PUBLIC HEALTH ASSESSMENT
BERTRAND CREEK AREA PROPERTIES
(a/k/a NORTH WHATCOM COUNTY GROUNDWATER CONTAMINATION)
LYNDEN, WHATCOM COUNTY, WASHINGTON
Figure 1. North Central Whatcom County, Washington
Figure 2. Study Area A (Meadowdale) and Study Area B (Bertrand Creek)
Figure 3. Approximate Boundaries and Well Locations of Study Area A (Meadowdale) and Study Area B (Bertrand Creek) within a 2-mile Radius
Figure 4. Boundaries of the Sumas-Blaine Aquifer
Figure 5. Direction of Groundwater Flow in the Sumas-Blaine Aquifer
Figure 6. Results of Whatcom County Well Testing for EDB from 1991-1999 (provided by WCHHS)
Figure 7. Results of Whatcom County Well Testing for 1,2-DCP from 1991-1999 (provided by WCHHS)
Figure 8. Results of Whatcom County Well Testing for Nitrate from 1991-1999 (provided by WCHHS)
APPENDIX B: Exposure Dose Calculations
This appendix provides the exposure assumptions and calculated doses used to estimate health risks associated with exposure to contaminants of concern in drinking water. The dose estimates for each of these pathways are discussed under the Pathways Analysis/Public Health Implications section of the document. The reader should be aware that maximum concentrations are used to calculate these doses. This represents a worst-case scenario that may overestimate actual exposure. Non-cancer dose calculations assumed a five-year exposure of a child from birth through 5 years of age. Cancer dose calculations assumed a 30-year exposure of a child growing to adulthood.
Maximum air concentrations reached during a 20-minute shower were estimated using a mathematical model.(c) Use of maximum concentrations will likely over estimate total shower inhalation exposure since maximum levels will not be present during the entire shower. This conservative approach was used to account for other sources of exposure such as clothes and dish washing that were not considered in the dose estimate. Dermal absorption during a 20-minute shower was estimated using EPA guidance.(d)
Ingestion
Inhalation - (Shower)
Table 4. Non-cancer Dose Calculations
| Receptor Population |
Media | Contaminant | Concentration (ppb) |
Exposure Route |
Estimated Dose
(mg/kg-day) |
MRL/RfD (mg/kg-day) |
Hazard Indexa | ||
| Ingestion | Inhalation | Dermal | |||||||
| Young
Child (0-5 years) |
Drinking water | EDB | 6.1 | Ingestion Inhalation Dermal |
3.3E-04 | 2.9E-04 | 1.1E-05 | NA | NA |
| 1,2-DCP | 28.4 | 1.5E-03 | 1.1E-03 | 1.1E-04 | 9.0E-02 | 0.03 | |||
| DBCP | 0.3 | 1.6E-05 | 3.5E-06 | 1.1E-06 | 2.0E-03 | 0.01 | |||
| 1,2,3-TCP | 2.4 | 1.3E-04 | 5.3E-05 | 9.1E-06 | 6.0E-03 | 0.03 | |||
| Infant | Formula (drinking water) | Nitrate | 56 | Ingestion | 8.6E+00 | NA | NA | 1.6 | 5 |
| Nitrate | 10 (MCL) | 1.5E+00 | NA | NA | 1.6 | 1 | |||
a = Hazard index is the total estimated dose divided by the RfD or MRL.
Table 5. Cancer Dose Calculations
| Receptor Population |
Media | Contaminant | Maximum Concentration (ppb) |
Exposure Route |
Cancer Slope Factor (mg/kg-day-1) |
Cancer Risk | EPA Cancer Class | |||
| Oral | Inhalation | Ingestion | Inhalation | Dermala | ||||||
| Child
Adult (30 years) |
Drinking water | EDB | 6.1 | Ingestion Inhalation Dermal |
8.5E+01 | 7.6E-01 | 5.8E-03 | 5.3E-05 | 2.8E-04 | B2 |
| 0.05 (MCL) | 4.7E-05 | 4.4E-07 | 2.3E-06 | |||||||
| 1,2-DCP | 28.4 | Ingestion Inhalation Dermal |
6.8E-02 | 6.3E-02 | 2.2E-05 | 1.7E-05 | 2.2E-06 | NA | ||
| 5 (MCL) | 3.8E-06 | 2.9E-06 | 3.9E-07 | |||||||
| DBCP | 0.3 | Ingestion Inhalation Dermal |
1.4E+00 | 2.4E-03 | 4.7E-06 | 2.0E-09 | 4.8E-07 | NA | ||
| 0.2 (MCL) | 3.1E-06 | 1.4E-09 | 3.2E-07 | |||||||
| 1,2,3-TCP | 2.4 | Ingestion Inhalation Dermal |
7.0E+00 | NA | 1.9E-04 | NA | 1.9E-05 | NA | ||
| 40 (LTHA) | 3.1E-03 | NA | 3.2E-04 | |||||||
APPENDIX C: ATSDR Conclusion Categories
CATEGORY A : URGENT PUBLIC HEALTH HAZARD
This category is used for sites where short-term exposures (< 1 yr) to hazardous substances or conditions could result in adverse health effects that require rapid intervention.
This determination represents a professional judgement based on critical data which ATSDR has judged sufficient to support a decision. This does not necessarily imply that the available data are complete; in some cases additional data may be required to confirm or further support the decision made.
