Laurie A. Piacitelli

Cancer mortality in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

BACKGROUND In both animal and epidemiologic studies, exposure to dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD) has been associated with an increased risk of cancer. METHODS We conducted a retrospective cohort study of mortality among the 5172 workers at 12 plants in the United States that produced chemicals contaminated with TCDD. Occupational exposure was documented by reviewing job descriptions and by measuring TCDD in serum from a sample of 253 workers. Causes of death were taken from death certificates. RESULTS Mortality from several cancers previously associated with TCDD (stomach, liver, and nasal cancers, Hodgkins disease, and non-Hodgkins lymphoma) was not significantly elevated in this cohort. Mortality from soft-tissue sarcoma was increased, but not significantly (4 deaths; standardized mortality ratio [SMR], 338; 95 percent confidence interval, 92 to 865). In the subcohort of 1520 workers with greater than or equal to 1 year of exposure and greater than or equal to 20 years of latency, however, mortality was significantly increased for soft-tissue sarcoma (3 deaths; SMR, 922; 95 percent confidence interval, 190 to 2695) and for cancers of the respiratory system (SMR, 142; 95 percent confidence interval, 103 to 192). Mortality from all cancers combined was slightly but significantly elevated in the overall cohort (SMR, 115; 95 percent confidence interval, 102 to 130) and was higher in the subcohort with greater than or equal to 1 year of exposure and greater than or equal to 20 years of latency (SMR, 146; 95 percent confidence interval, 121 to 176). CONCLUSIONS This study of mortality among workers with occupational exposure to TCDD does not confirm the high relative risks reported for many cancers in previous studies. Conclusions about an increase in the risk of soft-tissue sarcoma are limited by small numbers and misclassification on death certificates. Excess mortality from all cancers combined, cancers of the respiratory tract, and soft-tissue sarcoma may result from exposure to TCDD, although we cannot exclude the possible contribution of factors such as smoking and occupational exposure to other chemicals.

Evaluation of the revised NIOSH lifting equation. A cross-sectional epidemiologic study.

STUDY DESIGN A cross-sectional study of the 1-year prevalence of low back pain was conducted in workers employed in manual lifting jobs. OBJECTIVES To provide epidemiologic data to determine the correlation between the prevalence of low back pain and exposure to manual lifting stressors, measured with the lifting index component of the revised lifting equation from the National Institute for Occupational Safety and Health (NIOSH). SUMMARY OF BACKGROUND DATA The NIOSH lifting equation has been proposed as a practical, yet valid tool for assessing the risks of low back pain caused by manual lifting. To date, however, there have been few studies in which the effectiveness of the equation to identify jobs with elevated rates of low back pain has been evaluated. METHODS Fifty jobs from four industrial sites were evaluated with the NIOSH lifting equation. A symptom and occupational history questionnaire was administered to 204 people employed in lifting jobs and 80 people employed in nonlifting jobs. Regression analysis was used to determine whether there was a correlation between the lifting index and reported low back pain. RESULTS As the lifting index increased from 1.0 to 3.0, the odds of low back pain increased, with a peak and statistically significant odds ratio occurring in the 2 < lifting index < or = 3 category (odds ratio = 2.45). For jobs with a lifting index higher than 3.0, however, the odds ratio was lower (odds ratio = 1.45). CONCLUSIONS Although low back pain is a common disorder, the lifting index appears be a useful indicator for determining the risk of low back pain caused by manual lifting.

Review and update of the results of the NIOSH medical study of workers exposed to chemicals contaminated with 2,3,7,8‐tetrachlorodibenzodioxin

