PUBLIC HEALTH ASSESSMENT
BERTRAND CREEK AREA PROPERTIES
(a/k/a NORTH WHATCOM COUNTY GROUNDWATER CONTAMINATION)
LYNDEN, WHATCOM COUNTY, WASHINGTON
1) A public health hazard exists for residents exposed to pesticides found in drinking water wells in the north Whatcom County area. Ingestion of drinking water and inhalation of vapors during showering are the primary routes of exposure. Exposure to these pesticides at levels above respective MCLs can pose a moderate to low increase in cancer risk over many years of exposure. In addition, the presence of EDB or multiple pesticides in drinking water at levels below respective MCLs will also carry some cancer risk. These estimates of cancer risk are based on animal experiments involving doses well in excess of anything experienced by north Whatcom County residents. These pesticides have not been shown to cause cancer in humans although studies of human populations are limited.
Non-cancer adverse health effects are not anticipated to result from exposure to the levels of these pesticides found in north Whatcom County groundwater. MCLs for these pesticides appear to be protective against non-cancer endpoints.
2) A public health hazard exists for pregnant women and bottle-fed infants exposed to nitrate in drinking water at levels above the MCL. While this risk appears to be small, current data examining adverse birth outcomes and methemoglobinemia suggest that some risk exists at levels approaching 20 ppm. Further investigation of the health risks associated with nitrate in drinking water is warranted.
3) No apparent public health hazard exists for migrant farm workers exposed to pesticides in drinking water. Only very low levels of 1,2-DCP were detected in two of seven wells during the most recent sampling round while all other pesticides of concern were not detected. Non-cancer health effects are not expected and cancer risk is not considered significant at current levels of 1,2-DCP in these wells. Consistent with other wells in the area, levels of 1,2-DCP appear to be declining in these two migrant camp wells. The past presence of EDB in the Ehlers camp well did represent a low to very low cancer risk for long-term exposure.
4) Nitrate has consistently been detected at or above the MCL in many of the migrant camp wells and therefore, poses a hazard to pregnant women and bottle-fed infants. The additional exposure of migrant farm workers to pesticides in soil and indoor dust is also cause for concern. While these pathways were not quantified in this health assessment, they are a potential source of pesticide exposure.
5) No apparent public health hazard exists for persons exposed to mixtures of pesticides and nitrate in drinking water at or below respective MCLs. A recently published long-term animal study suggests that nitrate present with very low levels of aldicarb and atrazine could have subtle effects on the immune system. While these pesticides are not generally found in north Whatcom County groundwater, this study is important mainly due to the fact that effects were seen at environmentally relevant doses. Interactions between nitrate and pesticides commonly found in groundwater need to be examined more thoroughly in light of these data.
1) Residents using drinking water wells contaminated with pesticides above respective MCLs should take steps to reduce both ingestion and inhalation exposure. In addition, residents using domestic water supplies contaminated with any detectable levels of EDB or multiple pesticides should consider reducing exposure.
- Effective remedial measures include an alternate water source, drinking bottled water, increasing ventilation while showering/bathing, installing a carbon filtration device on shower-heads or installing a point-of-entry water treatment system.
- Effective remedial measures include an alternate water source, drinking bottled water and installing an appropriate treatment system for your drinking water.
- Effective remedial measures include an alternate water source, drinking bottled water, increasing ventilation while showering/bathing, installing a carbon filtration device on shower-heads and installing an appropriate treatment system for your drinking water.
- Annual sampling and analysis for 1,2-DCP should continue at those migrant camp wells that contain 1,2-DCP until decreasing trends are established. DOH will evaluate results of this testing. Nitrate sampling of these wells should adhere to current state and federal regulations.
- Growers should ensure that their workers observe proper
re-entry times when working in fields applied with pesticides. Re-entry time
information is provided on the pesticide label.
- Farm workers should take steps to reduce the amount of soil tracked inside the home from pesticide treated fields. Effective measures include removing work clothes and boots before entering the main living areas of the home and keeping pets outside the home and/or away from pesticide treated fields.