Criteria:
Evaluation of available relevant information* indicates that site-specific conditions or likely exposures have had, are having, or are likely to have in the future, an adverse impact on human health that requires immediate action or intervention. Such site-specific conditions or exposures may include the presence of serious physical or safety hazards, such as open mine shafts, poorly stored or maintained flammable/explosive substances, or medical devices which, upon rupture, could release radioactive materials.
* Such as environmental and demographic data; health outcome data; exposure data; community health concerns information; toxicologic, medical, and epidemiologic data.
ATSDR Actions:
Based on the degree of hazard posed by the site and the presence of sufficiently defined current, past, or future completed exposure pathways, one or more of the following public health actions can be recommended:
CATEGORY B: PUBLIC HEALTH HAZARD
This category is used for sites that pose a public health hazard due to the existence of long-term exposures (> 1 yr) to hazardous substance or conditions that could result in adverse health effects.
This determination represents a professional judgement based on critical data which ATSDR has judged sufficient to support a decision. This does not necessarily imply that the available data are complete; in some cases additional data may be required to confirm or further support the decision made.
Criteria:
Evaluation of available relevant information* suggests that, under site-specific conditions of exposure, long-term exposures to site-specific contaminants (including radionuclides) have had, are having, or are likely to have in the future, an adverse impact on human health that requires one or more public health interventions. Such site-specific exposures may include the presence of serious physical hazards, such as open mine shafts, poorly stored or maintained flammable/ explosive substances, or medical devices which, upon rupture, could release radioactive materials.
*Such as environmental and demographic data; health outcome data; exposure data; community health concerns information; toxicologic, medical, and epidemiologic data.
ATSDR Actions:
Based on the degree of hazard posed by the site and the presence of sufficiently defined current, past, or future completed exposure pathways, one or more of the following public health actions can be recommended:
CATEGORY C: INDETERMINATE PUBLIC HEALTH HAZARD
This category is used for sites when a professional judgement on the level of health hazard cannot be made because information critical to such a decision is lacking.
Criteria:
This category is used for sites in which "critical" data are insufficient with regard to extent of exposure and/or toxicologic properties at estimated exposure levels. The health assessor must determine, using professional judgement, the "criticality" of such data and the likelihood that the data can be obtained and will be obtained in a timely manner. Where some data are available, even limited data, the health assessor is encouraged to the extent possible to select other hazard categories and to support their decision with clear narrative that explains the limits of the data and the rationale for the decision.
ATSDR Actions:
Public health actions recommended in this category will depend on the hazard potential of the site, specifically as it relates to the potential for human exposure of public health concern. Actions on the recommendations may have occurred before the actual completion of the public health assessment.
If the potential for exposure is high, initial health actions aimed at determining the population with the greatest risk of exposure can be recommended. Such health actions include:
If the population of concern can be determined through these or other actions, any of the remaining follow-up health activities listed under categories A and B may be recommended.
In addition, if data become available suggesting that human exposure to hazardous substances at levels of public health concern is occurring or has occurred in the past, ATSDR will reevaluate the need for any follow-up.
This category is used for sites where human exposure to contaminated media may be occurring, may have occurred in the past, and/or may occur in the future, but the exposure is not expected to cause any adverse health effects.
This determination represents a professional judgement based on critical data which ATSDR considers sufficient to support a decision. This does not necessarily imply that the available data are complete, in some cases additional data may be required to confirm or further support the decision made.
Criteria:
Evaluation of available relevant information* indicates that, under site-specific conditions of exposure, exposures to site-specific contaminants in the past, present, or future are not likely to result in any adverse impact on human health.
*Such as environmental and demographic data; health outcome data; exposure data; community health concerns information; toxicologic, medical, and epidemiologic data; monitoring and management plans.
ATSDR Actions:
The following health actions, which may be recommended in this category, are based on information indicating that no human exposure is occurring or has occurred in the past to hazardous substances at levels of public health concern. One or more of the following health actions are recommended for sites in this category:
However, if data become available suggesting that human exposure to hazardous substances at levels of public health concern is occurring, or has occurred in the past, ATSDR will reevaluate the need for any follow-up.
This category is used for sites that, because of the absence of exposure, do NOT pose a public health hazard.
Criteria:
Sufficient evidence indicates that no human exposures to contaminated media have occurred, none are now occurring, and none are likely to occur in the future.
ATSDR Actions:
APPENDIX D: Response to Public Comments
1. In many places in the document phrases such as "no evidence exists" are used to describe potential health threats. This may be technically correct, but we believe that it would be clearer and more accurate to say something such as "little scientific study has been conducted, and currently no evidence exists" in most of these places.
Changes have been made to address this concern. Suggested language will be used or current phrases will be qualified with an indication as to the amount of negative studies that are available.
2. When we met with representatives from ATSDR we passed along a question from a past resident of Mallard's Landing regarding any possible link between area contaminants and Idiopathic Thrombocytopenic Puppura. At the same meeting the Whatcom County Health Officer acknowledged that he knew of a number of cases of Idiopathic Thrombocytopenic Puppura, and that that number seemed suspiciously high to him. Please address this question.