In 1987, the National Institute for Occupational Safety and Health conducted a cross-sectional medical study to examine the long-term health effects of occupational exposure to chemicals and materials contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). This study compared living workers employed more than 15 years earlier in the production of sodium trichlorophenol (NaTCP), and 2,4,5-trichlorophenoxyacetic ester (2,4,5-T ester) with an unexposed comparison group. Health status of the worker and comparison populations was collected through a comprehensive set of standardized interviews and medical examinations. Lipid adjusted serum TCDD levels were also measured. Workers had a statistically significantly elevated mean serum lipid-adjusted TCDD level (workers = 220 pg per g of lipid [range = not detected-3,400 pg per g of lipid], and referents 7 pg per g of lipid [range not detected-20 pg per g of lipid], P < 0.001). Compared to a community-based referent population, the prevalence of chronic bronchitis, chronic obstructive pulmonary disease, peripheral neuropathy, depression, cardiovascular outcomes (myocardial infarction, angina, cardiac arrhythmias, hypertension, and abnormal peripheral arterial flow), abnormal porphyrin levels, and abnormal ventilatory function parameters FEV1.0, FVC, or FEV1.0/FVC% in workers, was not statistically significantly different. In contrast, relationships were observed between serum 2,3,7,8-TCDD levels and the enzyme gamma-glutamyltransferase (GGT), the reproductive hormones serum testosterone, luteinizing, and follicle-stimulating hormones, and abnormal high-density lipoprotein concentration, counts of CD3/Ta1 cells (helper lymphocytes), and fasting serum glucose levels. Current diagnosis of chloracne was associated with the highest levels of serum 2,3,7,8-TCDD. Analysis of other endpoints continues.

Efficacy of the Revised NIOSH Lifting Equation to Predict Risk of Low Back Pain Due to Manual Lifting Expanded Cross-Sectional Analysis

Objective: To evaluate whether the Revised NIOSH Lifting Equation (RNLE) is a valid tool for assessing risk of low back pain (LBP) due to manual lifting by using combined data from two cross-sectional studies of 1-year prevalence. Methods: Results from a symptom and occupational history questionnaire and RNLE analysis for 677 subjects employed in 125 manual lifting jobs at nine industrial sites were combined from two studies. Results: The odds of LBP increased as the lifting index (LI) increased from 1.0 to 3.0. A statistically significant odds ratio (OR) was found for both the 1 < LI ⩽ 2 (OR = 1.81) and the 2 < LI ⩽ 3 categories (OR = 2.26). For jobs with an LI value greater than 3.0, however, the OR remained nonsignificant. The 2 < LI ⩽ 3 group remained statistically significant after adjusting for age, gender, body mass index, and psychosocial factors. Conclusions: It is clear that as the LI increases, the risk of LBP increases. Longitudinal studies are needed.

A retrospective job exposure matrix for estimating exposure to 2,3,7, 8-tetrachlorodibenzo-p-dioxin.

BACKGROUND A job exposure matrix was developed to estimate the 2,3, 7,8-tetrachlorodibenzo-p-dioxin exposure of 3,538 workers who produced 2,4,5-trichlorophenol and its derivatives. METHODS Daily TCDD exposure scores that were plant, process, and period specific were estimated for each job title as the product of 1) the concentration of TCDD (microg/g); 2) a qualitative factor to account for the extent of worker contact and 3) time exposed to TCDD contamination. Daily scores were summed to compute individual cumulative TCDD exposure scores. RESULTS Daily TCDD exposure scores ranged from 0.001 to 1,250. Cumulative TCDD scores ranged from 0.002 to 1,559,430. The 393 workers with records of chloracne in the TCDD exposure cohort (11%) had markedly higher cumulative scores than those with no record of chloracne (a median score of 11,546 vs. 77). CONCLUSIONS The cumulative TCDD exposure scores incorporate both duration and level of exposure, and permit the relative ranking of worker exposures for the evaluation of exposure-response relationships between TCDD exposure and mortality in an updated cohort study analysis.

Levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the serum of U.S. chemical workers exposed to dioxin contaminated products: Interim results

Abstract NIOSH is conducting a medical study to evaluate the current health status of 400 chemical workers who made products contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and an unexposed referent group matched for age, sex, race and neighborhood of residence. The workers are from two U. S. facilities which produced 2,4,5-trichlorophenol and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) between 1951 and 1972. As a measure of their exposure to 2,3,7,8-TCDD, serum from each worker and from a sample of referents was analyzed for the concentration of this isomer. In this preliminary report, we present the results of the analyses for 2,3,7,8-TCDD found in the serum of 46 study participants. In general, the mean of 8.2 parts per trillion (ppt) 2,3,7,8-TCDD found in the unexposed group is comparable to levels found in unexposed persons in industrialized nations. However, the mean level of 208.2 ppt found in the workers greatly exceeds background levels (p

