Margareta Littorin

Cancer mortality in workers exposed to chlorophenoxy herbicides and chlorophenols.

Epidemiological studies have revealed an increased risk of cancer, notably soft-tissue sarcomas and non-Hodgkins lymphomas, in people occupationally exposed to chlorophenoxy herbicides, including those contaminated by 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). We report here a historical cohort study of mortality in an international register of 18,910 production workers or sprayers from ten countries. Exposure was reconstructed through questionnaires, factory or spraying records, and job histories. Cause-specific national death rates were used as reference. No excess was observed in all-cause mortality, for all neoplasms, for the most common epithelial cancers, or for lymphomas. A statistically non-significant two-fold excess risk, based on 4 observed deaths, was noted for soft-tissue sarcoma with a standardised mortality ratio (SMR) of 196 and 95% confidence interval (Cl) 53-502; this was concentrated as a six-fold statistically significant excess, occurring 10-19 years from first exposure in the cohort as a whole (SMR = 606 [165-1552]) and, for the same time period, as a nine-fold excess among sprayers (SMR = 882 [182-2579]). Risks appeared to be increased for cancers of the testicle, thyroid, other endocrine glands, and nose and nasal cavity, based on small numbers of deaths. The excess of soft-tissue sarcomas among sprayers is compatible with a causal role of chlorophenoxy herbicides but the excess does not seem to be specifically associated with those herbicides probably contaminated by TCDD.

Soft tissue sarcoma and non-Hodgkin's lymphoma in workers exposed to phenoxy herbicides, chlorophenols, and dioxins: two nested case-control studies

We examined the effect of exposure to chemicals present in the production and spraying of phenoxy herbicides or chloro-phenols in two nested case-control studies of soft tissue sarcoma and non-Hodgkins lymphoma. Eleven sarcoma and 32 lymphoma cases occurring within an international cohort were matched for age, sex, and country of residence with 55 and 158 controls, respectively. Exposures to 21 chemicals or mixtures were estimated by three industrial hygienists who were blind to the subjects case-control status. Excess risk of soft tissue sarcoma was associated with exposure to any phenoxy herbicide [odds ratio (OR) = 10.3; 95% confidence interval (Cl) = 1.2–91] and to each of the three major classes of phenoxy herbicides (2,4-dichlorophenoxyacetic acid, 2,4,5-trichloro-phenoxyacetic acid, and 4-chloro-2-methylphenoxyacetic acid), to any polychlorinated dibenzodioxin or furan (OR = 5.6; 95% CI = 1.1–28), and to 2,3,7,8-tetrachlorodibenzo-p-dioxm (OR = 5.2; 95% CI = 0.85–32). Sarcoma risk was not associated with exposure to raw materials or other process chemicals. In the non-Hodgkins lymphoma study, associations were generally weaker than those found in the study on sarcoma. These findings indicate that workers exposed to phenoxy herbicides and their contaminants are at a higher risk of soft tissue sarcoma.

Development, validation and characterization of an analytical method for the quantification of hydrolysable urinary metabolites and plasma protein adducts of 2,4- and 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate and 4,4'-methylenediphenyl diisocyanate

Occupational exposure to diisocyanates within the plastic industry causes irritation and disorders in the airway. The aim of this study was to develop, validate and characterize a method for the determination of 2,4-toluenediamine (2,4-TDA), 2,6-toluenediamine (2,6-TDA), 1,5-diaminonaphthalene (1,5-NDA) and 4,4′-methylenedianiline (4,4′-MDA) in hydrolysed urine and plasma, and to study the correlation between the plasma and urinary levels of these potential biomarkers of 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 1,5-naphthalene diisocyanate (1,5-NDI) and 4,4′-methylenediphenyl diisocyanate (4,4′-MDI), respectively. Samples were hydrolysed with 0.3 M NaOH at 100°C for 24 h. The diamines were extracted, derivatized with pentafluoropropionic acid anhydride, and quantified by selected ion monitoring on gas chromatography-mass spectrometry. The repeatability and reproducibility of the method were 7-18% and 7-19%, respectively. Dialysis experiments showed that the metabolites of 2,4-TDI, 2,6-TDI, 1,5-NDI and 4,4′-MDI in plasma were exclusively protein adducts. No free diamines were found in urine, indicating that all diisocyanate-related metabolites were in a conjugated form. For each diisocyanate-related biomarker, there were strongly significant correlations (p<0.001) between individual levels of metabolites in plasma and urine, with Spearmans rank correlation coefficient (rs) values of 0.74-0.90. The methods presented here will be valuable for the development of biological monitoring methods for diisocyanates.