This health concern was not communicated to DOH. No sampling data were located for the former well at Mallard's Landing. According to DOH public drinking water records, this water system has been inactive since August 1979. Century Water Association currently supplies drinking water to Mallard's Landing. This source is listed as being active since February 1980. Periodic testing of this water supply since 1992 has not detected any of the pesticides associated with groundwater contamination in the area. However, no data were located for this system prior to 1992. For more information on the drinking water supply that served residences at Mallard's Landing please contact the WCHHS at 360-676-6724.
The PHA evaluated exposure and the potential for adverse health effects. Evaluating the relationship between an environmental exposure and a specific health condition requires an epidemiologic investigation that examines the potential relationship between occurrence of a health effect and an exposure. Such an investigation does not appear warranted based on the lack of contamination in the well serving Mallard's Landing.
The condition called idiopathic thrombocytopenic purpurea is characterized by a reduction in blood platelets due to the presence of a substance that agglutinates platelets.(e) By definition, the cause of this condition is unknown. In general, it is important to consult a physician when dealing with a specific health condition. DOH can supply your physician with information relative to the exposure and contaminants in question. In addition, there are physicians located throughout the state who specialize in environmental health. ATSDR supports one such group of physicians, the University of Washington's Occupational and Environmental Medicine Program located at Harborview Medical Center. For more information about physicians who specialize in environmental health in your area, please contact Sandi Shaw (DOH) toll-free at 1-877-485-7316 or directly at 360-236-3179.
3. The recent EPA investigation found fairly high levels of 1,3 DCP in groundwater samples. Our research has found that studies of 1,3 DCP show it to be a more potent carcinogen than 1,2 DCP. Why is contamination of groundwater by 1,3 DCP not mentioned in the entire assessment?
Analysis of groundwater samples taken by EPA during August and September 1998 detected 1,3 dichloropropane in seven groundwater samples at a maximum of 2.95 ppb.(f) Two of these detections came from private drinking water wells on Birch Bay-Lynden Road while the remaining detections came from monitoring probes. Analysis of groundwater samples taken by Ecology during June, September and October 1998 detected 1,3-dichloropropane in 4 samples at a maximum of 0.14 ppb.(g) 1,3-dichloropropane is produced only for use as an intermediate in the manufacture of other chemicals. Detections of 1,3-dichloropropane in groundwater may be the result of its presence as a contaminant in pesticide mixtures containing 1,3-dichloropropene as the active ingredient. No data on cancer potency were located for 1,3-dichloropropane and no RfDs or MRLs exist for this chemical. Due to its infrequent detection at very low levels, 1,3-dichloropropane was not selected as a contaminant of concern.
The chemical 1,3-dichloropropene is currently used as a soil fumigant but was not detected in any samples during the 1998 EPA and Ecology site investigations. Its use on raspberries is restricted to fumigation of soil prior to replanting. The California Environmental Protection Agency lists both 1,2-DCP and 1,3-dichloropropene in their report entitled, "Criteria for Carcinogens", released by the Standards and Criteria Work Group. This list of cancer potency factors shows that 1,3-dichloropropene has an oral cancer potency factor about three times higher than 1,2-DCP while the inhalation potencies are approximately equal. U.S. EPA currently lists 1,3-dichloropropene as a Group B2 probable human carcinogen but withdrew its cancer potency factor in October 1989 for further review.
4. In general some of the recommendations, (such as "Farm workers should observe proper re-entry times for fields applied with pesticides), may be difficult to control, and puts the onus of responsibility on the farm worker or home owner. This approach seems doomed to failure, and removes the responsibility from the pesticide applicators who are causing the problem. A better recommendation would be "Pesticide applicators should be required to ensure that farm workers observe proper re-entry times."
The role of ATSDR and DOH with respect to the public health assessment (PHA) process is an advisory one. Neither agency has regulatory authority to enforce these recommendations as that responsibility lies with other agencies (e.g., Ecology, EPA, OSHA). However, DOH does have regulatory authority to enforce drinking water regulations for public water supplies.
The recommendations contained within this PHA are designed to reduce or eliminate exposure to hazardous substances that have been determined to pose a health risk. Methods for reducing exposures of concern (risk management) are left to the regulatory agencies. DOH recognizes that some exposures of concern will not trigger a regulatory response. In such cases recommendations are targeted to the exposed population in order to provide them with guidance on how to reduce such exposure. With respect to the recommendation noted, (# 4, page 35), DOH has no information as to whether re-entry times are being observed or not. The recommendation serves to reiterate that following these existing guidelines could help reduce general exposure to pesticides. As stated in the recommendation, this information should be supplied by the employer and is also contained on the pesticide label.
5. In recommendation #5 we do not understand the rationale for only including migrant farm workers in the concern regarding combined exposure to "pesticides in soil and dust." Many of the residents in the area have nitrate contaminated wells, and are closely surrounded by agricultural pesticide use as well as the pesticides they may be using on their own yards, homes, and pets. We believe this recommendation needs to be expanded to all area residents, and needs to be backed up with a health action plan item to educate area residents about this exposure path.
It is beyond the scope of this document to address all potential sources of exposure beyond that associated with nitrate and pesticides in groundwater. The PHA addresses the potential for exposure of migrant workers to pesticides in soil and indoor dust because available data indicate that this pathway is of concern. In addition, community health concerns gathered by DOH indicated that this pathway was of concern to workers.
