DDT Again Rears Its Perilous Head in County Water, Soil

Mussels provided the first clue that all was not well in Newport Bay.

In 1979, the filter-feeding shellfish that had been collected in the lower bay as part of a marine monitoring program began showing high levels of harmful trace metals and chemicals, including the banned pesticide DDT. A search was launched for the source of the pollutants.

The trail led upstream in 1984, when small bait fish called red shiners from the bay’s tributary, San Diego Creek, showed toxic amounts of pesticides, including DDT at levels nearly 10 times the federal maximum for wildlife and nearly twice the level dangerous to humans.

Now DDT has turned up in sediment in the creek’s network of feeder channels that serve the single largest agricultural area in Orange County. At more than half the sites sampled in the central county area, low levels of DDT appear to have been “freshly released” into the environment, a spokesman for the Santa Ana Regional Water Quality Control Board said.

“We haven’t found any smoking gun in this detective story we started five years ago,” said James Anderson, executive director of the tri-county board, which ordered the sediment study.

“We don’t know who or what has caused it. But we need to look further, to what is around these samples--to see where it could be coming from.”

Where is the DDT coming from? Is it being used illegally despite a federal ban?

State and local authorities say the jury is still out, so the possibility that discarded DDT is leaking from landfills, being dumped illegally into Orange County waterways or sprayed illegally on crops cannot be discounted.

Yet new research in Monterey County suggests that DDT sprayed on crops decades ago can lie dormant until erosion, plowing or even grading of former agricultural lands sends pesticide-saturated soil into the watershed and back into the environment.

Rachel Carson made a persuasive case in her 1962 book “Silent Spring” that DDT had a persistent, far-reaching and largely unforeseen effect on the earth’s environment. The findings of dangerous levels of DDT long after they should have disappeared suggest that its legacy is only beginning to be understood.

DDT, which was widely used by U.S. farmers because it gave crops long-lasting protection from a variety of pests, was banned in 1972 by the Environmental Protection Agency because it was shown to endanger wildlife by getting into the natural food chain. It was also a suspected carcinogen because it produced liver tumors when fed in massive doses to mice. It is still used in other countries, including Mexico.

Now, 13 years later, when the pesticide was supposed to have disappeared from the environment, federal, state and local officials are alarmed about mysteriously escalating residues of DDT in fish and wildlife in Texas and throughout central and Southern California.

There is disagreement over whether it is newly applied pesticide or pre-1972 DDT that is just beginning to break down. Nonetheless, many experts say they fear the most serious ecological consequences of decades of its use are only beginning to emerge.

Dead or dying marine mammals have washed ashore along Southern California’s coastline. In autopsies, they have been found to have some of the highest levels ever recorded of DDT and PCB, an insulator formally called polychlorinated biphenyl.

On Thursday, the head of the state department of health services warned anglers against eating certain fish caught in coastal waters from the Santa Monica Bay south to the Los Angeles-Long Beach Harbor because of the levels of DDT and PCB. Women of child-bearing age and children were advised not to eat locally caught sport fish more than once a month and to avoid white croakers altogether.

One state environmental official who declined to be identified predicted that the warning may eventually become a prohibition against eating certain fish caught anywhere offshore from Ventura to San Diego because of mounting evidence of contamination.

“We try not to be alarmist,” said the official. “But it is likely that the problem you are seeing in Newport Bay . . . is symptomatic of the entire southern coastline.

“It’s not a deadly situation today, but it is one we don’t understand and one of great concern to us.”

DDT--the initials stand for dichloro diphenyl trichloroethane--is an insecticide from the family of mostly banned pesticides known as chlorinated hydrocarbons. It dissolves not in water, but in oils or lipids. It accumulates in the fatty tissues of many animals and can reach very high concentrations in predators that feed on smaller animals.

In the early 1960s, DDT was blamed for a serious decline in the population of brown pelicans, which feed on fish. Because of a chemical deficiency, the female pelicans were producing eggs with shells so thin that most would break before the embryos could mature.

Chemicals Found Since 1979

In both the Upper Newport Bay, a state ecological preserve and habitat for endangered species like the least tern and the clapper rail, and the lower bay, trace metals and toxic chemicals have been found since 1979.

Since then, swimming has been prohibited. Fishing is permitted, although the county Health Care Agency has posted warnings against consuming the fish.

