Association of bone mineral density with trichlorophenol: a population-based study

BACKGROUND

Trichlorophenols (TCPs) are metabolites of several organochlorine chemicals, including chlorobenzene, hexachlorocyclohexane, and chlorophenoxy acid, present in air, surface water, soil, and sediment. Many studies have shown that endocrine disruptors (EDs)may contribute to decreased bone mass and the increased risk of osteoporosis. However, the relationship between TCP and bone mineral density (BMD) has not been studied yet.

METHODS

We conducted a cross-sectional study by using data from the 2005-2010 National Health and Nutrition Examination Survey (NHANES). TCP levels were measured in urine samples from 3385 participants and bone mineral density was obtained by dual X-ray absorptiometry (DXA) lumbar spine and femur scanning. Multiple regression analysis, stratified analysis, curve fitting analysis, and trend tests were used to assess the relationship between TCP and BMD.

RESULT

After adjusting for confounding factors, the results of multiple regression analysis only showed that ln-2,4,5-TCP was negatively associated with BMD of lumbar spine. In stratified analyses, Male, Menstruating Female and Menopausal Female were divided into three groups for analysis. The results showed that ln-2,4,5-TCP and ln-2,4,6-TCP were not statistically associated with BMD in total femur, femoral neck, femoral tuberosity, intertrochanteric femur and lumbar spine, which was also confirmed by curve fitting analyses and trend tests.

CONCLUSION

This study demonstrated that 2,4,5-TCP and 2,4,6-TCP in urine samples were not significantly associated with BMD in the US population. Therefore, 2,4,5-TCP and 2,4,6-TCP may not be detrimental to BMD.

Indirect treatment comparison of cenobamate to other ASMs for the treatment of uncontrolled focal seizures

OBJECTIVE

The efficacy and safety of cenobamate relative to other antiseizure medications (ASMs) has not been evaluated. An indirect treatment comparison (network meta-analysis) was performed to determine if adjunctive cenobamate increases the odds ratio (OR) for ≥50% responder rate or for withdrawals due to treatment-emergent adverse events (TEAEs) leading to ASM discontinuation versus adjunctive therapy with other ASMs.

METHODS

A systematic literature review was conducted to identify randomized, double-blind, placebo-controlled trials (maintenance phase ≥ 12 weeks) assessing adjunctive ASMs in adults with uncontrolled focal seizures. Cenobamate was compared to a group of seven other ASMs, and to subgroups of branded (brivaracetam, eslicarbazepine acetate, lacosamide, and perampanel) and older (lamotrigine, levetiracetam, and topiramate) ASMs at FDA-recommended daily maintenance doses (FDA-RDMD), at all doses, and at maximum and minimum daily doses. Statistical significance was set at p < 0.05.

RESULTS

Twenty-one studies were eligible for analysis. The placebo-adjusted ≥ 50% responder rate for FDA-RDMD of cenobamate was superior (OR 4.200; 95% CI 2.279, 7.742) to FDA-RDMD of all seven assessed (OR 2.202 95% CI 1.915, 2.532; p = 0.044) and branded ASMs (OR 2.148; 95% CI 1.849, 2.494; p = 0.037). There was no significant difference for ≥50% responder rate between FDA-RDMD of cenobamate and FDA-RDMD of older ASMs (OR 2.617; 95% CI 1.767, 3.878; p = 0.202). No significant differences were identified for ≥50% responder rate when comparing all doses and maximum/minimum doses of cenobamate to all seven, branded, and older ASMs. Cenobamate demonstrated comparable TEAE withdrawal rates to all seven ASMs, branded ASMs, and older ASMs across each of the four dose ranges (all p > 0.05).

SIGNIFICANCE

Patients receiving FDA-RDMD of cenobamate were more likely to have ≥50% seizure reduction compared with FDA-RDMD of the seven assessed ASMs and branded ASMs, without an increase in treatment discontinuation due to TEAEs.

Suppression of the photoparoxysmal response in photosensitive epilepsy with cenobamate (YKP3089)

OBJECTIVE

To evaluate the effect of cenobamate in patients with photoparoxysmal-EEG response (PPR) to intermittent photic stimulation (IPS) as proof of principle of efficacy in patients with epilepsy.

METHODS

In this multicenter, single-blind study, adults with photosensitive epilepsy, with/without concomitant antiepileptic drug therapy, underwent IPS under 3 eye conditions after a single dose of placebo (day -1, day 2) or cenobamate (day 1; 100, 250, or 400 mg). Complete suppression was a standardized photosensitivity range reduction to 0 over ≥1 time points for all eye conditions. Partial suppression was a ≥3-point reduction over ≥3 testing times vs the same time points on day -1 in ≥1 eye condition. Pharmacokinetics and safety were assessed.

RESULTS

Of 6 evaluable patients, 5 reentered to receive higher doses. Cenobamate 100 mg produced partial suppression in 1 of 3 patients; 250 mg produced complete suppression in 1 of 4 and partial suppression in 4 of 4 patients; and 400 mg produced complete suppression in 1 of 4 and partial suppression in 2 of 4 patients. PPR was consistently reduced on days 1 and 2 (>24 hours after cenobamate) vs day -1 (placebo) with the 250- and 400-mg doses. Area under the plasma concentration-time curve (before dose to last measurable concentration) values between 201 and 400 μg/h/mL resulted in partial suppression in 4 of 6 (66%) patients. Most common adverse events were dizziness and somnolence.

CONCLUSIONS

This proof-of-principle study demonstrated that cenobamate is a potentially effective product for epilepsy.

CLINICALTRIALSGOV IDENTIFIER

NCT00616148.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that, for patients with photosensitive epilepsy, cenobamate suppresses IPS-induced PPR.

Anthropometric measures at age 3 years in associations with prenatal and postnatal exposures to chlorophenols

BACKGROUND

Chlorophenols (CPs), suspected as endocrine disrupting chemicals, exposure during early life may contribute to body size. However, limited human data with inconsistent findings have examined the developmental effects of CPs exposure.

OBJECTIVE

To explore associations between prenatal and postnatal CPs exposure and anthropometric parameters in children aged 3 years.

METHODS

A subset of 377 mother-child pairs with urinary five CP concentrations were enrolled from a prospective birth cohort. Generalized linear models were conducted to evaluate associations of CPs exposure with children's anthropometric measures.

