SECTION 4
DESCRIPTIVE DATA: ENVIRONMENTAL AND REGISTRANT
ON-SITE ACTIVITIES
In the summer of 1989, data collection for the TCE Subregistry began with face-to-face interviews with potential subregistry members from the Indiana and Michigan sites. People who were currently residing or had previously resided at the designated addresses served by TCE-contaminated wells were considered to be "potential" registrants. Potential subregistry members from the Illinois sites were contacted for a baseline interview in the summer of 1990.
Preparations for on-site data collection included a mailing to potential registrants. The mailing included a question-and-answer brochure that contained information about ATSDR, the National Exposure Registry, the TCE Subregistry, and the chemical TCE. It also included a chapter from the ATSDR Toxicological Profile for Trichloroethylene, which summarized all that was known about the association of adverse health outcomes and exposure to TCE (5). This information packet was sent to residents prior to a public meeting about the Registry and the data collection effort. Soon after the public meeting, interviewers began contacting residents at the designated household addresses in search of eligible subregistry members.
For each subregistry, the selection process uses definitions of eligibility and exposure that incorporate three key components: (1) valid information that indicates the presence of the contaminant(s) of interest in one or more of the media of interest; (2) evidence, for a given individual, of an appropriate route(s) of exposure; and (3) evidence of indicated transmission from the contaminated source to the individual during the period of exposure as verified by the potential registrant. For example, well water had to have been tested and validated at each subregistry site for the presence of TCE. Also, the well water had to have been the sole source of water for drinking, bathing, or cooking for all individuals at the site residential addresses. Finally, a registrant would had to have reported using the TCE-contaminated well water for drinking, cooking, or bathing during the exposure period.
Each eligible person or a proxy for that person was administered the TCE Subregistry baseline questionnaire that included a set of questions about health conditions that the registrant currently had or had ever had and that had been either confirmed or treated by a health practitioner. Each time the respondent reported the presence of one of these health conditions, a set of follow-up questions was asked about the date of first treatment by a physician, current treatment, prescribed medication, and hospitalization related to the condition.
Information on past residents at an exposure address was solicited from current residents and other knowledgeable persons (such as neighbors). Any names provided were traced, using a professional tracing service. Individuals located were contacted by telephone to determine if they were eligible to participate; if so, their participation was solicited and the core questionnaire was administered at that time.
Information on deceased eligible persons was obtained from a knowledgeable proxy (usually the spouse) in order to request a death certificate from the appropriate state office. Information on cause of death, along with other pertinent information, was extracted from the certificate and coded.
COVERAGE OF DESIGNATED HOUSEHOLD ADDRESSES
This section provides an assessment of coverage (that is, registrant occupancy at household addresses during the exposure period). There are several ways to assess coverage, each depending on available information. Since no preexisting list of potentially eligible persons was available to compare with the list of subregistry participants, the analyses reported here assessed coverage as having at least one registrant reside at a household address each month of the exposure period. The outcome of the coverage analysis will provide some indication, albeit limited, of the extent to which Registry procedures identified all potential registrants.
Using this definition, 100% coverage for a household address indicates that at least one registrant lived at the household address during each month of the exposure period. Similarly, 80% coverage of a household address indicates that at least one registrant lived at the household address during any 120 of 150 months in the exposure period (for example, if the exposure period was 12.5 years, 10 years were covered).
Coverage statistics were based on information registrants provided during the interview concerning "month/year moved in" and "month/year moved out" of the household address. A month was considered covered if (1) the household address was occupied by a registrant and (2) the month of occupation fell within the subregistry-specific exposure period. The following hypothetical example illustrates how coverage was calculated for each household address:
Two registrants were associated with a household address for which the period of exposure was January 1, 1970, through December 31, 1970. Person A resided at the address from months 2 through 5 (February through May). Person B resided at the address from months 3 through 9 (March through September). Taken together, the two registrants account for 8 (67%) of the 12 months of the exposure period. The result is 67% coverage of this particular household address.
