Dressed in waders, a life vest and surgical gloves, John Greene waded waist-deep into the Grindstone River, about two miles east of the Hinckley, Minn., sewage treatment plant, and carefully dipped water from the slow-moving stream into a plastic bottle.
Greene, a U.S. Geological Survey technician, collected about 40 liters of water, upstream and downstream from the treatment plant and directly from the plant’s treated effluent as it entered the river.
The water samples, packed in ice, were then shipped by overnight express to two USGS
|John Green collects a sample from the Grindstone River|
laboratories in Colorado. At the labs, the water was analyzed for tiny-parts-per billion and parts-per-trillion-quantities of 37 chemicals.
The state-funded research, which is being conducted at 22 wastewater treatment plants across Minnesota, is aimed at one of the newest, least understood and most troubling types of water pollution: endocrine disrupting compounds, or EDCs, that interfere with the endocrine systems of fish and other animals.
In the endocrine system, hormones produced in glands, such as the thyroid, pituitary, ovaries and testes, circulate through the blood and interact with cells to regulate bodily functions, such as metabolism, growth and reproduction.
Some EDCs mimic natural hormones, others block natural hormones.
Scientists in Minnesota and around the world have found EDCs in sewage treatment plant effluent since the mid-1990s. Other research, both on wild fish caught near treatment plants and in lab-reared fish, has demonstrated that EDCs sometimes “feminize” male fish.
The most common evidence of feminization is the production by males of vitellogenin, an egg-making protein normally found in measurable quantities only in females. EDCs also accentuate the female characteristics and conduct of female fish.
In studies across the country between 1995 and 2004, one-third of all the male smallmouth bass examined carried immature female eggs-a step beyond the production of vitellogenin, the USGS announced recently. Seventy-three percent of all the smallmouth males tested in the Mississippi River near Lake City showed such signs of “intersex,” the USGS said.
Environmental biologists worry that EDC exposure could affect the survival of whole populations of aquatic species. A Canadian experiment demonstrated that introducing synthetic estrogen, the kind used in birth control pills, into a lake caused the lake’s fathead minnow population to crash.
So far, there is no direct proof that EDCs damage human health at the low concentrations at which the compounds commonly are found in the environment.
But some scientists fear human health is being undermined by chemicals from hundreds of sources: the foods we eat and the products we use, prescription and over-the-counter drugs that we use and then excrete, outdated drugs we flush down the toilet, industrial byproducts, feedlot wastes and pesticides.
They suspect that, even in tiny quantities, the chemicals may be harming humans, especially developing fetuses and infants.
Human impacts sometimes attributed to EDCs include: decreased sperm counts, increased genital and urinary birth defects in boys and increases in obesity, diabetes and testicular cancer.
A best-selling 2007 book, Boys Adrift by Leonard Sax, speculated that endocrine disruptors-along with other social and biological factors like video games and over-medication of boys for Attention Deficit Hyperactivity Disorder-are responsible for a “growing epidemic of unmotivated boys and underachieving young men.”
A committee of scientists appointed by the prestigious National Research Council said in 1999 that EDCs could be harmful in high doses, but it said little was understood about human reactions to the low doses typically found in the environment. The committee said linkages between EDCs and lower sperm counts, male birth defects and testicular cancer had not been proven.
Eight years later, the National Institute of Environmental Health Sciences, the top U.S. agency responsible for environmental health, summed up the state of knowledge about EDCs and their potential impacts on humans this way:
“Many of these chemicals have been linked with developmental, reproductive, neural, immune, and other problems in wildlife and laboratory animals. Some scientists think these chemicals also are adversely affecting human health in similar ways resulting in declined fertility and increased incidences or progression of some diseases including endometriosis and some cancers.
The research at Hinckley and the other wastewater plants is aimed at natural and synthetic hormones; pharmaceutical drugs, such as antibiotics and anti-depressants; and industrial and agricultural wastes-all of which can be EDCs.
Chemicals the lab analyses will look for include: alkylphenols that result from the breakdown of industrial detergents; bisphenol A, an ingredient in many plastics; triclosan, an anti-bacterial agent found in soaps, deodorants and toothpastes; trenbolone, a growth steroid given to livestock; fluoxetine, an anti-depressant; and carbamazepine, an anti-convulsant and mood-stabilizing drug.
The water sampling at the 22 treatment plants began Sept. 1. It is an $896,000 project ordered by the Legislature last spring and paid for with the sales tax increase that Minnesota voters approved last year. The Minnesota Pollution Control Agency contracted with the USGS and St. Cloud State University to do most of the sampling and analysis.
Kathy Lee, a USGS hydrologist in Minnesota, is leading the sampling. The USGS will
|USGS hydrologist Kathy Lee|
collect bottom sediment, as well as water, at some of the plants.
Heiko Schoenfuss, a St. Cloud State professor of anatomy, will put fathead minnows in cages suspended in the rivers upstream and downstream from 10 of the wastewater treatment plants. After two weeks, the minnows will be dissected to examine their liver and reproductive organs, and their production of vitellogenin, the egg-making protein, will be measured.
