Scientific Investigations Report 2008–5027
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2008–5027
Table 8. Maximum benchmark quotients for pesticide concentrations in finished drinking-water samples from the study water-treatment plant on the lower Clackamas River, Oregon, 2004–2005.
[The maximum Benchmark Quotient (BQ max) is the ratio of the highest measured concentration of a detected compound in finished water to its benchmark. BQ values close to 1 indicate a potential concern and higher levels indicate greater potential risk. Human-health benchmarks: Low and high HBSL values correspond to 10-6 and 10-4 cancer risk, respectively, for unregulated carcinogens. HBSLs from Toccalino and others (2006), and MCLs from USEPA (2006). Abbreviations: e, estimated value (see Glossary); USEPA, U.S. Environmental Protection Agency; USGS, U.S. Geological Survey; HBSL, Heath-Based Screening Level; μg/L, microgram per liter; MCL, Maximum Contaminant Level; na, no benchmark available for these compounds]
| Pesticide or degradate |
Compound type |
Remark | Maximum concentration in finished water (μg/L) |
BQ max | Date | Pesticide concentrations (μg/L) | ||
|---|---|---|---|---|---|---|---|---|
| Human-health benchmarks | ||||||||
| USGS HBSL (Low) | USGS HBSL (High) | USEPA MCL | ||||||
| Diuron | Herbicide | 0.18 | 0.091 | 05-18-05 | 2 | 200 | na | |
| Ethoprop | Insecticide/Nematocide | .006 | .006 | 09-30-05 | 1 | 100 | na | |
| Simazine | Herbicide | .021 | .005 | 09-30-05 | 4 | |||
| Pronamide | Herbicide | .005 | .005 | 05-18-05 | 1 | 100 | na | |
| Atrazine | Herbicide | e | .006 | .002 | 05-18-05 | 3 | ||
| 2,4-D | Herbicide | .08 | .001 | 09-30-05 | 70 | |||
| Trifluralin | Herbicide | .005 | .0002 | 05-18-05 | 20 | 20 | na | |
| Propiconazole (trans)1 | Fungicide | e | .005 | .0001 | 09-30-05 | 70 | 70 | na |
| Dacthal (DCPA) | Herbicide | .005 | .00007 | 07-21-04 | 70 | 70 | na | |
| Hexazinone | Herbicide | .017 | .00004 | 05-18-05 | 400 | 400 | na | |
| Metsulfuron-methyl | Herbicide | e | .060 | .00003 | 05-18-05 | 2,000 | 2,000 | na |
| Metolachlor | Herbicide | e | .002 | .000003 | 09-30-05 | 700 | 700 | na |
| Diazinon-oxon | Degradate of the insecticide diazinon | e | .01 | na | 09-30-05 | na | na | na |
| DEET | Insect repellent | e | .008 | na | 08-25-04 | na | na | na |
| Deethylatrazine (CIAT) | Degradate of the herbicide atrazine | e | .005 | na | 05-18-05 | na | na | na |
1HBSL for propiconazole was used for propiconazole (trans).
U.S. Department of the Interior | U.S. Geological Survey
URL: http://pubs.usgs.gov/sir/2008/5027
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