6. A couple of times in the report you state that "The location and boundaries of groundwater contamination plumes have not been established." Recent investigation by the EPA have found level of 1,2 DCP much higher than recorded previously, and identified new potential plumes the boundaries of which are still unknown. We believe that a recommendation and health action plan needs to be added to actively determine the extent of the contamination to ensure public health. This also needs to be accomplished before legitimate analysis of potential alternative water supplies can logically move forward.
The lack of identifiable plume boundaries is indeed of concern and does present the possibility of unidentified exposure to contaminants in groundwater. Recommendation #5 (page 36) is intended to address this issue by encouraging residents to test their wells if they live in areas of concern. DOH has already commented to Ecology regarding the Bertrand Creek site investigation and the need to identify any other plumes that might be present in hte North Whatcom county area. Ecology is proposing more sampling to address this issue and this fact will be amended to the Public Health Action Plan
7. We are deeply concerned by the Departments inability to obtain pesticide application records. In answer to question #44 you state that "Pesticide applicators are required to keep records of what they apply." Yet in three different places you state that during the year and a half this assessment took you were unable to obtain such records. Please explain who has these records, and why state and federal health officials were unable to obtain them. We believe that a logical recommendation from this inability to obtain records would be to ask for an expansion of the applicators record keeping requirements. We also believe that citizens should also have access to such records so they can determine what is being used in their areas since citizens are required to cover the costs of protecting their health by testing their wells.
The PHA has been updated to reflect information on current pesticide use. The formal PHA process dates back to the initial acceptance by ATSDR of a community petition on November 16, 1998. At this time ATSDR agreed to conduct an exposure investigation and asked DOH to prepare a health consultation and conduct community health education. On March 30, 1999, DOH held a public availability session in Lynden to gather community health concerns. One of the concerns raised was related to current applications of pesticides. DOH pursued this information by contacting a pesticide applicator that serves berry growers in the north Whatcom County area. Unfortunately, no data were exchanged despite a verbal agreement to do so.
Applicators are required to keep files on pesticide application and make them accessible to the Washington State Department of Agriculture (WSDA). However, these are not public records. DOH contacted a local pesticide applicator and several state and federal agencies in order to obtain information concerning current use of pesticides on raspberry fields. Raspberry fields are the predominant crop in the north Whatcom County area. It is clear that there are several pesticides for a raspberry grower to choose from and not all growers will use the same pesticides in the same amounts. In order to make their crop profitable, growers tend to use as little pesticide as possible since the costs of such use can be significant. For example, a soil test for nematodes is often a prerequisite for determining the need for fumigation of a field. The market also dictates pesticide use since growers sending their harvest to juice makers will use less fungicide than those harvesting for produce.
Discussions with WSDA indicated that summary statistics provided by the USDA provide the best information with regard to pesticide usage on raspberry fields in the State of Washington. This information is presented in Appendix E. More complete information is available on the Internet at "http://pestdata.ncsu.edu/cropprofiles/Detail.CFM?FactSheets__RecordID=55". The USDA information provides an excellent overview of recent pesticide use organized by crop and state.
House Bill 2741, which is currently before the state of Washington legislature, calls for a pesticide use tracking system to be established that will make pesticide use information readily available to the public. Several factors play a role in determining whether a pesticide applied on a field will be a threat to a drinking water well. Among these factors are type of pesticide application (i.e., soil versus foliar), chemical physical properties of the pesticide, amount applied, frequency of application, movement of groundwater, location of drinking water wells and type of aquifer. If you are concerned about pesticides in your well and how to test for them, please contact the WCHHS at 360-676-6724 or DOH toll-free at 1-877-485-7316.
8. Your recommendations do not mention the need for pollution prevention. In a shallow aquifer, such as the one in northern Whatcom County, contamination can only be avoided if farmers, residents, and businesses all reduce the use of potential contaminants, and handle the contaminants they do use correctly. Local government also needs to provide adequate zoning to protect this valuable drinking water source. These ideas should form the foundation of protecting the public health and should be included in your recommendations.
Source reduction of pollutants entering the environment is an important aspect of public health protection. This comment speaks to the need for a reduction in "background" exposure as part of a valid attempt to reduce overall health risk. An additional recommendation directed at the WCHHS will be added regarding their participation in ongoing efforts to reduce the potential for pesticide and nitrate groundwater contamination in the north Whatcom County area..
This recommendation will be made with the understanding that efforts are already underway to achieve this goal. A local ordnance was passed in 1998 restricting the use of manure with respect to where and when it can be applied. In addition, WCHHS is working with local planning boards to prevent the siting of new private drinking water wells in areas of known contamination. WCHHS will continue efforts to implement Integrated Pesticide Management practices as specified in the Abbotsford Sumas International Task Force Agriculture Plan. WCHHS will also be involved in future activities relating to protection of the Sumas-Blaine aquifer that could include designating this aquifer as a Groundwater Management Area.
9. Finally, many of the public health actions already taken, and those yet to come, will take a significant amount of money. Please include an action plan for paying for ongoing programs, so these issues don't fall through the cracks like they did in the 1980s. We do not think that it is fair for taxpayers to continue to subsidize these cleanup costs so chemical companies can continue to pollute and make huge profits. We would like to see a recommendation that the State Attorney General actively seek to recoup costs of alternative water supplies, as well as educational efforts, either cooperatively or through the courts, from the chemical companies that produced the pesticides of concern.
