HEALTH CONSULTATION

COEUR D'ALENE RIVER BASIN
PANHANDLE REGION OF IDAHO
INCLUDING BENEWAH, KOOTENAI, & SHOSHONE COUNTIES

APPENDICES

 

Appendix A:

Coeur d'Alene River Basin Residential Properties Analytical Results for Lead in Soil, Dust, and Paint.

Location ID	Average Lead Concentration in Residential Yard (mg/kg)		Lead Concentration in Play Area (mg/kg)		Lead Concentration in Garden (mg/kg)		Lead Conc. in Mat	Lead Conc. in Vacuum Bag	Lead Conc. in Exterior Paint	Lead Conc. in Interior Paint	Water Sample Results exceeding RAL/MCL
	Surface Soil	Sub-surface	Surface Soil	Sub-surface	Surface Soil	Sub-surface	mg/kg)	(mg/kg)	(mg/kg)	(mg/kg)	(µg/L) all first-run
1	663	495	-	-	721	592	841	606	30300	409	-
2	804	729	-	-	-	-	797	480	98600	-	-
3	174	132	154	121	-	-	4250	764	-	-	-
4	448	343	-	-	-	-	658	173	-	-	-
5	1190	1100	-	-	-	-	790	978	2390	-	-
6	227	382	-	-	319	475	673	422	-	-	-
7	979	1460	-	-	-	-	588	154	-	-	-
8	290	321	-	-	-	-	300	389	-	-	-
9	665	408	-	-	-	-	15500	765	5300	-	-
10	342	777	-	-	-	-	1020	332	205	-	-
11	760	245	-	-	2440	266	2030	1260	-	-	-
12	3490	6820	-	-	1000	714	2800	604	-	-	-
13	5570	1980	-	-	1080	1210	995	1960	-	-	-
14	794	767	-	-	-	-	4250	1200	-	-	-
15	3790	4260	-	-	-	-	767	-	905	-	-
16	1010	307	-	-	213	218	1660	1660	-	-	-
17	276	236	-	-	-	-	1260	680	-	197	-
18	796	358	-	-	-	-	332	818	-	93	26.4
19	953	1050	-	-	315	473	950	512	-	-	-
20	451	1030	613	747	-	-	1280	639	-	-	-
21	1340	1250	-	-	-	-	3440	1350	-	-	-
22	1690	2760	1120	1290	1120	972	1660	798	130000	-	-
23	977	805	-	-	626	618	734	808	-	-	-
24	813	1190	-	-	257	245	847	703	-	-	-
25	438	153	-	-	-	-	-	84	-	-	-
26	682	886	-	-	-	-	-	762	20600	-	-
27	622	282	-	-	-	-	566	349	-	-	-
28	1320	858	-	-	-	-	2120	767	-	-	-
29	437	474	-	-	-	-	812	383	119	10	-
30	1580	1230	-	-	-	-	1550	1020	4140	86000	-
31	827	627	-	-	-	-	1250	710	-	-	-
32	3600	8570	12100	36100	885	732	1780	1020	-	-	-
33	278	377	-	-	278	693	496	427	783	-	-
34	1420	594	-	-	587	589	1490	1020	949	-	-
35	364	116	155	71.5	-	-	374	341	15800	-	-
36	766	958	-	-	-	-	2370	882	101000	-	-
37	769	433	-	-	-	-	732	23	-	-	56.1
38	688	346	-	-	-	-	8840	1820	-	-	-
39	16000	17300	-	-	-	-	14000	6150	-	-	-
40	718	536	-	-	-	-	791	2430	-	-	-
41	503	207	-	-	103	96.7	1640	769	19100	-	-
42	500	388	-	-	180	1590	713	387	-	-	-
43	3050	3510	-	-	5480	4770	27800	2730	-	-	-
44	3210	7030	-	-	-	-	59500	-	-	-	-
45	843	849	-	-	-	-	1020	619	-	-	-
46	852	994	-	-	1200	911	2040	3300	10900	47400	-
47	56.2	29.5	-	-	-	-	655	626	4860	-	-
48	319	186	-	-	-	-	468	504	-	-	-
49	256	224	-	-	-	-	368	492	1140	-	-
50	7060	12000	-	-	6605	15020	2420	-	-	-	15.7
51	3030	900	-	-	1240	1170	1060	621	19200	6820	-
52	787	759	-	-	406	895	1600	1550	-	-	-
53	735	739	1120	1530	89.6	80.4	380	315	-	-	-
54	544	213	316	109	85.8	80.7	778	504	679	-	-
55	642	650	-	-	-	-	615	384	-	-	-
56	353	179	-	-	-	-	1120	833	5210	-	-
57	1190	1470	-	-	-	-	1210	-	7600	-	-
58	2710	6970	-	-	-	-	1620	353	10700	-	-
59	1170	786	-	-	-	-	790	778	29900	-	26.9
60	188	182	48.7	15.9	142	133	182	232	-	-	-
61	284	234	-	-	-	-	2050	1680	-	-	-
62	2920	186	-	-	-	-	-	-	-	-	-
63	563	943	-	-	-	-	1370	655	31900	-	-
64	2700	4220	-	-	-	-	4460	1540	15300	-	-
65	1210	1190	516	558	287	292	858	937	4040	-	-
66	1090	1140	-	-	-	-	990	780	2250	1370	39.8
67	2430	2190	-	-	11800	9900	1130	1380	-	-	-
68	479	500	-	-	-	-	604	727	-	-	-
69	1270	663	-	-	-	-	-	-	115000	27400	-
70	1380	984	-	-	-	-	3100	405	1110	-	-
71	346	465	-	-	-	-	1730	942	155000	-	-
72	26.9	-	-	-	-	-	-	292	-	-	-
73	34	26.8	-	-	-	-	440	53	590	-	-
74	3840	2190	-	-	-	-	1360	362	-	-	-
75	453	958	216	444	365	314	1090	-	-	-	-
76	3290	3440	-	-	-	-	3210	2840	-	-	-
77	2560	2860	995	3250	1120	949	1550	-	1110	2170	-
78	654	249	-	-	-	-	2080	2400	-	-	-
79	510	120	-	-	-	-	-	-	-	-	-
80	748	333	354	281	-	-	1410	1000	142000	-	-