Complete occupancy data shown in Table 4-1 is less than the total number of TCE Subregistry participants for several reasons. All exposed people (n = 209) associated with the Verona Well Field and Dowagiac, Michigan, sites were excluded because they were not asked subregistry-specific eligibility questions. Their eligibility had been determined by Battle Creek health study researchers (12). Further, 210 other people(1) had incomplete data on tenure at their household address. Finally, decedents (n = 239) were excluded, because the information needed was not obtained from their proxies.
Table 4-1.--Living registrants with complete occupancy data.
| TCE Site | Number of
Household Addresses |
Number of Registrants with Complete Occupancy Data | Number of Registrants for Household Address | ||
| Mean* (sd) | Minimum | Maximum | |||
| Michigan | |||||
| Verona Well Field and Dowagiac†
McGraw-Edison Corporation |
---
47 |
---
182 |
---
4 (2.9) |
---
1 |
---
13 |
| Indiana | |||||
| Superior Street
Central Area Gemeinhardt Piccolo Company Conrail Rail Yard |
118
26 95 44 |
420
95 424 210 |
4 (2.2)
4 (1.9) 4 (3.8) 5 (2.8) |
1
1 1 1 |
11
8 24 12 |
| Illinois | |||||
| Acme Solvents Reclamation, Inc.
Beloit Corporation Byron Johnson Salvage Yard Frinks Industrial Waste Southeast Rockford Groundwater Contamination Warner Electric Brake and Clutch Company |
13
3 24 5 328 73 |
74
11 104 25 1,764 314 |
6 (3.2)
4 (3.8) 4 (4.4) 5 (2.3) 5 (6.4) 4 (1.9) |
2
1 2 3 1 1 |
13
18 17 9 80 11 |
| Total | 776 | 3,623 | 5 (4.7) | 1 | 80 |
*These values are rounded to nearest whole number; sd = standard deviation.
†Coverage cannot be determined for cases associated with these sites. Registry files have environmental data for all addresses associated with Verona Well Field and Dowagiac addresses. However, none of these people were asked the subregistry eligibility questions because eligibility had been determined in the Battle Creek health study (12).
All household addresses associated with the people represented in Table 4-1 were addresses for which there was at least one registrant who had complete eligibility data.(2) There were 776 household addresses for which at least one registrant had complete tenure data. On the average, five people were associated with each of these household addresses. That is, ATSDR identified and interviewed an average of five current or former residents of these site addresses, all of whom were eligible and agreed to participate. This average varied from site to site. Acme Solvents household addresses had the highest average number (n = 6) of registrants per household address; the lowest average number of registrants (n = 4) occurred at seven different sites. The largest number of registrants per household address was at the Southeast Rockford site, where 80 registrants were associated with one household address.
Table 4-2 displays the average registrant coverage--80% of the exposure period--for all of the household addresses. The highest coverage was associated with the Beloit Corporation site, where all three household addresses had 100% coverage. The lowest coverage was at the Gemeinhardt Piccolo site, where the 95 household addresses had an average of 71% coverage.
To summarize, these data reveal that registrant tenure at household addresses accounted for 80% of the exposure periods. The remaining 20% of the exposure periods might have been accounted for by several factors: normal or expected vacancy(3), screening and tracing activities that failed to list or locate all of the people who had ever lived at the household addresses, and occupancy by decedents for whom move-in/move-out dates were not obtained. It was impossible to determine which one or combination of these factors contributed most to the gap in coverage. For this reason, there is no prima facie evidence that registrant data were biased as a result of coverage.
POPULATION SUMMARY
Table 4-3 presents the number of living (those deemed eligible who were contacted and agreed to participate) and deceased registrants (those for whom death certificates were located) by site. For Michigan, the Verona Well Field and Dowagiac registrants were combined. All registrants associated with these two sites were derived from a list of participants of a previous health study (12) and the researchers for that study did not distinguish cases according to site area. For Illinois, four sites were combined for purposes of maintaining confidentiality. Altogether, there were 4,281 exposed participants in the baseline data collection, of whom 239 were deceased.