As noted previously, some recommendations are not within the scope of this document. DOH does not have the authority or responsibility to recoup cleanup costs from potentially liable parties. The state of Washington filed suit in 1988 against the Great Lakes Chemical Company to recoup costs associated with investigations of EDB contamination in groundwater. A $575,000 settlement was reached in January 1992 that defined the boundaries of investigation for four sites two of which were located in Whatcom County (Meadowdale and Bertrand Creek).
10. The summary states that "no apparent public health hazard exists for migrant farm workers exposed to pesticides in drinking water." It also states that "no apparent public health hazard exists for persons exposed to mixtures of pesticides and nitrate in drinking water at or below respective MCLs." However, the recent University of Wisconsin study that looked at exposure to mixtures of pesticides and nitrate does show that there are adverse effects. Results of this study should be reflected in the summary statements.
The summary is intended to provide the most important elements of each section of the document. Conclusion are given in the summary along with other clarifying statements. The Conclusions section (page 34) of the PHA provides more detail in support of the each conclusion.
11. In the 'recommendations' section, the draft report states that 'migrant farm workers should take steps to reduce exposure…to pesticides…" Farm workers have no control over the amount and/or type of pesticides used in their work environment and therefore cannot take steps to reduce their exposure in any meaningful way. The burden should not be placed on the farm worker. The recommendation as written is disingenuous; it should instead call for action on the part of employers and regulatory agencies in order to protect farm workers from exposure to dangerous chemicals. These action steps should include pollution prevention and the use of the precautionary principle.
Recommendation #4 emphasizes the need to observe proper re-entry times. Regulations already exist regarding re-entry times and other aspects of pesticide handling by workers. DOH has no evidence that existing regulations are not being observed. The recommendation was made to reiterate the need to follow these regulations. Recommendation #4 will be modified to reflect that the employer is in the only position to ensure that proper re-entry times are observed.
Although some exposure will invariably occur when working with pesticides or in pesticide-treated fields, workers can certainly take steps to limit their exposure. For example, farm workers can reduce the amount of pesticide contaminated soil tracked inside the home. This pathway of exposure is not readily apparent but is easily reduced by removing work clothes prior to entering the home.
12. Further, the Recommendations section states that 'residents using drinking water with nitrate at or above the MCL and detectable levels of pesticides should consider steps to reduce exposure." However, there is no mention of the migrant farm worker camps, many of which had high nitrate levels above the MCL, as well as detections of 1,2-DCP. Dept. of Health should take action to ensure that workers and their families have a safe water supply - levels of nitrate in the range found in migrant camp wells of 16 - 25 ppm are NOT acceptable. All camps except 1 had nitrate levels at or above the MCL.
The issue of nitrate and pesticide exposure of migrant camp workers is addressed in Recommendation #4. However, Recommendation #3 will be modified to include migrant camp workers. There is currently only one migrant camp well that has detectable levels of pesticides (1,2-DCP). Continued sampling of this well for 1,2-DCP is recommended along with nitrate sampling in accordance with current regulations.
13. There is no mention of current pesticide use or 1,3-DCP. Though not as persistent in groundwater, information from California shows that 1,3-DCP has 10 times the carcinogenic potential of 1,2-DCP. Potential health effects from current pesticide applications should be explored in this document.
Please see response to Comment #3.
14. The recommendations on testing for pesticides in migrant camp wells should specify that testing should be done yearly.
The Division of Drinking Water within DOH recently completed an evaluation of 150 water systems supplying 189 temporary farm worker facilities. This effort was directed by the Governor and conducted in the summer and fall of 1999. This effort covered the entire state and included all active water systems serving temporary farm worker facilities except 16 to which DOH was denied access. Analysis of drinking water samples included volatile organic compounds (VOC), synthetic organic compounds (SOC), inorganic, nitrate ans bacteria. These systems are currently required to test regularly for only nitrate and bacteria. Only two systems (1%) contained organic chemicals (EDB) above drinking water standards. Approximately 20% of these system were in violation of the nitrate standard. Based on this finding DOH concluded that current testing requirements for these wells are sufficient. Recommendation #4 was modified in light of this report which is available on the Internet at "http://www.doh.wa.gov/water/final_report.htm" or by calling DOH at (360) 236-3110.
15. Why was the EPA data, which shows concentrations of 1,2-DCP as high as 52 ppb, not mentioned in this draft report? The fact that these high levels were detected, and that the boundaries of the contamination have never been defined and thus we do not by any means have a clear idea of the total population potentially affected, should be made clear in this report.
A level of 51.4 ppb 1,2-DCP was detected in a push-probe sample taken by EPA during their 1998 site investigation and will be noted Table 1. Most of the EPA groundwater samples taken during this investigation were extracted from push-probes as opposed to drinking water wells. Push-probes serve as temporary, single-sample monitoring wells. The data summarized in Table 1, (page 7) represents groundwater samples collected from drinking water wells between 1984 and 1999. The vast amount sampling data available for drinking water wells provided a good basis for estimating actual exposure.
