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1. ATSDR > Public Health Assessments & Consultations

PUBLIC HEALTH ASSESSMENT

MCCLELLAN AIR FORCE BASE
SACRAMENTO, SACRAMENTO COUNTY, CALIFORNIA

APPENDIX A: LIST OF SITES

CS = Confirmed Site
PRL = Potential Release Location
SA = Study Area
IWL = Industrial Wastewater Line
IWTP = Industrial Wastewater Treatment Plant
UST = Underground Storage Tank
Ref (3)

APPENDIX B: DEMOGRAPHICS

TABLE I. POPULATION DATA

	South Area	North Area	Impact Area	Sacramento County
Total persons	4,847	1,757	6,604	1,041,219
Total area, square miles	1.33	2.83	4.16	965.69
Persons per square mile	3,640	621	1,588	1,078
% Male	48.0	52.1	49.1	48.9
% Female	52.0	47.9	50.9	51.1
% White	79.0	87.7	81.3	75.1
% Black	9.9	4.2	8.4	9.3
% American Indian, Eskimo, or Aleut	2.5	1.8	2.3	1.2
% Asian or Pacific Islander	2.7	3.0	2.8	9.3
% Other races	5.9	3.4	5.2	5.1
% Hispanic origin	12.4	10.3	11.8	11.7
% Under age 10	18.2	15.2	17.4	15.9
% Age 65 and older	11.5	12.0	11.6	10.6

Source: 1990 Census of Population and Housing, Summary Tape File 1 (California). Prepared by Bureau of the Census, Washington, DC, 1991

TABLE II. HOUSING DATA

	South Area	North Area	Impact Area	Sacramento County
Households*	1,769	589	2,358	394,530
Persons per household	2.74	2.98	2.80	2.58
% Households owner-occupied	60.4	71.1	63.1	56.6
% Households renter-occupied	39.6	28.9	36.9	43.4
% Households mobile homes	11.9	3.2	9.8	3.1
% Persons in group quarters	0.0	0.0	0.0	2.1
Median value, owner-occupied households, $	61,200	~119,000	~80,000	129,800
Median rent paid, renter-occupied households, $	382	~425	~390	462

* A household is an occupied housing unit, but does not include group quarters such as military barracks, prisons, and college dormitories.

Source: 1990 Census of Population and Housing, Summary Tape File 1 (California). Prepared by Bureau of the Census, Washington, DC, 1991.

TABLE III. YEAR HOUSEHOLDER MOVED INTO CURRENT HOUSING UNIT

All Households (percent)
Year Occupied	North Area	South Area	California
1989-90	26.8	24.1	25.6
1985-88	25.4	28.3	31.7
1980-84	9.4	12.0	13.1
1970-79	17.6	19.5	17.0
1960-69	10.6	6.7	7.3
Before 1960	10.2	9.4	5.4
Owner Occupied Households (percent)
Year Occupied	North Area	South Area	California
1989-90	17.4	11.8	12.0
1985-88	23.0	21.2	28.2
1980-84	10.6	12.8	14.4
1970-79	21.9	28.7	24.4
1960-69	14.2	10.0	11.8
Before 1960	13.0	15.5	9.2
Renter Occupied Households (percent)
Year Occupied	North Area	South Area	California
1989-90	49.9	42.8	42.7
1985-88	31.3	39.1	36.0
1980-84	6.4	10.8	11.4
1970-79	7.0	5.6	7.6
1960-69	1.9	1.7	1.6
Before 1960	3.5	0.0	0.7

Source: 1990 Census of Population and Housing, Summary Tape File 3 (California). Prepared by Bureau of the Census, Washington, DC, 1992.

APPENDIX C: HEALTH EVALUATION GUIDANCE

To link a site's human exposure potential with health effects that may occur under site-specific conditions, ATSDR estimates human exposure to site contaminants from ingestion and/or inhalation of different environmental media. The following relationship is used to determine the estimated exposure to the site contaminant:

ATSDR uses standard intake rates for ingestion of water and soil. The intake rate for drinking water is 2 L/day for adults and 1 L/day for children. For incidental ingestion of soil and sediment, the intake rate is 100 mg/day for adults, 500 mg/day for school age children, and 5000 mg/day for children with pica behavior (repeated ingestion of non-nutritive substances). The intake rate for inhalation is 23 m³/day for adults and 3.8 m³/day for children. Standard body weights for adults, school age children, and pre-school age children are 70 kg, 35 kg, and 10 kg, respectively. The maximum contaminant concentration detected in a specific medium at a site is used to determine the estimated exposure; use of the maximum concentration results in an evaluation that is most protective of human health. When unknown, the biological absorption from environmental media (soil, water, etc.) is assumed to be 100%. Some exposure may occur on an intermittent or irregular basis. For these kinds of exposures, an exposure factor can be calculated to average the exposure dose over the exposure interval.

Cancer risk is evaluated using weight-of-evidence classifications of carcinogenicity and EPA's cancer slope factor. The slope factor is the cancer risk per unit of estimated exposure dose. The slope factor can be used to compare the relative potency of different chemical substances on the basis of estimated exposure does.

CANCER RISK = CHRONIC DAILY INTAKE (lifetime average dose) x CANCER SLOPE FACTOR

Where sufficient toxicologic information is available, ATSDR has derived minimal risk levels (MRLs) for inhalation and oral routes of entry at each duration of exposure (acute, intermediate, and chronic). These MRLs are not meant to support regulatory action; but to acquaint health professionals with exposure levels at which adverse health effects are not expected to occur in humans.

The most suitable endpoint for deriving a MRL is the no-observed-adverse-effect-level (NOAEL). The calculation is as follows:

MRL = NOAEL/UF
where:	NOAEL = no-observed-adverse-effect-level
	UF = uncertainty factor

To derive an MRL, ATSDR generally selects the most sensitive endpoint (judgement of ATSDR) which represents the most sensitive human health effect for a given exposure route and duration. ATSDR cannot derive an MRL unless (quantitative or qualitative) is available for potential systemic, neurological, and developmental effects. ATSDR derives an MRL using the most sensitive species with the highest NOAEL that does not exceed any adverse effect levels. When a NOAEL is unavailable, a lowest-observed-adverse-effect-level (LOAEL) is used. Uncertainty factors (multiples of 10) are employed in the derivation of an MRL. Uncertainty factors are used for derivation from a LOAEL, human variability, and for interspecies variability. In deriving the MRL, these individual UFs are multiplied together. The concentration from the study is divided by the product of the UFs.

REFERENCES

Agency for Toxic Substances and Disease Registry. Public Health Assessment Guidance Manual. Atlanta: ATSDR, March 1992.

IRIS. 1992. Integrated Risk Information System (IRIS). Online Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati.

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