APPENDIX B: METHODS

Method I: Calculation of an estimated dose and comparison to the IOC

The following routes of exposure were considered:

Ingestion:

Soil & Dust - Soil and dust ingestion were analyzed quantitatively through calculation of an external dose using average lead concentrations.

Homegrown Foods - Lead levels in garden vegetables were analyzed and their contribution examined quantitatively. However, this data was not incorporated with garden soil lead levels, because sources of the vegetables were not matched with soil sample locations. Future work should include this pathway.

Tap Water - Potable water was included where sampling indicated lead levels exceeded the EPA's action level for lead.

Inhalation:

Air particulates - No sampling data were available, therefore background levels were used.

Dermal:

Soil - This pathway is considered negligible as appreciable levels of lead do not penetrate through the skin (ATSDR, 1999)

External dose for children's soil ingestion was calculated:

Dosesoil =	C x IR x BF x CF BW	=	Conc x 0.5 x 200mg/day x 10 -6 16kg

where

C = concentration of lead in soil, mg/kg
IR = ingestion rate, mg/day
BF = bioavailability factor
BW = body weight, kg
CF = conversion factor (kg to mg)

Concentrations used were the surface soil composite samples. The ingestion rate of 200 mg/day was used as a conservative mean estimate of children's soil ingestion (EPA, 1999)^*. An average recommended body weight of 16 kg was used as a mean estimate (EPA, 1999)^*. An absolute bioavailability factor of 50% for soil-born lead was used.^** This leads to a mean estimate of children's exposed dose, although it needs to be remembered that use of composite surface soil measurements may result in an underestimation of the true concentration, because Ahotspots@ may not be detected.

