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HEALTH CONSULTATION

Perchlorate Contamination in the Arden Cordova Water Service Area

AEROJET-GENERAL CORPORATION
RANCHO CORDOVA, SACRAMENTO COUNTY, CALIFORNIA


Table 1:

Cordova System Well Descriptions and Perchlorate Sampling Results
Well Drawing Depth
(ftbgs)
Status of Well Description of Service Neighborhood Description of Use Perchlorate Analysis (ppb)
Februaryb
Perchlorate Analysis (ppb)
March
11/13/18/ 24/25/27c
Perchlorate Analysis (ppb)
April
9 or 10c
Perchlorate Analysis (ppb)
May
12/15/13c
Perchlorate Analysis (ppb)
June
18/19/20c
Perchlorate Analysis (ppb)
July 9d
Perchlorate Analysis (ppb)
August 13e
1-Alicante 102-306   Commercial Summer and Fire Flows <35 4.0 a ns 4.0 a 4.0 a 4.0 a 4.0 a
2- --- Destroyed                  
3-Gilbert 152-240   Residential Summer and Fire Flows ns 4.0 a ns 4.0 a 4.0 a 4.0 a 4.0 a
4-El Segundo 102-306   Residential Summer and Fire Flows ns 4.0 a ns 4.0 a 4.0 a 4.0 a 4.0 a
5-Marcel 152-480   Residential Daily in Summer ns 4.0 a ns 4.0 a 4.0 ns 4.0
6-Dolecetto 152-405   Residential Daily ns 4.0 a ns 4.0 a 4.0 a 4.0 a 4.0 a
7-Georgetown 240-445   Residential Daily, Continuous Summer ns 4.0 a ns 4.0 a 4.0 4.0 4.0 a
8-Agnes 250-470   Residential Daily in Summer ns 4.0 ns 4.0 4.0 4.0 4.0
9-McGregor 233-460 Off-line- 9/95
Destroyed- 11/97
Residential Fire Protection only ns ns 65 ns ns ns ns
10-Negrara 276-416   Residential Fire Protection ns 4.0 ns ns ns ns 4.0
11-Cristobal 214-468 Off-line 4/8/97 thru 6/19/97 Residential Daily, Continuous in Summer ns 4.4 5.1 4.0 a 4.0 a 4.8 4.2
12-Woodcliff 268-556   Residential Manual On ns 4.0 ns 4.0 4.0 <4.0 4.0
13-Citrus 222-500 Off-line- 2/11/97 Residential Continuous 220/220* 260 250 250 320 ns 310
14-Whistler 236-446 Off-line 4/8/97 thru 6/19/97 Residential Daily, Continuous in Summer <35 4.4 4.0 11 8.7 4.8 4.2
15-Folsom Blvd. 237-568 Off-line- 2/11/97 Commercial Continuous 95/65* 120 120 130 140 120 140
16-Pyrites 195-565 Off-line- 2/11/97 Commercial Continuous 210/220* 240 250 240 270 260 260
17-Park 89~271   Residential / Park Daily ns 4.0 ns 4.0 4.0 ns 4.0
18-Mather Field 363-533 Date Drilled - 05/86 Commercial Daily ns 4.0 ns 4.0 4.0 4.0 4.0
19-Kilgour 330-575 Date Drilled -
3/88
Off-line 4/8/97 thru 6/19/97
Commercial Daily <35 6.8 7.6 12 4.0 11 8.5
20-Coloma 430-590 Date Drilled -
10/92
Commercial Continuous ns ns 4.0 4.0 4.0 4.0 4.0
21-Gold Country 290-580 Date Drilled -
6/94
Residential - <35 4.0 ns 4.0 a 4.0 a 4.0 4.0

*= average of triplicate

ns= not sampled

a= Perchlorate detected at a concentration <4.0 ppb, but not quantitated

b= Data taken from Reference (11)

c=Data taken from Reference (13)

d=Data taken from Reference (14)

e= Data taken from Reference (15)

ft bgs= feet below ground surface

Table 2:

Perchlorate Contamination in the Cordova System-
Completed Exposure Pathway for Different Receptor Populations
Receptor Group Pathway Name Source Environmental medium Point of Exposure Route of Exposure Exposed Population Time
Residential Exposure in the Cordova System Aerojet, McDonnell Douglas (?) Groundwater wells in the Cordova System Groundwater wells in the Cordova System Ingestion Adult Residents Past
Current
Worker exposure in the Cordova System Aerojet, McDonnell Douglas (?) Groundwater wells in the Cordova System Business Tap Ingestion Workers Past
Current
Frequent customer or visitor to a business in the Cordova System Aerojet, McDonnell Douglas (?) Groundwater wells in the Cordova System Business Tap Ingestion Frequent customer;
Frequent visitor
Past
Current

Table 3.

Exposure Factors for Each Receptor Population of the Completed Exposure Pathway in the Cordova System
Receptor Group Pathway Name Exposure Parameter Value
Resident exposure in the Cordova System Ingestion Rate 2 liters (8.4 cups)/day
Body Weight 70 kilograms (154 pounds)
Exposure Frequency 7 days/week
52 weeks/year
Averaging factor 365 days/year
Worker exposed at a business served by the Cordova System Ingestion Rate 3.7 liters (15.6 cups)/day
Body Weight 70 kilograms (154 pounds)
Exposure Frequency 8 hours/day
5 days/week
50 weeks/year
Averaging factor 365 days/year
Frequent customer or visitor to a business in the Cordova System Ingestion Rate 0.24 liters (1 cup)/visit
Body Weight 70 kilograms (154 pounds)
Exposure Frequency 5 visits/week
50 weeks/year
Averaging factor 365 days/year

Figure 1. Perchlorate Groundwater Plume in Relation to Aerojet and Cordova Water System
Figure 1. Perchlorate Groundwater Plume in Relation to Aerojet and Cordova Water System