Most of the registrants resided within a site area state (that is, Illinois, Indiana, or Michigan) or in the North Central region of the United States. Figure 4-1 shows that over 90% (n = 4,025) of the registrants (living and deceased) were concentrated in the eastern North Central region of the United States, which includes Illinois, Indiana, Michigan, Ohio, and Wisconsin. Those participants who had moved out of the site area states were dispersed throughout the United States, with the second highest concentration in the western North Central region (n = 53)(4).
Table 4-2.--Descriptive coverage by site.
TCE Site |
Number of Household Addresses | Percent Coverage* (sd) |
| Michigan | ||
| Verona Well Field and Dowagiac†
McGraw-Edison Corporation |
---
47 |
---
81 (31.7) |
| Indiana | ||
| Superior Street
Central Area Gemeinhardt Piccolo Company Conrail Rail Yard |
118
26 95 44 |
84 (26.2)
82 (29.1) 71 (34.6) 62 (35.6) |
| Illinois | ||
| Acme Solvents Reclamation, Inc.
Beloit Corporation Byron Johnson Salvage Yard Frinks Industrial Waste Southeast Rockford Groundwater Contamination Warner Electric Brake and Clutch Company |
13
3 24 5 328 73 |
89 (18.3)
100 (0.0) 92 (13.5) 90 (15.3) 80 (31.0) 88 (21.7) |
| Total | 776 | 80 (30.2) |
*These values are rounded to nearest whole number; sd = standard deviation.
†Coverage cannot be determined for cases associated with these sites. Subregistry files have environmental data for all addresses associated with Verona Well Field and Dowagiac addresses. However, none of these people were asked the subregistry eligibility questions because their eligibility was determined in the Battle Creek health study (12).
Table 4-3.--Number of participants in the TCE baseline.
| TCE Subregistry Site Location | Number of Living | Number of
Deceased |
| Michigan | ||
| Verona Well Field and Dowagiac | 209 | 14 |
| McGraw-Edison Corporation | 218 | 21 |
| Indiana | ||
| Superior Street | 481 | 31 |
| Central Area | 103 | 3 |
| Gemeinhardt Piccolo Company | 493 | 29 |
| Conrail Rail Yard | 236 | 12 |
| Illinois | ||
| Beloit Corporation; Byron Johnson Salvage Yard; Acme
Solvents Reclamation, Inc.; Frinks Industrial Waste |
214 | 9 |
| Southeast Rockford Groundwater Contamination | 1,772 | 113 |
| Warner Electric Brake and Clutch Company | 315 | 7 |
| Total | 4,041 | 239 |
The 4,281 participants represented 98% of the eligible people (see Table 4-4) who were contacted and asked to take part in the subregistry. The Central Area site in Elkhart, Indiana, had a 100% participation rate. The total and site-specific participation rates were calculated by dividing the number of registrants (living and deceased) by the number of potentially eligible persons contacted and asked to participate.
REGISTRANT DESCRIPTIVE DATA
Tables 4-5 through 4-7 contain information about the characteristics of TCE Subregistry members (n = 4,280); information from all sites is included in these tables. Table 4-5 indicates that 52% of the registrants who were alive at time of baseline data collection were female. Approximately 38% of the registrants were from 25 through 44 years of age at the time of the
Figure 4-1.--Geographic distribution of registrants (living and deceased).
