Venetoclax and Cobimetinib in Relapsed/Refractory AML: A Phase 1b Trial

BACKGROUND

Therapies for relapsed/refractory acute myeloid leukemia remain limited and outcomes poor, especially amongst patients who are ineligible for cytotoxic chemotherapy or targeted therapies.

PATIENTS AND METHODS

This phase 1b trial evaluated venetoclax, a B-cell lymphoma-2 (BCL-2) inhibitor, plus cobimetinib, a MEK1/2 inhibitor, in patients with relapsed/refractory acute myeloid leukemia, ineligible for cytotoxic chemotherapy. Two-dimensional dose-escalation was performed for venetoclax dosed daily, and for cobimetinib dosed on days 1-21 of each 28-day cycle.

RESULTS

Thirty patients (median [range] age: 71.5 years [60-84]) received venetoclax-cobimetinib. The most common adverse events (AEs; in ≥40.0% of patients) were diarrhea (80.0%), nausea (60.0%), vomiting (40.0%), febrile neutropenia (40.0%), and fatigue (40.0%). Overall, 66.7% and 23.3% of patients experienced AEs leading to dose modification/interruption or treatment withdrawal, respectively. The composite complete remission (CRc) rate (complete remission [CR] + CR with incomplete blood count recovery + CR with incomplete platelet recovery) was 15.6%; antileukemic response rate (CRc + morphologic leukemia-free state/partial remission) was 18.8%. For the recommended phase 2 dose (venetoclax: 600 mg; cobimetinib: 40 mg), CRc and antileukemic response rates were both 12.5%. Failure to achieve an antileukemic response was associated with elevated baseline phosphorylated ERK and MCL-1 levels, but not BCL-xL. Baseline mutations in ≥1 signaling gene or TP53 were noted in nonresponders and emerged on treatment. Pharmacodynamic biomarkers revealed inconsistent, transient inhibition of the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSION

Venetoclax-cobimetinib showed limited preliminary efficacy similar to single-agent venetoclax, but with added toxicity. Our findings will inform future trials of BCL-2/MAPK pathway inhibitor combinations.

Venetoclax and idasanutlin in relapsed/refractory AML: a nonrandomized, open-label phase 1b trial

This phase 1b trial (NCT02670044) evaluated venetoclax-idasanutlin in patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) ineligible for cytotoxic chemotherapy. Two-dimensional dose escalation (DE, n = 50) was performed for venetoclax daily with idasanutlin on days 1 to 5 in 28-day cycles, followed by dosing schedule optimization (n = 6) to evaluate reduced venetoclax schedules (21-/14-day dosing). Common adverse events (occurring in ≥40% of patients) included diarrhea (87.3% of patients), nausea (74.5%), vomiting (52.7%), hypokalemia (50.9%), and febrile neutropenia (45.5%). During DE, across all doses, composite complete remission (CRc; CR + CR with incomplete blood count recovery + CR with incomplete platelet count recovery) rate was 26.0% and morphologic leukemia-free state (MLFS) rate was 12%. For anticipated recommended phase 2 doses (venetoclax 600 mg + idasanutlin 150 mg; venetoclax 600 mg + idasanutlin 200 mg), the combined CRc rate was 34.3% and the MLFS rate was 14.3%. Pretreatment IDH1/2 and RUNX1 mutations were associated with higher CRc rates (50.0% and 45.0%, respectively). CRc rate in patients with TP53 mutations was 20.0%, with responses noted among those with co-occurring IDH and RUNX1 mutations. In 12 out of 36 evaluable patients, 25 emergent TP53 mutations were observed; 22 were present at baseline with low TP53 variant allele frequency (median 0.0095% [range, 0.0006-0.4]). Venetoclax-idasanutlin showed manageable safety and encouraging efficacy in unfit patients with R/R AML. IDH1/2 and RUNX1 mutations were associated with venetoclax-idasanutlin sensitivity, even in some patients with co-occurring TP53 mutations; most emergent TP53 clones were preexisting. Our findings will aid ongoing/future trials of BCL-2/MDM2 inhibitor combinations. This trial was registered at www.clinicaltrials.gov as #NCT02670044.

An exploratory, open-label, randomized, multicenter study to investigate the pharmacodynamics of a glycoengineered antibody (imgatuzumab) and cetuximab in patients with operable head and neck squamous cell carcinoma

BACKGROUND

In addition to inhibiting epidermal growth factor receptor (EGFR) signaling, anti-EGFR antibodies of the IgG1 'subtype' can induce a complementary therapeutic effect through the induction of antibody-dependent cell-mediated cytotoxicity (ADCC). Glycoengineering of therapeutic antibodies increases the affinity for the Fc-gamma receptor, thereby enhancing ADCC.

PATIENTS AND METHODS

We investigated the changes in immune effector cells and EGFR pathway biomarkers in 44 patients with operable, advanced stage head and neck squamous cell carcinoma treated with two preoperative doses of either glycoengineered imgatuzumab (GA201; 700 or 1400 mg) or cetuximab (standard dosing) in a neoadjuvant setting with paired pre- and post-treatment tumor biopsies.

RESULTS

Significant antitumor activity was observed with both antibodies after just two infusions. Metabolic responses were seen in 23 (59.0%) patients overall. One imgatuzumab-treated patient (700 mg) achieved a 'pathological' complete response. An immediate and sustained decrease in peripheral natural killer cells was consistently observed with the first imgatuzumab infusion but not with cetuximab. The functionality of the remaining peripheral natural killer cells was maintained. Similarly, a pronounced increase in circulating cytokines was seen following the first infusion of imgatuzumab but not cetuximab. Overall, tumor-infiltrating CD3+ cell counts increased following treatment with both antibodies. A significant increase from baseline in CD3+/perforin+ cytotoxic T cells occurred only in the 700-mg imgatuzumab group (median 95% increase, P < 0.05). The most prominent decrease of EGFR-expressing cells was recorded after treatment with imgatuzumab (700 mg, -34.6%; 1400 mg, -41.8%). The post-treatment inflammatory tumor microenvironment was strongly related to baseline tumor-infiltrating immune cell density, and baseline levels of EGFR and pERK in tumor cells most strongly predicted therapeutic response.

CONCLUSIONS

These pharmacodynamic observations and relationship with efficacy are consistent with the proposed mode of action of imgatuzumab combining efficient EGFR pathway inhibition with ADCC-related immune antitumor effects.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01046266 (ClinicalTrials.gov).

