Cancer Mortality in Workers Exposed to Phenoxy Herbicides, Chlorophenols, and Dioxins An Expanded and Updated International Cohort Study

Abstract

The authors examined cancer mortality in a historical cohort study of 21,863 male and female workers in 36 cohorts exposed to phenoxy herbicides, chlorophenols, and dioxins in 12 countries. Subjects in this updated and expanded multinational study coordinated by the International Agency for Research on Cancer were followed from 1939 to 1992. Exposure was reconstructed using job records, company exposure questionnaires, and serum and adipose tissue dioxin levels. Among workers exposed to phenoxy herbicides contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or higher chlorinated dioxins, mortality from soft-tissue sarcoma (6 deaths; standardized mortality ratio (SMR) = 2.03, 95% confidence interval (CI) 0.75-4.43) was higher than expected from national mortality rates. Mortality from all malignant neoplasms (710 deaths; SMR = 1.12, 95% CI 1.04-1.21), non-Hodgkin's lymphoma (24 deaths; SMR = 1.39, 95% CI 0.89-2.06), and lung cancer (225 deaths; SMR = 1.12, 95% CI 0.98-1.28) was slightly elevated. Risks for all neoplasms, for sarcomas, and for lymphomas increased with time since first exposure. In workers exposed to phenoxy herbicides with minimal or no contamination by TCDD and higher chlorinated dioxins, mortality from all neoplasms (398 deaths; SMR = 0.96, 95% CI 0.87-1.06), non-Hodgkin's lymphoma (9 deaths; SMR = 1.00), and lung cancer (148 deaths; SMR = 1.03) was similar to that expected, and mortality from soft-tissue sarcoma was slightly elevated (2 deaths; SMR = 1.35). In a Poisson regression analysis, workers exposed to TCDD or higher chlorinated dioxins had an increased risk for all neoplasms (rate ratio = 1.29, 95% CI 0.94-1.76) compared with workers from the same cohort exposed to phenoxy herbicides and chlorophenols but with minimal or no exposure to TCDD and higher chlorinated dioxins. These findings indicate that exposure to herbicides contaminated with TCDD and higher chlorinated dioxins may be associated with a small increase in overall cancer risk and in risk for specific cancers.

Serum concentrations of chlorinated dibenzo-p-dioxins, furans and PCBs, among former phenoxy herbicide production workers and firefighters in New Zealand

“…For serum concentrations below LOD, half of the detection limit was used in all calculations b Duration of employment at production plant; for firefighters duration of stationed near production plant divided by 2 to account for rostering Pesticide producers (n = 244) Firefighters (n = 39) Difference between groups p-value (ANOVA) Group 1: production workers phenoxy/TCP Group 2: production workers Other (male) Group 3: production workers Other (female) than phenoxy herbicide production (groups 2 and 3), but lower than those directly involved in phenoxy herbicide production. Phenoxy herbicide producers from several countries have been serum tested for TCDD concentrations (reported in (Kogevinas et al 1997). Direct comparison with these populations is difficult because the selection of tested workers was often not random (e.g., only those with chloracne), and because the studies differ greatly in the length of time between last exposure and year of serum sampling.…”

“…In 1980 IARC established an international cohort of producers and sprayers of phenoxy herbicides (Kogevinas et al 1997;Saracci et al 1991). The collaboration involved 36 cohorts from 12 countries, including a New Zealand cohort of 1025 phenoxy herbicide producers which constituted the source population for this study.…”

The non-Hodgkin lymphomas: A review of the epidemiologic literature

“…97 Steenland et al 94 combined workers from 12 US plants that produced 2,3,7,8-tetrachlorodibenzo-pdioxin (TCDD)-contaminated products and reported no association with NHL mortality (SMR 5 1.10, 95% CI: 0.56-1.91). In a multinational study of workers enrolled in the International Agency for Research on Cancer (IARC) cohort, Kogevinas et al 96 reported no significant excess of NHL mortality (SMR 5 1.27, 95% CI: 0.88-1.78) among workers exposed to phenoxy herbicides or chlorophenols, with no exposure-response relationship based on duration of exposure. Furthermore, the only significant association was observed among workers with less than one year of exposure (SMR 5 2.43, 95% CI: 1.21-4.35).…”

Occupational cancer in the United Kingdom.

“…In addition to the well-established causes of cancer that have been discussed, various other occupational exposures are suspected Wales), and even in the minority of people with heavy occupational exposure, the relative risk is unlikely to be more than 10-fold (45,46). Some studies have also suggested an association between phenoxy herbicides and non-Hodgkin lymphoma, but this finding has been inconsistent (46).…”