Figure 2. Well Locations and Names for Cordova Water System
Figure 2. Well Locations and Names for Cordova Water System




ATTACHMENTS

Attachments A-E were not available in electronic format for conversion to HTML at the time of preparation of this document. To obtain a hard copy of the document, please contact:

Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Attn: Chief, Program Evaluation, Records, and Information Services Branch, E-56
1600 Clifton Road NE, Atlanta, Georgia 30333


APPENDIX A. RESPONSE TO COMMENTS FROM SITE TEAM REVIEW

In 1995, EHIB formed a site team to assist us in identifying public health concerns and to oversee what we do during the health assessment process for the Aerojet General site. The site team is composed of community residents, state and federal environmental and health agency staff, Aerojet staff, as well as EHIB staff. Health consultations that are produced as apart of the health assessment process are released for comment to site team prior to them becoming final. We received comments on this health consultation from the Drinking Water Branch of CDHS, U.S. EPA, DTSC, RWQCB, Aerojet, and a community member. In this appendix, we will respond to the submitted comments.

COMMENTS RECEIVED FROM THE DRINKING WATER BRANCH OF CDHS

The Drinking Water Branch of CDHS regulates water purveyors in the state, and their comments were minor technical corrections to the numbers we cited in the text. These corrections were made to the original document.

COMMENTS RECEIVED FROM A COMMUNITY MEMBER ON THE SITE TEAM:

We received comments with attachments from one community member. It was not possible to add the attachments to the document.

Community member's comment: Page 1, bottom of paragraph 3. Is Purity Oil still a suspect?

CDHS response: We are listing this company as a source being investigated by the regulatory agencies, but we are not aware of the status of the source investigation since we are not a part of this on-going investigation.

Community member's comment: Page 3, 1st paragraph. Mike Benbow and Paul Shubert of ACWS told me in the first week of January, 1997 that Well 9 was shut down on Christmas Eve 1996 and that it was "being destroyed as we speak. " Obviously it wasn't destroyed, since it was sampled at a later date.

CDHS response: In Table 1, we had indicated that well #9 was taken off-line on September 1995. However, even though the well was not being used as a water source for the Cordova System after this date, it was not destroyed (filled with concrete) until November 1997. Thus it was possible to sample the well until fairly recently. When the well was pumped to take a sample, no water from the well was added to the Cordova System.

Community member's comment: Page 4, third paragraph. ACWS was officially aware of potential perchlorate contamination in early January 1997 when they sent a letter to Robert McGarvey of the Rancho Cordova Incorporation Committee. This letter acknowledged information on perchlorate I had given Mike Benbow of ACWS in December.

CDHS response: While Southern California Water Company was made aware of a potential perchlorate problem in January 1997, it was not until February 11, 1997 that they were notified of any well sample results that showed perchlorate to be present in their wells.

Community member's comment: Fourth paragraph. The Sacramento Bee was absent from the March 18, 1997 meeting. People who received highest exposures next to perchlorate from Well 13 are not aware they have been exposed because they are renters.

CDHS response: Comment noted.

Community member's comment: Page 5, third paragraph. See my comments on Perchlorate in Drinking Water, May 1997.

CDHS response: The fact sheet is already finalized and was added to this health consultation as an attachment for reference only. At this time, we are not planning on revising it.

Community member's comment: Page 6, second paragraph. I'm eager to learn more about re-injection in 1984. See my Hypothesis I on distribution of perchlorate in Rancho Cordova.

CDHS response: CDHS appreciates the various hypotheses that have been put forth by the community member and while it is not the place to respond to them here, we will take them into consideration as we continue to work on the site.

Community member's comment: Page 7, third paragraph. What are the relevant chemical similarities of cadmium chloride and perchlorate? Is there any thinking that perchlorate's chaotropy in solution acts in a manner similar to cadmium or mercury?

CDHS response: The most relevant characteristic is that both chloride and perchlorate are anions. According to a highly regarded dermal absorption reference source, the permeability of charged ions is extremely low and membranes appear to be more permeable to cations than anions (42).

Community member's comment: Page 7, fifth paragraph. My concern for nitrate-perchlorate synergy was based on a proposed perchlorate reference level of 400 p.p.b. when the baby bottle model suggested that 500 p.p.b. Apparently there are more sophisticated toxicological concerns about perchlorate at lower concentrations, so nitrate-perchlorate synergy is not an issue for me at this time.

CDHS response: Comment noted.

Community member's comment: Page 8, first paragraph. Are you certain there were only seven fatalities? I'll double-check.

CDHS response: We were quoting a second-hand report in which it was stated that there were seven fatalities; however, since this may not reflect the total number, we revised the text so that we did not have to indicate how many deaths had occurred due to aplastic anemia developing in Graves' patients treated with potassium perchlorate.

Community member's comment: page 8, second paragraph. The physiological differences between children and adults do not make comparison of perchlorate effects between them a two-tailed test -- children being more robust than healthy adults in matters of iodine deficiency is not a possible outcome. Given the need for iodine in infant neurological development, there is no way infants can be more resilient than adults in this regard. Theoretically, the uncertainties should demand a lower reference level of 4 p.p.b. But the twin specters of a consumer scare on Imperial Valley produce and mobs of irate hypochondriacs in Orange County and San Diego dictate the 18 p.p.b. reference limit not be lowered to take children into account until more is known.

CDHS response: Based on this comment and similar comments by others, we have added more information about the importance of the thyroid for a developing child and other information about the physiology of a child that make them more sensitive to insults on the thyroid.

Community member's comment: page 8, third paragraph. I have serious problems with calling an acute half-blocking of thyroid iodide uptake a no-observable-adverse-effect. I'd like to talk about this with Dr. Peter Houser of the U.S. E.P.A.'s Endocrine Disrupter Screening Test Advisory Committee. My idea of thyroid NOAEL is TSH levels below the TSH minimum prompted by thyroid autonomy (i.e. greater sensitivity to TSH by the thyroid).

