From May 15 to July 19, 1958, about 500,000 pounds of DDT were applied in the county. It was just the first of a series of sweeping DDT applications. The Pink Bollworm Eradication Program continued well into the 1960s.
Despite the deluge of DDT, the pest survived.
And so, too, have DDT's progeny, long after the probable human carcinogen was banned in Arizona in 1969.
DDT's primary derivative is DDE, which also is considered by federal and international health agencies to be a probable human carcinogen. While DDT has essentially disappeared from Arizona's soils, DDE continues to persist in the soil and to spread through the food chain.
DDE has become so pervasive in the environment that it shows up in small quantities in nearly every carton of milk produced and sold in Arizona. And just as cows' milk passes DDE to humans, nursing mothers can pass DDE on to their infants.
In fact, human-breast milk can contain a higher concentration of DDE than cows' milk because DDE tends to settle in fatty tissue, and human milk has a higher fat content than cows' milk, according to a 1993 report on DDT and DDE prepared by the U.S. Department of Health and Human Services.
"As a result, breast-fed infants may receive higher dietary exposure [of DDE] than children who are not breast-fed," the report states.
Some reports also point to DDE as a possible cause of breast cancer. But the scientific evidence is inconclusive and only a few studies have been conducted, none in Arizona.
A 1993 study on Long Island found that women who suffered from breast cancer had 35 percent more DDE in their bodies than women who didn't have breast cancer. But a 1994 study by Nancy Krieger of the Kaiser Foundation Research Institute in Oakland, California, found no link between DDT or DDE and breast cancer. But Krieger called for further investigation into possible links between DDE and breast cancer. And she cautioned that even if the chemicals are not linked to breast cancer, they are known to cause other diseases.
Arizona's breast-cancer mortality rate of 24.8 per 100,000 women is below the national average of 27.5 per 100,000. Maricopa County's rate is similar to the state's, according to a December 1994 Arizona Department of Health Services report titled "Women's Cancer Control Project."
The Arizona Department of Agriculture found DDE in all 18 samples of milk the agency tested in February. The samples--which included milk taken off the shelves at grocery stores and from tankers at dairies--contained DDE residues within a range considered by the U.S. Environmental Protection Agency to be safe.
But it is not unusual for Arizona dairies to produce milk that exceeds the federal DDE safety standards. The Agriculture Department's Dairy Products Control Division has four inspectors monitoring the state's 120 dairies, which house an average of 850 cows.
When the division finds a load of milk exceeding the federal safety standard of 125 parts per million, it forces the producer to dump the milk.
This has been a routine occurrence lately for Higley dairyman James "Butch" Ray.
"He's had a terrible, terrible time controlling DDE," says Roy Collier, the Dairy Products Control director.
Department records show milk produced by Ray's herd exceeded DDE standards from December 13, 1994, until March 29. Milk produced by the dairy finally met the standard in April, passing three tests in a row, Collier says.
A dairyman for 30 years, Ray says he's battled the DDE residues in his herd's milk for two years. He has been relying on locally grown hay as well as feed imported from Yuma and Parker, he says.
Local hay is a particular problem because it tends to have higher DDE residues than hay grown in areas that were not subject to heavy DDT applications 37 years ago, Collier says.
"The majority of the dairies do not use local hay," Collier says.
Another problem, Ray says, is that he hasn't been able to bring new cows into the herd from outside the area.
"I haven't been bringing cattle in from anywhere else and they have DDE built up in their system," Ray says. "It builds up in the fat and some kind of stress brings it out."
The DDE outbreak has nearly ruined Ray financially. Ray says he suffered $100,000 in losses last year and has reduced his herd to 150 head from 450 two years ago.
Ray has learned a lot about DDE the past two years and is convinced that the pesticide residue is found only in milk fat. "It is locked in the fat," he says.
People concerned about absorbing trace DDE from whole milk should drink skim milk instead, Ray suggests.
"There shouldn't be any DDE in it," he says.
Scientific evidence supports Ray's contention, says Collier. The state has changed its monitoring of DDT and DDE in milk from testing whole milk to focusing on milk fat, because that is where the chemicals settle, Collier says.
While the impact of DDT and its by-products on humans is uncertain, the pesticide's impacts on wildlife are well-documented. DDE is found in birds and fish living along the Gila River southwest of Phoenix at some of the highest concentrations monitored in wildlife in the United States.
DDE is transported into the river by irrigation drainage canals that contain runoff from DDT-contaminated fields. The U.S. Fish and Wildlife Service says that DDT and DDE cause reproductive problems in birds and fish.
DDE is so pervasive in the Gila River that the state Department of Health Services in 1991 posted signs along the river warning the public that eating fish and aquatic wildlife posed an excessive risk of cancer and toxic effects on the central nervous system and the liver.
The state even closed Painted Rock State Park along the Gila River because fish were loaded with