Humoral response to catumaxomab correlates with clinical outcome: results of the pivotal phase II/III study in patients with malignant ascites

The trifunctional antibody catumaxomab is a targeted immunotherapy for the intraperitoneal treatment of malignant ascites. In a Phase II/III trial in cancer patients (n = 258) with malignant ascites, catumaxomab showed a clear clinical benefit vs. paracentesis and had an acceptable safety profile. Human antimouse antibodies (HAMAs), which could be associated with beneficial humoral effects and prolonged survival, may develop against catumaxomab as it is a mouse/rat antibody. This post hoc analysis investigated whether there was a correlation between the detection of HAMAs 8 days after the fourth catumaxomab infusion and clinical outcome. HAMA-positive and HAMA-negative patients in the catumaxomab group and patients in the control group were analyzed separately for all three clinical outcome measures (puncture-free survival, time to next puncture and overall survival) and compared to each other. There was a strong correlation between humoral response and clinical outcome: patients who developed HAMAs after catumaxomab showed significant improvement in all three clinical outcome measures vs. HAMA-negative patients. In the overall population in HAMA-positive vs. HAMA-negative patients, median puncture-free survival was 64 vs. 27 days (p < 0.0001; HR 0.330), median time to next therapeutic puncture was 104 vs. 46 days (p = 0.0002; HR 0.307) and median overall survival was 129 vs. 64 days (p = 0.0003; HR 0.433). Similar differences between HAMA-positive and HAMA-negative patients were seen in the ovarian, nonovarian and gastric cancer subgroups. In conclusion, HAMA development may be a biomarker for catumaxomab response and patients who developed HAMAs sooner derived greater benefit from catumaxomab treatment.

Progress and prospects: gene therapy clinical trials (part 1)

Over the last two decades gene therapy has moved from preclinical to clinical studies for many diseases ranging from single gene disorders such as cystic fibrosis and Duchenne muscular dystrophy, to more complex diseases such as cancer and cardiovascular disorders. Gene therapy for severe combined immunodeficiency (SCID) is the most significant success story to date, but progress in many other areas has been significant. We asked 20 leaders in the field succinctly to summarize and comment on clinical gene therapy research in their respective areas of expertise and these are published in two parts in the Progress and Prospect series.

Advances in the Treatment of Chronic Granulomatous Disease by Gene Therapy

Gene transfer into hematopoietic stem cells has been successfully used to correct immunodeficiencies affecting the lymphoid compartment. However, similar results have not been reported for diseases affecting myeloid cells, mainly due to low engraftment levels of gene-modified cells observed in unconditioned patients. Here we review the developments leading to a gene therapy approach for the treatment of Chronic Granulomatous Disease (CGD), a primary life threatening immunodeficiency caused by a defect in the oxidative antimicrobial activity of phagocytes. Although the disease can be cured by bone marrow transplantation, this treatment is only available to patients with HLA-identical sibling or matched unrelated donors. One therapeutic option for patients without suitable donor is the genetic modification of autologous hematopoietic stem cells. Although early attempts to correct CGD by gene therapy were unsuccessful, these studies demonstrated the safety and limitations of gene transfer into hematopoietic stem cells (HSC) of CGD patients using retroviral vectors. The recent development of advanced gene transduction protocols together with improved retroviral vectors, combined with low intensity chemotherapy conditioning, allowed partial correction of the granulocytic function with a significant clinical benefit in treated patients. These results may have important implications for future applications of gene therapy in myeloid disorders and inherited diseases using hematopoietic stem cells.

Gene therapy for chronic granulomatous disease

Chronic granuloniatous disease (CGD) is a rare inherited imnunodeficiency characterized by recurrent, often life threatening bacterial and fungal infections due to a functional defect in the microbial-killing activity of phagocytic neutrophils. If regular care and conventional therapy fail, tile disease can be cured by bone marrow transplantation. This treatment is, however, only available to patients with human leukocyte antigen-identical sibling or matched unrelated donors. One therapeutic option for patients lacking suitable donors is the genetic modification of autologous hematopoietic stem cells. This review discusses the developments that have led to the realization of a successful gene therapy protocol for the correction of CGD.

Correction of X-linked chronic granulomatous disease by gene therapy, augmented by insertional activation of MDS1-EVI1, PRDM16 or SETBP1

Gene transfer into hematopoietic stem cells has been used successfully for correcting lymphoid but not myeloid immunodeficiencies. Here we report on two adults who received gene therapy after nonmyeloablative bone marrow conditioning for the treatment of X-linked chronic granulomatous disease (X-CGD), a primary immunodeficiency caused by a defect in the oxidative antimicrobial activity of phagocytes resulting from mutations in gp91(phox). We detected substantial gene transfer in both individuals' neutrophils that lead to a large number of functionally corrected phagocytes and notable clinical improvement. Large-scale retroviral integration site-distribution analysis showed activating insertions in MDS1-EVI1, PRDM16 or SETBP1 that had influenced regulation of long-term hematopoiesis by expanding gene-corrected myelopoiesis three- to four-fold in both individuals. Although insertional influences have probably reinforced the therapeutic efficacy in this trial, our results suggest that gene therapy in combination with bone marrow conditioning can be successfully used to treat inherited diseases affecting the myeloid compartment such as CGD.

Specific Helicobacter pylori antigens unable to distinguish nonucler dyspepsia or peptic ulcer cases from asymptomatic seropositive controls: a nested case-control study in employees of a large company

We investigated in a large industrial population the antibody response to specific H. pylori antigens (CagA and seven others) in relation to peptic ulcer and nonulcer dyspepsia (NUD). The two groups consisted of 37 and 39 employees, respectively, with endoscopically proven peptic ulcer and NUD. Age- and gender-matched controls were H. pylori seropositive employees without abdominal complaints or history of ulcer disease. IgG antibodies against CagA and other antigens were analyzed by western immunoblot. Relative percentages of CagA-positive individuals were 89 and 76% for ulcer cases and their controls (P = 0.22) and 77% and 74% for NUD cases and their controls. The corresponding percentages of VacA-positive individuals were 87 and 76% for ulcer cases and controls and 64% and 77% for NUD cases and controls, respectively. Analysis of other H. pylori-specific antigens was not particularly helpful in discriminating between symptomatic and asymptomatic seropositive individuals for either disease group. In conclusion, assessment of IgG response against specific H. pylori antigens was not predictive of peptic ulcer or NUD case status in this active employee population and would not appear to be useful in routine clinical practice.