CDHS response: Comment noted.

Community member's comment: Page 9, first paragraph. How about perchlorate inducing hypothyroidism that leads to preferential absorption of carcinogenic I-131? See Hypothesis I, Test B.

CDHS response: We consulted with thyroid experts about this comment, and no one was aware of any evidence that suggested a person with hypothyroidism would preferentially absorb or incorporate radioactive iodine into the thyroid or thyroid hormone. We are also unaware of the Rancho Cordova area being affected by releases from Rancho Seco, and whether there were any releases of I-131 in particular.

Community member's comment: Page 9, fourth paragraph. See comment on page 8, second paragraph.

CDHS response: See previous response to similar comment.

Community member's comment: Page 10, first paragraph. I do not agree with the conclusion "it is unlikely that the residential exposure to well #13 did cause any non-cancer health effects." Reference Appendix II.E.F.

CDHS response: Comment noted.

Community member's comment: Page 12, second paragraph. Exposure as early as 1987, see Hypothesis 1.

CDHS appreciates the various hypotheses that have been put forth by the community member and while it is not the place to respond to them here, we will take them into consideration as we continue to work on the site.

Community member's comment: Page 13, second paragraph. I'm not sure about the conclusion of safety below 18 p.p.b. Until more is known, I now avoid my tap water.

CDHS response: Comment noted.

Community member's comment: Page 13, eighth paragraph, Planned Action 2, Genetic Disease Branch data - while you're checking thyroid problems, you might look into the Angelman's syndrome variant that involves a break in chromosome 15. Grandmother from Well 13 area reports her daughter and two of her friends from Cordova High have children with this malady.

CDHS response: The Genetic Disease Branch does not collect information about Angelman's syndrome and we have no reason to suspect, based on chemical characteristics or toxicological mechanism, that perchlorate exposure would cause chromosomal abnormalities.

Community member's comment: Page 14, first paragraph. Will Food and Drug Administration be involved with Perchlorate Group's bioconcentration study?

CDHS response: We can not answer for the Air Force or the Perchlorate Study Group, but we are not aware that the U.S. Food and Drug Administration is involved in the perchlorate studies.

Community member's comment: Page 14, second paragraph. I heard first report in April.

CDHS response: Comment noted.

Community member's comment: Recommendations for further action: Revise Fact sheet? Poll local endocrinologists and map ratio of their toxic nodular goiter/graves disease cases by zip code? See Baltisberger, Minder, and Burgi's "Decrease of incidence of toxic nodular goiter in a region of Switzerland after full correction of mild iodine deficiency" in the European Journal of Endocrinology 1995, 132: 546-549.

CDHS response: We are willing to issue another fact sheet that deals with the perchlorate issue when there is new information that would make another fact sheet needed, at this time we do not believe this is needed. We have looked into goiter as a possible health outcome, but at this time we are going to focus our efforts on studying newborn thyroid function.


COMMENTS RECEIVED FROM THE U.S ENVIRONMENTAL PROTECTION AGENCY

The EPA offers the following comments for your consideration:

USEPA comment: Page 7 - fourth sentence - the statement that "ammonium perchlorate has relevant physical and chemical characteristics similar to cadmium chloride does not appear to be justified. Although both of these compounds are salts, on dissolution (a necessary step in absorption) perchlorate would become an anion (negative charge) and cadmium would become a cation (positive charge). Therefore, one could conclude on this basis alone that cadmium would not be an appropriate surrogate for perchlorate. Comment applies to all reports but Fair Oaks Water District Report.

CDHS response: According to a highly regarded dermal absorption reference source, the permeability of charged ions is extremely low and membranes appear to be more permeable to cations than anions (42). Thus, the comparison of perchlorate should not be made between the cation, cadmium, but the anion, chloride, that is found when cadmium chloride is in solution.

USEPA comment: Page 8 - third paragraph - NOAEL term use - The NOAEL is an experimentally derived value that is often used as a basis for the RfD, however, the NOAEL is not regarded by EPA as a value that "would not be expected to be associated with any adverse effect". Rather, this definition better fits the RfD that is derived from a NOAEL after considering uncertainties in the database. Comment applies to all reports but Fair Oaks Water District Report.

CDHS response: We have corrected the use of NOAEL and RfD in the text.

USEPA comment: Page 11 - last paragraph - Suggest changing the text from "noncancer (thyroid depression) health effects would not have occurred . . ." to" would not be expected".

CDHS response: We preferred the original wording, so no changes have been made to the text.

USEPA comment: Page 23 -Table 3 - Worker exposure - The tap water ingestion rate for workers is listed as (3.7 liters/day) which is almost twice the assumption that is used for a residential scenario. Should this be 0.37? This applies to Mather Air Force Base Water Service Area Report Table 3 - page 21 and the Sunrise District of the Sacramento County Water Service Report Table 2 - page 18. Also, the Citizens Utilities' Suburban & Security Park Water Service Areas Report Table 3 - page 19 lists worker exposure at 2.0 liters/day should this be 0.37?

CDHS response: We are using a reference from USEPA document entitled "Exposure Factors Handbook", published in 1989. In this document, the total fluid intake for a moderately active man is cited as being 3.7 liters/day. This document cites the Report of the Task Group on Reference Man from the International Commission on Radiological Protection, published in 1981 for this number. This higher intake of water does seem appropriate given the labor-intensive commercial businesses that are located near the perchlorate-contaminated wells.

USEPA comment: Figure 1 - Is it possible to make the Cordova System standout? Found figure hard to use.

CDHS response: Unfortunately, this figure is copied from a hard copy and is not electronically produced, so it is probably not possible to improve upon the quality.

