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HEALTH CONSULTATION

PRELIMINARY HEALTH REVIEWS IN RANCHO CORDOVA, SACRAMENTO COUNTY, CALIFORNIA

AEROJET-GENERAL CORPORATION
RANCHO CORDOVA, SACRAMENTO COUNTY, CALIFORNIA


CONCLUSION

The preliminary information which was reviewed included: neonatal thyroid hormone levels, goiter, agranulocytosis, aplastic anemia, all cancers, thyroid cancers and leukemia in individuals residing in zip codes near Aerojet (which were used as a proxy for exposure to perchlorate) during the assumed time period that perchlorate contaminated the Arden Cordova drinking water system. Investigation found that:

  • mean neonatal thyroid hormone levels were higher in the suspected exposed zip codes than the corresponding statewide rates (lower mean levels would have suggested a possible effect of perchlorate);
  • there was no increase in cases of neonatal hypothyroidism in the exposed zip codes than expected;
  • the OSHPD data base was not considered a useful source of information for assessing the incidence of goiter;
  • there was no increase in the rate of hospitalizations for agranulocytosis;
  • cases of aplastic anemia in a suspected perchlorate-exposed zip code were higher than the statewide rate, but most of the cases in the affected area were related to other likely causes, such as chemotherapy, radiation or AIDS infection;
  • rates for all cancers, thyroid cancers, and leukemias were not higher than the expected rates, based on statewide figures.

The major handicap with these preliminary studies was the limitation imposed by the lack of good exposure measurements in the affected population. It is unclear at this time exactly when the perchlorate groundwater plume first contaminated the drinking water supply of the Arden Cordova System. Thus, the time periods analyzed may have been too broad. The other difficulty with using zip codes as proxies for exposure is that there are more refined dose-reconstruction techniques used in hydrological modeling, which may better determine which neighborhoods or streets received contaminated water. Here again, one must assume that zip codes are much less reflective of actual exposure to perchlorate-contaminated drinking water and that the actual number of exposed persons may be much smaller. Finally, the other difficulty with assessing these health outcome surveys is that perchlorate is not specific for producing thyroid dysfunction or hematological abnormalities. Thus, any case that was ascertained may have other, more likely causes.


PUBLIC HEALTH RECOMMENDATIONS AND ACTIONS

The Public Health Recommendations and Action Plan (PHRAP) for this site contains a description of actions taken, to be taken, or under consideration by ATSDR and CDHS at and near the site. The purpose of the PHRAP is to ensure that this health consultation not only identifies public health hazards, but also provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. The CDHS and ATSDR will follow-up on this plan to ensure that actions are carried out.

Actions Completed

1. CDHS performed preliminary surveys of health outcomes related to known or suspected effects of perchlorate ingestion by individuals in zip codes nearby to the site.

2. CDHS prepared a fact sheet about perchlorate and health. CDHS made this fact sheet available to the affected water purveyors, including the Arden Cordova Water Service to provide to their customers.

Actions Planned

1. The Air Force and the Perchlorate Work Group are sponsoring an investigation into fate and transport questions regarding perchlorate. They will investigate the skin permeability of perchlorate.

2. The Air Force and the Perchlorate Work Group are sponsoring a series of animal investigations to address some of the information lacking in perchlorate toxicology. Several animal toxicology studies will be funded to review the genetic and neurological toxicity of perchlorate.

3. ATSDR will conduct an exposure investigation and will model perchlorate contamination of the Arden Cordova drinking water supply.

4. ATSDR and CDHS will conduct an epidemiological investigation reviewing the association between exposure to perchlorate-contaminated drinking water and neonatal thyroid levels.

Recommendations for Further Action

1. CDHS and ATSDR will continue communicating with the Arden Cordova Water System customers about the perchlorate issue.

REFERENCES

  1. U.S. Agency for Toxic Substances and Disease Registry, Division of Health Assessment and Consultation. Preliminary Health Assessment of the Aerojet-General Corporation, Rancho Cordova, CA. December 5, 1988.