External dose for children indoor dust ingestion was calculated:

Dosedust =	C x IR x BF x CF BW	=	Conc x IR x BF x 10 -6 16kg >

The ingestion rate for dust was taken from estimates of soil and total soil and dust ingestion from the Exposure Factors Handbook (EPA, 1999). Average dust ingestion as a percentage of total soil and dust ingestion was calculated for mean and high-end estimates. Dust ingestion was separated from soil ingestion in this consultation in order to ascertain the specific contributions of dust lead and soil lead to total exposure. Prior studies have ascertained a high indoor dust contribution to total lead exposures (IDHW, 1999).

Similar methodologies were utilized for the other input routes, with the input variables presented in Table B-1 below.

Table 1.

Input parameters used to quantify mean background air and food lead exposures, and tap water lead exposures when the action level was exceeded.

Route	Lead concentration	Reference	Ingestion/ Inhalation rate	Reference
Tap water	residence-specific	see data, Appendix A	0.58 L/day	EPA, 1999 for children ages 1-4
Air (background only)	0.10 µg/m3	EPA, 1994	5 m3/day	EPA, 1994 median ventilation rate
Food	6 µg/day	EPA, 1994, median value	n/a

L/day = liters per day  m³/day = cubic meters per day

µg/m³ = micrograms per cubic meter  n/a = not applicable

Method 2: Calculation of expected blood lead levels

Surface soil and indoor house dust lead levels were entered into the EPA's IEUBK model (EPA, 1994). Based on the above calculations, soil and dust incidental ingestion were found to have an appreciably greater contribution to total dose than other exposure routes. Therefore, when using the model, other input distributions were left at default values. Only the effect of soil and indoor dust lead levels were examined. In order to keep the IEUBK model consistent with the previous calculations, soil ingestion as a percentage of total soil and dust ingestion was increased from the default value of 45% to 71%. Expected blood lead levels were then recorded as being between an upper and lower range. Expected blood lead level data can be seen in Appendix C. The blood lead upper and lower range values were then averaged to calculate an average blood lead level, and locations were categorized as having an average blood lead level either greater or less than 10 µg/dl. Several residences had average blood lead levels less than 10 µg/dl, but as the blood lead range included 10 µg/dl they were considered to represent an intermediate category.

In the IEUBK model, the Geometric mean blood lead level which corresponds to a probability of 10 µg/dl is approximately 5 µg/dl. This relationship is sensitive to the geometric standard deviation (GSD): default = 1.6.

Method 3: ATSDR's integrated exposure regression analysis

Numerous longitudinal and cross-sectional studies have attempted to correlate environmental lead levels with blood lead levels. These studies have provided a number of regression analyses and corresponding slope factors () for various media including air, soil, dust, water, and food. The ATSDR integrated exposure regression analysis utilizes slope values from select studies to integrate all exposures from various pathways, thus providing a cumulative exposure estimate expressed as total blood lead (ATSDR 1999).

The general form of the model is:

where,
Pb_s = soil lead concentration
Pb_d = dust lead concentration
Pb_w = water lead concentration
Pb_ao = outside air lead concentration
Pb_ai = inside air lead concentration
Pb_f = food lead concentration
T = relative time spent

Table B- 2.

Selected Slope Factors for Specific Media (ATSDR 1999)

Media	Population	Slope	Source
Air	Children (1-18 yrs)	1.92 + 0.60	Angle et al, 1984 as cited in ATSDR 1999, App D
Water	Children	0.16 at <15 µg/L 0.03 at >15 µg/L	Laxen et al, 1987 as cited in ATSDR 1999, App D
Diet	Infants & Toddlers	0.24	Ryu et al, 1983 as cited in ATSDR 1999, App D
Soil	Children (1-72 mo)	0.002 + 0.00082	Stark et al, 1982 as cited in EPA 1986
Dust	Children (2 yrs old)	0.002 + 0.00066	Stark et al, 1982 as cited in ATSDR 1999, App D

µg/L = micrograms per liter

Table B-3.