COMMENTS RECEIVED FROM THE CALIFORNIA DEPARTMENT OF TOXIC SUBSTANCES CONTROL

Below are DTSC's comments which may be considered as the documents are finalized.

DTSC comment: In the "Exposure Pathways" sections of the Arden Cordova, Mather Air Force Base and the Sacramento County water district consultations, it is stated that Aerojet began reinjecting water from their treatment plants on the west boundary of the site in 1984 and 1985. The assumption is then made that it took "a couple of years for the perchlorate to move from the reinjection wells" to the water district's wells. An accurate assessment of when the perchlorate contamination occurred and the location of the source of the perchlorate cannot be made without further information and analysis. The reinjection field may not be the source of the perchlorate contamination in many of the affected wells. Aerojet is currently investigating the extent of the perchlorate contamination to the west of its facility pursuant to an order from the Regional Water Quality Control Board. A technical memorandum documenting the results of that investigation is currently scheduled to be submitted in May of 1998, with an Engineering Evaluation/Cost Analysis of remedial alternatives to be submitted in October of 1999. Additional investigations of groundwater to the west of the Inactive Rancho Cordova Test Site (IRCTS), the likely source of perchlorate in several of the affected wells, are also proceeding. DTSC's Project Manager for the IRCTS is Mr. Marvin Woods who can be reached at (916) 255-3666.

CDHS response: EHIB recognizes that a good analysis of the perchlorate migration which would allow us to know when the perchlorate reached the public drinking water supply well, has not yet been done. In fact, we start off the first paragraph in the "Exposure Pathways" section by saying, "It is not clear when the perchlorate contamination reached the Cordova System wells...". However, since the reinjection of treated water is at least one source of the perchlorate found in some of the drinking water supply wells, we found it was important to share information about this source with the reader. We look forward to reviewing the reports that DTSC is referring to, and hope that they will give a more accurate picture of past well contamination levels.

DTSC comment: In the third paragraph of the consultations, it is stated that the Regional Water Quality Control Board is the lead regulatory agency. While this is correct for some aspects of the project, the lead regulatory agency controlling water district activities is the Department of Health Services, Office of Drinking Water. For matters concerning the Aerojet Superfund Site, the United States Environmental Protection Agency is the lead federal regulatory agency. A co-lead situation exists for certain matters covered under the Aerojet Superfund Site Partial consent Decree (United States District Court, Eastern District of California, Civil Action Nos. CIVS-86-0063-EJG and CIVS-86-0064-EJG).

CDHS response: Being a part of the complex government oversight at this site, we appreciate the clarification to the agency responsibilities. We have tried to rectify this in the text.

COMMENTS RECEIVED FROM AEROJET GENERAL CORPORATION:

Aerojet's comment about the attribution of source of the perchlorate in public water supply wells: Each draft Health Consultation assumes that perchlorate being found in public water supply wells came from the Aerojet Operating Plant, specifically from the reinjection wells associated with the GET facilities. There are numerous locations where such references appear. (See, for example, Arden Cordova Health Consultation at:

Page 6, paragraph 2 and page 22, Table 2.) This assumption is used to project length of exposure and concentrations in the wells over time. The conclusion is made for each well, for every water purveyor, regardless of the well's location, chemical concentrations or differing hydrogeological conditions.

We are aware of no detailed evaluation of sources, groundwater conditions and groundwater and contaminant movement undertaken by DHS or any other agency that would support statements in the DHS Consultations that attempt to link perchlorate in a well to an upgradient source, and it does not appear necessary for DHS to ascribe a source to reach its conclusions. The Health Consultations should identify that potential sources of perchlorate include the Aerojet Operating Plant, Purity Oil site, and the McDonnell Douglas (MDC) Site. DHS should not assert that the only source of the perchlorate is the GET facility recharge wells on the Aerojet Operating Plant. Neither should the period of operation of the GET wells form the basis for assumptions of exposure of potential receptors. As the Health Consultations discuss potential sources, it should discuss the various uses of perchlorate, other than in rocket motor manufacturing, such as the use of perchlorate in pyrotechnics (fireworks), explosives and other industrial activities. It should also note that perchloric acid, which is used in various industrial activities, including metal-plating, in laboratories, and in other operations, when released can result in the formation of perchlorate and its movement into soils and groundwater.

Aerojet believes that there have been no health impacts associated with any exposure to perchlorate in the water supply. If the Health Consultations seek to discuss long term impact by assuming exposure for some period (e.g., 10 years), they can do so without assigning a source, but simply by positing the potential for such exposure (without reference to a source) and developing an exposure assessment.

CDHS response: These health consultations are written as a part of CDHS's public health review of the impact of the Aerojet General site. Thus, the documents are written in respect to Aerojet General and not to other sites or facilities. We do recognize that perchlorate may have also gotten into the groundwater from sources other than Aerojet and that is why in last sentence of the third paragraph on page 1, we refer to the RWQCB's investigation of Aother sources of the perchlorate such as the McDonnell Douglas (now Boeing) and Purity Oil Sales sites.

Aerojet's comment about the toxicology: Aerojet recommends modifications to the discussion on toxicology. We are concerned that the draft consultations do not provide sufficient information about what is known about perchlorate toxicity (thyroid function) and end up, unintentionally, providing a less balanced presentation of the potential for impact and risk. For example, we believe there should be more discussion related to the past use of perchlorate in the treatment of Graves patients and its current use in Europe at very high doses without ill effects. Similarly, we recommend the inclusion of a statement that the mechanism of perchlorate on the thyroid as well as basic thyroid functions are well understood and we believe that the discussion as to exposure associated with children may lead to unnecessary concern and should be changed. Finally, we believe that there ought to be mention of the ongoing studies being conducted at the direction of the Air Force.