As discussed in the Background section of the PHA (Part C. Nature and Extent of Contamination, page 6), it is likely that several groundwater contaminant plumes exist in north Whatcom County. Extensive sampling has been conducted by several state and federal agencies as well as private well owners that have helped to delineate the areas with the highest levels of pesticides in groundwater. Ecology has proposed to re-sample pesticide contaminated wells that do not currently qualify for an alternate water source (i.e., detections below one-half the MCL). Wells located near these areas of known contamination that have not yet been sampled will also be included in the plan.
16. Page 14. "There is little evidence, however, of such synergistic effects between chemicals…" I found statements of this type to be a problem throughout the document, in light of the fact that virtually NO testing of ANY nature has been done on the synergistic effects of chemicals. This type of statement is misleading, as it implies that testing HAS been done and no adverse effects have been found, when in fact we haven't done the testing and don't have any idea what the long-term synergistic effects are.
The issue of synergy between chemicals and the toxicity of chemical mixtures in general has received considerable attention in recent years. While the database for evaluating chemical mixtures is small, relevant studies are discussed in the Public Health Implications section of the PHA (Part D. Multiple Chemical Exposure, page 17). One such study exposed rats and mice to a mixture of contaminants in drinking water that included EDB, DBCP, 1,2-DCP and nitrate at levels much higher than those encountered in north Whatcom County groundwater. No adverse reproductive or developmental effects were noted. Reproductive toxicity has been identified as an endpoint of concern in animals given high doses of EDB and DBCP. In addition, developmental toxicity is often the most sensitive endpoint of chemical exposure. Therefore, this study provides good evidence that synergistic effects between the contaminants of concern in north Whatcom County groundwater are unlikely.
17. Page 16, "..cancer risk associated with pesticides at levels of health concern is likely overestimated. There is no evidence that this level of pesticide exposure can cause cancer in humans." What data is the first statement based on, that the risk is 'likely overestimated?" In the second sentence, here again it is implied that tests of low levels of pesticide exposure have been done and have shown no increase in cancer risk. Do we have conclusive evidence that low levels do NOT cause cancer? The Department of Health should endorse the precautionary approach.
The approach used in the PHA to estimate cancer risk relies on exposure assumptions that are used to calculate a dose. Since levels of contamination vary between wells, a "worst-case" evaluation was made assuming a 30-year exposure to the maximum detected levels of each pesticide (see Appendix B). This approach ensures that exposure will not be underestimated. However, no individual is or has been exposed at this level since the maximum pesticide levels are not found in the same well. In addition, a 30-year exposure will likely be incurred in only a small percent of the exposed population. Uncertainty accompanies both the exposure and toxicity assessment components of the process. This uncertainty has made the "precautionary approach" inherent in the process of analyzing health risks associated with exposure to hazardous chemicals in the environment.
As noted in the response to Comment #1, statements noting the lack of evidence that a contaminant causes cancer in humans will be qualified.
18. Page 18. "..there is little evidence demonstrating this …." Again, is there evidence proving the contrary?
Please see response to Comment #16.
19. Page 18, last paragraph begins by discussing toxic effects from interactions between chemicals. The bulk of the paragraph then tends to discount this finding, then the last sentence suggests that there may in fact be a reason for concern. The intervening statements between the first and last sentence should be removed, as they cloud the main point that there are interactions between chemicals and there is some evidence that adverse health effects result. Also, it is not relevant when talking about chemical mixtures that the chemicals were not those detected in Whatcom County - the point is about the effects of mixtures of chemicals.
Health risk assessment is fraught with uncertainty especially with respect to chemical mixtures. This paragraph provides an overview of the preceding discussion and how the available science relates to the exposures occurring in north Whatcom County. Addressing the uncertainties involved in risk assessment is vital in making an informed recommendation.
We respectfully disagree with the final statement "it is not relevant when talking about chemical mixtures that the chemicals were not those detected in Whatcom County". The recent study from the University of Wisconsin that found mild immunological effects in mice exposed to nitrate, atrazine and aldicarb is relevant. However, these pesticides differ from those found in north Whatcom County groundwater. Even small differences in chemical structure can significantly change the metabolism and toxicity of a chemical. Further, no reproductive or developmental effects were found in rats and mice exposed to chemical mixtures that included EDB, 1,2-DCP, DBCP and nitrate. Taken as a whole, this evidence does not indicate that nitrate and those pesticides found in north Whatcom County groundwater interact to produce a toxic effect.
However, the Wisconsin study is cause for concern since the exposure levels were not the traditional high dose variety but closer to what might actually be encountered in the environment. This fact generated Recommendation #6 that advises residents to consider reducing exposure when nitrate is present above the MCL along with detectable levels of pesticides. Infants and pregnant women should not drink any water with nitrate above the MCL.
20. Page 19. "Interactions between the pesticides found in north Whatcom County groundwater and nitrate are not of concern for reproductive or developmental endpoints. " What data exists to support this statement?
Please see response to Comments 16 and 19. This issue is also discussed in the Public Health Implications of the PHA (Part D. Multiple Chemical Exposure, page 17)
21. Page 20, first line. "…no evidence exists that chronic, low doses can impact humans." Again, is there data that shows that low doses do not impact humans?
This statement relates only to liver and kidney effects seen in animals at high doses and will be revised for clarity. As noted in the text, reproductive effects have been observed in workers exposed to EDB. However, these studies have limitations with respect to statistical power, exposure assessment and appropriate control groups. Please see response to Comment #1.