BASF studies: epidemiological and clinical investigations on dioxin-exposed chemical workers

First in 1953 and again later in 1988, BASF Aktiengesellschaft, Ludwigshafen, Germany, faced production-related dioxin contamination problems. In both situations, the immediate actions were efforts to limit the potential for employee exposure. In 1953, after a reactor accident, the production of trichlorophenol was stopped and extensive clean-up and demolition work was undertaken. In 1988, major technical improvements were made to an extrusion blending process and the flame retardants were changed to substances that chemically should not be dioxin precursors. The health experience of the potentially exposed populations has been followed extensively in both situations. Five recent epidemiological investigations: a long-term mortality follow-up, a morbidity study, a clinical laboratory study, and a chromosome study of persons from the 1953 accident cohort, as well as immunological studies of employees assigned to the extrusion operations, are discussed. In addition, considerable dioxin biomonitoring data from blood lipids for both populations are summarized.

[Leptospirosis after a staff outing]

HISTORY AND CLINICAL FINDINGS

Three male colleagues aged between 34 and 38 years were admitted at the same time to three different Rhein-Main area Hospitals. They presented with a variety of symptoms, including high fever (39.0 to 40.0 degrees C), chills, headache with meningismus or facial paralysis, mild hepatitis and renal involvement. About 18 days before they had been together on a boat rafting tour when the boat capsized when they had fallen into a river in high flood.

INVESTIGATIONS

Laboratory tests showed elevated inflammatory parameters, signs of a mild hepatitis and renal involvement. All patients had leptospirosis antibodies, detected by immunofluorescence test. In two cases there was evidence of antibodies against Leptospira interrogans serovar bataviae in the microscopic agglutination test (MAT).

TREATMENT AND COURSE

The history and clinical presentation indicated leptospirosis in all patients, in two cases confirmed by laboratory findings. Following therapy with doxycycline or ceftriaxone, symptoms resolved quickly and permanently.

CONCLUSION

Leptospires of serogroup Bataviae is a known pathogen of anicteric non-Weil leptospirosis. The symptoms are non-specific and, moreover, in some cases the laboratory tests are negative, so that clinical diagnosis remains crucial. Typically there is a history of contact with contaminated water or urine. In our cases striking neurotropism was observed, which may be characteristic for this serovar.

Gene therapy of chronic granulomatous disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency disorder which results from absence or malfunction of the respiratory burst oxidase normally expressed in neutrophils and other phagocytic leukocytes. Two-thirds of the patients are males hemizygous for mutations in the X-linked gene coding for gp91-phox. As a therapeutic approach towards the X-linked form of CGD bicistronic retroviral vectors containing the gp91-phox gene and a selectable marker gene were constructed. The ability of these vectors to restore NADPH oxidase activity was tested in a human myeloid leukemic cell line that is defective in superoxide production, as well as in primary CD34+ cells obtained from X-CGD patients. Under optimal conditions 80% of the CD34+ cells derived from bone marrow of one X-CGD patient were transduced. The level of superoxide production, in phagocytes derived from transduced cells was 68.9% of normal levels. Considering that low levels of superoxide generating activity are sufficient for normal host defense, the present experiments provide the basis for the development of a gene replacement therapy for the X-linked form of CGD.

Respiratory health surveillance in a toluene di-isocyanate production unit, 1967-97: clinical observations and lung function analyses

OBJECTIVES

To characterise irritant and allergic airway responses and assess changes in forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) relative to exposure to toluene di-isocyanate (TDI).

METHODS

Employees (n = 313) ever assigned to a TDI production unit for > or = 3 months (1967-92) were identified from personnel records along with 158 frequency matched referents without known exposure to TDI. Reports made during visits to the occupational clinic of incidents related to exposure to TDI and annual periodic examination results (questionnaire, physical findings, and spirometry) were abstracted and assessed relative to industrial hygiene estimates of exposure to TDI.

RESULTS

Mean 8 hour time weighted average estimates of TDI concentrations ranged from 9.9 ppb in jobs with potentially high exposure during the early years of plant operations to 0.5 ppb in jobs with potentially low exposure in more recent years. The corresponding rates of visits to the clinic due to incidents of exposure to TDI (including both irritant and allergic airway responses) declined from 20.5 to 1.0 visits per 100 years of employment at the unit. The annual incidence of asthma induced by TDI declined from 1.8% before 1980 to 0.7% afterwards. Neither cross sectional nor longitudinal analyses of FVC and FEV1 showed significant dose-response findings relative to exposure to TDI across the total exposed population. Among cases of occupational asthma there was an apparent initial decline in FEV1 within 2 years of first reporting symptoms, but not an accelerated rate of decline in follow up tests from 4-30 years after induction of asthma.

CONCLUSIONS

Occurrences of both asthma induced by TDI and irritant airway responses due to exposure to TDI were found in this cohort, but there was no relation between cumulative exposure to TDI and irreversible airflow obstruction as assessed by spirometry.

Diisocyanates in polyurethane plastics applications

Diisocyanates are a group of low molecular weight aromatic and aliphatic compounds, widely used in the manufacture of polyurethanes. The most commonly used of these compounds are toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), and hexamethylene diisocyanate (HDI). This article presents a brief summary of the use of diisocyanates in the manufacture of polyurethane products and a review of the epidemiology, medical surveillance, and clinical diagnosis of respiratory and dermal effects of diisocyanates, with emphasis on diisocyanate asthma.

Correction of respiratory burst activity in X-linked chronic granulomatous cells to therapeutically relevant levels after gene transfer into bone marrow CD34+ cells

Chronic granulomatous disease (CGD) is a disorder of the lymphohematopoietic system, whereby phagocytes of affected patients are unable to kill microorganisms. CGD is caused by a functional defect in the phagocytic nicotinamide adenine dinucleotide phosphatase (NADPH) oxidase (phox) enzyme complex, leading to a lack of microbicidal metabolites. As a therapeutic approach toward the predominant X-linked form of CGD, we have developed a bicistronic retroviral vector containing the coding sequences of gp91-phox and a cytoplasmically truncated version of the human low-affinity receptor for nerve growth factor (deltaLNGFR). Full reconstitution of superoxide-generating activity was achieved with this vector in a gp91-phox-deficient cell line. Using an optimized gene transfer protocol, up to 85% of the CD34+ cells obtained from the bone marrow of X-CGD patients were transduced. CD15+ cells differentiated in vitro from transduced X-CGD CD34+ cells showed correction of NADPH oxidase activity to 45-52% of normal levels whereas deltaLNGFR expression was found in 40-67% of the CD15+ cells. Moreover, immunoblots prepared from extracts of transduced CD15+ cells revealed gp91-phox protein levels similar to those found in neutrophils derived from normal CD34+ cells. Taking into consideration that superoxide production in only 5 to 10% of wild-type neutrophils is sufficient to protect X-CGD heterozygotes from serious infections, the results achieved in this study shows that for X-CGD patients a curative approach based on the genetic modification of hematopoietic stem/progenitor cells is feasible.