CDHS response: We did provide more information in the toxicology section. For instance, we have added more information about past and current uses of perchlorate and what is known and not known about toxicity to the developing fetus and young child. We did have a reference in the recommendations section about the on-going studies by the Air Force and the Perchlorate Study Group and we have added a sentence in the toxicology section referring the reader to the recommendations section for more information about these studies.

Aerojet's comment about the water system operations: The draft Health Consultations, especially in the background sections, contain statements of fact as to the manner of well and system operation of each water entity over time, including detail on well construction and operation in tables. Aerojet has not had an opportunity to complete an evaluation of the accuracy of such statements. We further note that the factual statements generally do not seem to impact the exposure assessment, as the exposure assessment is based upon an assumed concentration that is not generally associated with the specifics of well interties or well operation. We would recommend the Health Consultations state that the water system information is based on current understanding unless DHS has had the opportunity to perform a detailed evaluation of the information.

CDHS response: In each health consultation, we cite the CDHS reports or other reports from which we gained this information. We refer Aerojet to those documents if Aerojet would like to evaluate the accuracy of such statements. We do think it is important to describe for the reader the basic structure of a particular water system; on the other hand, we don't want to add more information then is necessary. We hope that the amount of information we have provided will allow a Cordova System customer to more easily understand that only some of the water wells in the system have been contaminated with perchlorate. By describing the water system information in this document, it also helps us to decide where we might consider follow-up activities, like an exposure dose reconstruction.

Aerojet's comment about the Exposure Conclusions: The draft Health Consultations are based upon a set of assumptions, including assumed receptors, exposure rates, and concentrations. From these assumptions, an assumed dose is calculated and then compared to the provisional RfD. We believe that the Health Consultations should carefully describe each assumption upon which the Health Consultations were based, and clarify that these assumptions have not been fully evaluated. For example, a preliminary assessment of proximity to a well is used to determine the type of "receptor" (e.g., resident, worker), but the exposure does not assume any dilution of water from that well with water from any other well.

CDHS response: All of the exposure parameters are listed in the table and a Cordova System user can look at these exposure parameters and apply them to their own situation. Thus it does not seem necessary to explain distributions of exposure parameters or in any other way describe each assumption. As for the concentration of perchlorate used in the calculations, in talking with Cordova System staff, they have explained that a person living next to a well may receive 100% water from that source. Thus it does seem proper to use this concentration in a dose calculation.

With these general comments identified, we now progress to the specifics. We use the Arden Cordova Health Consultation as the template for our comments, and emphasize that typically the same issue exists in the other draft Health Consultations.

Aerojet's comment: Page 1, Paragraph 2 and Throughout: The term "perchlorate contamination" is subject to misinterpretation and references should be to "water containing perchlorate" or like phrase.

CDHS's response: In Webster's New Collegiate Dictionary, it says "contaminate" means "to make impure or unclean". Perchlorate is not typically found in groundwater, as would be the case with certain chemicals like arsenic or sulfates which are naturally occurring in groundwater. Thus it does seem appropriate to describe the "contamination" of groundwater by a chemical such as perchlorate. Likewise, it may be appropriate to describe "water containing arsenic" if you are describing water which contains unusually high levels of arsenic due to natural reasons and arsenic-contaminated water if higher levels than normal may be due to non-natural reasons.

Aerojet's comment: Page 1, Paragraph 3: The description of Aerojet operations and Cordova operations has been taken from earlier documents. Aerojet has historically pointed out the inaccuracies in the statements and rather than do so again we recommend, at a minimum, elimination of a reference to Cordova Chemical Company, because we do not believe it used perchlorate. We also recommend an elimination of the reference to the deep injection wells, because they are not relevant to the issue and can result in confusion when there is later discussion about recharge or reinjection wells associated with the GET facilities, which are different wells.

CDHS response: In the background paragraph, we are describing the lay of the land regarding the general site issues and thus we did not directly suggest that Cordova Chemical did use perchlorate, but rather this company was a part of the history of the site. Since perchlorate is reinjected at the site boundary as a part of the GET operations, we do not agree that reference to these should be eliminated.

Aerojet's comment: Page 1, Paragraph 3: Delete "property" after "Aerojet's."

CDHS response: This incorrect grammar has been corrected in the text.

Aerojet's comment: Page 1, Paragraph 3: Aerojet is not reinjecting treated water at the site's northern boundary.

CDHS response: This has been changed in the text.

Aerojet's comment: Page 1, Paragraph 3: The Regional Water Quality Control Board (RB) is not the lead Agency; DTSC, USEPA and RB together provide oversight pursuant to the Partial Consent Decree.

CDHS response: The description of the lead agency/agencies was changed in the text.

Aerojet's comment: Page 1, Paragraph 4: Southern California Water Company is an "investor owned" company. We believe it to be subject to regulation as a public utility.

CDHS response: Southern California Water Company staff reviewed an earlier draft of the health consultation and this sentence reflects changes that were made based on their comment. Thus, it seems that it would be inappropriate to change this based on Aerojet comments.

Aerojet's comment: Page 2, Paragraph 1: DELETE COMMENT. Aerojet suggests replacement of the phrase: "it is unlikely that it will ever be affected" with, "and no perchlorate contamination has been detected."

CDHS response: We have not seen any data that would suggest "and no perchlorate contamination has been detected" in the Arden System; however, we don't believe based on the data that has been collected that "it is unlikely that it will ever be affected". Thus, the text was not changed.

Aerojet comment: Page 3, Continuing Paragraph: Aerojet installed carbon treatment on Well #1 6 in February of 1985.

CDHS response: We revised the text to reflect this comment.