Table B-3: Default Values for Missing Data (ATSDR 1999)

Media	Default
Outdoor Air	0.1-0.2 µg/m3
Indoor Air	0.03-0.06 µg/m3 (0.3 x outdoor conc.)
Food	5 µg/day
Water	4 µg/L
Indoor Dust	947 (ave. Indoor dust conc. for 71 residences sampled)

µg/m³ = micrograms per cubic meter
µg/day = micrograms per day
µg/L = micrograms per liter

Bioavailability was not estimated for this method, as each slope factor is based upon observed blood lead levels correlated with environmental concentrations. The average surface soil concentration was used unless a surface soil concentration was available in a Aplay area@, which was then used. For indoor dust, vacuum bag concentrations were used. For those few residences without vacuum bag data, the average vacuum bag concentration of the other 71 residences with data was used.

The example described within Appendix D of the ATSDR Toxicological Profile for Lead selected larger soil/dust slope values plus or minus three standard deviations to determine the high and low range of blood leads. In this health consultation, values more specific to children aged 1- 3 were selected, and only one standard deviation was added or subtracted for determining the low and high range of blood leads. Subtracting three standard deviations from the slope values selected for this health consultation created negative slopes at the low end, therefore, this was not done. The net effect would be to make the method utilized in this health consultation much less conservative than the example outlined in Appendix D of the Toxicological Profile. Based upon the results provided in Table 5, Appendix D of the Toxicological Profile (which showed this method to correlate well with actual blood lead levels), this would result in an underestimation of the number of residences at which the blood lead range could exceed 10 µg/dl. A benefit to be gained by this method, however, is that those residences most likely to be a problem should be highlighted in this health consultation.

Appendix C:

Coeur d'Alene River Basin Residential Properties. Estimated dose, the number of time the dose is greater than the IOC, and the expected blood lead ranges by residential location ID.