RESULTS

Maternal urinary 2,4,6-trichlorophenol (2,4,6-TCP) concentrations were significantly negatively associated with weight z scores [regression coefficient (β) = -0.51, 95% confidence interval (CI): -0.96, -0.05; p = 0.01], weight for height z scores (β = -0.54, 95% CI: -1.02, -0.06; p = 0.01) and body mass index (BMI) z scores (β = -0.53, 95% CI: -1.03, -0.03; p = 0.01) of children aged 3 years, after adjustment for potential confounders and postnatal CPs exposure. In the sex-stratified analyses, these inverse associations remained among boys, while in girls, positive associations of prenatal 2,4,6-TCP exposure with weight for height z scores and BMI z scores were observed. Postnatal exposure to 2,5-diclorophenol (2,5-DCP) was positively associated with weight z scores (β = 0.26, 95% CI: 0.02, 0.50; p = 0.04), after controlling for possible confounders and maternal CPs exposure during pregnancy. Considering potential sex-specific effects, these associations were only observed in girls.

CONCLUSIONS

Our findings indicate that prenatal 2,4,6-TCP exposure and postnatal 2,5-DCP exposure may have adverse and sex-specific effects on children's physical development.

Associations between urinary concentrations of 2,5-dichlorophenol and metabolic syndrome among non-diabetic adults

We investigated in this study the relationship between exposure to para-dichlorobenzene (p-DCB), measured as urinary concentrations of 2,5-dichlorophenol (2,5-DCP), and metabolic syndrome in non-diabetic adult participants. A nationally representative subsample of 1706 non-diabetic adult participants aged 20-79 years randomly selected for measurement of urinary concentrations of 2,5-DCP in the 2007-2010 US National Health and Nutrition Examination Survey was analyzed. A dose-dependent increase in the prevalence of metabolic syndrome was observed in the study participants across quartiles of urinary 2,5-DCP (p-trend = 0.0025). After adjusting for potential confounders, individuals in the third and fourth quartile of urinary 2,5-DCP had 1.47 (95% CI 1.02, 2.14) and 1.56 (95% CI 1.10, 2.23) increased odds of metabolic syndrome, respectively, compared with individuals with the lowest quartile. Of the five components of metabolic syndrome, waist circumference and HDL-cholesterol showed a significant and monotonic association with urinary 2,5-DCP. Participants with the highest quartile of 2,5-DCP had 3.18 cm (95% CI 1.34, 5.02) higher mean waist circumference and 2.83 mg/dL (95% CI -4.68, -0.98) lower mean HDL-cholesterol than the participants in the lowest quartile. This study suggests a potential relationship between p-DCB exposure and metabolic syndrome in non-diabetic adults. Prospective epidemiological and mechanistic studies are needed to further explore these interactions.

Mortality rates among trichlorophenol workers with exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin

The authors examined 1,615 workers exposed to dioxins in trichlorophenol production in Midland, Michigan, to determine if there were increased mortality rates from exposure. Historical dioxin levels were estimated by a serum survey of workers. Vital status was followed from 1942 to 2003, and cause-specific death rates and trends with exposure were evaluated. All cancers combined (standardized mortality ratio (SMR) = 1.0, 95% confidence interval (CI): 0.8, 1.1), lung cancers (SMR = 0.7, 95% CI: 0.5, 0.9), and nonmalignant respiratory disease (SMR = 0.8, 95% CI: 0.6, 1.0) were at or below expected levels. Observed deaths for leukemia (SMR = 1.9, 95% CI: 1.0, 3.2), non-Hodgkin lymphoma (SMR = 1.3, 95% CI: 0.6, 2.5), diabetes (SMR = 1.1, 95% CI: 0.6, 1.8), and ischemic heart disease (SMR = 1.1, 95% CI: 0.9, 1.2) were slightly greater than expected. No trend was observed with exposure for these causes of death. However, for 4 deaths of soft tissue sarcoma (SMR = 4.1, 95% CI: 1.1, 10.5), the mortality rates increased with exposure. The small number of deaths and the uncertainty in both diagnosis and nosology coding make interpretation of this finding tenuous. With the exception of soft tissue sarcoma, the authors found little evidence of increased disease risk from exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Staining potential of calcium hydroxide and monochlorophenol following removal of AH26 root canal sealer

AIM

The focus of this study was to examine the staining potential of calcium hydroxide (Ca(OH)2) on tooth structure following the removal of AH26 root canal sealer.

METHODS AND MATERIALS

Fifty maxillary anterior teeth were prepared and obturated with AH26 and gutta percha. The sealers were then removed 24 hours later and the teeth were randomly divided into two groups. Ca(OH)2 was then placed in the root canals of the first group of teeth as a medicament and camphorated monochlorophenol (CMCP) was placed in the second group of teeth after the filling material was removed. The color of the external tooth surfaces was determined before tooth preparation and two weeks after the placement of the medicaments. The Z test was used for statistical analysis.

RESULTS

All experimental teeth showed varying degrees of coronal discoloration with the Ca(OH)2 group showing more discoloration than the CMCP group (p<0.05).

CONCLUSION

Using Ca(OH)2 as a medicament after removing AH26 caused progressive discoloration of the teeth, whereas using CMCP caused only slight discoloration.

CLINICAL SIGNIFICANCE

To avoid staining of the treated tooth, AH26 root canal sealer must be completely removed from the dentin walls before using a medicament.

Evaluation of a standard shade guide for color change after disinfection

OBJECTIVE

To determine if surface disinfectants cause a change in the shade perception of a standard Classic Vitapan shade guide.

METHOD AND MATERIALS

Consistency in shade selection for dental restorations involves many factors, and one of the most important is the shade tabs used in the selection process. Ten shade tabs each of shades B2, D2, C1, and A3.5 were selected from the Classic Vitapan shade guide (Vident). All tabs were measured with the EasyShade shade device (Vident) at baseline. Three tabs of each shade were set aside as controls. The other 7 tabs of each shade were treated with the surface disinfectant Cavicide (Metrex Research) for 480 cycles to simulate a year's usage. After each 480 cycles, all the tabs were again measured with the EasyShade. This process was repeated to simulate 2 and 3 years of use.

RESULTS

The data were analyzed to calculate the delta E 2000 for any change. A statistically significant increase was observed in the value (L*) and chroma (C*) after 2 and 3 years of simulated treatments. These changes were not perceptible to the clinician.

CONCLUSIONS

The authors suggest that 1 standard shade guide be set aside to compare against those in clinical use to determine when they should be replaced.

