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SECTION 2

Environmental And Registrant Information

At the time of its selection as the primary chemical for a subregistry, trichloroethylene (TCE) was the most prevalent contaminant reported at National Priorities List (NPL) sites. TCE was identified at 37% of all NPL sites and was a groundwater contaminant at 91% of the TCE sites (1). The chemical selection procedures for developing subregistries in the National Exposure Registry (NER) are detailed in the policies and procedures manual (4); also included are the site selection procedures. During the site selection process, a total of 279 potential sites were identified as having TCE as a contaminant of the drinking water.

A total of 13 sites located in 3 states (see Table 2-1) were selected for inclusion in the TCE Subregistry at the start of the 1989 Baseline activities. The exposure period for each of these sites represents a conservative estimate of the beginning and ending points of contamination. These estimates were based on existing environmental data and other information obtained from local, state, or other federal agencies. The registrants' documented exposure occurred from use of TCE-contaminated private wells; in most cases, the documentation for a given household address was based on one environmental sample. Since the completion of Baseline activities, two additional sites have been added to the TCE Subregisty--one in Pennsylvania and one in Arizona. However, to be consistent with the Baseline report, the registrants from these additional sites are not included in the analysis of Followup 1 data.

Table 2-1 provides the name and location of each site. The table also provides a summary of environmental data by site. A more detailed discussion of the 13 sites in the TCE Subregistry that includes a brief description of the source of contamination, the time period of documented contamination, and the contaminants detected in sampling activities is in the TCE Baseline report (1).

DATA COLLECTION

In 1990, the first followup of the TCE Subregistry was completed at the Indiana and Michigan sites; the Baseline data were collected in 1989. The Subregistry members from the Illinois sites were contacted for a Baseline interview in the summer of 1990, and first followup was conducted in 1991. Computer-assisted telephone interviews (CATI) were used for collecting the most of the data.

The age groupings were realigned in the Followup 1 database to compensate for the one-year time lapse since Baseline; that is, 0 through 9 years became 1 through 10 years; 10 through 17 became 11 through 18 years, and so forth. The realigned ages were used for the National Health Interview Survey (NHIS) age groupings for the statistical analyses.

Table 2-1.--Summary of environmental data by site.

TCE Subregistry Site	Year Exposure Began	Exposure Period* (Years)	Level of TCE Reported (ppb†)
			Maximum	Median
Michigan
Verona Well Field Dowagiac	1970 1975	13.0 7.0	2,000	6.0
McGraw-Edison Corporation	1975	7.0	733	1.0
Indiana
Superior Street (Elkhart)	1976	11.0	19,380	84.0
Central Area (Elkhart)	1980	7.0	114	0.4
Gemeinhardt Piccolo Company	1972	17.0	1,600	4.0
Conrail Rail Yard	1970	18.0	1,520	78.0
Illinois
Acme Solvents Reclamation, Inc.	1980	10.5	100	1.0
Beloit Corporation	1983	7.5	3	2.0
Byron Johnson Salvage Yard	1980	10.5	249	9.1
Frinks Industrial Wastes	1978	12.5	16	14.0
Southeast Rockford Groundwater Contamination	1978	12.5	122	15.0
Warner Electric Brake and Clutch Company	1978	6.5	5,220	234.0

*Exposure period is based on best available evidence of when contamination occurred and when exposure ceased following water treatment or switch to an alternative water source.

†ppb - parts per billion.

The procedures for locating the registrants were as follows. Four to five weeks prior to the start of data collection activities, the contractor began tracing efforts of those registrants known to have moved since last interview. These tracing cases were usually identified through mailings to the registrant being returned as undeliverable. During data collection, cases requiring tracing were identified through attempts made to the telephone number on record. A case was forwarded to locating if the registrant or proxy had moved (no new telephone number provided), if the telephone number had been disconnected or calling the number resulted in 8 "ring no answer" or 8 "busy" (this would be considered a non-working number). The locating specialist would then attempt to locate the registrant by one of the following methods (in the order listed): 1) directory assistance; 2) calling the contacts provided during the last interview; 3) credit bureau searches; and 4) state departments of motor vehicles searches.