Table 4-4.--Participation rate by site.
| TCE Site Name | Participation Rate (%)* |
| Michigan | |
| Verona Wells and Dowagiac | 98.0 |
| McGraw-Edison Corporation | 99.2 |
| Indiana | |
| Superior Street | 98.9 |
| Central Area Street | 100.0 |
| Gemeinhardt Piccolo Company | 98.9 |
| Conrail Rail Yard | 99.2 |
| Illinois | |
| Beloit Corporation; Byron Johnson Salvage Yard; Acme Solvents Reclamation, Inc.; Frinks Industrial Waste | 98.9 |
| Southeast Rockford Groundwater Contamination | 98.4 |
| Warner Electric Brake and Clutch Company | 98.8 |
| Total | 98.9 |
*Participation rate = [number of participants (living and deceased) ÷ (number of potentially eligible persons contacted and asked to participate)] x 100.
Table 4-5.--Descriptive data for living registrants (all sites).
| Variable | Males
N (%) |
Females
N (%) |
Total
N (%) |
| Sex | 1,941 (48.0) | 2,100 (52.0) | 4,041 (100.0) |
| Age (years)
17 18-24 25-44 45-64 65-74 75 |
473 (24.4)
229 (11.8) 734 (37.8) 352 (18.1) 95 (4.9) 58 (3.0) |
474 (22.6)
239 (11.3) 797 (38.0) 372 (17.7) 141 (6.7) 77 (3.7) |
948 (23.5)
468 (11.6) 1,531 (37.9) 724 (17.9) 236 (5.8) 135 (3.3) |
| Race
White Nonwhite Missing |
1,875 (96.6)
66 (3.4) 0 (<1.0) |
2,040 (97.2)
58 (2.8) 2(<1.0) |
3,915 (96.9)
124 (3.1) 2 (<1.0) |
| Education (25 years of age)
Not high school graduate High school graduate Some college College graduate or more Missing |
1,239
403 (32.5) 523 (42.2) 189 (15.2) 121 (9.8) 3 (<1.0) |
1,387
407 (29.3) 615 (44.3) 258 (18.6) 105 (7.7) 2(<1.0) |
2,626
810 (30.8) 1,138 (43.3) 447 (17.0) 226 (8.6) 5 (<1.0) |
| Occupational Status (19 years of
age) Currently employed Previously employed Never employed Missing |
1,437
1,132 (78.8) 298 (20.7) 7 (0.5) 0 (0.0) |
1,595
951 (59.6) 580 (36.4) 61 (4.0) 3 (1.0) |
3,032
2,083 (68.7) 878 (29.0) 68 (2.3) 3 (<1.0) |
| Place of residence (at time of
interview) On site Off site |
1,788 (92.1)
153 (7.9) |
1,897 (90.3)
203 (9.7) |
3,685 (91.2)
356 (8.8) |
| Type of Interview
Subject Proxy Missing |
1,411 (72.7)
530 (27.3) 0 (0.0) |
1,586 (75.6)
512 (24.4) 2 (1.0) |
2,997 (74.2)
1,042 (25.8) 2 (<1.0) |
Table 4-6.--Tobacco use data for TCE registrants 18 years of age or older (all sites).
Variable |
Males
N (%) |
Females
N (%) |
Total N (%) |
| Sex | 1,468 (47.4) | 1,626 (52.6) | 3,094 (100.0) |
| Cigarettes
Current smoker Ex-smoker Never smoked Missing |
632 (43.1)
348 (23.7) 487 (33.2) 1 (<1.0) |
610 (37.5)
296 (18.2) 719 (44.3) 1 (<1.0) |
1,242 (40.2)
644 (20.8) 1,206 (39.0) 2 (<1.0) |
| Pipes
Current smoker Ex-smoker Never smoked Missing |
49 (3.3)
161 (11.0) 1,255 (85.7) 3 (<1.0) |
1 (0.1)
1 (0.1) 1,623 (99.9) 1 (<1.0) |
50 (1.6)
162 (5.2) 2,878 (93.1) 4 (<1.0) |
| Cigars
Current smoker Ex-smoker Never smoked Missing |
69 (4.7) 134 (9.1) 1,263 (86.2) 2 (<1.0) |
0
3 (0.2) 1,621 (99.8) 2 (<1.0) |
69 (2.2)
137 (4.4) 2,884 (93.3) 4 (<1.0) |
| Snuff
Current user Ex-user Never used Missing |
28 (1.9)
46 (3.1) 1,393 (85.7) 1 (<1.0) |
2 (0.1)
3 (0.2) 1,620 (99.7) 1 (<1.0) |
30 (1.0)
49 (1.6) 3,013 (97.4) 2 (<1.0) |
| Chewing Tobacco
Current user Ex-user Never used Missing |
38 (2.6)
62 (4.2) 1,367 (93.2) 1 (<1.0) |
2 (0.1)
4 (0.2) 1,619 (99.6) 1 (<1.0) |
40 (1.3)
66 (2.1) 2,986 (96.6) 2 (<1.0) |
Table 4-7.--Descriptive data for deceased registrants (all sites).