2,4-Dichlorophenol Degradation by an Integrated Process: Photoelectrocatalytic Oxidation and E-Fenton Oxidation

A new reactor system was designed for an integrated process involving photoelectrocatalytic oxidation (PECO) and electro-Fenton (E-Fenton) oxidation. Its efficiency was evaluated in terms of 2,4-dichlorophenol (2,4-DCP) degradation in aqueous solution. In this process, a TiO2 electrode and an iron (Fe) electrode were used as anodes in parallel, while graphite felt (GF) was used as a cathode. When an electrical current is applied between the anodes and the cathode, the iron anode can release Fe2+ and the GF cathode can generate H2O2 continuously in the reaction solution. Under UV-A illumination, while a H2O2-assisted PECO reaction occurs on the surface of the TiO2 photo anode, an E-Fenton reaction takes place in the solution. The experimental results demonstrated that 2,4-DCP degradation in aqueous solution was greatly enhanced because of the interaction between the two types of reactions. Moreover, the effect of pH as an important factor was investigated. It was found that the combined reaction becomes less pH sensitive than the typical E-Fenton reaction and may be suitable for application in a wide pH range.

Impact of the Specificity of the Exposure Metric on Exposure???Response Relationships

BACKGROUND

Exposure misclassification may occur when nonspecific exposure indicators are used. Developing estimates of more specific measures may be difficult due to sampling limitations or a paucity of historical measurements and, thus, often requires substantial effort. We examine the impact on exposure-response relationships of moving from 2 measures of exposure mixtures (dust, chlorophenols) to more specific exposure indicators (wood dust, pentachlorophenol, tetrachlorophenol) in a retrospective cohort.

METHODS

The study population consisted of 26,847 male sawmill workers (> or =1 year employment between 1950 and 1995) with linkage to national cancer registries. A subcohort (n = 11,273 employed more than 1 day between 1985 and 1995) was linked to hospital discharge records. We evaluated the shape (log-linear vs log-log models), goodness of fit, precision, and expected versus observed attenuation of the exposure-response relationships.

RESULTS

The correlation between the cumulative exposure indices was moderately high (dust/wood dust, r = 0.68; total chlorophenol/pentachlorophenol, r = 0.88; total chlorophenol/tetrachlorophenol, r = 0.78). An increase in chronic obstructive pulmonary disease hospitalizations was found with wood dust but not with total dust. Stronger associations for non-Hodgkin lymphoma and kidney cancer incidence were observed with pentachlorophenol than with total chlorophenol; no association was observed with tetrachlorophenol. We observed greater attenuation than expected using total dust, but less than expected using total chlorophenol.

CONCLUSIONS

The relationships between health outcomes were substantially attenuated when nonspecific exposure indicators were used. This study demonstrates the importance of developing exposure metrics as specific to the disease-causing agent as possible, particularly when the composition of mixed exposures varies by work areas.

Non-Hodgkin lymphoma and pesticide exposure: 25 years of research

Over the past 40 years, a substantial rise in the incidence of non-Hodgkin lymphoma (NHL) has been observed. Epidemiologic studies aimed at understanding this rise have revealed some association with occupational exposure. NHL is common among farmers, where pesticides have been described as the culprit. The association between pesticides and NHL has been demonstrated mainly in case-control studies, while retrospective cohorts have been less convincing. Pesticides including chlorphenol and phenoxyacetic acid herbicides, organochlorines, and organophosphate insecticides, carbamates, and fungicides have been associated with NHL. Although the causality has not been clearly proven, both genotoxic and nongenotoxic mechanisms for lymphomagenesis have been proposed. The leveling-off of NHL incidence in certain countries may be the result of a favorable change in pesticide usage patterns. Future studies, such as the Agricultural Health Study, may clarify the uncertainties regarding this issue.

Deriving freshwater quality criteria for 2,4,6-trichlorophenol for protection of aquatic life in China

Freshwater quality criteria of 2,4,6-trichlorophenol (2,4,6-TCP) were developed with particular reference to the aquatic biota in China, and based on USEPA's guidelines. Acute toxicity tests were performed on nine different domestic species indigenous to China to determine 48 h LC(50) and 96 h LC(50) values for 2,4,6-TCP. In addition, 21 d survival-reproduction test with Daphnia magna, 30 d embryo-larval test with Carassius auratus, 60 d fry-juvenile test with Ctenopharyngodon idellus, 30 d early life stage test with Bufo bufo gargarizans and 96 h growth inhibition test with Scenedesmus obliqaus were also conducted to estimate lower chronic limit and upper chronic limit values. The final acute value (FAV) was 2.01 mg/l 2,4,6-TCP. Acute-to-chronic ratios ranged from 5.01 to 12.2. The final chronic value (FCV) and the final plant value (FPV) of 2,4,6-TCP were 0.226 and 2.24 mg/l respectively. Based on FAV, FCV and FPV for 2,4,6-TCP, a criteria maximum concentration of 1.01 mg/l and a criterion continuous concentration of 0.226 mg/l were derived. The results of this study provide useful data for deriving national or local water quality criteria for 2,4,6-TCP based on aquatic biota in China.

Spectrum of cross-photosensitization in 18 consecutive patients with contact photoallergy to ketoprofen: associated photoallergies to non-benzophenone-containing molecules

Contact photoallergy to ketoprofen gels has been widely reported, and cross-sensitivity reactions with other compounds, such as tiaprofenic acid, fenofibrate and benzophenones, are well known. However, positive photopatch tests to other different non-benzophenone-related compounds have recently been observed. We report the results of photopatch testing in patients with contact photoallergy to ketoprofen and discuss the spectrum of cross-sensitization to ketoprofen. 18 consecutive patients with a history of photocontact dermatitis from ketoprofen were investigated. Patch and photopatch tests were performed. As expected, we observed positive photopatch tests to Ketum* gel and ketoprofen 2.5% in petrolatum in all patients (100%). However, it was remarkable to note positive photopatch tests to other unexpected and non-relevant allergens, including fentichlor (67%), tetrachlorosalicylanilide (28%), triclosan (17%), tribromsalan (11%) and bithionol (11%), with no clinical relevance. Interestingly, these agents belong to the family of halogenated salicylanilides and related compounds, which have been forbidden in Europe since the 1970s. Our results raise the question of hyper-photosusceptibility to non-relevant allergens induced by photosensitivity to ketoprofen. The mechanism may involve the high photoreactivity induced by the association of a benzene ring with an oxygen group.