Serum levels of PCDDS and PCDFS among workers exposed to 2,3,7,8-TCDD contaminated chemicals

Abstract The National Institute for Occupational Safety and Health (NIOSH) collected serum from workers exposed to chemicals contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and from unexposed referents. A subset of serum samples were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). In addition to a marked difference in serum levels between workers and referents for 2,3,7,8-TCDD, there was a small but significant difference for 2,3,7,8-PnCDF and 1,2,3,4,7,8-HxCDF. Funding was received for this study from the Agency for Toxic Substances and Disease Registry.

Comparison of serum levels of 2,3,7,8-TCDD in TCP production workers and in an unexposed comparison group

Abstract Serum 2,3,7,8-TCDD levels were measured as an estimate of exposure to this isomer in 143 workers who were employed at either of two plants in New Jersey and Missouri which manufactured chemicals contaminated with 2,3,7,8-TCDD and in 54 unexposed referents. The mean serum 2,3,7,8-TCDD levels for all workers was 251.7 parts per trillion (ppt) and, for all referents combined, the mean serum level was 7.8 ppt. The mean level of 2,3,7,8-TCDD present in the serum of workers at the date of termination of exposure (half-life extrapolated) was 2600 ppt and 870 ppt for the New Jersey and Missouri workers, respectively. Overall, the levels in the workers significantly correlated with duration of exposure in 2,3,7,8-TCDD-contaminated processes (r = 0.83, p

Paternal Occupational Exposure to 2,3,7,8-Tetrachlorodibenzo-p-dioxin and Birth Outcomes of Offspring: Birth Weight, Preterm Delivery, and Birth Defects

Agent Orange is a phenoxy herbicide that was contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We studied pregnancy outcomes among wives of male chemical workers who were highly exposed to chemicals contaminated with TCDD and among wives of nonexposed neighborhood referents. For exposed pregnancies, we estimated serum TCDD concentration at the time of conception using a pharmacokinetic model. The mean TCDD concentration for workers’ births was 254 pg/g lipid (range, 3–16,340 pg/g). The mean referent concentration of 6 pg/g was assigned to pregnancies fathered by workers before exposure. A total of 1,117 live singleton births of 217 referent wives and 176 worker wives were included. Only full-term births were included in the birth weight analysis (≥37 weeks of gestation). Mean birth weight among full-term babies was similar among referents’ babies (n = 604), preexposure workers’ babies (n = 221), and exposed workers’ babies (n = 292) (3,420, 3,347, and 3,442 g, respectively). Neither continuous nor categorical TCDD concentration had an effect on birth weight for term infants after adjustment for infant sex, mother’s education, parity, prenatal cigarette smoking, and gestation length. An analysis to estimate potential direct exposure of the wives during periods of workers’ exposure yielded a nonstatistically significant increase in infant birth weight of 130 g in the highest exposure group (TCDD concentration > 254 pg/g) compared with referents (p = 0.09). Mothers’ reports of preterm delivery showed a somewhat protective association with paternal TCDD (log) concentration (odds ratio = 0.8; 95% confidence interval, 0.6–1.1). We also include descriptive information on reported birth defects. Because the estimated TCDD concentrations in this population were much higher than in other studies, the results indicate that TCDD is unlikely to increase the risk of low birth weight or preterm delivery through a paternal mechanism.

Serum levels of polychlorinated dibenzo-p-dioxins and dibenzofurans in pulp and paper mill workers.

Serum levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) among 46 long-term workers at a pulp and paper mill were compared to the levels in 16 community residents who never worked at the mill. Overall, there were no appreciable differences among the three exposure groups (community resident, low-exposure-potential worker, high-exposure-potential worker) for specific PCDDs or PCDFs. Neither exposure group nor duration in high-exposure-potential-jobs was related to total toxic equivalents (I-TEQ). Serum levels of PCDDs and PCDFs in this study generally were within the range previously reported for persons with no known occupational exposure.