  2. Environmental Health Investigations Branch California Department of Health Services. Site Review and Update of the Aerojet-General Corporation, Rancho Cordova, CA. Prepared for U.S. Agency for Toxic Substances and Disease Registry. March 19, 1993.

  3. Environmental Health Investigations Branch California Department of Health Services. Health Consultation- Perchlorate contamination in the Mather Air Force Base Water Service Area. Prepared for U.S. Agency for Toxic Substances and Disease Registry. September 1997.

  4. Environmental Health Investigations Branch California Department of Health Services. Health Consultation- Perchlorate contamination in the Fair Oaks Water District. Prepared for U.S. Agency for Toxic Substances and Disease Registry. September, 1997.

  5. Environmental Health Investigations Branch California Department of Health Services. Health Consultation- Perchlorate contamination in the Sunrise District of the Sacramento County Water Service Area. Prepared for U.S. Agency for Toxic Substances and Disease Registry. September, 1997.

  6. Environmental Health Investigations Branch, California Department of Health Services. Health Consultation- Perchlorate contamination in the Citizens Utilities' Suburban and Security Park water Service Areas. Prepared for U.S. Agency for Toxic Substances and Disease Registry. September, 1997.

  7. Environmental Health Investigations Branch, California Department of Health Services. Draft Health Consultation- Perchlorate Contamination in the Arden Cordova Water Service Area. Prepared for U.S. Agency for Toxic Substances and Disease Registry. September 29, 1997.

  8. California Department of Health Services, Drinking Water Field Operations Branch, Sacramento. Inspection Report for California Water Service, Cordova Water Service. May 15, 1996.

  9. DiGeorge A. "Disorders of the thyroid gland" in Nelson: Textbook of Pediatrics. Behrman RE and Vaughan VC (eds.). Philadelphia: W.B. Saunders Company, 1983.

  10. Toxicology Excellence for Risk Assessment. Proposed perchlorate reference dose (RfD). February, 1997, 5.

  11. Rappeport JM and Bunn HF. "Bone marrow failure: aplastic anemia and other primary bone marrow disorders" in Harrison's Principles of Internal Medicine, Isselbacher KJ,et.al. (eds.). New York: McGraw Hill, 1994.

  12. Shu XO. Epidemiology of childhood leukemia. Current Opinion Hematology 1997; 4: 227-32.

  13. Bhatia S and Neglia JP. Epidemiology of childhood acute myelogenous leukemia. Journal of Pediatric Hematology and Oncology 1995; 17: 94-100.

APPENDIX

Table 1: Neonatal hypothyroidism status for potentially-exposed and unexposed zip codes in California, 1985-1996.

Exposure Status/Location Hypothyroid Cases
(expected cases)
Total Screens
     
Rancho Cordova (exposed) 4 (3.76) 11,814
Rancho Cordova (unexposed) 6 (6.41) 20,135
Rest of State (unexposed) 2,068 (-) 6,494,193


T
able 2: Neonatal thyroid hormone values (T4) per suspected exposure group, 1985-1996.

Exposure Status Number
of Screens
Mean Median Standard
Deviation
         
Exposed 11,773 15.04 14.6 4.57
Unexposed 20,077 15.27 14.9 4.57
Rest of State 6,479,190 14.77 14.4 4.38



Table 3: Neonatal thyroid stimulating hormone values (TSH) per suspected exposure group, 1985-1996*.

Exposure Status Number
of Screens
Mean Median Standard
Deviation
         
Exposed 1368 8.6 5 20.9
Unexposed 2105 8.99 6 21.1
Rest of State 799820 8.59 6 17.3

* TSH values are not routinely obtained on every newborn child, but are determined from a second phase of testing on those neonates with borderline-low initial levels of thyroid hormone.


Table 4: Hospitalizations listing agranulocytosis as one of the top five diagnoses for individuals residing in 95670 zip code, 1991-1995.