Physiological and cytological responses of the marine diatom Skeletonema costatum to 2,4-dichlorophenol

Physiological and cytological responses of the marine diatom, Skeletonema costatum, to 2,4-dichlorophenol (2,4-DCP) were investigated after exposing algal cultures to 1-6 mg x l(-1) of 2,4-DCP for 96 h. Growth rate of the diatom was significantly reduced by 2,4-DCP at and above 3.0 mg x l(-1) while other biological parameters such as photosynthetic and respiration rates, carotenoid and protein content, ATP level and adenylate energy charge were unaffected. Exposure to 6.0 mg x l(-1) 2,4-DCP for 96 h resulted in the total lipid content being increased to 304%, while the RNA/DNA ratio was reduced to 31% of the control values. A parallel study by transmission electron microscopy further confirmed the increase in cellular lipid content, as evidenced by the accumulation of lipid droplets within diatom cells. A slight increase in carbohydrate (+37.8%) and decrease in chlorophyll a (-20.4%) and total chlorophyll c (-14.4%) were also found at 6.0 mg x l(-1) 2,4-DCP. Although 2,4-DCP is known to uncouple oxidative phosphorylation, our results show that energy production was not significantly inhibited at sublethal concentrations of 2,4-DCP. The observed growth inhibition in S. costatum caused by 2,4-DCP was associated with an increase in energy storage and inhibition of protein synthesis, as indicated by a reduction in RNA/DNA ratio.

[Photocontact dermatitis due to ketoprofen and photosensitization to tetrachlorosalicylanide and to Fenticlor(R)]

BACKGROUND

Photoallergy to ketoprofen and cross reactivity of ketoprofen with diphenylketones are well known; here are some cases of photoreaction to ketoprofen and unusual substances.

PATIENTS AND METHODS

Eleven photoallergic to ketoprofen patients were photo patch tested with Ketum(R), ketoprofen, oxybenzone, tiaprofenic acid, fenofibrate, and also chlorphenesin, sunscreen series, and photobiologists series (without lichen mix and benzocaine). We performed tests at day 0, we irradiated them with UVA at day 2, and control series remained closed. We performed readings at day 3 and 4 according to ICDRG's recommendations.

RESULTS

Nine tested patients had positive reactions to the irradiated tests with no expected allergens: fenticlor (9 cases), halogenated salicylanilides (4 cases), dibenzoylmethane (3 cases) and cinnamate (1 case).

DISCUSSION

The mechanism of these unusual photosensitizations is discussed. These cases show that it is important to test sunscreen series and photobiologists series in patients photoallergic to ketoprofen.

Life-cycle effects of sediment-associated 2,4,5-trichlorophenol on two groups of the midge Chironomus riparius with different exposure histories

Effects of 2,4,5-trichlorophenol (TCP) on life-cycle traits of the midge Chironomus riparius and the ability of the midge to evolve tolerance to TCP were assessed using a reference group and a group preexposed to TCP during three generations, both originating from the same laboratory culture. F1 larvae of these groups were then exposed to nominal TCP concentrations of 51, 177, 355, and 532 micromol TCP/kg dry sediment and a control sediment in a life-cycle experiment. Most studied life-cycle traits (mortality, egg production, life span, male dry wt) were fairly insensitive to TCP, and significant effects were observed only at high (> or = 355 micromol/kg) concentrations. Larval development rate was variable, and in some cases it responded more readily to low TCP concentrations than other life-cycle parameters. Some of the observed responses were attributed to changes in food availability. No clear evidence of tolerance to 2,4,5-trichlorophenol was found, but the preexposed midges produced more eggs than the reference group. They also emerged earlier and at a smaller size than the reference midges. These differences between the midge groups suggest that some changes toward tolerance induction had occurred during the preexposure.

[Efficacy and tolerance of trichlorophene in hymenolepiasis and taeniarinchiasis]

The paper deals with the clinical trials of the anthelmintic trichlorofen. The clinical and parasitological efficacy and tolerance of the agent for hymenolepiasis and taeniarinchiasis were studied. Twelve patients with hymenolepiasis and 5 with taeniarinchiasis were examined. Trichlorofen was shown to be effective in treating these infections, fairly tolerated and convenient for outpatient treatment. Eleven of the 12 with hymenolepiasis and 5 with taeniarinchiasis were cured.

Cancer mortality in four northern wheat-producing states

Chlorophenoxy herbicides are used both in cereal grain agriculture and in nonagricultural settings such as right-of-ways, lawns, and parks. Minnesota, North Dakota, South Dakota, and Montana grow most of the spring and durum wheat produced in the United States. More than 90% of spring and durum wheat is treated with chlorophenoxy herbicides, in contrast to treatment of approximately 30% of winter wheat. In this ecologic study I used wheat acreage as a surrogate for exposure to chlorophenoxy herbicides. I investigated the association of chlorophenoxy herbicides with cancer mortality during 1980-1989 for selected counties based on level of agriculture ([greater and equal to] 20%) and rural population ([greater and equal to] 50%). Age-standardized cancer mortality rates were determined for grouped counties based on tertiles of wheat acreage per county or for individual counties for frequently occurring cancers. The cancer sites that showed positive trends of increasing cancer mortality with increasing wheat acreage were esophagus, stomach, rectum, pancreas, larynx, prostate, kidney and ureter, brain, thyroid, bone, and all cancers (men) and oral cavity and tongue, esophagus, stomach, liver and gall bladder and bile ducts, pancreas, cervix, ovary, bladder, and other urinary organs, and all cancers (women). Rare cancers in men and women and cancers in boys and girls were studied by comparing counties above and below the median of wheat acreage per county. There was increased mortality for cancer of the nose and eye in both men and women, brain and leukemia in both boys and girls, and all cancers in boys. These results suggest an association between cancer mortality and wheat acreage in counties of these four states.