Location ID	Total Pb dose	Times Dose > IOC	EPA IEUBK BPb Range (µg/dl)	ATSDR Regression BPb Range (µg/dl)
	mg/kg/day	[-]	Lower	Upper	Lower	Upper
1	0.0054	2.9	5.6	9.9	3.4	5.3
2	0.0061	3.3	6	10.5	3.4	5.4
3	0.0027	1.5	3.7	6.4	3	4.3
4	0.0033	1.8	3.8	6.7	2.6	3.6
5	0.0094	5.1	8.4	14.4	4.4	7.7
6	0.0024	1.3	3.3	5.6	2.6	3.6
7	0.0066	3.6	6.2	10.8	3.2	5.1
8	0.0027	1.5	3.5	6.1	2.7	3.7
9	0.0058	3.1	5.9	10.4	3.6	5.7
10	0.0030	1.6	3.6	6.3	2.7	3.7
11	0.0072	3.9	7.1	12.4	4.3	7.2
12	0.0231	12.5	15	24	6.7	13.3
13	0.0386	20.8	22	33	10.7	22.5
14	0.0074	4.0	7.2	12.5	4.2	7.2
15	0.0239	12.9	15	25	7.3	14.5
16	0.0095	5.1	8.8	15	5	8.9
17	0.0032	1.7	4	7	3	4.4
18	0.0072	3.9	6.5	11.4	3.9	6.4
19	0.0071	3.8	6.7	11.7	3.6	5.9
20	0.0042	2.3	4.7	8.3	3.4	5.3
21	0.0111	6.0	9.6	16.2	5	9.1
22	0.0122	6.6	10	16.9	4.1	7.1
23	0.0078	4.2	7.3	12.6	4	6.7
24	0.0066	3.5	6.4	11.2	3.7	6
25	0.0031	1.7	3.6	6.3	2.5	3.4
26	0.0058	3.2	6	10.5	3.6	5.8
27	0.0047	2.5	5	8.7	3	4.6
28	0.0098	5.3	8.6	14.7	4.3	7.6
29	0.0036	2.0	4.2	7.3	2.9	4.1
30	0.0120	6.5	9.9	16.8	4.9	8.9
31	0.0066	3.6	6.5	11.4	3.7	6
32	0.0246	13.3	16.5	25.8	17.4	38.6
33	0.0027	1.5	3.5	6.1	2.7	3.8
34	0.0110	5.9	9.3	15.9	4.8	8.5
35	0.0031	1.7	3.8	6.6	2.5	3.2
36	0.0066	3.6	6.5	11.4	3.8	6.3
37	0.0060	3.3	5	8.9	3.9	5.2
38	0.0078	4.2	7.8	13.4	4.8	8.4
39	0.1114	60.2	42.5	60.9	27.9	62.3
40	0.0091	4.9	8.9	15.1	5.6	10
41	0.0048	2.6	5.2	9.2	3.4	5.3
42	0.0040	2.2	4.5	7.9	2.9	4.3
43	0.0242	13.1	16.9	26.3	8.7	17.3
44	0.0202	10.9	14.1	22.5	74.7	158.6
45	0.0066	3.6	6.4	11.2	3.6	5.9
46	0.0115	6.2	10.7	17.8	6.7	12.5
47	0.0017	0.9	2.8	4.8	2.7	3.7
48	0.0031	1.7	3.9	6.8	2.9	4.1
49	0.0027	1.5	3.5	6.2	2.8	3.9
50	0.0446	24.1	24.1	35.5	12.9	27.7
51	0.0202	10.9	14.3	22.9	6.2	12
52	0.0080	4.3	7.7	13.4	4.6	8
53	0.0054	2.9	5.4	9.5	3.6	5.9
54	0.0045	2.4	4.9	8.6	2.9	4.1
55	0.0049	2.6	5.1	9	3.1	4.7
56	0.0039	2.1	4.6	8.2	3.3	5
57	0.0076	4.1	6.8	11.9	4.3	8.3
58	0.0178	9.6	12.9	21	5.5	10.5
59	0.0094	5.1	8	13.8	4.3	7.3
60	0.0018	1.0	2.7	4.5	2.2	2.7
61	0.0050	2.7	5.9	10.3	4.2	6.9
62	0.0184	10.0	13.2	21.3	5.4	10.4
63	0.0049	2.6	5.2	9.3	3.3	5.2
64	0.0198	10.7	14.5	23	6.9	13.4
65	0.0094	5.1	8.4	14.4	3.6	5.7
66	0.0092	4.9	7.7	13.3	4.6	7.5
67	0.0179	9.7	13.4	21.6	6	12.2
68	0.0045	2.4	5	8.8	2.9	5.1
69	0.0081	4.4	7.1	12.4	3.1	5.7
70	0.0096	5.2	8.2	14.2	3.6	6.8
71	0.0040	2.2	4.8	8.5	3	5.3
72	0.0009	0.5	2	3.2	1.9	2.8
73	0.0005	0.3	1.6	2.2	1.6	2.2
74	0.0248	13.4	16.4	25.6	6.4	13.7
75	0.0031	1.6	3.5	6.1	3	5.3
76	0.0259	14.0	17.7	27.3	8.7	18.3
77	0.0162	8.8	11.9	19.6	6.3	13
78	0.0086	4.7	8.6	14.7	5	9.7
79	0.0034	1.8	3.8	6.6	2.2	3.6
80	0.0067	3.6	6.6	11.6	3.5	6.5

Appendix D.