To determine where these hazardous materials were entering the bay watershed, analysts from the regional board and the Orange County Environmental Management Agency collected sediment samples in January from 22 sites on various tributaries to Newport Bay. DDT or its breakdown products were found at all locations.

Anderson said concentrations of DDT and its breakdown compounds, DDD and DDE, that were found in samples taken in the Tustin-Irvine area in January were well below federal guidelines and pose no threat to public health.

However, he said the presence of even small amounts of DDT and its derivatives in soil sediments in the bay’s watershed does represent a serious threat to aquatic life.

The proportion of DDT to the breakdown compounds, according to Anderson, can provide some indication of how recently the DDT was sprayed. DDT breaks down into DDE, then DDD, in anywhere from four to 30 years, he said.

Concentrations in Watershed

In the Newport Bay watershed, the highest concentration of the pesticide--166.2 parts per billion--was found in a tributary to San Diego Creek near Irvine Center Drive. But more than 80% of that consisted of DDE and DDD.

The highest levels of what appeared to be active DDT were found in the Barranca Channel in Irvine at 44.9 parts per billion, and in the Peters Canyon Wash south of the Santa Ana Freeway at 25.6 parts per billion. The National Academy of Science has set the toxic threshold at 1,000 parts per billion in fish and wildlife and 5 parts per billion for humans.

Twelve of the 22 sites appeared to have unusually high concentrations of original DDT that had not yet degraded into derivative compounds.

However, results of a new study conducted jointly by the state Department of Agriculture and the regional water quality board of Monterey County suggest that DDT can remain stabilized in soil for many years and not begin the degradation process until it comes in contact with sunlight, bacterial microbes and/or water.

In Monterey County’s Blanco Drain area, “we were finding DDT, DDE and DDD in ratios that would suggest it was new, even though we were sure it had not been applied since the 1972 ban,” said Ronald J. Oshima, chief of environmental monitoring for the Department of Agriculture.

Re-entry Into Soil

“What I think we are seeing throughout California is the (re-entry) of DDT in the soil,” Oshima said. “It’s being turned over by bulldozers or tractors and being swept down through storm discharges or agricultural drains and turning up as what appears to be fresh DDT.”

If Oshima’s conclusions are correct, and the pesticide does not begin to break down until it is exposed in the environment, the implication “is that the phenomenon of DDT may last out all of our lifetimes and beyond,” a water resources official said grimly. “We may be seeing adverse impacts right now and we just aren’t recognizing them.”

Still, most experts say illegal spraying cannot be ruled out as an explanation for increasing DDT residues. Indeed, some of the areas of highest concentrations are located downstream of areas where there are large nurseries, citrus groves, strawberry fields and other agricultural interests.

But pesticide enforcement officers for Orange County and the state Agriculture Department say that is unlikely--particularly because most growers found insects had become resistant to the chemical years before it was banned.

“We stopped using DDT about a year before it was banned,” said Carl Lindgren, manager of farming for the Irvine Ranch, Orange County’s largest grower. “The reason we quit is there was a more effective way of controlling the pests.”

Frank Parsons, Orange County deputy agricultural commissioner for pesticide use and enforcement, said an intensive search for illegally stored DDT after the red shiner study turned up nothing. No DDT was found in spot tests of chemicals being used or on crops just sprayed.

‘No Percentage’ in Using DDT

The increasing sophistication of farming techniques, combined with the agriculture commission’s licensing requirements and surveillance tends to discourage misuse of pesticides, Parsons said. “There is absolutely no percentage in it for a grower,” said Parsons.

But as one environmental expert pointed out, “It is not impossible for people to get DDT, if they want to go to the trouble to do it.”

Some suggest it could be a combination of midnight dumping of old stores of DDT and leaky landfills, as well as illegal spraying. So far, few people have been caught dumping chemicals illegally in Orange County and no leaks of DDT have been uncovered.

Others point to dicofol, an insecticide containing as much as 12% DDT residues that has been used for nearly three decades to combat mites on cotton, citrus and ornamental plants. Because its DDT residues--which are impurities left over from the manufacturing process--are classified as “inert ingredients,” dicofol escaped the EPA ban.

The EPA has now proposed outlawing all uses of products containing dicofol, much of which is sold under the trade name Kelthane, including many mite killers for home gardening use. Pros and cons of such a ban will be discussed April 17 at a public forum in Rosslyn, Va.