Childhood cancer in the offspring of male sawmill workers occupationally exposed to chlorophenate fungicides

The objective of this study was to determine whether paternal occupational exposure to chlorophenol fungicides and their dioxin contaminants is associated with childhood cancer in the offspring of sawmill workers. We used data from 23,829 British Columbian sawmill workers employed for at least 1 continuous year between 1950 and 1985 in 11 sawmills that used chlorophenates. Probabilistic linkage of the sawmill worker cohort to the provincial marriage and birth files produced an offspring cohort of 19,674 children born at least 1 year after the initiation of employment in the period 1952-1988. We then linked the offspring cohort to the British Columbia Cancer Registry. We included all malignancies in cases younger than 20 years of age that appeared on the cancer registry between 1969 and 1993. We calculated standardized incidence ratios (SIRs) using the British Columbia population as a reference. A nested case-control analysis assessed the effects of paternal cumulative exposure and windows of exposure on the risk of developing cancer in the offspring. We identified 40 cases of cancer during 259,919 person-years of follow-up. The all-cancer SIR was 1.0 [95% confidence interval (CI), 0.7-1.4]; the SIR for leukemia was 1.0 (CI, 0.5-1.8); and the SIR for brain cancer was 1.3 (CI, 0.6-2.5). The nested case-control analysis showed slightly increased risks in the highest categories of chlorophenol exposure, although none was statistically significant. Our analyses provide little evidence to support a relationship between the risk of childhood cancer and paternal occupational exposure to chlorophenate fungicides in British Columbian sawmills.

Occupational exposure to chlorophenol and the risk of nasal and nasopharyngeal cancers among U.S. men aged 30 to 60

BACKGROUND

Elevated rates of nasal and nasopharyngeal cancers have been associated with wood-related occupational exposures, including chlorophenols, formaldehyde, and wood dust.

METHODS

Occupational information was obtained from 43 nasal carcinoma cases, 92 nasopharyngeal carcinoma cases, and 1909 controls, by interview. Exact conditional logistic regression was used to evaluate the association of these cancers with chlorophenol exposure, estimated from a review of verbatim responses.

RESULTS

Both nasal and nasopharyngeal cancers were significantly associated with estimated duration of chlorophenol exposure. For nasopharyngeal cancer, elevated risk was observed among those who held jobs assigned medium or high intensity chlorophenol exposure (n(exposed)=18, OR=1.94, 95% CI=1.03-3.50) and among those with 10+ years in jobs assigned high intensity with high certainty (n(exposed)=3, OR=9.07, 95% CI=1.41-42. 9). Controlling for estimated formaldehyde and wood dust exposure did not alter these findings, as much of the estimated chlorophenol exposure was among machinists.

CONCLUSIONS

These findings support the hypothesis that occupational exposure to chlorophenol is a risk factor for nasal and nasopharyngeal cancer, although the role of machining-related exposures warrants further assessment.

Maternal occupational exposure to chemical substances and the risk of infants small-for-gestational-age

BACKGROUND

The association between maternal occupational exposure to specific chemical substances (organic solvents, carbon tetrachloride, herbicides, chlorophenols, polychlorinated biphenyls, aromatic amines, lead and lead compounds, mercury and mercury compounds) and birth of small-for-gestational-age (SGA) infants was evaluated using data from a prospective cohort study of 3,946 pregnant women in West Germany from 1987 to 1988.

METHODS

Occupational, medical, and psychosocial information was gathered through a questionnaire from pregnant women who were recruited between 15 and 28 gestational weeks. Exposure to chemical substances at the current workplace was assessed by a job-exposure matrix constructed by Pannett in 1985 and weighted for the number of working hours per week. Women not working at the time of the interview, women with multiple births, and women with stillbirths were excluded from analysis. Data were analyzed using dichotomous and polytomous logistic regression to control for age, smoking status, alcohol consumption, body mass index, and number of former births.

RESULTS

The results of the dichotomous logistic regression analysis suggest that leather work might be associated with the birth of infants small-for-gestational-age through exposure to chlorophenols (P = 0.02) and aromatic amines (P = 0.05). In the polytomous logistic regression analysis, only the association between exposure to mercury and growth retardation reached statistical significance (P = 0.02); however, the power of the study is limited. Further adjustment for income, shift work, and heavy physical work had no substantial effect on the results.

CONCLUSIONS

These findings suggest that maternal exposure to specific chemicals at work may be a risk factor for the birth of SGA infants.

Occupational chlorophenol exposure and non-Hodgkin's lymphoma

Occupational exposure to chlorophenols is suspected to increase non-Hodgkin's lymphoma (NHL) risk. This association was examined using data on 995 NHL cases and 1783 controls from the Selected Cancers Study, a population-based case-control study of men aged 32 to 60 years from eight population-based cancer registries conducted from 1984 to 1988. Potential chlorophenol exposure was characterized by an industrial hygienist using intensity estimates and confidence ratings, based upon review of verbatim job histories. Cases with substantial chlorophenol exposure had a significantly greater number of years of chlorophenol exposure (median years: cases, 4.0; controls, 2.0; P = 0.046); however, in conditional logistic regression models, the odds ratio for more than 8 years of substantial exposure was 1.51 (95% CI, 0.88 to 2.59). Overall, the findings do not provide strong support for an association with NHL risk. Chlorophenol exposure in this study is not based upon measured values and, therefore, may fail to characterize actual chlorophenol exposures accurately. Because of the large presence of machinists in the potentially chlorophenol-exposed group, these results may be underestimated by exposure misclassification if these subjects were not exposed to chlorophenolic biocides. However, these results are consistent with other findings, which suggest that chlorophenol exposure is not likely to be a strong risk factor for NHL.

Occupational chlorophenol exposure and soft tissue sarcoma risk among men aged 30-60 years

To evaluate the association of chlorophenol exposure with soft tissue sarcoma risk independent of phenoxyherbicide exposure, the authors analyzed data from the Selected Cancers Study, a population-based case-control study that included 295 male soft tissue sarcoma cases, aged 32-60 years, from eight population-based cancer registries and 1,908 male controls. Chlorophenol exposure was assigned using both an intensity and a confidence estimate by an industrial hygienist based on verbatim job descriptions. Seventeen percent of the jobs rated as high intensity involved wood preservation, while 82% involved cutting oils. Soft tissue sarcoma risk, modeled using conditional logistic regression, was significantly associated with ever having high-intensity chlorophenol exposure (odds ratio = 1.79, 95% confidence interval 1.10-2.88). A duration-response trend was evident among more highly exposed subjects (p for trend < 0.0001). For subjects with 10 or more years of substantial exposure, the odds ratio was 7.78 (95% confidence interval 2.46-24.65). These results suggest that chlorophenol exposure independent of phenoxyherbicides may increase the risk of soft tissue sarcoma. Because of the large number of machinists in the exposed group and the complex composition of cutting fluids, it is possible that another exposure involved in machining is responsible for the observed excess risk.