Health Effects Summary Table

Species	System	Exposure Duration	LOAEL mg/kg/day	Effect
Human	hemato	7 wk at7 days/wk	0.01	decrease ALAD activity; increased RBC porphyrin
Human	hemato	21days at 7 days/wk	0.02	increased protoporphyrin IX in RBC (F)
Rat	hepatic	20-30 d	0.05	decreased RNA, glycogen: pyknosis of Kupffer cells; increased liver weight
Rat	hemato	6-12 mo	0.005	impaired heme synthesis
Rat	hepatic	6-12 mo	0.005	decreased glycogen, RNA, sulfhydryl groups, alterations in activities of oxidizing enzymes
Rat	cardio	159 d	0.3	increased systolic blood pressure
Monkey	neuro	200 d; 5 d/wk	0.05	Impaired nonspatial discrimination at 3 yrs of age
Rat	neuro	6-12 mo	0.005	disruption of conditioned responses and motor activity
Rat	repro	30 d	0.013	increased prostate weight (M)
Rat	repro	30 d	0.014	irregular estrus cycles (F)
Rat	repro	6-12 mo	0.05	decreased activity of AIDH, SDH, NAD, and DADPH-diaphorase in spermatogenic epithelium and swelling of lollicular epithelial cells in males
Rat	repro	23-30 d	0.005	dystrophy of Leydig cells
Rat	cardio	<18 mo; 7 d/wk	0.014	increase in systolic blood pressure
Monkey	neuro	1 yr; 7 d/wk	0.19	deficit in fixed interval schedule

ALAD = aminolevulinic acid dehydratase; cardio = cardiovascular; d = days; F = female; hemato = hematological;
LOAEL = lowest-observable-adverse-effect level; M = male; mg/kg/day = milligrams per kilogram per day; mo =
month; neuro = neurological; RBC = red blood cell; repro = reproductive; RNA = ribonucleic acid; wk = week; yr = year

*
Blood Lead Level (BLL); (CDC 1997, table 4.3)">

Appendix E.

Comprehensive Follow-up Services Recommended According to Diagnostic^*
Blood Lead Level (BLL); (CDC 1997, table 4.3)

BLL (µg/dl)	Action
<10	Reassess or rescreen in 1 year. No additional action necessary unless exposure source changes.
10-14	Provide Family lead education. Provide follow-up testing. Refer for social services, if necessary.
15-19	Provide Family lead education. Provide follow-up testing. Refer for social services, if necessary. If BLLs persist (i.e., 2 venous BLLs in this range at least 3 months apart) or worsen, proceed according to actions for BLLs 20-44.
20-44	Provide coordination of care (case management). Provide clinical management (described in text). Provide environmental investigation. Provide lead-hazard control.
45-69	Within 48 hours, begin coordination of care (case management), clinical management (described in text), environmental investigation, and lead hazard control.
>70	Hospitalize child and begin medical treatment immediately. Begin coordination of care (case management), clinical management (described in text), environmental investigation, and lead hazard control immediately.

ATSDR Plain Language Glossary of Environmental Health Terms

Absorption: How a chemical enters a person's blood after the chemical has been swallowed, has come into contact with the skin, or has been breathed in.

Acute Exposure: Contact with a chemical that happens once or only for a limited period of time. ATSDR defines acute exposures as those that might last up to 14 days.

Adverse Health Effect: A change in body function or the structures of cells that can lead to disease or health problems.

ATSDR: The Agency for Toxic Substances and Disease Registry. ATSDR is a federal health agency in Atlanta, Georgia that deals with hazardous substance and waste site issues. ATSDR gives people information about harmful chemicals in their environment and tells people how to protect themselves from coming into contact with chemicals.

Background Level: An average or expected amount of a chemical in a specific environment. Or, amounts of chemicals that occur naturally in a specific environment.

Biota: Used in public health, things that humans would eat B including animals, fish and plants.

Cancer: A group of diseases which occur when cells in the body become abnormal and grow, or multiply, out of control

Carcinogen: Any substance shown to cause tumors or cancer in experimental studies.

Chronic Exposure: A contact with a substance or chemical that happens over a long period of time. ATSDR considers exposures of more than one year to be chronic.

Completed Exposure Pathway:  See Exposure Pathway.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA): CERCLA was put into place in 1980. It is also known as Superfund. This act concerns releases of hazardous substances into the environment, and the cleanup of these substances and hazardous waste sites. ATSDR was created by this act and is responsible for looking into the health issues related to hazardous waste sites.

