens is that on some occasions there are clandestine sales (of bottled water),” he said of the growing number of bottled water brands available in Mexico City.
There is, however, by law “a strict standard for (levels of) pesticides” in drinking water in Mexico, Cordova said.
Tom Lauria, vice president of the International Bottled Water Association (IBWA), a trade organization for bottled water companies that is located in New York, said it has members that bottle in Mexico City, including Danone and Nestle – along with Coca Cola and Pepsi, the four major bottled water companies in Mexico.
“We certainly meet and sometimes exceed the regulatory standards of the FDA over bottled water, which are already extensive,” he said.
Bottled water is not “tap water in a bottle,” Lauria said. “It has to go through rigorous purification to meet government standards to be called purified.”
Meanwhile, questions linger over why the government has been unable to improve the quality of tap water.
The UN has water improvement programs in countries throughout Latin America, but not Mexico, said Laura Jaloma, Program Assistant for UN-HABITAT in Mexico.
“It’s because there hasn’t been any interest on the part of the government,” she said.
Many chilangos, as Mexico City residents call themselves, are suspicious of attempts to privatize, and theoretically improve, the city’s tap water. The World Water Forum, held here in 2006, brought fierce public protests, for example.
But without reliable tap water and with bottled water booming, the city’s water market has effectively already been privatized, Jaloma said.