Cytogenetic characteristics of herbicide production workers in Ufa

In the present study, we investigated the effect of dioxin-containing products on the cytogenetic characteristics of peripheral blood lymphocytes of herbicide plant workers in Ufa. We found that the mean incidence of cells with chromosomal abberations (CHA) was two fold higher in the herbicide plant workers than the mean incidence level of controls groups consisting of people with no professional contact to herbicides or hospital stuff working in the close vicinity of the herbicide plant in Ufa (for both cases: p < 0.05). Moreover, the mean CHA cell incidence in the controls groups was also two times higher than the average level of spontaneous abberations in humans. The chemical herbicides 2,4,5-trichlorphenol (2,4,5-T) and 2,4-dichlorophenoxiacetic acid (2,4-D) appeared to affect various cellular cycle phases. Chromosomal type abberations occurred in the G0 stage of cellular cycle and chromatic type aberrations in the G2 stage. In the S stage, the aberrations of both types were observed. Our results indicate that the herbicides 2,4,5-T and 2,4-D have mutagenic effects in humans.

Second follow-up of a Dutch cohort occupationally exposed to phenoxy herbicides, chlorophenols, and contaminants

A retrospective cohort study of workers exposed to phenoxy herbicides, chlorophenols, and contaminants (2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other polychlorinated dioxins and furans) has been conducted in a chemical factory in the Netherlands. Male workers exposed to phenoxy herbicides or chlorophenols showed increased relative risks (adjusted for age, calendar period at end of follow-up, and time since first exposure/employment) for total mortality (relative risk (RR)=1.8, 95% confidence interval (CI) 1.2-2.5), cancer mortality (RR=4.1, 95% CI 1.8-9.0), respiratory cancer (RR=7.5, 95% CI 1.0-56.1), non-Hodgkin's lymphoma (RR=1.7, 95% CI 0.2-16.5), and ischemic heart diseases (RR=1.8, 95% CI 0.9-3.6) compared with an internal referent group of nonexposed workers. By using TCDD levels (predicted at the time of maximum exposure), based on extrapolated TCDD levels that were measured in a subset of the cohort, estimated relative risks for workers with medium and high TCDD levels were comparable with risks derived from the simple and earlier applied dichotomous exposure classification. In general, relative risks were highest in the highest category, indicating exposure-related increases in risk with TCDD level. In conclusion, results of this cohort study support the evidence of a high cancer risk in workers exposed to phenoxy herbicides, chlorophenols, and contaminants.

Second follow-up of a Dutch cohort occupationally exposed to phenoxy herbicides, chlorophenols, and contaminants

A retrospective cohort study of workers exposed to phenoxy herbicides, chlorophenols, and contaminants (2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other polychlorinated dioxins and furans) has been conducted in a chemical factory in the Netherlands. Male workers exposed to phenoxy herbicides or chlorophenols showed increased relative risks (adjusted for age, calendar period at end of follow-up, and time since first exposure/employment) for total mortality (relative risk (RR)=1.8, 95% confidence interval (CI) 1.2-2.5), cancer mortality (RR=4.1, 95% CI 1.8-9.0), respiratory cancer (RR=7.5, 95% CI 1.0-56.1), non-Hodgkin's lymphoma (RR=1.7, 95% CI 0.2-16.5), and ischemic heart diseases (RR=1.8, 95% CI 0.9-3.6) compared with an internal referent group of nonexposed workers. By using TCDD levels (predicted at the time of maximum exposure), based on extrapolated TCDD levels that were measured in a subset of the cohort, estimated relative risks for workers with medium and high TCDD levels were comparable with risks derived from the simple and earlier applied dichotomous exposure classification. In general, relative risks were highest in the highest category, indicating exposure-related increases in risk with TCDD level. In conclusion, results of this cohort study support the evidence of a high cancer risk in workers exposed to phenoxy herbicides, chlorophenols, and contaminants.

Blood lipid concentrations of dioxins and furans in a sample of BASF employees included in the IARC registry of workers exposed to phenoxy acid herbicides and/or chlorophenols

Depending on process conditions, polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) may be generated as low-level byproducts of chlorophenol and chlorophenoxy herbicides manufacture. A stratified random sample of 20 active employees from a cohort of phenoxy herbicide workers was selected in 1995 for determining PCDD and PCDF congeners in blood lipids to assess the extent of past PCDD and PCDF exposure in this cohort and whether that exposure might explain site-specific cancer findings in the total cohort. This cohort is included in the IARC International Registry of Persons Exposed to Phenoxyacid Herbicides and Their Contaminants. For the 19 persons who participated, median PCDD and PCDF concentrations were comparable to background concentrations in the general population. Median levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin, the sum of hexachlorodibenzo-p-dioxin, pentachlorodibenzofurans, and two dioxin toxicity equivalents values were statistically higher in 7 employees assigned to synthesis operations than for 12 employees assigned to other operations. However, the PCDD and PCDF concentrations were low relative to those seen in other dioxin-exposed cohorts. We conclude that PCDD and PCDF exposures of cohort members are unlikely to explain the elevated standardized mortality ratios observed in this cohort for several cancer sites.

Exposure to dioxin and nonneoplastic mortality in the expanded IARC international cohort study of phenoxy herbicide and chlorophenol production workers and sprayers

The authors studied noncancer mortality among phenoxyacid herbicide and chlorophenol production workers and sprayers included in an international study comprising 36 cohorts from 12 countries followed from 1939 to 1992. Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin or higher chlorinated dioxins (TCDD/HCD) was discerned from job records and company questionnaires with validation by biologic and environmental measures. Standard mortality ratio analyses suggested a moderate healthy worker effect for all circulatory diseases, especially ischemic heart disease, among both those exposed and those not exposed to TCDD/HCD. In Poisson regression analyses, exposure to TCDD/HCD was not associated with increased mortality from cerebrovascular disease. However, an increased risk for circulatory disease, especially ischemic heart disease (rate ratio [RR] 1.67, 95% confidence interval [Cl] 1.23-2.26) and possibly diabetes (RR 2.25, 95% Cl 0.53-9.50), was present among TCDD/HCD-exposed workers. Risks tended to be higher 10 to 19 years after first exposure and for those exposed for a duration of 10 to 19 years. Mortality from suicide was comparable to that for the general population for all workers exposed to herbicides or chlorophenols and was associated with short latency and duration of exposure. More refined investigations of the ischemic heart disease and TCDD/HCD exposure association are warranted.