Aerojet comment: Page 3, Paragraph 1: The discussion as to detection of perchlorate ought to be rewritten. Prior to the summer of 1996, Aerojet's laboratory used an ion specific electrode method. In 1997 Aerojet's laboratory did not use a different analytical method for perchlorate analysis to obtain the detection limit of 35 ppb but rather refined or improved the sensitivity of the existing ion chromatography method. In addition, it is accurate to say the "method" detection limit.

CDHS response: Based on this comment and a similar comment by other reviewers, the description of the analytical method was revised in the text.

Aerojet comment: Page 4, Continuing Paragraph: There is no Appendix A.

CDHS response: This was corrected to "Attachment A".

Aerojet comment: Page 4, Paragraph 2: Reference should be to 1997, not 1977.

CDHS response: This was corrected in the text.

Aerojet comment: Page 4, Paragraph 3: The manner in which the audience was asked to respond, the lack of any information as to what each person who responded intended, and the differences in views as to the percentage of persons responding, makes the reference to the hand raising event questionable in a Health Consultation. We suggest it be deleted. If reference is made, it should point out that the reference is made to indicate potential community concern, not that a health problem exists that is associated with perchlorate. Further, the number of people at the March 1997 meeting who raised their hands to respond to an inquiry about a thyroid problem were not tallied. It would be more correct to say "a number of people in the audience responded."

CDHS response: Based on another reviewer's comment this statement was revised in the text to state "significant", rather than 80%, but we do not agree that it should be deleted, as it relates to the health concerns of the community that were expressed at a public meeting.

Aerojet comment: Page 4, Paragraph 4: The letters sent by Aerojet invited attendance to the April meeting.

CDHS response: We revised the text to reflect this comment.

Aerojet comment: Page 5, Paragraph 1: The discussion of the Regional Board's response to questions on continuing injection might lead to a misunderstanding. The Regional Board stated that it was important for Aerojet to continue extraction, treatment and recharge to control the migration of TCE and other volatile organic chemicals (VOCs). The Regional Board staff also stated that continued reinjection of the perchlorate containing water from the VOC treatment system would not affect the movement of perchlorate containing water off-site in the near future.

CDHS response: Since RWQCB did not comment on this, and we think that the description in the text essentially states the same thing as has been commented here, no changes to the text has been made.

Aerojet comment: Page 3, Paragraph 3: We believe it would be appropriate to note that it was Aerojet that notified the water purveyors of perchlorate levels in their wells.

CDHS response: We confirmed this comment with Southern California Water Company and then corrected the text.

Aerojet comment: Page 6, Paragraph 1: See the discussion above regarding the history of perchlorate sampling. It is not accurate to say that the analytical method Aerojet had been using was not sensitive to adequately assess the migration of perchlorate. It would be more accurate to state that Aerojet's historical analytical method's practical quantitation limit (PQL) for perchlorate was 400 ppb. As stated previously, there was no "alternative analytical method" used but the existing method was refined or improved and the PQL lowered.

CDHS response: According to the third sentence of the comment, the older method was indeed not sensitive enough to detect the perchlorate contamination. We did, however, revise the text to reflect the last two sentences of the comment.

Aerojet comment: Page 6, Paragraph 2 and following: This paragraph, as well as others below which need not be separately itemized, make an assumption about source and length of exposure which is not presently supportable. See discussion in general comments.

CDHS response: We realize that historical monitoring of the drinking water wells at low enough detection limits and thus we do not have a good understanding of the migration of perchlorate and past exposures to the Cordova System customers. We also realize that we have not yet seen any attempts to model the movement of perchlorate based on groundwater flow patterns and perchlorate levels in monitoring wells. Thus in trying to review the past exposures, we are left to make the best assumptions possible.

Aerojet comment: Page 6, Paragraph 5: See the comments above as to statements regarding water purveyor and system operation. We note that an assumption is made that geographical proximity to the well is the sole determinant for exposure of a receptor to a particular well. This may be a reasonable assumption for the Health Consultation being undertaken, but we are not aware of a detailed evaluation confirming the accuracy of the assumption and it should be stated as an assumption.

CDHS response: In talking with Cordova System staff, they have explained that a person living next to a well (or intertie) may receive 100% water from that source and we have added a statement in the Background Section that more clearly describes this point. Thus it does seem proper to use concentration of perchlorate measured in an individual well for dose calculation purposes; however, since this exposure dose may not reflect exposures to other Cordova System customers who live farther away from the affected wells, we have added a statement about this in the Exposure Pathways Section.

Aerojet comment: Page 8, Continuing Paragraph and following: We refer you to the general comments on toxicology above. The draft Health Consultations would be better balanced if there was more discussion related to the use of perchlorate in the treatment of Graves patients and its current use in Europe at very high doses without ill effects. A strong statement that stresses how unlikely it would be to suffer any of these side effects at the levels addressed in the health consultation would be appropriate. In particular, the draft Health Consultations ought to point out that perchlorate has been used successfully and without incident in a fairly large patient population and with a very small number of reports of aplastic anemia even at the very high therapeutic concentrations A statement that the mechanism of perchlorate on the thyroid as well as basic thyroid functions are well understood would help to clarify the presentation. While the provisional RfD is stated as a level in drinking water at 18 ppb, the remaining levels discussed in the document are stated in terms of mg/kg/day. A direct comparison of those doses with the LOAEL/NOAEL and the provisional RfD in the same unit of PPB's would be very useful to give perspective to the dose issue.

CDHS response: As noted on the response to a General Comment from Aerojet, we did provide more information in the toxicology section. For instance, we have added more information about past and current pharmacological uses of perchlorate and what is known and not known about toxicity to the developing fetus and child. We also added a statement in the toxicological section that equates the dose to the drinking water concentrations.

