Pesticides present — at low levels

LIHUE — A new study by the state Department of Health detected trace amounts of pesticides in streams and waterways across the state, including eight locations on Kauai.

While the data doesn’t answer questions about seasonal changes or long-term trends, it does provide a “snapshot in time” about pesticides — a fiery topic of debate in recent years.

The good news for Kauai, according to DOH environmental toxicologist and supervisor Fenix Grange, is that the substances found did not exceed state and federal regulatory limits.

“None of these levels present a risk to human health or the environment,” she said.

However, a number of chemicals were detected around the island, with two exceeding aquatic life benchmarks established by the Environmental Protection Agency.

“Atrazine and metolachlor, two restricted use herbicides, were detected on Kauai at agricultural sites downstream of seed crop operations,” states the 25-page draft document provided to The Garden Island Tuesday. “One location had levels that exceeded aquatic life guidelines for both compounds, but remain below regulatory standards.”

The DOH study analyzed water from 24 streams across Kauai, Oahu, Maui and Big Island for a total of 136 different products. While the department found no violations of state or federal water quality standards for pesticides still used today, Dieldrin — a historically used insecticide now banned in most of the world — did exceed regulatory limits at three separate locations on Oahu.

On Kauai, trace amounts of current-use chemicals were detected at all eight sample sites, which spanned from the island’s far Westside to the taro fields in the Hanalei National Wildlife Refuge on the North Shore. The statewide pilot project was conducted by HDOH in light of growing community concerns about pesticide use by large agricultural operations, including biotech seed companies like Syngenta and DuPont Pioneer. 

Statewide, urban areas on Oahu saw the highest number of different pesticides detected, with Manoa Stream at the University of Hawaii counting 20 different products.

Two locations on Kauai’s Westside — the drainage canal at Kikiaola Boat Harbor and an unnamed ditch on Kekaha Road — saw 11 detections each, according to the findings. Kikiaola exceeded aquatic life benchmarks for both atrazine and metalachlor.

Atrazine, a restricted use pesticide manufactured by Syngenta, was the most commonly found pesticide in the statewide study. Of the 24 sample sites, 20 — or 83 percent  — detected atrazine, according to the findings.

At Kikiaola, atrazine was measured at 2.05 micrograms per liter (ug/l), which is below the state and federal drinking water standard of 3 ug/l but exceeds EPA’s aquatic life benchmark of 1 ug/l established for the protection of freshwater algae, according to the study. Additionally, metolachlor was detected in five locations on Kauai, including four downstream of seed crop operations. One detection of 1.07 ug/l at Kikiaola slightly exceeded the EPA aquatic life benchmark of 1 ug/l for freshwater invertebrates. 

When asked if any of the atrazine detected on Kauai could be attributed to modern use, Grange said, “Yes.” 

Two locations, including Kikiaola harbor on Kauai and another site on Maui, reflected “elevated concentrations suggestive of current use,” according to the study. The rest of the atrazine, Grange said, likely represents “background noise” from historical use, and are far below state and federal benchmarks.

In their findings for Kauai, DOH officials said pesticide detections varied widely between locations and crop types.

“In contrast, one location on Kauai’s North Shore at Waiakalua had no detections of current pesticides, except for trace levels of atrazine and its degradates, residual evidence of former sugar cane use in that area,” read the findings. 

Due to concerns about pesticide usage on Kauai’s Westside, the department’s sampling design included three locations on Westside drainage canals downstream of seed corn operations, as well as another in Hanamaulu Stream, which has both seed corn and mixed agriculture upstream. DOH’s findings were later compared to the sales of restricted use pesticides being reported by Kauai’s five largest agricultural entities as part of the state’s voluntary Kauai Agricultural Good Neighbor Program, according to Grange. 

Five RUPs were detected at one or more of these sites, and three — atrazine, metolachlor and chlorypyrifos — were reported to have been used by seed crop operators a few weeks prior to sampling, according to the findings. Two, hexazinone and simazine, were also found in trace concentrations at seed crop locations despite not being reported as part of the voluntary program, according to Grange. However, she said that could simply be a result of the products being applied at an earlier time. 

The study also tested seven locations in Hawaii for glyphosate, a commonly used herbicide known by its trade name Roundup. Three of those locations, including two on Kauai, detected the chemical at low levels in water, while all seven came up positive in sediment samples. 

While the findings provide useful information about pesticide occurrence across different land uses (monoculture ag, mixed use ag, turf uses and urban areas), it may not be representative of typical conditions or identify specific sources, according to the report. 

Grange said although it is technically still a draft, the report is thorough and will help the public understand what was found and the tools available to interpret the data. 

As for what’s next, Grange said the funding picture changed at the end of the legislative session when a proposal that would have increased funding and allowed for additional work fell through. 

“This was a one-time study,” she said. “We do not have additional funds to continue this work.”

For more information or to view the study findings, visit http://eha-web.doh.hawaii.gov/eha-cma/Org/HEER/.