Exposure of workers to 2,3,7,8-substituted polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) compounds in sawmills previously using chlorophenol-containing antistain agents

The use of chlorophenol-containing antistain agents (e.g., Ky5, a wood preservative) ceased in Finland at the end of the 1980s, after 5 decades of use. Exposure of workers to the impurities in these agents (i.e., polychlorinated dibenzo-p-dioxins [PCDDs] and dibenzofurans [PCDFs]) was assessed at three sawmills at which personnel used a sodium chlorophenate product as an antistain agent. Given that compounds accumulate in body fat and their half-lives in humans are long, we could determine 2,3,7,8-substituted PCDDs and PCDFs 5-9 y after the last exposure occurred. We used high-resolution gas chromatography/high-resolution mass spectrometry to determine PCDDs/PCDFs in plasma from 39 Ky5-exposed workers and 18 nonexposed workers. The average total plasma concentration of PCDD/PCDF of the Ky5-exposed workers at the three sawmills were 1018, 945, and 1165 pg/g fat, and corresponding concentrations in the nonexposed workers were 743, 1124, and 844 pg/g fat, respectively. We found no significant differences in total levels between Ky5-exposed workers and nonexposed workers. However, concentrations of the 1,2,3,4,6,7,8-HpCDF isomer were significantly higher (p < .01) among the Ky5-exposed workers at all three sawmills (averages of 224, 99, and 148 pg/g fat) than among their respective nonexposed workers (averages of 43, 48, and 44 pg/g fat). These results indicate that workers had handled Ky5. When we expressed concentration levels in international toxic equivalents (I-TEQs), the mean total I-TEQ PCDD/PCDF of Ky5-exposed workers was significantly lower at one of the sawmills (average = 42 pg I-TEQ/g) than at the other two sawmills (averages of 64 and 62 pg I-TEQ/g)(p < .05). Nevertheless, total concentrations at the sawmills studied were within the range of background levels in the general population.

Fertility among a cohort of male sawmill workers exposed to chlorophenate fungicides

The purpose of this study was to determine whether exposure to chlorophenate fungicides and their dioxin contaminants is associated with male infertility among sawmill workers. The study was conducted using fertility data compiled from 26,487 sawmill workers in 14 British Columbian sawmills. Our analysis was restricted to workers who had been employed for at least 1 continuous year between 1950 and 1985 and to live-births born at least 1 year after the initiation of employment in the period 1955-1988. We assessed fertility trends by internal comparison using Mantel-Haenszel rate ratios and by calculating standardized fertility ratios using an external and an internal reference population. We identified 19,684 births in the study period. Initially, both external and internal analyses showed that sawmill workers from mills using chlorophenates had lower fertility than workers employed in mills not using chlorophenates. After controlling for time since first hire, however, we found no inverse relation between cumulative exposure to chlorophenate fungicides and fertility. Based on the results of our study, there is little evidence for a reduction in fertility among chlorophenate-exposed sawmill workers in British Columbia. The analyses indicate the importance of time since hire as a potentially strong confounder in this type of investigation.

Cancer mortality in workers exposed to phenoxy herbicides, chlorophenols, and dioxins. An expanded and updated international cohort study

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

Mortality and cancer incidence among sawmill workers exposed to chlorophenate wood preservatives

OBJECTIVES

This study examined the association between exposure to chlorophenates and the risk of soft tissue sarcoma; non-Hodgkin's lymphoma; Hodgkin's disease; and cancers of the lung, nose, and nasopharynx.

METHODS

A retrospective cohort study was conducted of 26487 workers employed for at least 1 year between 1950 and 1985 in 11 chlorophenate-using and 3 non-using sawmills in British Columbia, Canada. Exposures by job were ascertained with interviews of senior employees.

RESULTS

Probabilistic record linkage to the Canadian Mortality Data Base and the British Columbia Cancer Registry found 4710 deaths between 1950 and 1990, and 1547 incident cases of cancer between 1969 and 1989. None of the cancers of interest had elevated mortality related to chlorophenate exposure. Non-Hodgkin's lymphoma incidence (n = 65) increased with increasing chlorophenate exposure hours, yielding the following standardized incidence ratios: less than 120 hours 0.68; 120 to 1999 hours, 0.59; 2000 to 3999 hours, 1.04; 4000 to 9999 hours, 1.02; and 10000 or more hours, 1.30.

CONCLUSIONS

These results are consistent with the borderline positive associations seen in other recently reported studies of chlorophenate-exposed workforces.

Reliability of retrospective chlorophenol exposure estimates over five decades

For a cohort study of chlorophenate-exposed sawmill workers, historical exposures from the 1940s to the 1980s were estimated by teams of 9-20 employees (each interviewed individually). The mill histories were divided into eras when jobs and exposures were relatively stable. Raters with at least 5 years of work experience in an era were asked to estimate the frequency and duration of exposure for each job in the mill. Reliability measures for these estimates were calculated for each of the 39 mill and time period combinations, using the individual intraclass correlation coefficient (ICCind) to assess agreement between raters and the group intraclass correlation coefficient (ICCgroup) to assess the stability of the mean estimates of exposure. ICCind were low, with means that increased from 0.24 to 0.35 over the five decades. ICCgroup were considerably higher (means increasing from 0.78 to 0.88 over time), indicating that the number of raters used in this study was sufficient to produce stable average estimates of exposure throughout the study period. These data confirm the intuitive expectation that reliability of exposure estimates decreases when reconstruction of conditions in the distant past is required, and therefore that the random component of exposure misclassification is a greater threat to validity in these earlier time periods.

Reproductive effects of paternal exposure to chlorophenate wood preservatives in the sawmill industry

OBJECTIVES

The purpose of the study was to determine whether paternal occupational exposure to dioxincontaminated chlorophenols is associated with an increased risk of congenital anomalies or other adverse reproductive outcomes in offspring.

METHODS

As a result of a multistep linkage, 19675 births between 1952 and 1988 were identified as children of a cohort of 9512 fathers who had worked at least one year in British Columbia sawmills where chlorophenate wood preservatives had been used. A nested case-referent analysis was applied, using conditional logistic regression, with five referents matched per case according to year of birth and gender. Chlorophenate exposure was based on expert raters' estimations of hours of exposure applied to specific time windows prior to birth.

RESULTS

The offspring of male sawmill workers were at increased risk for developing congenital anomalies of the eye, particularly congenital cataracts; elevated risks for developing anencephaly or spina bifida and congenital anomalies of genital organs were shown according to specific windows of exposure. No associations were found for low birthweight, prematurity, stillbirths, or neonatal deaths.

CONCLUSIONS

The study adds further support to the hypothesis of male-mediated developmental toxicity. Paternal exposure to chlorophenates was associated with the development of certain congenital anomalies in offspring.