22. Page 25. Risks from current pesticide applications. The Department of Health should conduct a public health assessment from current pesticide applications. 1,2-DCP has been replaced by 1,3-DCP in most cases. Although not as persistent in groundwater, 1,3-DCP is more highly carcinogenic. This fact should be noted in the public health assessment, and a follow-up study should be done.
Please see response to Comment #3. Detections of 1,3-dichloropropane were infrequent and at low levels while 1,3-dichloropropene was not detected in either of the 1998 site investigations conducted by EPA and Ecology. The data do not warrant a follow-up study.
23. Page 33, number 43. "Natural degradation will slowly remove the pesticides…" It should be noted that this process may take decades to occur.
Responses to Community Health Concerns # 42 and 43 (page 33) will be modified accordingly.
24. Page 33, number 44. Why are attempts to get information on current products and quantities (of pesticide applications) "not yet successful"? This statement is very alarming. Pesticide application information should be readily available to the public and agencies. Relevant government agencies should take steps immediately to determine why this data is not immediately available. The Dept. of Health should perform a follow-up study regarding current pesticide/fertilizer applications after obtaining this data.
Please see response to Comment #7 for information on current pesticide use. Regarding a follow-up health study on fertilizer/pesticides exposure, Recommendation #7 (page 36) suggests that the issue of concurrent exposure to nitrate and pesticides be further examined. A health study examining the relationship between adverse health effects and exposure to nitrate and pesticides will require a much more detailed exposure assessment than mere application rates for a particular field. It is likely that any such exposed population will have to be studied on a state or regional basis in order to obtain an adequate study population. It is important to note that the University of Wisconsin study is but one piece of information suggesting a further look into this type of exposure. In addition, this study looked at different pesticides, in conjunction with nitrate, than were found in north Whatcom County groundwater. It may be more appropriate for ATSDR to look at Midwest populations exposed to nitrate and those same pesticides.
25. Page 34. "…additional exposure of migrant farm workers to pesticides in soil and indoor dust is also cause for concern." There is a serious lack of data on this point. Dept. of Health should conduct a study of health risks to migrant workers and their families from exposure to pesticides and nitrate via multiple pathways.
Researchers at the University of Washington (UW) and other institutions have made significant contributions towards the understanding of worker exposure to pesticides including the indoor dust pathway. A current project by the UW is underway to determine the overall exposure of farm workers and their families to pesticides. This project will help to identify the pathways of greatest significance with respect to farm worker exposure (e.g., spray drift, soil contact, indoor dust). Recommendation #4 indicates the steps that farm workers can take to reduce their exposure to pesticides.
26. Page 35. "Farm workers should observe proper re-entry times for fields applied with pesticides." This places the burden on farm workers. It is not the decision of the farm workers as to when to re-enter a field.
Please see response to Comment #11.
27. Page 35. Dept. of Health should undertake a study of health risks to farm workers and their families from chronic exposure to pesticides and nitrate through multiple exposure pathways.
The University of Washington (UW) and the Fred Hutchinson Cancer Research Center are currently evaluating exposure of workers and their families to pesticides. This project is part of a larger effort by the UW to evaluate various environmental health issues under a grant from the EPA and the National Institute of Environmental Health Sciences. DOH currently evaluates discrete incidences of pesticide exposure to workers as part of the Pesticide Incidence Reporting and Tracking Review Panel.
The UW study will be helpful in discerning the major exposure pathways for farm workers. Concerning the evaluation of health effects as a result of nitrate exposure in combination with these multiple pesticide exposure, Recommendation #7 encourages such an effort. DOH has asked ATSDR's Division of Health Studies to consider whether such an effort is feasible and warranted.
28. Page 35. All wells in migrant farm worker camps should be tested yearly for pesticides and nitrate.
Please see response to Comment #14.
29. Page 37/38 - Action Plan. Dept. of Health should commit to studying synergistic effects of exposure to multiple chemicals, including farm workers and their families through multiple pathways.
Please see response to Comment #27.
30. Page 37/38 - Action Plan. Dept. of Health should undertake steps to conclusively determine the extent of the groundwater contamination in north Whatcom County.
Ecology is currently implementing another sampling plan (Phase III) to better determine the extent of groundwater contamination and the need for an alternate water source.
APPENDIX E: Current Pesticide Use on Raspberry Fields in Washington State
The information presented below in Tables A1 and A2 was obtained from the USDA Office of Pest Management Policy and the Pesticide Impact Assessment Program and is provided in response to questions raised about the current use of pesticides in north Whatcom County. This information is specific to raspberries as they are the major crop in north Whatcom County. More complete information regarding pesticide use on raspberries can be accessed on the Internet at "http://pestdata.ncsu.edu/cropprofiles/Detail.CFM?FactSheets__RecordID=55".
The reader should be aware that application rates will vary between growers. Table A2 provides a typical application profile for a grower targeting high-end markets such as produce. Growers selling to lower-end markets such as juice are expected to use about half of the fungicide estimated in Table A2. In addition, not all pesticides are applied annually. The soil fumigant 1,3-dichloropropene (Telone II®) is not listed in Table A2 because it is used only prior to planting and not on existing fields.