Variable< P>> |
Males
N (%) |
Females
N (%) |
Total N (%) |
| Sex | 140 (58.6) | 99 (41.4) | 239 (100.0) |
| Age (years)
17 18-24 25-44 45-64 65-74 75 |
0
6 (4.3) 9 (6.4) 50 (35.7) 31 (22.2) 44 (31.4) |
4 (4.0)
3 (3.0) 4 (4.0) 15 (15.2) 25 (25.3) 48 (48.5) |
4 (1.7)
9 (3.8) 13 (5.4) 65 (27.2) 56 (23.4) 92 (38.5) |
| Location at death
In state Out of stat e |
125 (89.3)
15 (10.7) |
92 (93.0)
7 (7.0) |
217 (90.8)
22 (9.2) |
baseline interview; over 20% were under the age of 18 years. Over 96% of males and females were white, indicating an overall overrepresentation of whites compared with the general U.S. population (see Section 5).
Among registrants who were 25 years of age or older, 70% had at least a high school diploma. Slightly more females than males had completed high school (44.4% versus 42.3%) or some college (18.6% versus 15.3%). A higher percentage of males (9.8%) than females (7.6%) had completed college or some post-college education.
Over two-thirds of the registrants who were 19 years of age or older were employed either full- or part-time. This percentage varied substantially between males and females; 80% of the males versus 60% of the females were employed at the time of the interview. On the average, registrants were exposed to TCE at household addresses for about 5.52 years. The minimum length of exposure was 30 consecutive days (.08 years); the maximum was 18 years.
Table 4-6 provides data on registrants' use of tobacco products. A large percentage (40.2%) of registrants reported being current cigarette smokers. Slightly more males (43.1%) than females (37.5%) were current cigarette smokers; more females than males (44.3% versus 33.2%) reported having never smoked cigarettes. A small number of the registrants reported ever using other tobacco products: pipes (6.8%), cigars (6.6%), snuff (2.6%), and chewing tobacco (3.4%). Smoking rates for registrants are compared with national data in Section 4.
Information collected on deceased registrants was limited to that required to request a death certificate from the state of death; hence, no lifestyle data were available for the decedents. Table 4-7 indicates that there were 239 decedents in the subregistry for whom death certificates were obtained. Most of these decedents were males (58.6%), or were 65 years of age or older at the time of death (males and females, 61.9%). About 91% of them died in one of the site states (Michigan, Indiana, or Illinois).
1. 1 There were 210 persons omitted from this analysis because of missing tenure data or because they did not provide complete information on the month or year they moved into or out of the residence.
2. 2 Two site residences were excluded from the analysis because they had incomplete coverage data.
3. 3 All of the residences were not expected to be occupied all of the time. In 1985, national vacancy rates were 6.5% for rental units and 1.7% for homeowner units (13).
4. 4 One criteria for inclusion in the Subregistry at the point of baseline data collection was residency in the United States. After the baseline interview, registrants who moved out of the country were, and continue to be, traced and interviewed by telephone, as are all other registrants.
Agency for Toxic Substances and Disease Registry, 1825 Century Blvd, Atlanta, GA 30345
Contact CDC: 800-232-4636 / TTY: 888-232-6348