Cancer incidence and mortality in women occupationally exposed to chlorophenoxy herbicides, chlorophenols, and dioxins

The association between exposure to chlorophenoxy herbicides contaminated with dioxins and occurrence of cancer has been studied mainly in male populations. In animal experiments, gender differences have been recorded in the cancer response to administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Mortality and cancer incidence in an international cohort of 701 women from an International Register of Workers occupationally exposed to chlorophenoxy herbicides, chlorophenols, and dioxins is examined. Cause-specific, national death rates and cancer incidence rates were used as referents. Cancer risk was not increased overall, with a standardized incidence ratio (SIR) of 96 and 95 percent confidence interval (CI) of 64–137, based on 29 cases. Among workers exposed to those chlorophenoxy herbicides contaminated with TCDD, excess cancer incidence (for all sites) was observed (SIR=222, CI=102–422, 9 cases); this was highest in the first 10 years after exposure. No excess was observed for breast cancer, the most common cancer in this cohort. Results on cancer mortality were consistent with those on incidence.

Exposure biomarkers and risk from gluing and heating of polyurethane: a cross sectional study of respiratory symptoms.

OBJECTIVES To define the relation between exposure to polyurethane (PUR) glue, biomarkers of exposure and effect, and work related symptoms that occur at least once a week. METHODS In a cross sectional study, 152 workers and 14 clerks in a factory with exposure to sprayed and heated PUR glue containing 4,4′-diphenylmethane (MDI) or 1,6-hexamethylene (HDI) di-isocyanate were examined with gas chromatography-mass spectrometry (GC-MS) for metabolites of MDI in plasma (P-MDX) and urine (U-MDX), 2,4- and 2,6-toluene di-isocyanate (TDI; P-TDX, U-TDX) and HDI in plasma and urine, specific serum IgG (S-IgG-MDI, S-IgG-HDI, and S-IgG-TDI, respectively) and IgE (S-IgE-MDI). Work related symptoms of the eyes and airways (nose or lower airways, or both), and lung function were also evaluated. RESULTS P-MDX was detected in 65% of the workers, U-TDX in 47%, HDX in none. Three per cent were positive for S-IgE-MDI, 33% for S-IgG-MDI, 32% for S-IgG-TDI, and 12% for S-IgG-HDI. A few clerks had metabolites, and some had antibodies. Most metabolites and immunoglobulins were slightly correlated—for example, P-MDX v S-IgG-MDI: rs=0.21. Workers who heated glue had increased P-MDX (odds ratio (OR)=12 for a value above the median) and S-IgG-MDI (OR=3.7), sprayers P-2,4-TDX (OR=6.2) and P-2,6-TDX (OR=16). Twenty six per cent of the workers had work related symptoms of the airways, 21% from the nose, 11% from the lower airways. Spraying of glue increased the risk of work related symptoms and slightly decreased lung function. U-MDX was associated with work related symptoms from the airways (OR=3.7) and P-2,6-TDX with work related symptoms from the lower airways (OR=6.6). S-IgG-MDI was related to work related symptoms from the airways (OR=2.6). CONCLUSIONS There were relations between exposures to sprayed and heated PUR glue based on MDI and HDI, concentrations of metabolites of MDI and TDI in plasma and urine, specific IgG serum antibodies against MDI, TDI, and HDI, and work related symptoms.