Year Diagnosed Number of Cases Rate/100K individuals*
     
1991 15 35.3
1992 20 47.1
1993 13 30.6
1994 10 23.6
1995 18 42.4
_________________________________________________________
Total 76 35.8

* Rate = number of cases per year / 1990 census population of 42,457 x 100,000.


Table 5: Hospitalizations listing aplastic anemia as one of the top five diagnoses for individuals residing in 95670 zip code, 1991-1995.

Year Diagnosed Number of Cases Rate/100K individuals*
     
1991 4 9.4
1992 3 7.1
1993 0 0
1994 0 0
1995 1 2.4
_________________________________________________________
Total 8 3.8

* Rate = number of cases per year / 1990 census population of 42,457 x 100,000.


Table 6: Expected and observed numbers of cancer cases, all sites combined, by census tract and gender, Rancho Cordova, Sacramento County, California, 1988-94.

Census Tract Number Expected # Observed # 99% Confidence Interval
       
8700      
  Males
Females
65
55
63
62
44.2 - 86.2
43.3 - 85.1
         
8903        
  Males
Females
103
99
108
82
82.9 - 137.6
60.3 - 108.1
         
8904        
  Males
Females
80
85
88
111
65.5 - 115.0
85.5 - 140.9
         
8905        
  Males
Females
74
78
90
71
67.2 - 117.2
51.0 - 95.5
         
8907        
  Males
Females
53
57
65
61
45.9 - 88.6
42.5 - 83.9
         
8908        
  Males
Females
92
93
103
108
78.5 - 131.9
82.9 - 137.6
         
9003        
  Males
Females
53
53
60
69
41.7 - 82.8
49.3 - 93.2



Table 7: Expected and observed numbers of thyroid cancer cases, by census tract and gender, Rancho Cordova, Sacramento County, California, 1988-94.

Census Tract Number Expected # Observed # 99% Confidence Interval
         
8700        
  Males
Females
0.7
1.4
2
2
0 - 9.1
0 - 9.1
         
8903        
  Males
Females
0.7
2.1
3
4
0.2 - 10.8
0.5 - 12.4
         
8904        
  Males
Females
0.7
2.1
2
7
0 - 9.1
1.8 - 16.9
         
8905        
  Males
Females
0.7
1.4
0
0
-----
-----
         
8907        
  Males
Females
0.7
1.4
2
1
0 - 9.1
0 - 7.3
         
8908        
  Males
Females
0.7
1.4
0
0
------
------
         
9003        
  Males
Females
0.7
1.4
0
3
-----
0.2 - 10.8



PREPARERS OF REPORT

ENVIRONMENTAL AND HEALTH EFFECTS ASSESSORS:

Jeffrey A. Jacobs, M.D., M.P.H.
Medical Specialist
Environmental Health Investigation Branch
California Department of Health Services

Marilyn C. Underwood, Ph.D.
Staff Toxicologist
Environmental Health Investigation Branch
California Department of Health Services


COMMUNITY RELATIONS COORDINATOR:

Jane Riggan, M.S.W.
Public Health Social Work Consultant II
Environmental Health Investigation Branch
California Department of Health Services


ATSDR REGIONAL REPRESENTATIVES

William Nelson
Gwendolyn Eng
William Deviny
Dan Strausbaugh
Regional Representatives, Region IX
Agency for Toxic Substances and Disease Registry


ATSDR TECHNICAL PROJECT OFFICER:

William Greim, M.S., M.P.H.
Environmental Health Scientist
Division of Health Assessment and Consultation
Superfund Site Assessment Branch, State Programs Section


CERTIFICATION

The Preliminary Health Reviews in Rancho Cordova, Aerojet-General Corporation Health Consultation was prepared by the California Department of Health Services 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.

William Greim
Technical Project Officer, SPS, SSAB, DHAC

The Division of Health Assessment and Consultation, ATSDR, has reviewed this health consultation and concurs with its findings.

Richard Gillig
Chief, SPS, SSAB, DHAC, ATSDR

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