Biomonitoring in Washington State

Statewide General Population Study

From May 2010 through June 2011, Washington Environmental Biomonitoring Survey (WEBS) staff collected 1422 urine samples from a statewide representative sample of Washington residents age 6 and older (PDF). Urine samples are analyzed at the Washington State Department of Health Public Health Laboratories for total and speciated arsenic, twelve metals, and pyrethroid and organophosphate pesticide metabolites. WEBS staff compared survey levels with national levels found by CDC in the National Report on Human Exposure to Environmental Chemicals.


Washington State Department of Health recruited participants for statewide general population biomonitoring from April 2010 through June 2011. The department randomly selected a total of 70 census block groups (PDF). Twenty-seven households within each block group were selected at random to participate. All adults and children ages six and older living in the household were invited to participate.


Urine samples were collected to test for the following substances:

Arsenic: Total arsenic and six arsenic compounds (arsenic (V) acid, arsenous (III) acid, arsenobetaine, arsenocholine, monomethylarsonic acid, dimethylarsenic acid).

Metals: antimony, barium, beryllium, cadmium, cesium, cobalt, lead, molybdenum, platinum, thallium, tungsten, and uranium.

Pyrethroid pesticide metabolites: trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (trans-DCCA), 3-phenoxybenzoic acid (3-PBA), 4-fluoro-3-phenoxybenzoic acid (4F-3PBA), and cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (DBCA).

One organophosphate pesticide metabolite: 3,5,6-trichloro-2-pyridinol (TCPY), which is a metabolite of the pesticide chlorpyrifos.

Testing water samples: The department collected drinking water samples from participating households to test for metals beginning in July 2010. Water samples were tested for six metals: arsenic (total), cadmium, lead, thallium, uranium (total) and manganese. Water testing was paid for by the Washington Tracking Network. A total of 498 water samples were collected from households participating in the statewide general population project.

Test results for arsenic and metals in urine and drinking water were reported to participants in a letter about eight weeks after sample collection. Pesticide testing of urine samples completed in 2012 and test results for pesticides have been sent to all participants.

Major Findings

  • Urine levels of total arsenic were higher in Washington (median 11.9 μg/g creatinine) compared to U.S. levels reported by CDC (7.9 μg/g creatinine). About 11 percent of WEBS participants had urine levels above CDC's reporting level of 50 ug/L.
  • Arsenic from seafood contributed to the higher levels. People who ate shellfish, fish, kelp or sushi in the previous three days had higher urine levels of arsenic. Arsenic compounds in food occur naturally and have low toxicity.
  • In Washington, median urine levels were higher for cadmium and cobalt, and lower for cesium, lead and thallium compared to the entire U.S.
  • Almost all drinking water samples met Environmental Protection Agency (EPA) standards. Most water samples (76 percent) came from large public water systems.
  • In Washington, median urine levels were higher for pyrethroids and lower for chlorpyrifos compared to the most recent U.S. levels from 2001 through 2002. We expected these differences because chlorpyrifos was banned for home use in 2001 and home use of pyrethroids has increased since that time.
  • Pyrethroid levels were higher in people who reported recent use of home insecticides and were lower in people who reported eating organic fruits and vegetables.