4,4′-Methylenedianiline in hydrolysed serum and urine from a worker exposed to thermal degradation products of methylene diphenyl diisocyanate elastomers

A 45-year-old mechanic employed in blowing hot air (350°–600°C) onto the surface of a polyurethane methylene diphenyl diisocyanate (MDI) conveyer belt developed dyspnoea, rhinoconjunctivitis and fever. The illness was suggestive of an MDI-associated illness, compatible with both immediate hypersensitivity and a complement-mediated immune-complex reaction. In his serum there were specific IgG and IgE antibodies against MDI and other isocyanates, and high values of circulating immune complexes. The patients blood and urine samples were analysed for the presence of 4,4′-methylenedianiline (MDA) in hydrolysed urine and plasma. MDA was derivatized to amides using pentafluoropropionic acid anhydride (PFPA). Gas chromatography-mass spectrometry determinations were made monitoring the (M-20; M = molecular mass) fragments from the MDA-PFPA and the [2H2]MDA-PFPA derivative. The first urine sample was obtained 22 h and the last sample 114 h after start of exposure. The urine concentrations of MDA were corrected for creatinine. The half-time of MDA was 70–80 h. The first serum sample was obtained 19 h and the last sample 1967 days after the start of exposure. The half-time was 21 days, which suggests the presence of MDI/MDA plasma protein adducts in the exposed worker.

Influence of genetic factors on toluene diisocyanate-related symptoms: evidence from a cross-sectional study

BackgroundToluene diisocyanate (TDI) is a highly reactive compound used in the production of, e.g., polyurethane foams and paints. TDI is known to cause respiratory symptoms and diseases. Because TDI causes symptoms in only a fraction of exposed workers, genetic factors may play a key role in disease susceptibility.MethodsWorkers (N = 132) exposed to TDI and a non-exposed group (N = 114) were analyzed for genotype (metabolising genes: CYP1A1*2A, CYP1A1*2B, GSTM1*O, GSTM3*B, GSTP1 I105V, GSTP1 A114V, GSTT1*O, MPO -463, NAT1*3, *4, *10, *11, *14, *15, NAT2*5, *6, *7, SULT1A1 R213H; immune-related genes: CCL5 -403, HLA-DQB1*05, TNF -308, TNF -863) and symptoms of the eyes, upper and lower airways (based on structured interviews).ResultsFor three polymorphisms: CYP1A1*2A, CYP1A1*2B, and TNF -308 there was a pattern consistent with interaction between genotype and TDI exposure status for the majority of symptoms investigated, although it did reach statistical significance only for some symptoms: among TDI-exposed workers, the CYP1A1 variant carriers had increased risk (CYP1A1*2A and eye symptoms: variant carriers OR 2.0 95% CI 0.68–6.1, p-value for interaction 0.048; CYP1A1*2B and wheeze: IV carriers OR = 12, 1.4–110, p-value for interaction 0.057). TDI-exposed individuals with TNF-308 A were protected against the majority of symptoms, but it did not reach statistical significance. In the non-exposed group, however, TNF -308 A carriers showed higher risk of the majority of symptoms (eye symptoms: variant carriers OR = 2.8, 1.1–7.1, p-value for interaction 0.12; dry cough OR = 2.2, 0.69–7.2, p-value for interaction 0.036). Individuals with SULT1A1 213H had reduced risk both in the exposed and non-exposed groups. Other polymorphisms, showed associations to certain symptoms: among TDI-exposed,NAT1* 10 carriers had a higher risk of eye symptoms and CCL5 -403 AG+AA as well as HLA-DQB1 *05 carriers displayed increased risk of symptoms of the lower airways. GSTM1, GSTM3 and GSTP1 only displayed effects on symptoms of the lower airways in the non-exposed group.ConclusionSpecific gene-TDI interactions for symptoms of the eyes and lower airways appear to exist. The results suggest different mechanisms for TDI- and non-TDI-related symptoms of the eyes and lower airways.