Aerojet comment: Page 8, Continuing and Paragraph 1: The discussion of animal studies should be modified. There are animal studies where toxicologists have interpreted a NOAEL [(e.g. Mannisto (1970) and Caldwell (1996)]. As to the reference to children, in two places there is a discussion that suggests that nothing can be said about children. Aerojet is concerned that the reference might leave the reader with the impression that toxicologists do not consider impact to the thyroid as the focus of the evaluation or it might cause the reader to think that toxicologists view the child's thyroid as not understood. It would be more accurate to state that the mechanism of perchlorate intake on the thyroid is understood and that in evaluating the dose, one must evaluate the possibility that the child may have less iodine reserve which must be considered in evaluating how the child's thyroid compensates in comparison to an adult thyroid. However, any reference should also include the fact that all new-borns are routinely tested for thyroid hormone. levels. Aerojet believes that it would be inappropriate for the Health Consultations to be construed as indicating that children are at risk at the provisional RFD or that exposure to the higher concentrations before well shut down would be associated with any health impact.

While it appears in the text, we believe there should be a clear reference both in the toxicology discussion and in the exposure section, that perchlorate is discharged from the body very quickly and that one would not expect to see any continuing impact on the thyroid once the exposure ends.

CDHS response: See response to previous comment.

Aerojet comment: Page 8, Paragraph 3: Regarding the discussion of safety factors, various toxicologists believe that the hypothyroid individual would not be a sensitive subpopulation. Also, the Health Consultations should recognize that the sensitive subpopulation factor is already being accounted for with respect to DHS comments on exposure of children.

CDHS response: Comment noted.

Aerojet comment: Page 9, Paragraph 2: We recommend that the parenthetical, which describes the concentrations used, be taken out of the parenthetical. It is important that DHS clearly state its assumptions.

CDHS response: We agree and have done so in the text.

Aerojet comment: Page 9, Paragraph 3: See discussion above on children. We believe that the two locations of discussion on children should be combined in one location.

CDHS response: See previous responses.

Aerojet comment: Page 9, Paragraph 4: Exposure discussion includes the volume of tap water consumed per day in liters and perhaps the inclusion of a unit like the number of 8 oz. glasses per day would benefit the average reader, or public citizen. This could be included in the text and in the Table.

CDHS response: We have added this information to the text and table.

Aerojet comment: Page 9, Paragraph 4 and following: While the Health Consultations do note the potential for mixing of water from various sources within the water distribution system, they assume that the person exposed was exposed at the level reported for the well on the date closest to well closure. The Health Consultations should explain that the evaluation uses the assumed concentration at a well to assess impact of a receptor using the well, even though further evaluation may show that mixing and blending of water during water distribution potentially could occur and reduce the estimated level of exposure.

CDHS response: See previous responses to similar comments.

Aerojet comment: Page 9, Paragraph 4 and Following: There is the repeated statement that the estimated doses for [identified type of exposure] from well # [identified well number] exceeded the provisional RfD range and a conclusion stating "health effects may have occurred." The phrase "may have occurred" could be misinterpreted as it may suggest a higher level of risk than existed, given the low levels of perchlorate found in relation to the provisional NOAEL described. Given the uncertainty factors associated with the provisional RfD, Aerojet believes that it would be more appropriate for the Consultations simply to conclude that the level was over the RFD and then follow with a conclusion as to the unlikely nature of any health impact. If DHS does continue to want to use "may have occurred" language, then the "may have occurred" language should be clarified when presented by referring to the key assumptions, the exposure assessment, etc., (e.g., the number of 8 ounce glasses of tap water needed to be consumed). The health consultations should also stress that there is a significant range between the provisional RfD of 18 ppb and the NOAEL level translated to 4900 ppb (assuming a NOAEL of .1 4 mg/kg/day and a 70 kilogram male drinking 2 liters per day). It would also be useful either to change the reference of "uncertainty" factors to "safety" factors or use the term uncertainty (safety) factors" for the benefit of the reader.

CDHS response: Comment noted.

Aerojet comment: Page 12, Paragraph 2: See the above comments regarding speculation as to source.

CDHS response: See previous response to similar comments.

Aerojet comment: Page 12, Paragraph 4: There are a number of paragraphs that repeat statements made in the exposure section. See discussion above (page 9) relative to language about dose above the RfD. Aerojet does not believe that it is appropriate to conclude that there "may" have been a "health hazard." If language as to hazard is described, it should not be separated from the DHS assumptions about exposure nor should it be stated without the conclusion as to the unlikeliness of any impact. Aerojet further notes that the various Consultations do not always use the same language on "health hazard," and the differences in language do not appear justified (e.g., see Mather page 12 paragraph 3).

CDHS response: Comment noted.

Aerojet comment: Page 13, Bullets #1 and 2 (Actions Planned): Aerojet believes that any dose reconstruction investigation should await completion of further investigations and should not assume sources. See general discussion above.

CDHS response: Comment noted.

Aerojet comment: Aerojet believes that any health statistics review of newborn thyroid testing raises significant issues regarding appropriate protocols for such study, timing of such study in light of ongoing animal studies, appropriateness of such a study in Sacramento and presumes confidence in the "dose reconstruction" exposure assessments. Aerojet requests the opportunity to review draft DHS protocols for any such study.

CDHS response: We will try to include an outside review of the study protocol.

Aerojet comment: Page 13, Bullet #3 and Page 14, Bullet #4: The reference should be to the Perchlorate Study Group, not Perchlorate Work Group.

CDHS response: This has been corrected in the text.

Aerojet comment: Page 14, Bullet #2: The use of the word "safe" is inappropriate, Reference should be to the provisional RfD.

CDHS response: We have modified the text so as to remove the word "safe".

Aerojet comment: References, No. 17. The citation to the authors should be corrected.

CDHS response: This citation has been corrected.

Aerojet comment on Table 1: We have not had adequate opportunity to evaluate the descriptions of all of the wells and the well system. We note that the comments in the Table are based upon assumptions made as discussed in the text and our comments apply.

CDHS response: Comment noted.