Helicobacter pylori infection: prevalence and clinical relevance in a large company

Although gastrointestinal (GI) illnesses account for considerable sick absenteeism, there have been few workplace studies of GI disorders. We determined the prevalence of Helicobacter pylori infection by serology and assessed its relation to upper GI tract complaints, personal ulcer history, and family history of stomach cancer in 6,143 employees (mean age, 40.4 years) at BASF's main chemical production facilities in Ludwigshafen, Germany. Employees were recruited during occupational health clinic visits (n = 4,488) and through broad communications efforts (n = 1,655). Participation among clinic attendees was 66%, and this recruitment method was particularly effective in reaching shift employees. Positive immunoglobulin G (IgG) serology (38.2%), ulcers (4.9%), nonulcer dyspepsia (20.4%), and a family history of stomach cancer (6.1%) were common occurrences in this work setting. Further diagnostic evaluation and eradication therapy was recommended for 795 employees (12.9%), based on a combination of positive serology and either upper GI tract complaints or family stomach cancer history, and has been completed for 541 employees. A weak but consistent association was seen between positive serology and cigarette smoking, and shift work was found to be associated with positive serology, but not with ulcer or nonulcer dyspepsia occurrence.

Morbidity study of extruder personnel with potential exposure to brominated dioxins and furans. II. Results of clinical laboratory studies

OBJECTIVE

To test whether dioxins affect liver and thyroid function, lipid metabolism and glucose or immunological variables, in workers exposed to brominated dioxins and furans.

METHODS

34 male production employees (29 were extruder operators) and eight technical support personnel were studied, all of whom were potentially exposed to polybrominated dibenzo-p-dioxins (PBDDs) and furans (PBDFs) during production of resins containing polybrominated diphenyl ethers (PBDEs). Controls were from a similar resin producing plant that did not use PBDEs. Blood samples were analysed for tetra, penta, and hexabrominated congeners, but 2,3,7,8-TBDD was the only exposure measure used in the regression analyses. Seven liver function indicators, five measures of blood lipids and glucose, four haematology and blood coagulation measures, and three measures of thyroid function were examined.

RESULTS

None of the variables was statistically related to concentration of 2,3,7,8-TBDD in the regression analyses. Cigarette smoking was related to several outcomes at the 0.05 level: aspartate aminotransferase, alanine aminotransferase, glutamate dehydrogenase (GLDH), erythrocyte sedimentation rate, and white blood cell count. Body mass index was also related to alanine aminotransferase, gamma-glutamyltranspeptidase, cholinesterase, GLDH, cholesterol, triglycerides, high density lipoprotein, low density lipoprotein, and glucose concentrations. No definitive associations between liver, blood lipid, thyroid, or immunological variables and exposure to brominated dioxins or blood lipid concentration of 2,3,7,8-TBDD were found.

CONCLUSIONS

The study population was small and hence the findings must be interpreted with caution. Nevertheless, these results provide a base for interpreting the results of clinical studies in similarly exposed populations.

Cause specific mortality and cancer incidence among employees exposed to 2,3,7,8-TCDD after a 1953 reactor accident

OBJECTIVE

To evaluate the long term health consequences of past occupational exposure to 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD).

METHODS

Cancer incidence and cause specific mortality were examined up to and including 1992 in a group of 243 men with external comparisons and internal dose-response analyses. Model based estimates of TCDD dose (expressed in micrograms/kg body weight) were developed for all cohort members with an approach that incorporated detailed accounts of each employee's work activities, analyses of TCDD in blood lipid of 138 employees, and internally derived estimates of elimination rates of TCDD.

RESULTS

The estimated dose of TCDD for 135 men was > or = 0.1 microgram/kg body weight and for 69 men > or = 1 microgram/kg body weight. Increased cancer risk ratios were found with higher doses of TCDD and longer interval since first exposure for all sites combined and digestive and respiratory cancers in particular. Within the high dose group (> or = 1 microgram/kg body weight), total cancer mortality was increased > or = 20 years after first exposure (13 cases, standardised mortality ratio (SMR) 1.97, 95% confidence interval (95% CI) 1.05-3.36) as was respiratory cancer (six cases, SMR 3.06; 95% CI 1.12-6.66). Among current cigarette smokers, 12 cancer deaths occurred in the high dose group (SMR 3.42, 95% CI 1.77-5.97) compared with seven deaths at lower doses of TCDD (SMR 1.29, 95% CI 0.52-2.66). Regression analyses based on the Cox's proportional hazards model provided further evidence of a relation between cumulative dose of TCDD and occurrence of both overall and digestive cancer. No evidence of an effect of TCDD on overall mortality or deaths due to circulatory disease was found and no cases of non-Hodgkin's lymphoma or soft tissue sarcoma have been found to date.

CONCLUSIONS

Our findings are consistent with a carcinogenic effect induced by TCDD at doses > or = 1 microgram/kg body weight. With such a small cohort, the risk estimates are not very stable and could be affected by selection and confounding.

Mortality experience among Louisiana chemical manufacturing employees, 1957-1992

A cohort mortality study was undertaken of persons ever employed at BASF's Geismar, Louisiana chemical manufacturing facilities for 3+ months prior to 1992. The 1,870 men and 263 women employees were traced through 1992 (99% follow-up) using employment and pension records, National Death Index searches, social security record matching, and credit bureau checks. Death certificates were obtained and coded for 92% of the 128 decedents. Overall and total cancer deaths among short-term ( < 10 years of site employment) and long-term hourly and salaried employees were fewer than expected based on comparisons to US general population death rates. Deaths due to external causes were higher than expected among short-term hourly employees (23 observed compared to 16 expected deaths). Among all employees, three accidental deaths occurred at work, the most recent in 1981. Four deaths each, due to urinary and brain cancers, exceeded expectation; however, there was no pattern of job assignments suggesting a work-related etiology for these occurrences.