Focal epilepsy and exposure to organic solvents: a case-referent study

Organic solvent exposure was studied in 104 cases of idiopathic focal epilepsy and 312 matched referents. Exposure to solvents was classified as O, I, II, or III on the basis of occupational codes. The relative risk (RR) of epilepsy for those in exposure class I, II, or III, relative to O, was estimated using conditional logistic regression. An increasing trend in RR was observed with higher exposure classes. The attributable risk for cases with focal epilepsy of deep hemispherical origin was estimated to be 8%.

The GSTP1 Ile105 Val polymorphism modifies the metabolism of toluene di-isocyanate.

Background Toluene di-isocyanate (TDI) is widely used in the production of polyurethane foams and paints. As TDI causes respiratory disease in only a fraction of exposed workers, genetic factors may play a key role in disease susceptibility. Polymorphisms in TDI metabolising genes may affect elimination kinetics, resulting in differences in body retention, and in its turn differences in adverse effects. Objectives To analyze how genotype modifies the associations between (i) TDI in air (2,4-TDI and 2,6-TDI) and its metabolites toluene diamine (TDA; 2,4-TDA and 2,6-TDA) in hydrolyzed urine; and (ii) 2,4-TDA and 2,6-TDA in hydrolyzed plasma and 2,4-TDA and 2,6-TDA in urine. Methods Workers exposed to TDI were analyzed for 2,4-TDI and 2,6-TDI in air (N=70), 2,4-TDA and 2,6-TDA in hydrolyzed urine (N=124) and in plasma (N=128), and genotype: CYP1A1*2A, CYP1A1*2B, GSTA1-52, GSTM1O, GSTM3B, GSTP1 I105V, GSTP1 A114V, GSTT1O, MPO-463, NAT1*3, *4, *10, *11, *14, *15, NAT2*5, *6, *7, and SULT1A1 R213H. Results GSTP1 105 strongly modified the relationship between 2,4-TDA in plasma and in urine: ValVal carriers had about twice as steep regression slope than IleIle carriers. A similar pattern was found for 2,6-TDA. CYP1A1*2A, GSTM1, GSTP1, GSTT1, and MPO possibly influenced the relationship between TDA in plasma and urine. Conclusion Our results show, for the first time, genetic modification on the human TDI metabolism. The findings suggest that GSTP1 genotype should be considered when evaluating biomarkers of TDI exposure in urine and plasma. Moreover, the results support earlier findings of GSTP1 105 Val as protective against TDI-related asthma.

Analysis of ethylenethiourea as a biomarker in human urine using liquid chromatography/triple quadrupole mass spectrometry.

Ethylenebisdithiocarbamates (EBDCs) are widely used fungicides. Ethylenethiourea (ETU), the main metabolite and also a contaminant in the commercially available products, is of major toxicological concern. In this study, a method using liquid chromatography/triple quadrupole mass spectrometry (LC/MS/MS) is described for the analysis of ETU in human urine after a single-step extractive derivatization using pentafluorobenzyl bromide (PFBBr). Analysis was carried out using selected reaction monitoring (SRM) in the positive ion mode. Quantification of ETU was performed using [(2)H(4)]-labeled ETU as internal standard (IS). The limit of detection (LOD) was determined to 0.05 ng/mL. The method was linear in the range 0.1-54 ng/mL urine and had a within-run precision of 3-5%. The between-run precision was determined at an average urine level of 2 and 10 ng/mL urine and found to be 9%. The inter-batch precision was 6%. To validate ETU as a biomarker of exposure, the method was applied in a human experimental oral exposure to the commercial fungicide Ridomil Gold, containing 64% mancozeb and 4.5% ETU. Two healthy volunteers received 8.9 microg/kg body weight (b.w.) Ridomil Gold in a single oral dose followed by urine sampling for 104 h post-exposure. The elimination half-life of ETU was estimated to 17-23 h.