Aerojet comment on Table 2: We believe a "source" category for this Table is inappropriate. Please see general comment above on sources.

CDHS response: Comment noted.

Aerojet comment on Figures 1 and 2: The figures are illegible at this size and difficult for the reader to understand. The figures that present chemical distributions were draft figures and were not prepared for the purpose being used and are not reflective of present understanding of groundwater conditions.

CDHS response: We apologize for the quality of the figures. They are only meant to give the reader a basic layout of the perchlorate flow and the well locations and hopefully, this information is still conveyed with these poor quality figures.

COMMENTS FROM THE CENTRAL VALLEY REGIONAL WATER QUALITY CONTROL BOARD

Regional Board staffs comments on the documents are supplied below.

RWQCB General Comment: We recommend that the use of the term "contaminated" be selectively used. Contaminated should be used when the water represents a hazard to the public health. In the case of perchlorate, "contaminated" should not be used when discussing concentrations less than 18 ppb. It is even unclear whether the term should be applied to those concentrations that are currently found in some of the groundwater supply wells (up to 300 ppb). Instead of saying "perchlorate-contaminated water", we would recommend saying "water containing perchlorate".

CDHS response: As was stated under a similar comment raised by Aerojet, in Webster's New Collegiate Dictionary, it says "contaminate" means "to make impure or unclean". Perchlorate is not typically found in groundwater, as would be the case with certain chemicals like arsenic or sulfates which are naturally occurring in groundwater. Thus it does seem appropriate to describe the "contamination" of groundwater by a chemical such as perchlorate. Likewise, it may be appropriate to describe "water containing arsenic" if you are describing water which contains unusually high levels of arsenic due to natural reasons and arsenic-contaminated water if higher levels than normal may be due to non-natural reasons.

RWQCB General Comment: There is a paragraph in each of the health consultations which discusses the "reporting level to the RWQCB" of 400 ppb and a change in method which allowed for a detection level of 35 ppb. In the early 1990's, up until around 1995/96, Aerojet was using a ionspecific electrode to measure perchlorate concentrations in water with a detection level of 400-500 ppb. Aerojet then developed an alternate method using a GC which provided a detection level of 35 ppb and a reporting level of 400 ppb. This method was then used by Aerojet in all work required under the Partial-Consent Decree. In early 1996 RWQCB staff requested Aerojet to report all concentrations between the detection level (35 ppb) and reporting level (400 ppb) as trace. Aerojet was then able to lower their PQL to 100 ppb, while maintaining their detection level at 35 ppb. No method changes were made to get to the lower reporting level. It was in February 1996 that the concentrations in the off-site water supply wells were first reported.

CDHS response: Based on this comment and comments by others, the text was revised.

RWQCB General Comment: When discussing the nitrate levels, make sure that the values reported are designated as milligrams per liter as nitrate, or milligrams per liter as nitrogen. The MCL for nitrate should be expressed in the same units. There are two values for the MCL used in the five health consultations, 20 and 45 mg/l. A single value for the MCL should be used.

CDHS response: We have corrected this in the text.

RWQCB General Comment: We will not supply comments on the toxicological issues presented in the documents. We will rely on the experts at the Department of Health Services to make those evaluations.

CDHS response: Comment noted.

RWQCB comment: Page 2, paragraph 5. The value for the MCL for nitrate should be supplied to allow the reader to determine the significance of the values presented.

CDHS response: We have added the MCL as a reference in the text.

RWQCB comment: Page 4, paragraph 4. The last sentence refers to "80% of the audience responded". We do not recall that a positive response was so high. We recommend not specifying a percentage, but instead saying that a significant number of the audience responded positively, or something similar.

CDHS response: Per this comment, we have revised this statement in the text.

RWQCB comment: Page 6, paragraph 2. There is quite a bit of supposition in the statement that "perchlorate was probably a contaminant in the Cordova System wells since 1987". GET E started injecting in 1985 and GET F did not start injecting until late 1988. Without historical data, it is a stretch to provide a specific date. If the 1987 date remains the uncertainties and assumptions used in deriving that date should be supplied. This comment also applies to the second paragraph of page 12.

CDHS response: We look forward to the RWQCB or other agencies supplying us with better historical information about the historical movement of perchlorate; in the absence of this, we have clearly stated our guesses as to when perchlorate contamination may have affected drinking water wells.

RWQCB comment: Page 9, last paragraph. Though it is discussed in subsequent paragraphs on page 10, we would recommend that since this paragraph talks about exposures with Well No, 13 online, that the exposures be referred to as past exposures.

CDHS response: Given the structure of the health consultation, it seems that the description of the time frame of exposure from well #13 is appropriately addressed two paragraphs later.

RWQCB comment: Page 10, paragraph 3. Are Well Nos. 11 and 14 used as main production wells or are they on stand-by and respond to low pressure system demands? This would change the potential concentrations in the water in the distribution system in the vicinity of the wells.

CDHS response: The proposed dose reconstruction will more accurately explore this comment.

RWQCB comment: Page 10, paragraph 4. Well Nos. 15 and 16 provided water for the residents of the community of Gold River, especially prior to the development of the industrial area and the construction of Well No. 21.

CDHS response: The proposed dose reconstruction will more accurately explore this comment.

RWQCB comment: Page 13, second paragraph. Insert a "the" after "actions" in the second line.

CDHS response: There was a grammatical problem in the sentence, which we have corrected.

RWQCB comment: Page 13, First Planned Action. September has already passed. Has the ATSDR representative already come out for the visit?

CDHS response: Unfortunately the ATSDR has been delayed in responding to our request for assistance. We have revised the text to indicate a visit is expected.

RWQCB comment: Page 14, Item No. 4. Delete the verbiage in the parenthesis since it was already covered in Item No. 3.

CDHS response: We have deleted the repetitive information.

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