Investigation of a cluster of ten cases of Hodgkin's disease in an occupational setting

The objective of this study was to identify occupational exposures that might be etiologically linked to an unusual cluster of ten cases of Hodgkin's disease. The cases were identified within the active workforce of a large chemical manufacturing firm over a 23-year period by the medical director of the facilities. Based on comparison with regional cancer incidence rates, the standardized incidence ratio for Hodgkin's disease was 497 (95% confidence interval: 238-915) for the period from the construction of the facilities in 1966 through early 1992. A nested case-control study was undertaken with 200 controls selected according to case-cohort sampling. Simultaneously, efforts were initiated to confirm and characterize each case more fully. Occupational exposures were identified and categorized using process, work history, medical record, and industrial hygiene data. Tissue slides were available for eight cases and a second review confirmed the diagnosis of Hodgkin's disease. For one case, a final diagnosis of large-cell anaplastic lymphoma was determined after histology review. Among 214 different chemical agents studied, eight were identified to which three or more of the cases had been exposed prior to the date of their initial diagnosis. Exposure odds ratios were statistically elevated for five of these agents; dose-response evaluations for two of the agents, ethylene oxide and benzene, failed to provide additional support for a causal relationship. In conclusion, although several statistical associations were identified, no substance emerged as a likely candidate for explaining the observed Hodgkin's disease cluster.

Peripheral natural killer cell activity and intraperitoneal soluble p55 tumor necrosis factor receptor in patients with malignant ascites: two possible indicators for response to intraperitoneal combined tumor necrosis factor alpha and interferon gamma treatment

Tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma) are important immunomodulators. They are capable of acting in a synergistic manner on tumor cells in vitro and in vivo. In a clinical phase I study 13 patients with malignant ascites due to abdominal spread of different primary tumors received intraperitoneally (i.p.) TNFalpha and IFNgamma once weekly over 3-8 weeks in order to evaluate the effect of locoregionally administered TNFalpha/IFNgamma on ascites formation. Therefore some peripheral and local immunological functional parameters of peripheral blood and malignant ascites were investigated. Mononuclear lymphocytes and natural killer (NK) cell activity of peripheral blood and ascites, TNF-inhibitory activity, soluble p55 and p75 TNF receptors, and prostaglandin E2 values in ascites were measured immediately before and 24 h after each TNFalpha/IFNgamma infusion. Peripheral mononuclear lymphocytes and NK activity decreased significantly 24 h after i.p. TNFalpha/IFNgamma application. However, over the entire treatment schedule, peripheral NK activity in all responders showed a continuous increase, when compared to pre TNFalpha/IFNgamma treatment levels. In contrast, NK activity in non-responders constantly decreased. In contrast to non-responders, TNF-inhibitory activity and soluble p55 TNF receptor levels, determined in ascites, decreased in responders. Taken together, our findings suggest, that successful locoregional i.p. TNFalpha/IFNgamma therapy induces systemic immunological reactions possibly after saturation of soluble p55 TNF receptors in ascites, which leads to an increase of peripheral NK activity.

Study of morbidity of personnel with potential exposure to vinclozolin

OBJECTIVES

To examine internal exposure and targeted health outcomes of employees exposed to 3-(3,5-dichlorophenyl)-5-methyl-5-vinyl-1,3-oxazolidine-2,4-dione; chemical abstracts service (CAS) number: 50471-44-8 (vinclozolin).

METHODS

A cross sectional study of 67 men exposed to vinclozolin for one to 13 years during synthesis and formulation operations and 52 controls. Biomonitoring was based on determination of urinary metabolites that contained a 3,5-dichloroaniline (3,5-DCA) moiety. Targeted health endpoints were the same as in previous subchronic and chronic animal studies--namely, reversible changes in the concentrations of hormones of the adrenocorticotrophic and gonadotrophic feedback systems, signs of liver injury, haemolytic anaemia, cataract formation (uniquely in rats), and hormonally induced hyperplasia and tumours at high doses. The clinical investigation consisted of a medical and occupational history questionnaire, physical examination, laboratory determinations (including testosterone, LH, and FSH measurements), ultrasonography of the liver and prostate, a detailed eye examination, and routine spirometry.

RESULTS

The mean 3,5-DCA concentration for two thirds of the study group exceeded an equivalent of the vinclozolin acceptable daily intake (ADI) used for consumer regulatory purposes. Even the highest concentrations were, however, at least 10 times below the no observable adverse effect level (NOAEL) based on animal studies. Analysis of physical examination and laboratory data provided no evidence of hormonal responses induced by vinclozolin. Furthermore, no evidence of liver injury, prostate changes, cataract formation, or haemolytic anaemia was found.

CONCLUSION

There was no evidence of any health effects induced by vinclozolin among employees with potential long term exposure. In particular, no antiandrogenic effects were found.

Laboratory results for selected target organs in 138 individuals occupationally exposed to TCDD

Blood specimens for dioxin congener analysis and clinical laboratory studies were recently obtained for 138 employees who had been potentially exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) following a 1953 trichlorophenol autoclave accident. Results for 34 clinical tests were regressed on three exposure measures (current TCDD concentration, log TCDD concentration back-calculated to the time of exposure, and chloracne status). Age, smoking status and body-mass-index were included as additional explanatory factors in the analyses. Positive associations were found between each of the exposure measures and both serum thyroxine (T4) and thyroxine binding globulin (TBG). Additional exposure-response associations were detected relative to several immune system parameters, erythrocyte sedimentation rate, platelet count and serum alkaline phosphatase. These data will be specifically helpful in interpreting the results of additional morbidity and mortality studies conducted within the same target population.

Morbidity follow up study of BASF employees exposed to 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) after a 1953 chemical reactor incident

OBJECTIVE

The aim was to examine the long term morbidity experience of men exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

METHODS

A retrospective cohort morbidity study of 158 men first exposed to TCDD between 17 November 1953 and 16 November 1954 subdivided by chloracne state and back calculated TCDD blood lipid concentration, and 161 referents. Cause specific illness absence and admissions to hospital were examined between 1953 and 1989.

RESULTS

On an ever or never basis, thyroid disease and appendicitis were diagnosed more often in the study group; these diseases were not differentially distributed by chloracne state, but were increased in the high TCDD subgroup. An 18% increase in total illness episodes was also seen (p = 0.002); illness rates increased with severity of chloracne and higher TCDD concentration within the chloracne subgroup. There were increases in infectious and parasitic diseases (primarily ill defined intestinal infections), disorders of the peripheral nervous system and sense organs, upper respiratory tract infections, and other skin diseases. Several of these increases correlated with chloracne state and infections disease episodes increased with higher TCDD concentration as well. Occurrences of mental disorders correlated with severity of chloracne, but not TCDD concentration. Benign and unspecified neoplasms were marginally increased in the severe chloracne and high TCDD subgroups. Chronic liver disease was marginally increased in the high TCDD subgroup. Findings relative to occurrence of ulcers, chronic lung disease, and kidney and metabolic disorders were unremarkable.