Table A1. Estimate of Usage of the Most Common Pesticides* in
Raspberries in Washington State During the 1997 crop year
|
Pesticide
|
% Area treated
|
# Applications
per year |
Lb. AI/acre
per application |
Lb. AI/treated acre per
season
|
| Insecticides | ||||
| »»Bifenthrin** |
81
|
1.0
|
0.10 | 0.10 |
| Bt |
46
|
2.1
|
||
| »»Diazinon |
77
|
1.4
|
1.10 | 1.54 |
| Esfenvalerate |
36
|
1.0
|
0.06 | 0.06 |
| »»Malathion |
44
|
1.0
|
1.07 | 1.07 |
| Fungicides |
|
|
||
| »»Benomyl |
76
|
1.7
|
0.49 | 0.83 |
| »»Captan |
94
|
5.0
|
1.17 | 5.85 |
| Ferbam |
61
|
1.3
|
1.23 | 1.60 |
| Iprodione |
71
|
1.3
|
0.60 | 0.78 |
| »»Lime Sulfur |
70
|
1.0
|
9.16 | 9.16 |
| »»Metalaxyl |
49
|
1.2
|
0.49 | 0.59 |
| Vinclozolin |
58
|
2.6
|
0.54 | 1.40 |
| Herbicides *** |
|
|
||
| »»Diuron |
31
|
1.0
|
0.97 | 0.97 |
| Norflurazon |
4
|
1.0
|
1.20 | 1.20 |
| »»Oryzalin |
62
|
1.0
|
1.20 | 1.20 |
| »»Oxyfluorfen |
74
|
1.0
|
0.10 | 0.10 |
| »»Paraquat |
85
|
1.1
|
0.32 | 0.35 |
| Sethoxydim |
5
|
1.0
|
0.19 | 0.19 |
| »»Simazine |
56
|
1.1
|
0.62 | 0.68 |
Source: Adapted from the National Agriculture Statistics Service, USDA Pesticide Data Program, Fruit summary for the 1997 Crop Year. URL: http://www.usda.gov/nass/pubs/estindx1.htm#agchem
* Limited to pesticides used to control insects, diseases, and weeds only.
** Materials shown in red or marked with this symbol (»») are heavily relied upon and have few or no currently registered and effective substitutes.
*** Discrepancies in rates between this table and text in the weed control section are due to different methods of reporting. The text shows labeled rates per acre. Because these materials are typically applied in 3-4 ft. wide bands in the row, actual use per acre is 30-40% of the labeled/broadcast rate as shown here.
Table A2. Typical Pesticide Spray Program for the Year
On an Average Farm
| Date | Pesticide | Lbs ai/acre | Method | Target Pest* | Crop Stage |
| March | Diazinon |
2.0
|
Banded | Crown borer | Dormant |
| Diuron |
1.6-2.4
|
Banded | Weeds | Dormant | |
| Metalaxyl |
0.5
|
Banded | Root rot | Dormant | |
| Late March | Lime Sulfur |
9
|
Foliar | Cane diseases | Delayed dorm. |
| Early April | Oxyfluorfen |
0.1
|
Directed base | Cane burn | Pre-bloom |
| Early May | Captan |
2.0
|
Foliar | SB | Pre-bloom |
| Mid May | Captan |
2.0
|
Foliar | SB | Early Bloom |
| Iprodione |
0.5
|
Foliar | Botrytis, SB | Early Bloom | |
| Diazinon |
1.0
|
Foliar | Fruitworm | Early Bloom | |
| Late May | Captan |
2.0
|
Foliar | Botrytis, SB | Bloom |
| Early June | Captan |
2.0
|
Foliar | Botrytis, SB | Bloom |
| Vinclozolin |
0.5
|
Foliar | Botrytis | Bloom | |
| Mid June | Captan |
2.0
|
Foliar | Botrytis, SB | Bloom |
| Late June | Captan |
2.0
|
Foliar | Botrytis, SB | Pre-Harvest |
| Iprodione |
0.5
|
Foliar | Botrytis, SB | Pre-Harvest | |
| Bifenthrin |
0.1
|
Foliar | Insects | Pre-Harvest | |
| August | Benomyl |
0.375
|
Foliar | Cane blight | Post-Harvest |
| Fenbut. Oxide |
1.0
|
Foliar | Spider Mites | Post-Harvest | |
| October/Nov | Fenamiphos |
6.0
|
Banded | Nematodes | Post-Harvest |
Source: WSU Vancouver, Lynden Satellite Station IPM Project (1998) and personal communication with raspberry growers
*Target pest codes where abbreviated:
· Crown borer: Raspberry Crown Borer, Pennisetia marginata
· Root rot: primary target is Phytophthora fragariae var rubi
· Cane burn: Primocane suppression
· SB: Spur Blight, Didymella applanata
· Botrytis: Gray mold fruit rot; Botrytis cinerea
· Insects: Adult root weevils and miscellaneous harvest- contaminating insects and spiders
· Nematodes: Root Lesion Nematodes, Pratylenchus spp.
This Whatcom County Groundwater Public Health Assessment was prepared by the Washington State Department of Health under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was begun.
Debra Gable
Technical Project Officer, SPS, SSAB, DHAC
ATSDR
The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and occurs with the findings.
Richard Gillig
Chief, SPS, SSAB, DHAC
ATSDR