Using CATI, each registrant or proxy for the registrant was administered the NER core questionnaire. The core questionnaire, which is also administered at Baseline and all other data collection points, includes a set of questions about health practitioner confirmed or treated health conditions that the registrant currently has or had since the last interview (in this case, the Baseline interview. If a respondent reported positive to a health condition, follow-up questions were asked about the date of first treatment, current treatment, prescribed medication, and hospitalization history.

Information on deceased registrants was obtained, as at Baseline, from a knowledgeable person (usually the spouse or parent) and a death certificate was requested from the appropriate state. Information on the cause of death, along with other pertinent information, was extracted from the certificate and coded. Analysis of the mortality data is not included in this report.

Table 2-2 summarizes the number of living and deceased registrants at Baseline and at Followup 1. At Baseline, there were a total of 4,775 registrants-- 4,280 exposed (4,041 living, 239 deceased) and 495 controls (480 living, 15 deceased). The controls were participants in a epidemiological study conducted at one of the sites prior to the commencement of the NER activities. At Followup 1, an attempt was made to contact the 4,521 registrants alive at Baseline. A total of 4,020 interviews (3,579 exposed and 441 controls) were completed; 28 registrants (24 exposed and 4 controls) had died since Baseline (for a total of 263 deceased registrants). Of the 3,579 living exposed respondents at Followup 1, 3,471 reported their race as white; this white subpopulation was the basis, as at Baseline, for the statistical analyses. Table 2-3 summarizes the number of registrants by site.

Table 2-4 summarizes the outcome of the exposed registrant contacts. The overall participation rate (the percentage of the living registrants contacted who participated) was 96%, compared with greater than 97% at Baseline. We were unable to locate 113 (2.9%), unable to contact 151 (3.8%) and 158 (4.0%) were contacted and refused to complete the interview. The demo-graphics and health reporting patterns of the nonrespondents versus those remaining on the Subregistry differ in that the nonrespondents had a greater percentage of males, were younger (average of 4 years), were less educated (lower proportion of college educated), and had a higher rate of cigarette smoking than those remaining on the Subregistry. There were no clear patterns of differences in reporting rates for health conditions (based on Baseline data) between the two subpopulations--those remaining on the Subregistry and those lost to followup.

Table 2-2.--Summary of number of exposed registrants, by race.

Status	Location of TCE Subregistry Site (State)
	Indiana		Illinois		Michigan		Total
	All	White Only	All	White Only	All	White Only	All	White Only
Baseline
Living*	1,313	1,259	2,301	2,238	427	418	4,041	3,915
Deceased	75	75	130	130	35	35	239	239
Total†	1,388	1,334	2,431	2,368	462	453	4,280	4,154
Followup 1
Living*	1,197	1,149	1,995	1,941	387	381	3,579	3,471
Deceased	8	8	13	13	3	2	24	23
Subtotal	1,205	1,157	2,008	1,954	390	383	3,603	3,494
Total	1,280 (92%)§	1,232 (92%)	2,138 (93%)	2,084 (88%)	425 (92%)	418 (92%)	3,843 (90%)	3,734 (90%)

*Subtotal is Subregistry total for that specific data collection (does not include deceased).

†Total is number on Subregistry (including all deceased) at that point in time.

§Percentage of total number of living registrants at previous data collection and 255 deceased.

Tables 2-5 and 2-6 contain information about the characteristics of TCE Subregistry members at the first followup; information from all Michigan, Indiana, and Illinois sites is included in these tables. Table 2-6 shows the Followup 1 reported smoking rates. When the TCE Subregistry Baseline and Followup 1 population demographics are compared, it is noted that the sex ratio, race ratio, and type of interview did not change appreciably from Baseline to Followup 1. However, in keeping with the previous discussion of the nonrespondents, the percentage with less than a high school diploma decreased from 31% to 28% and the current smoker rate dropped from 40% to 36% for those remaining on the NER. Given the basic similarity of the two populations, the losses to followup did not appear to compromise the comparisons made between Baseline and Followup 1.

Table 2-3.--Number of living participants in the TCE Subregistry Baseline and Followup 1 by site.