At five plants, Schoenfuss also will raise minnows in aquariums filled with varying concentrations of the sewage effluent.
In addition, Dalma Martinovic, a University of St. Thomas biologist and former post-doctoral fellow with the U.S. Environmental Protection Agency in Duluth, will use human breast cancer cells to measure overall levels of chemicals in the water samples that mimic actions of female estrogen hormones. Martinovic also will test liver tissue from the fish with an assay that uses 15,000 genes to measure potential impacts of EDCs on about 1,000 different bodily functions in fish.
Because of the number of chemicals the lab analyses will seek – each analysis costs about $5,000 – and because of the range of other scientific testing planned for the water, fish and sediment, the project is one of the most comprehensive investigations of EDCs in the country.
Minnesota became a big player in national EDC research because of its citizens’ intense interest in water quality and the willingness of lawmakers to fund studies. The research has been aided by a collection of talented researchers at the University of Minnesota, St.
|Heiko Schoenfuss of St. Cloud State|
Cloud State, the USGS state headquarters in Mounds View and the EPA office in Duluth.
The current research at the treatment plants follows research in Minnesota last year that demonstrated-for the first time-the widespread presence of EDCs in lakes, as well as rivers.
In that project, researchers found pharmaceutical products or chemicals from industrial detergents in the water and sediment in a dozen lakes throughout the state. Two pristine lakes, near the Boundary Waters Canoe Area and near the headwaters of the Mississippi River, were among the lakes where EDCs were found.
The researchers also caught and dissected fish-perch, sunfish, shiner minnows and fathead minnows-from the lakes.
“In many of the lakes, the males were producing a considerable level of vitellogenin,” said Mark Ferrey of the Minnesota Pollution Control Agency, who oversaw the lake sampling and is coordinating the wastewater treatment plant testing “That is an indication these fish have been exposed to EDCs.” The MPCA recently released its report on the lake sampling.
Until the discovery of EDCs and other chemicals in lakes not connected to any wastewater treatment plants, many researchers had focused on treatment plants as the main avenue by which such compounds were funneled into rivers. In the aftermath of the lakes research, scientists are taking a harder look at diffuse, nonpoint sources of EDC contamination-septic systems and runoff from feedlots and other agricultural and urban lands.
“We know they are big sources in some places,” Paige Novak, a University of Minnesota associate professor of civil engineering, said of the treatment plants. “But I don’t think they are THE source. I think they are one of the sources.”
Jeff Writer, a USGS biochemist who worked on the lake research and now is working on the treatment plant analyses, said: “We’re seeing these compounds everywhere we look, so we’ve got to start looking at what kinds of compounds we’re producing.”
Research on EDCs around the world began with scientists looking for answers to biological oddities like eagles that showed no interest in mating; male alligators, inhabiting a lake where there had been a pesticide spill years before, that seemed to have smaller-than-normal penises; and female seagulls that chose other females as nesting partners.
In a scientific paper published in 1993 and later in a book, Our Stolen Future, Theo Colborn, a scientist with the World Wildlife Fund, popularized the term “endocrine-disrupting chemicals.” She argued that EDCs caused the behavior of the eagles and the gulls and the alligators’ stunted development.
Congress began investigating EDCs in 1993, and in 1996 it directed the Environmental Protection Agency to develop an endocrine disruptor screening program for pesticides and drinking water contaminants. It was not until this spring that the EPA promulgated final rules identifying the first 67 pesticide ingredients to be tested.
The emergence of the theory by
Colborn and other scientists that
environmental EDCs were affecting birds and other animals coincided with development of new lab techniques allowing chemicals to be measured in much lower concentrations.
Scientists now routinely measure EDCs in parts per trillion.
But EDCs are operative at incredibly low concentrations, and sometimes they cause physiological responses at low concentrations, but not at higher ones.
Despite all the research on EDCs in the environment, scientists have many more questions than answers about the sources of the chemicals and their potential impacts on fish and other
species, including humans.
“We’re concerned about the effect of these compounds on fish and wildlife, the ecosystem and the overall impact on the environment,” said Ferrey, the Minnesota Pollution Control Agency scientist coordinating the treatment plant research. “We’re also concerned, of course, about their impact on human health. Right now we don’t have any evidence that they are affecting human health at these concentrations.”
The possible link between EDCs in the environment and damage to human health may be the most difficult part of the EDC puzzle to research and prove or disprove.
An April 2009 report prepared for Congress by the Congressional Research Service explained:
“Except for strong poisons with clear, short-term effects on health, the effects of chemical exposures on humans are difficult to demonstrate scientifically. Ethically, scientists cannot manipulate levels of human exposure to a chemical if there is a chance that harm might results.”
The report said numerous epidemiologic studies had suggested associations between EDCs and impacts on human development or health. “However, causality has not been (and possibly cannot be) clearly demonstrated for any adverse health effect as a result of exposure to an endocrine disruptor at levels typically present in the environment,” it said.