DISCUSSION

For various conditions, increased illness episodes were seen among TCDD exposed employees compared with referents and were associated with either or both chloracne severity and back calculated TCDD concentration. The results are derived from insurance data; hence, it is possible that heightened awareness and personal health concerns led to greater utilisation of medical services in the exposed group. The findings based on TCDD concentration should be less subject to this potential bias.

Cytogenetic studies in lymphocytes of workers exposed to 2,3,7,8-TCDD

Chromosome aberrations and sister chromatid exchanges (SCEs) were evaluated in 27 workers with current 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) blood lipid concentrations exceeding 40 parts per trillion (ppt) and in 28 unexposed referents of similar age. No statistical differences were found between the two groups in the percentages of gaps, chromatid or chromosome exchanges, chromatid or chromosome breaks/fragments/deletions, multiple aberrations, or the overall percentage of aberrations including gaps (1.33% in the exposed group vs 1.75% in the referent group) or excluding gaps (0.54% in each group). There was an increased rate of SCEs per cell (P = 0.051) and a higher percentage of cells with more than 10 SCEs (P = 0.064) in the exposed group; however, these associations were no longer significant when smoking status was included as covariate. Additionally, neither current nor back-calculated TCDD concentration was a significant predictor of these parameters based on multiple linear and rank regression analyses.

Assessment of past occupational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin using blood lipid analyses

Current 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) concentrations were determined in blood samples for 138 persons who had been involved in assessment, clean-up and demolition activities after the 1953 BASF trichlorophenol reactor accident. From these data and detailed descriptions of the circumstances and duration of individual exposure, a regression model was developed for describing the relationships between various exposure situations and TCDD concentration. The model explained 65% of the variability in log (TCDD) concentration. Using half-life assumptions and the regression model parameters we estimated cumulative TCDD concentrations back-calculated to the time of exposure for all 254 members of the accident cohort. The geometric mean cumulative TCDD concentration for all cohort members averaged 137.7 ppt. Estimated cumulative TCDD concentrations correlated well with chloracne severity. The mean TCDD concentrations were 38.4 ppt for the no chloracne subgroup (n = 139), 420.8 ppt for the moderate chloracne subgroup (n = 59) and 1008 ppt for the severe chloracne subgroup (n = 56). The estimation procedure should be helpful in assessing the relationships between various health outcomes and TCDD exposure in this cohort.

Morbidity study of extruder personnel with potential exposure to brominated dioxins and furans. I. Results of blood monitoring and immunological tests

The potential for exposure of employees to polybrominated dibenzofurans (PBDFs) and dibenzo-p-dioxins (PBDDs) during extrusion blending of resins containing decabromodiphenyl ether was established through previous air monitoring (area samples) and biomonitoring studies. The findings presented herein are further biomonitoring results for 42 employees and immunological tests for exposed and referent employees. Among potentially exposed men, 2,3,7,8-TBDF and 2,3,7,8-TBDD concentrations in blood lipid ranged from non-detectable to 112 parts per trillion (ppt) and from non-detectable to 478 ppt respectively. Biomonitoring results correlated well with assignments in the extruder work area when adjusted for process changes and engineering improvements and provided biological half life estimates of between 1.1 and 1.9 years for 2,3,7,8-TBDF and between 2.9 and 10.8 years for 2,3,7,8-TBDD. Results for 16 measures of the immune system were examined in relation to exposure (exposed v referent group) and in relation to the biomonitoring data. Some individual trends in immunological parameters with exposure and covariates such as age and cigarette smoking were found (for example, an increase in complement C4 with increasing concentrations of PBDFs and PBDDs, increased lymphocyte subpopulation counts with cigarette smoking); however, the overall clinical assessment was that the immune system of exposed employees was not adversely impacted at these burdens of PBDFs and PBDDs.

Mortality study of ethanol and isopropanol production workers at two facilities

The mortality experience of alcohol process workers (N = 1031) from two chemical plants was followed from the early 1940s to 1983. Reported associations of the production of ethanol and isopropanol by the strong-acid process with upper respiratory tract cancers, heart disease, and lympho- and reticulosarcoma were tested with both external and internal comparisons. Excesses of cancers of the larynx, buccal cavity, and pharynx, based on very small numbers, were observed. There was one death due to sinus cancer. It could not be concluded that there were work-related effects on mortality due to heart disease or lympho- or reticulosarcoma. Workers assigned to the production of isopropanol by the weak-acid method showed no evidence of excess cancer mortality (0 observed, 1.9 expected cancer deaths). The absence of major risks among strong-acid workers can be explained by the initiation of engineering controls and health monitoring that took place after the original medical observations.

Importance of the study protocol in epidemiologic research

The overall quality of an epidemiologic research project depends on how well both the design and execution phases of the project have been accomplished. The written prestudy protocol, by serving as a bridge between these two project phases, plays a pivotal role in determining the success of the total research effort. The study protocol can contribute to improved observational research in four key areas. Arguments are presented for enhancing the scientific integrity of observational studies and for providing better study documentation, efficiency, and communications, all through careful prestudy planning.

A review of medical surveillance records of employees exposed to ethyleneamines

A review of medical surveillance records was undertaken for 197 personnel who had been assigned to an ethyleneamines (EA) production unit for one or more months between 1947 and 1983. Dispensary visit reports were examined relative to EA and other chemical exposures, medical records were reviewed for allergy and asthma histories, spirometry data were evaluated, and the mortality experience of these employees was studied relative to exposure status. All findings were evaluated in reference to a comparable group of employees who did not work in plant areas where contact with EA was likely. Among 75 persons reporting EA exposures, 7 definite and 8 suspect cases of respiratory sensitization were identified. Similarly, there were 23 definite and 17 suspect cases of skin sensitization. Pulmonary function did not differ between study and referent groups and was unrelated to both EA assignment duration and skin or respiratory sensitization. There were no indications of increased mortality in the study group. Careful selection of employees for assignment to this unit may have occurred by plant physicians, who were aware of the potential sensitizing properties of EA.