Concern: A belief or worry that chemicals in the environment might cause harm to people.

Concentration: How much or the amount of a substance present in a certain amount of soil, water, air, or food.

Contaminant: See Environmental Contaminant.

Delayed Health Effect: A disease or injury that happens as a result of exposures that may have occurred far in the past.

Dermal Contact: A chemical getting onto your skin. (see Route of Exposure).

Dose: The amount of a substance to which a person may be exposed, usually on a daily basis. Dose is often explained as Aamount of substance(s) per body weight per day@.

Dose / Response: The relationship between the amount of exposure (dose) and the change in body function or health that result.

Duration: The amount of time (days, months, years) that a person is exposed to a chemical.

Environmental Contaminant: A substance (chemical) that gets into a system (person, animal, or the environment) in amounts higher than that found in Background Level, or what would be expected.

Environmental Media: Usually refers to the air, water, and soil in which chemcials of interest are found. Sometimes refers to the plants and animals that are eaten by humans. Environmental Media is the second part of an Exposure Pathway.

U.S. Environmental Protection Agency (EPA): The federal agency that develops and enforces environmental laws to protect the environment and the public's health.

Epidemiology: The study of the different factors that determine how often, in how many people, and in which people will disease occur.

Exposure: Coming into contact with a chemical substance.(For the three ways people can come in contact with substances, see Route of Exposure.)

Exposure Assessment: The process of finding the ways people come in contact with chemicals, how often and how long they come in contact with chemicals, and the amounts of chemicals with which they come in contact.

Exposure Pathway: A description of the way that a chemical moves from its source (where it began) to where and how people can come into contact with (or get exposed to) the chemical.

ATSDR defines an exposure pathway as having 5 parts:

1. Source of Contamination,
2. Environmental Media and Transport Mechanism,
3. Point of Exposure,
4. Route of Exposure, and
5. Receptor Population.

When all 5 parts of an exposure pathway are present, it is called a Completed Exposure Pathway. Each of these 5 terms is defined in this Glossary.

Frequency: How often a person is exposed to a chemical over time; for example, every day, once a week, twice a month.

Hazardous Waste: Substances that have been released or thrown away into the environment and, under certain conditions, could be harmful to people who come into contact with them.

Health Effect: ATSDR deals only with Adverse Health Effects (see definition in this Glossary).

Indeterminate Public Health Hazard: The category is used in Public Health Assessment documents for sites where important information is lacking (missing or has not yet been gathered) about site-related chemical exposures.

Ingestion: Swallowing something, as in eating or drinking. It is a way a chemical can enter your body (See Route of Exposure).

Inhalation: Breathing. It is a way a chemical can enter your body (See Route of Exposure).

LOAEL: Lowest Observed Adverse Effect Level. The lowest dose of a chemical in a study, or group of studies, that has caused harmful health effects in people or animals.

MRL: Minimal Risk Level. An estimate of daily human exposure B by a specified route and length of time -- to a dose of chemical that is likely to be without a measurable risk of adverse, noncancerous effects. An MRL should not be used as a predictor of adverse health effects.

NPL: The National Priorities List. (Which is part of Superfund.) A list kept by the U.S. Environmental Protection Agency (EPA) of the most serious, uncontrolled or abandoned hazardous waste sites in the country. An NPL site needs to be cleaned up or is being looked at to see if people can be exposed to chemicals from the site.

NOAEL: No Observed Adverse Effect Level. The highest dose of a chemical in a study, or group of studies, that did not cause harmful health effects in people or animals.

No Apparent Public Health Hazard: The category is used in ATSDR's Public Health Assessment documents for sites where exposure to site-related chemicals may have occurred in the past or is still occurring but the exposures are not at levels expected to cause adverse health effects.

No Public Health Hazard: The category is used in ATSDR's Public Health Assessment documents for sites where there is evidence of an absence of exposure to site-related chemicals.