TCE Subregistry Site Location	Living Participants
	Baseline	Followup 1
Michigan
Verona Well Field and Dowagiac	209	184
McGraw-Edison Corporation	218	203
Indiana
Superior Street (Elkhart)	481	436
Central Area (Elkhart)	103	98
Gemeinhardt Piccolo Company (Elkhart)	493	440
Conrail Rail Yard (Elkhart)	236	223
Illinois
Beloit Corporation; Byron Johnson Salvage Yard; Acme Solvents Reclamation, Inc.; Frinks Industrial Wastes	214	181
Southeast Rockford Groundwater Contamination	1,772	1,532
Warner Electric Brake and Clutch Company	315	282
Total	4,041	3,579

Table 2-4.--Summary of registrant response at TCE Subregistry Followup 1.

Recontact Outcome	Number	Percent of Baseline (Living Only)
Completed interview, subject living	3,471	88.6
Completed interview, subject deceased	23	0.6
Refusal, some data	158	4.0
Unable to contact or unavailable during interview period (includes 3 other categories)	151	3.8
Unable to locate	113	2.9
Total	3915	100.0

Table 2-5.--Descriptive data for TCE Subregistry Followup 1 living registrants (all races).

Variable	Males N (%)	Females N (%)	Total N (%)
Sex	1,699* (47.5)	1,880* (52.5)	3,579
Age (years) at Followup 1 1-18 19-25 26-45 46-65 66	399 (23.5) 194 (11.4) 653 (38.4) 313 (18.4) 140 ( 8.2)	411 (21.9) 203 (10.8) 725 (38.6) 345 (18.4) 196 (10.4)	810 (22.6) 397 (11.1) 1,378 (38.5) 658 (18.4) 336 (9.4)
Race White Nonwhite Don't know, refuse Missing	1,641 (96.6) 56 ( 3.4) 1 ( <.1) 1 ( <.1)	1,830 (97.3) 46 ( 2.4) 2 ( 0.1) 2 ( 0.1)	3,471 (97.0) 102 ( 2.8) 3 ( <.1) 3 ( <.1)
Education; (25 years of age) Not high school graduate High school graduate Some college College graduate or more Don't know, refuse	1,137 (46.8) 337 (29.6) 484 (42.6) 188 (16.5) 120 (10.6) 8 (0.7)	1,293 (53.2) 353 (27.3) 579 (44.8) 240 (18.6) 114 (8.8) 7 ( 0.5)	2,430 (100.0) 690 (34.7) 1,063 (14.0) 428 (17.6) 234 (9.6) 15 ( 0.6)
Type of interview Proxy Subject	444 (26.1) 1,255 (73.9)	423 (22.5) 1,457 (77.5)	867 (24.2) 2,712 (75.8)

*Row totals are used to calculate these percentages; all other percentages are calculated

using column totals.

Table 2-6.--Tobacco use data for TCE Subregistry Followup 1 registrants 18 years of age or older (all races).

Variable	Males		Females		Total
	N	%	N	%	N	%
Sex	1,325	47.0*	1,494	53.0*	2,819	100
Cigarettes Current smoker Ex-smoker Never smoked Missing, refused	520 348 454 3	39.2 26.3 34.3 0.2	497 295 700 2	33.3 19.8 46.8 0.1	1,017 643 1,154 5	36.1 22.8 40.9 0.2
Pipes Current smoker Ex-smoker Never smoked Missing, refused	35 154 1,134 2	2.6 11.6 85.6 0.2	0 3 1,490 1	0 0.2 99.7 0.1	35 157 2,624 3	1.2 5.6 93.1 0.1
Cigars Current smoker Ex-smoker Never smoked Missing, refused	47 153 1,124 1	3.6 11.5 84.8 0.1	2 3 1,487 2	0.1 0.2 99.5 0.1	49 156 2,611 3	1.7 5.5 92.6 0.1
Snuff Current user Ex-user Never used Missing, refused	29 52 1,243 1	2.2 3.9 93.8 0.1	2 1 1,489 2	0.1 0.1 99.7 0.1	31 53 2,732 3	1.1 1.9 96.9 0.1
Chewing Tobacco Current user Ex-user Never used Missing, refused	32 57 1,234 2	2.4 4.3 93.1 0.1	2 3 1,487 2	0.1 0.2 99.5 0.1	34 60 2,721 4	1.2 2.1 96.5 0.1

*Row percentages. All other percentages are column percentages.