Assessment of 1,3-butadiene epidemiology studies

Positive carcinogenicity studies in mice and rats have led to concerns that 1,3-butadiene may be carcinogenic in humans under exposure conditions that have existed in occupational settings and perhaps exist today. The principal settings of interest are the styrene-butadiene rubber (SBR) manufacturing industry, which uses large quantities of 1,3-butadiene, and the 1,3-butadiene monomer industry. The potential for 1,3-butadiene exposure is highest during monomer transfer operations and is lowest in finishing areas of polymerization plants where the polymer products are processed. Three large cohort mortality studies have been conducted in the SBR and monomer producing industries since 1980. These studies, which examined the mortality experience of over 17,000 men employed in one monomer and 10 SBR facilities, are the subject of this review. All but one of the facilities began operations during the early 1940s. The mortality experience observed within these employee cohorts is comparable to that seen in other long-term studies of men employed in the petroleum, chemical, and rubber industries for all causes of death, total malignant neoplasms, and for the specific cancers seen in excess in the toxicologic studies. This paper discusses discrepant findings observed in more detailed analyses within individual cohorts and among employment subgroups, as well as selected limitations of the particular studies. Additional efforts to refine 1,3-butadiene exposure categories are needed. Within the context of sample size limitations inherent in these studies, there is currently inadequate evidence to establish a relationship between cancer mortality outcomes and 1.3-butadiene exposure in humans.

Men assigned to ethylene oxide production or other ethylene oxide related chemical manufacturing: a mortality study

A retrospective cohort study was conducted to examine the mortality experience of 2174 men employed between 1940 and 1978 by a large chemical company and who had been assigned to a chemical production department that used or produced ethylene oxide (EO). Comparisons were made with the general United States population, the regional population, and with a group of 26,965 unexposed men from the same plants. Comparisons with general United States death rates showed fewer deaths than expected in the EO group due to all causes and for total cancers. There was no statistically significant excess of deaths due to any cause. Seven deaths each due to leukaemia and pancreatic cancer were observed with 3.0 and 4.1 deaths expected. Among the subcohort of men who worked where both average and peak exposure levels were probably highest, however, one death due to pancreatic cancer (0.9 expected) and no deaths due to leukaemia were observed. Four of the seven who died from leukaemia and six of the seven who died from pancreatic cancer had been assigned to the chlorohydrin department where the potential for exposure to EO is judged to have been low. The relative risk of death due to each disease was strongly related to duration of assignments to that department. When men who worked in the chlorohydrin department were excluded, there was no evidence for an association of exposure to EO with pancreatic cancer or leukaemia. Together with the failure to show independent EO associations, the chlorohydrin department results suggest that leukaemia and pancreatic cancer may have been associated primarily with production of ethylene chlorohydrin or propylene chlorohydrin, or both. These results emphasise the importance of examining additional concurrent/asynchronous exposures among human populations exposed to EO.

Mortality surveillance in a large chemical company: the Union Carbide Corporation experience, 1974-1983

The mortality experience of 88,000 Union Carbide Corporation employees from 1974 to 1983 is presented using a population-based surveillance system. The study included many long-term employees, with most deaths contributed by those retired or terminated. The total population exhibited 30% lower mortality overall and 10% lower cancer mortality, as compared with the general U.S. population. Excesses of benign neoplasms and malignant melanoma of the skin were observed in both hourly and salaried males. Mortality rates for lymphosarcoma and reticulosarcoma were significantly elevated due to higher rates among hourly male employees and a cluster in one location. This same location also exhibited an excess of liver cancer associated with vinyl chloride operations. There were no other significant excesses in the hourly male workers and fewer deaths than expected due to brain cancer, respiratory cancer, and nonmalignant respiratory diseases. Salaried, and particularly hourly, women experienced favorable mortality, although for the women, time since hire was relatively short. Location-specific findings were similar to what had been observed in the company's previously conducted cohort studies. Future value lies in the development of a database that will have greater power to address possible effects of past exposures and outcomes related to more recent lower level exposures.

Assessment of exposure to chemicals in a complex work environment

Exposure information was evaluated for two large chemical manufacturing facilities and a research and development center in support of occupational health studies of employees assigned to these facilities. Methodology and rationale underlying the exposure categorization are provided, and descriptive exposure statistics are presented for a sample of 774 employees. Analysis of work patterns and exposure profiles revealed that 1) employee transfers among various production work areas did not follow a predictable pattern, 2) over 41% of the chemicals identified were present in multiple work areas, and 3) individuals exposed to one chemical of toxicologic interest were also likely to be exposed to other similarly toxic materials. The use of both work area and chemical-specific exposure measures is recommended, as each may be helpful in addressing etiologic questions regarding complex work environments.

Lymphatic and hematopoietic tissue cancer in a chemical manufacturing environment

Nested case-control studies of non-Hodgkin's lymphoma (52 cases), multiple myeloma (20 cases), nonlymphocytic leukemia (39 cases), and lymphocytic leukemia (18 cases) were conducted within a cohort of employed men from two chemical manufacturing facilities and a research and development center. Exposure odds ratios were examined in relation to 111 work areas, 21 specific chemicals, and 52 chemical activity groups. Associations were observed for a maintenance and construction subgroup (non-Hodgkin's lymphoma) and a chlorohydrin production unit (nonlymphocytic leukemia). The odds ratio for the association of "foremen and others" with non-Hodgkin's lymphoma was 3.2 (CI95 = 1.47-7.2) based on 11 cases. A duration-response trend was observed for the chlorohydrin unit with three of four cases assigned 5+ years to that unit. An association between non-Hodgkin's lymphoma and assignment to strong acid alcohol production units (OR = 8.3; CI95 = 2.3-30.7) was not supported by a duration-response trend. Two highly correlated chemical groups, antioxidants (five cases) and nitriles (four cases), were over-represented among multiple myeloma cases. A duration effect was observed. However, examination of work histories did not reveal common jobs or departments among these cases.

A mortality study of a research, engineering, and metal fabrication facility in western New York State

The mortality experience of 8,146 male employees of a research, engineering, and metal fabrication facility in Tonawanda, New York state was examined from 1946 to 1981. Potential workplace exposures included welding fumes, cutting oils, asbestos, organic solvents, and environmental ionizing radiation, as the result of disposal of wastes during the Manhattan Project of World War II. External comparisons with the US male population were supplemented by regional comparisons. For the total cohort, deficits were observed for all causes of death (standardized mortality ratio (SMR) = 87) and most non-cancer causes. The observed number of cancer deaths was close to expected (SMR = 99). There was an excess of connective and soft tissue cancer deaths, most notably in hourly employees hired prior to 1946. Among all hourly employees, there was an excess of respiratory cancer, which did not appear to be associated with length of employment. Mesothelioma was recorded as the cause of death for three decedents, two of whom were hourly employees who worked in production areas with high potential for asbestos exposure. The standardized mortality ratio for cirrhosis of the liver was elevated among long-term hourly employees hired prior to 1946. The roles of carbon tetrachloride exposure in the 1940s and alcohol consumption are discussed as possible contributory risk factors for the cirrhosis findings. The data do not provide evidence of radiation-induced cancers within this employee population.