5) Residents living in areas of concern who have not had their wells tested should consider testing for EDB, 1,2-DCP, 1,2,3-TCP, DBCP and nitrate. Areas of concern include Study Areas A and B (see Figure 2) and any other agricultural areas with historical use of soil fumigants.
- WCHHS has information on past and present agricultural land use as well as information on certified laboratories that test for pesticides and nitrate. WCHHS can be contacted at 360-676-6724. Ecology is currently evaluating groundwater contamination in the north Whatcom County area and may conduct further testing of private drinking wells.
6) DOH and ATSDR should pursue opportunities to examine the relationship between exposure to nitrate in drinking water and adverse health effects, specifically, methemoglobinemia in infants and adverse birth outcomes.
7) DOH and ATSDR should pursue opportunities to study the potential for adverse health effects, specifically on the immune system, from exposure to mixtures of nitrate and pesticides in drinking water.
8) WCHHS should continue to provide input to county and local planning departments to ensure that no new drinking water wells are located in contaminated areas. In addition, WCHHS should take an active role in developing strategies to reduce the potential for further contamination of the Sumas-Blaine aquifer.
- The water quality database compiled by WCHHS for the north Whatcom County area should provide an excellent resource with which to make informed planning decisions with regard to reducing the potential for exposure to contaminants in groundwater.
The Public Health Action Plan (PHAP) for the Whatcom County Groundwater site is outlined below. The purpose of the PHAP is to ensure that this health assessment not only identifies public health hazards, but also provides a plan of action designed to prevent or mitigate adverse human health effects resulting from exposure to hazardous substances in the environment. Included is a commitment on the part of ATSDR and DOH to ensure that these actions are taken.
The Washington State Department of Ecology (Ecology) is currently providing bottled water and carbon filtration devices to homes with contamination at or above the MCL.
The Washington State Department of Health (DOH) has evaluated potential links between elevated leukemia rates in north Whatcom County and pesticides in drinking water. The results of this evaluation were presented at a public meeting on July 19, 1999.
The Environmental Protection Agency (EPA) conducted a Site Investigation of the north Whatcom County area in response to a petition expressing concern over possible source areas of pesticide groundwater contamination.
The Agency for Toxic Substances and Disease Registry (ATSDR) conducted an exposure investigation to determine the potential for inhalation of pesticides that volatilize from water during a shower.
DOH conducted state-wide testing of drinking water wells serving migrant farm worker facilities in the summer and fall of 1999.
DOH held an open house on March 30, 1999, to hear community health concerns related to groundwater contamination in the north Whatcom County area.
A joint public meeting organized by Ecology and DOH was held on October 20, 1999, to present the findings of this health assessment and the evaluation of remedial alternatives for contaminated wells.
Several fact sheets and consultations have been distributed to affected residents by Whatcom County Health and Human Services (WCHHS) and other agencies, providing information relative to drinking water contaminants, potential health effects and mitigative actions.
Ecology will propose long-term solutions for domestic water contaminated with EDB and 1,2-DCP for residences in the Bertrand Creek study area based on an evaluation of available options, including alternative sources, filtration and bottled water. A companion decision-making tool is being developed that may assist in assessing cost effective solutions for other similar contaminants.
ATSDR is considering a pilot study using mailed questionnaires or medical record review along with existing water supply sampling data to evaluate the risk of spontaneous abortion relative to exposure to nitrates in drinking water. This pilot would determine the feasibility of a retrospective approach to investigating this health risk, and of conducting a larger case-control study.
DOH is evaluating the feasibility of a targeted surveillance project that will help determine the incidence of methemoglobinemia in infants and its relationship to nitrate levels in drinking water. The project would require collaboration with local health departments. The WCHHS has agreed to assist DOH in such efforts.
WCHHS will continue to work with county and local planning departments to ensure that no new residential drinking water wells are located in areas of groundwater contamination.
Robert M. Duff
Office of Environmental Health Assessments
Washington State Department of Health
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