Bruce Kapner, manager of the EPA’s special review branch, said an estimated 2 million to 2.5 million pounds of pesticides containing dicofol are used annually on U.S. crops, two-thirds of it on citrus and cotton crops in southern and western states.

‘Hazard to the Environment’

Based on two studies--in California’s Kings County and in the Arroyo Colorado River Basin in southern Texas--Kapner said projections have convinced EPA officials that “there is a hazard to the environment with dicofol in the concentrations as it has been registered.”

“We believe that enough DDT residues are being applied to cause adverse ecological effects,” Kapner said.

San Joaquin Valley cotton growers oppose a ban on dicofol because they say it will double or triple the amount of alternate pesticides needed to control spider mites, said Olaf Leifson, chief of pesticide registration for the state Agriculture Department.

The manufacturer of Kelthane products, Philadelphia-based Rohm & Haas, contends that there is no more than 42% dicofol in any of their products, and never more than 5% DDT. Company officials, in arguing against a ban, say they have brought DDT residues down to less than 2% and are in the process of building a new plant in Europe that will reduce DDT impurities to less than 0.1%.

“Clearly, we don’t want to add more DDT to the environment; I think that is a generally held view,” said Leifson. “But one solution is to work with the manufacturer to reduce the contaminant in dicofol that could be causing the problem.”

Parsons said Orange County growers use about 400 pounds of insect killers containing dicofol annually, most of it by ornamental nurseries.

Little Use of Kelthane

The Irvine Ranch uses very little Kelthane, according to company officials.

“My records show that in the last two years, it was only used on one orchard, a 20-acre lemon orchard” in September, 1984, farm manager Lindgren said. The Irvine Ranch has 5,200 acres of citrus groves.

“We would only use dicofol in very, very specific instances,” Lindgren said. “The reason we don’t use it is because it is very, very hard on our beneficial insects. . . . We’ve found there are better ways to take care of the problem.”

Contrary to the EPA’S findings, officials with the state Agriculture Department and Water Resources Board, and environmental specialists with the regional water quality board for Orange, Riverside and San Bernardino counties, say they doubt dicofol is responsible for all or even some of the DDT contamination being found.

“If that were the case, we should have found other chemicals contained in dicofol; we didn’t find any,” Anderson said.

In fact, high levels of DDT contamination are not occurring where most of the dicofol in California is used, or where DDT spraying historically was heaviest--in the San Joaquin Valley, according to state agriculture and water quality officials.

That lends support to the theory that in areas like Orange County that are undergoing heavy development of formerly agricultural lands, soil harboring old deposits of DDT is being bulldozed, graded and ultimately eroded into the network of waterways feeding Newport Bay.

Cleanup Plans Uncertain

How to clean up the pollution is an issue yet to be addressed.

For now, the extent of the DDT problem and where it is coming from is still being assessed, authorities said.

In Orange County, more samples will be taken next month in five of six “hot spots” where the highest total DDT levels were found. Anderson said they hope to verify the January results and track contamination to possible sources.

Areas to be tested further are:

- A county flood control channel near Irvine Center Drive and Sand Canyon Avenue, in an area of citrus, avocado, row crops and wholesale nurseries near the Laguna, Santa Ana and San Diego freeways. Total DDT compounds measured 166.22 parts per billion.

- Barranca Channel, in an area of mostly light industrial complexes west of Harvard Avenue and south of Barranca Parkway in Irvine. DDT compounds totaled 78.06 parts per billion.

- Bonita Channel just upstream of its confluence with San Diego Creek, near the UC Irvine campus, and in a watershed area that includes the Coyote Canyon landfill. DDT compounds totaled 63.3 parts per billion.

- A county flood control channel upstream of the Peters Canyon Wash, near Walnut Avenue and Myford Road in Irvine, where row crops and citrus groves mix with residential, commercial and light industrial land use. DDT compounds totaled 49.28 parts per billion.

- Central Irvine Channel, west of Yale Avenue and north of Trabuco Road, in an area mixed with groves of citrus and avocado, seasonal row crops, wholesale nurseries and some residential development. DDT compounds totaled 39.19 parts per billion.

Anderson said four samples will be taken in each of the five areas from middle to late May. Laboratory results were expected back by early summer.

A sixth site, San Diego Creek at Campus Drive in Irvine, where the second-highest concentration of DDT compounds were found (81.37 parts per billion), will not be tested because there has been extensive dredging in the creek bed.