PHA: Public Health Assessment. A report or document that looks at chemicals at a hazardous waste site and tells if people could be harmed from coming into contact with those chemicals. The PHA also tells if possible further public health actions are needed.

Point of Exposure: The place where someone can come into contact with a contaminated environmental medium (air, water, food or soil). For examples:

the area of a playground that has contaminated dirt, a contaminated spring used for drinking water, the location where fruits or vegetables are grown in contaminated soil, or the backyard area where someone might breathe contaminated air.

Population: A group of people living in a certain area; or the number of people in a certain area.

Public Health  Assessment(s): See PHA.

Public Health Hazard: The category is used in PHAs for sites that have certain physical features or evidence of chronic, site-related chemical exposure that could result in adverse health effects.

Public Health Hazard Criteria: PHA categories given to a site which tell whether people could be harmed by conditions present at the site. Each are defined in the Glossary. The categories are:

• Urgent Public Health Hazard
• Public Health Hazard
• Indeterminate Public Health Hazard
• No Apparent Public Health Hazard
• No Public Health Hazard

Receptor Population: People who live or work in the path of one or more chemicals, and who could come into contact with them (See Exposure Pathway).

Reference Dose (RfD): An estimate, with safety factors (see safety factor) built in, of the daily, life-time exposure of human populations to a possible hazard that is not likely to cause harm to the person.

Route of Exposure: The way a chemical can get into a person's body. There are three exposure routes:

- breathing (also called inhalation),

- eating or drinking (also called ingestion), and

- or getting something on the skin (also called dermal contact).

Safety Factor: Also called Uncertainty Factor. When scientists don't have enough information to decide if an exposure will cause harm to people, they use Asafety factors@ and formulas in place of the information that is not known. These factors and formulas can help determine the amount of a chemical that is not likely to cause harm to people.

Source (of Contamination): The place where a chemical comes from, such as a landfill, pond, creek, incinerator, tank, or drum. Contaminant source is the first part of an Exposure Pathway.

Special Populations: People who may be more sensitive to chemical exposures because of certain factors such as age, a disease they already have, occupation, sex, or certain behaviors (like cigarette smoking). Children, pregnant women, and older people are often considered special populations.

Statistics: A branch of the math process of collecting, looking at, and summarizing data or information.

Subclinical: The presence of a disease without apparent symptoms in the individual. May be an undiagnosed or early stage of a disease, or result in impaired development or reduced potential. Effects may only be apparent after scientific comparisons of many children.

Superfund Site: See NPL.

Toxic: Harmful. Any substance or chemical can be toxic at a certain dose (amount). The dose is what determines the potential harm of a chemical and whether it would cause someone to get sick.

Toxicology: The study of the harmful effects of chemicals on humans or animals.

Uncertainty Factor: See Safety Factor.

Urgent Public Health Hazard: This category is used in ATSDR's Public Health Assessment documents for sites that have certain physical features or evidence of short-term (less than 1 year), site-related chemical exposure that could result in adverse health effects and require quick intervention to stop people from being exposed.

FIGURES

Figure 1 - Effects of Inorganic lead in children and adults

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     * The typical infant and toddler oral exploratory behaviors include repetitive mouthing which results in continuous ingestion by these children of small amounts of dust and soil over the course of a play period, ultimately adding up to a daily intake of 100 to 200 mg (Mushak 1998).

  * 16 kg (roughly 35 pounds) is approximately the body weight of a child one to two years of age. The Centers for Disease Control and Prevention (CDC) has said that focus should be on children between the ages of 12 and 36 months (1-and 2-year-old children) because blood lead levels tend to be highest in this age group, and more chiuldren in this age group have blood lead levels equal to or greater than 10 µg/dl (CDC, 1997).

    **The value of 50% bioavailability was selected as representative of the upper range of values seen in a variety of studies measuring absolute and relative lead bioavailability (Mushak, 1998; Maddaloni, 1998; Henningsen, 1998).

  * A diagnostic BLL is the first venous BLL obtained within 6 months of an elevated screening for BLL.

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