Table 4.
Selected RR estimates for NHL associated with TCE exposure (overall and highest exposure group) from cohort and case-control studies.
| Overall Exposure | Highest TCE Exposure Group | |||||
|---|---|---|---|---|---|---|
| Study | RR (95% CI) | Alternate RR estimates | Exposure Category | RR (95% CI) | Alternate RR estimates | Comments |
| Cohort Studies | ||||||
| Anttila et al. [38] | 1.81 (0.78, 3.56) | None | 100+ μmol/L U-TCA a | 1.4 (0.17, 5.04) | None | ICD-7 200 + 202. SIR. |
| Axelson et al. [37] | 1.52 (0.49, 3.53) | 1.36 (0.44, 3.18) with estimated female contribution to SIR added b | ≥2 year exposure and 100+ mg/L U-TCA | 6.25 (0.16, 34.83) | 5.62 (0.14, 31.3) with estimated female contribution added b | ICD-7 200 + 202. SIR reported for males only, but there was a small female component to the cohort. |
| Boice et al. [41] | 1.19 (0.83, 1.65) | 1.19 (0.65, 1.99) for potential routine exposure | ≥5 years exposure | 1.62 (0.82, 3.22) | None | ICD-9 200 + 202. Overall exposure SMR for any potential exposure. Mortality RR for highest exposure group for any potential exposure adjusted for date of birth, dates 1st and last employed, race, and sex; referent group is workers not exposed to any solvent. |
| Greenland et al. [42] | 0.76 (0.24, 2.42) | None | NA | ICD-8 200–202. Mortality OR from nested case-control study. Overall exposure only. | ||
| Hansen et al. [39] | 3.1 (1.3, 6.1) b | None | ≥1,080 months × mg/m3 | 2.7 (0.56, 8.0) b | 3.7 (1.0, 9.5) for >75 months exposure duration; b 2.9 (0.79, 7.5) for >19 mg/m3 mean exposure b |
ICD-7 200 + 202. SIR for highest exposure group presented only for males; female results estimated and combined with male results. |
| Morgan et al. [43] | 1.01 (0.46, 1.92) | 1.36 (0.35, 5.21) RR for ICD 200 |
High cumulative exposure score | 0.81 (0.1, 6.49) | 1.31 (0.28, 6.08) for medium/high peak | ICD 200 + 202, ICD Revision 7, 8, or 9, depending on year of death. Overall SMR reported by Mandel et al. [18] Alternative overall mortality RR for ICD 200 as reported in Morgan et al. [57] and adjusted for age and sex. Mortality RR for highest exposure group is for ICD 200 only and adjusted for age and sex. |
| Raaschou-Nielsen et al. [40] | 1.24 (1.01, 1.52) | 1.5 (1.2, 2.0) for subcohort with expected higher exposures | ≥5 years in subcohort with expected higher exposure levels | 1.6 (1.1, 2.2) | 1.45 (0.99, 2.05) for ≥5 years in full cohort b | ICD-7 200 + 202. SIR. |
| Radican et al. [27] | 1.36 (0.77, 2.39) | None | >25 unit-years | 1.41 (0.71, 2.81)c | 0.97 (0.42, 2.2) for incidence (Blair et al. [44])c | ICD-8,-9 200 + 202; ICD-10 C82–C85. Mortality RR adjusted for age, sex and race, with workers with no chemical exposures as referent group. |
| Zhao et al. [25] | 1.44 (0.90, 2.30) d | Incidence RR: 0.77 (0.42, 1.39); d SMR for ICD-9 200 + 202: 0.21 (0.01, 1.18) (Boice et al. [26]) | High exposure score | 1.30 (0.52, 3.23) | Incidence RR: 0.20 (0.03, 1.46) | Most lymphohematopoietic cancers, ICD-9 200–208, ICD-10, C81–C95, ICD-O 2, morphology code 9590–9716, 9723, 9800–9980. Mortality RRs used in primary analyses since reflect more exposed cases than do the incidence results. Males only; adjusted for age, SES, time since first employment. |
| Case-Control Studies:e | ||||||
| Cocco et al. [21] | 0.8 (0.5, 1.1) | None | High cumulative exposure | 0.7 (0. 4, 1.3) | None | NHL. Grouping consistent with traditional definition provided by author. Incidence OR. High-confidence subgroup. Adjusted for age, sex, center, and education. |
| Hardell et al. [46] | 7.2 (1.3, 42) | None | NA | NHL. Rappaport classification system. Incidence OR. Males only; controls matched for age, place of residence, vital status. Overall exposure only. | ||
| Miligi et al. [20] | 0.93 (0.67, 1.29) | None | Medium/high exposure intensity | 1.2 (0.7, 2.0) | 1.0 (0.5, 2.6) for med/high intensity and >15 years | NHL + CLL. NCI Working Formulation. Adjusted OR for overall exposure not presented; overall crude incidence OR calculated as described in methods section. OR for highest exposure group adjusted for age, sex, education, and area. |
| Nordstrom et al. [47] | 1.5 (0.7, 3.3) | None | NA | HCL. Incidence OR. Males only; controls matched for age and county; analysis controlled for age. Overall exposure only. | ||
| Perrson and Frederikson [48] | 1.2 (0.5, 2.4) | None | NA | NHL. Classification system not specified. Incidence OR. Controls selected from same geographic areas; OR stratified on age and sex. Overall exposure only. | ||
| Purdue et al. [22] | 1.4 (0.8, 2.4) | None | Cumulative exposure > 234,000 ppm-hours | 3.3 (1.1, 10.1) | 2.3 (1.0, 5.0) for highest exposure tertile (>112,320 ppm-hours) | ICD-O-3 codes 967–972. Incidence OR. Probable-exposure subgroup. Adjusted for age, sex, SEER center, race, and education. |
| Siemiatycki [53] | 1.1 (0.5, 2.5) | None | Substantial | 0.8 (0.2, 3.3) | None | ICD-9 200 + 202. Incidence OR. SE and 95% CI calculated from reported 90% CIs; males only; adjusted for age, income, and cigarette smoking index. |
| Wang et al. [23] | 1.2 (0.9, 1.8) | None | Medium-high intensity | 2.2 (0.9, 5.4) | None | ICD-O M-9590–9595, 9670–9688, 9690–9698, 9700–9723. Incidence OR. Females only; adjusted for age, family history of lymphohematopoietic cancers, alcohol consumption, and race. |
a
Mean personal trichloroacetic acid in urine. 1 μmol/L = 0.1634 mg/L.
b
Male and female results combined assuming Poisson distribution. Details of the approach used to estimate the female contribution for Axelson et al. [37] are presented in U.S. EPA [60].
c
Male and female results combined using inverse-variance weighting, as in a fixed-effect meta-analysis.
d
To derive an overall RR estimate, results were combined across exposure groups using inverse-variance weighting, under assumptions of group independence, although the exposure groups share a referent group and, hence, are not actually independent.
e
The RR estimates are all ORs for incident cases.
CI = confidence interval, CLL = chronic lymphocytic leukemia, HCL = hairy cell leukemia, ICD = International Classification of Diseases, NCI = National Cancer Institute, NHL = non-Hodgkin lymphoma, NA = not available, OR = odds ratio, RR = relative risk, SES = socioeconomic status, SIR = standardized incidence ratio, SMR = standardized mortality ratio, TCE = Trichloroethylene, U-TCA = urinary trichloroacetic acid.