Cohort mortality study of chemical workers with potential exposure to the higher chlorinated dioxins

This cohort study evaluated mortality patterns, 1940 through 1982, of 2,192 chemical workers who, having engaged in the manufacture of higher chlorinated phenols and derivative products, had potential occupational exposures to chlorinated dioxins. Relative to United States white male mortality experience, there were no statistically significant deviations from expected for the following categories: all causes, total malignant neoplasms, or specific malignancies of particular interest: stomach cancer, liver cancer, connective and other soft-tissue cancer, the lymphomas, or nasal and nasopharyngeal cancer. For the cirrhosis of the liver category, internal comparisons demonstrated increasing trends associated with duration of employment in the Chlorophenol Production and Finishing areas; but available evidence suggests this finding was related to alcohol abuse. The study does not support a causal association between chronic human disease as measured by mortality and exposures to the higher chlorinated phenols, derivative products, or their unwanted contaminants, the chlorinated dioxins.

Population based mortality surveillance in carbon products manufacturing plants

The utility of a population based, corporate wide mortality surveillance system was evaluated after a 10 year observation period of one of the company's divisions. The subject population, 2219 white male, long term employees from Union Carbide Corporation's carbon based electrode and specialty products operations, was followed up for mortality from 1974 to 1983. External comparisons with the United States male population were supplemented with internal comparisons among subgroups of the study population, defined by broad job categories and time related variables, adjusting for important correlates of the healthy worker effect. Significant deficits of deaths were observed for all causes and the major non-cancer causes of death. The numbers of deaths due to malignant neoplasms and respiratory cancer were less than, but not statistically different from, expected. There was a non-significant excess of deaths from lymphopoietic cancer, occurring predominantly among salaried employees. When specific locations were examined, operations with potential exposure to coal tar products exhibited a mortality pattern similar to that of the total cohort. The risk for lung cancer was significantly raised (five observed, 1.4 expected) in one small, but older, location which did not involve coal tar products during the period of employment of these individuals, but which historically used asbestos materials for several unique applications. Although these findings are limited by small numbers and a short observation period, the population based surveillance strategy has provided valuable information regarding the mortality experience of the population, directions for future research, and the allocation of epidemiological resources.

Mortality among employees engaged in chemical manufacturing and related activities

A retrospective cohort mortality study was conducted among men employed for one or more years, between 1940 and 1969, at an operating division of a large chemical company. Vital status follow-up for the cohort of 1,919 men was determined through 1979 and identified 390 deaths. Overall mortality in the study group and in each of eight employment subgroups was less than that of the corresponding United States white male population. Additionally, standardized mortality ratios were not significantly elevated for any of the examined cause-of-death categories. Cause-specific mortality comparisons were also made among the employment subgroups and by duration of employment in the company division using an internal analysis method. There were no relationships observed for employment duration. Several significant differences (p less than 0.05) by employment subgroup were noted; however, neither the decreases nor increases presently could be ascribed to identifiable environmental factors.

Mortality among a sample of chemical company employees

A general mortality survey was done on a 5% random-start systematic sample (N = 1,666) of present and former white male employees of a Texas chemical plant. The purpose was to determine whether there were any unusual patterns of cause-specific mortality that would require further research with case-control studies. Mortality risks were examined by duration of employment and year of hire as surrogates for more specific exposure data. Among all employees in the sample, there was significant excess mortality due to All Cancer, Ill-Defined Conditions, and All External Causes of Death, and a significant deficit from All Circulatory Diseases. The excess mortality from All Cancer was primarily attributable to excess cancers of the kidney, lung, and pancreas. The excesses for lung and kidney cancer were statistically significant. Those employed for 1 year or more experienced significantly lower mortality from All Causes than those employed for less than 1 year.

Mortality experience of employees with occupational exposure to DBCP

Concern about the carcinogenic potential of 1,2-dibromo-3-chloropropane(DBCP) has arisen recently, focusing on six organ sites: stomach, liver, kidney, lung, testes, and skin. To examine the mortality experience of persons potentially exposed, a cohort of 550 employees involved in production and formulation from 1957 to 1976 was defined. A total of 35 deaths was observed through 1979 (39.2 expected). No statistically significant excess was observed for any cause of death. No cancer deaths were noted for five of the hypothesized sites. For the lung cancer category, five deaths were observed (2.7 expected, P greater than .135), two of which occurred in a subgroup directly exposed for at least 1 yr (0.5 expected, P greater than .077). Aside from arsenicals exposure, potential confounding resulting from smoking or multiple chemical exposures could not be evaluated.

A mortality survey of men engaged in the manufacture of organic dyes

The mortality experience of 342 employees assigned to three aromatic amine-based dye production areas was examined in relation to duration of employment and interval since entry into these areas. No deaths due to bladder cancer were observed, and no statistically significant increases in mortality by work area or duration of exposure within work area were found, based on comparison with the mortality experience of the U.S. white male population. There were incidental findings of more digestive malignancies than expected in one production area, and more digestive and respiratory malignancies than expected in a second area; none of these were statistically significant. Because the digestive malignancies were not site-specific, and because similarities in specific job assignments were lacking for both digestive and respiratory malignancies, it is unlikely that these findings were work related. Nonetheless, in subsequent assessments of the present cohort and other populations exposed to similar materials an effort should be made to evaluate the occurrence of digestive and respiratory malignancies.

Medical and morbidity surveillance findings among employees potentially exposed to TCDD

Available medical and morbidity surveillance findings from 1976 to 1978 for two employee cohorts potentially exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were compared with those of matched unexposed employees. The medical surveillance findings were derived from a screening programme offered to all active employees and included an analysis of various medical history questions and blood chemistry results. Group medical insurance claims served as the source of morbidity surveillance data and the period prevalence of selected diseases was analysed. Few significant differences between the exposed and unexposed were detected. Among the cohort of employees potentially exposed during the manufacture of 2,4,5-trichlorophenoxyacetic acid (2,4,5,-T), a significantly greater frequency of x-ray proved ulcer was reported and significantly more members of this group had diseases of the digestive system diagnosed. Such findings were absent in the more highly TCDD-exposed cohort engaged in 2,4,5-trichlorophenol production, making it unlikely that dioxin was a cause.