Cancer incidence and specific occupational exposures in the Swedish leather tanning industry: a cohort based case-control study

OBJECTIVE

To study the effect on the incidence of cancer of exposure to chemicals handled in the leather tanning industry.

MATERIALS AND METHODS

A case-control study was performed within a cohort of 2487 workers employed for at least six months during the period 1900-89 in three Swedish leather tanneries. 68 cancer cases (lung, stomach, bladder, kidney, nasal, and pancreatic cancers and soft tissue sarcomas) and 178 matched controls were studied. Effects of chemical exposures on cancer incidence, adjusted for age at risk, sex, and plant were estimated with a conditional logistic regression model.

RESULTS

A significant association was found between exposure to leather dust and pancreatic cancer (odds ratio (OR) 7.19, 95% confidence interval (95% CI) 1.44 to 35-89). An association was indicated between leather dust from vegetable tanning and lung cancer. After adjustment for smoking habits a tentative association between organic solvents and lung cancer lost its significance. No association was found between exposure to chlorophenols and soft tissue sarcomas.

CONCLUSIONS

The significant association between leather tanning and soft tissue sarcomas that was found in our previous cohort analysis could not be explained by exposure to chlorophenols. On the other hand a significant association was found between exposure to leather dust and pancreatic cancer, and exposure to leather dust from vegetable tanning was often present in cases with lung cancer. Due to the small numbers of cases, the results can, however, only lead to tentative conclusions.

Cancer mortality in German male workers exposed to phenoxy herbicides and dioxins

In an occupational cohort study, the relation between exposure to phenoxy herbicides, and contaminants (dioxins and furans) and cancer mortality was investigated. A total of 2,479 workers from four plants in Germany were included, with a mortality follow-up until the end of 1989 (for one cohort, until the end of 1992). A total of 484 deaths were recorded yielding a standardized mortality ratio (SMR) of 101 (95 percent confidence interval [CI] = 92-111) for total mortality, and an SMR of 119 (CI = 100-141) for all malignant diseases. A variety of herbicides was produced, including those which are known to have been contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). High dioxin and furan exposure (in particular, exposure to TCDD, but also to higher chlorinated dioxins) had occurred in two of the four plants as shown by blood-fat measurements in a sample of workers. Mortality from all neoplasms increased with latency and was highest in the largest plant where the highest TCDD blood levels were recorded. An increased mortality in the total cohort from respiratory cancer (SMR = 154, CI = 115-202), cancer of the buccal cavity and pharynx (SMR = 295, CI = 135-560), and non-Hodgkin's lymphoma (SMR = 326, CI = 119-710) was observed. Our findings are consistent with results from other cohorts which showed an increased overall cancer mortality and mortality of respiratory cancer after long-term exposure to these phenoxy herbicides and dioxins.

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 chlorophenols in two nested case-control studies of soft tissue sarcoma and non-Hodgkin's 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 subject's 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 (CI) = 1.2-91] and to each of the three major classes of phenoxy herbicides (2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic 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-dioxin (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-Hodgkin's 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.

[Chlorophenols in urine as an environmental medicine monitoring parameter]

Chlorophenols occur ubiquitously in the environment. They are taken up as such in man or are formed in intermediary metabolism e.g. from chlorobenzenes. In particular pentachlorophenol (PCP) is one of those chemical substances used up to the early 70's as a component of wood preservatives also indoors; for many years it has been at the centre of discussion about the environment. Mono, di, tri and tetrachlorophenols as well as pentachlorophenol occur in the urine in the general population often in surprisingly high concentrations. An increased chlorophenol excretion under certain circumstances also indicates an increased dioxin exposure (pre-dioxins). Possible sources of emission and routes of absorption for corresponding organochlorine compounds can be found in industry, agriculture and also private households. Environmental analysis in the air, in earth or dust do not allow any evaluation of health risks. Only biological monitoring with qualitative and quantitative determination of the actual concentration of the substance taken up by the organism allows a reliable estimation of the individual health risk. The background exposure of the general population not occupationally exposed to organochlorine compounds can be used for the determination of so-called norm values. For the determination of the chlorophenol spectrum 50 ml urine are necessary. The following values can be given as reference values for the most important chlorophenols: 4-monochlorophenol: 7.5 micrograms/l, 2.4-dichlorophenol and 2.5-dichlorophenol: 33.6 micrograms/l, 2.4.6-trichlorophenol: 4.7 micrograms/l, 2.4.5-trichlorophenol: 4.5 micrograms/l, 2.3.4.6-tetrachlorophenol and 2.3.5.6-tetrachlorophenol: 22.0 micrograms/l, pentachlorophenol 9.0 micrograms/l urine.

Blood levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin and gamma-globulins in a follow-up investigation of employees with chloracne

In a follow-up investigation of 8 employees who partly contracted chloracne between 1973 and 1976, elevated concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 'Seveso dioxin') were found in blood lipids. The concentrations measured were between 163 and 1935 pg TCDD/g blood lipids, other 'dioxin' levels being normal or only slightly increased in comparison to the background level in the general population. The cause of this was exposure at work during the manufacture of trichlorophenol (TCP). Apart from high cholesterol levels, there was a conspicuous reduction in gamma-globulins.

Retrospective assessment of exposure through modeling in a study on cancer risks among workers exposed to phenoxy herbicides, chlorophenols and dioxins

OBJECTIVES

The study aimed at developing a model for the retrospective assessment of exposures in epidemiologic studies when little or no data on past exposures are available.

METHODS

A deterministic model was developed for the level of exposure by industrial hygienists involved in an international study on cancer risks among phenoxy herbicide or chlorophenol manufacturing workers and pesticide sprayers. The general source-receptor model was used as the conceptual framework for the model.

RESULTS

The model included variables related to job, the emission of chemicals, contact with chemicals, personal protection, and other relevant determinants of exposure. Cumulative dose indices were calculated from the duration of exposure (from the work histories) and the level of exposure (from the model).

CONCLUSIONS

Deterministic modeling in complex exposure situations may provide more valid and reliable results than its conventional alternative, subjective assessment by an expert.

Exposure to phenoxyacetic acids, chlorophenols, or organic solvents in relation to histopathology, stage, and anatomical localization of non-Hodgkin's lymphoma

Results on 105 cases with histopathologically confirmed non-Hodgkin's lymphoma (NHL) and 335 controls from a previously published case-control study on malignant lymphoma are presented together with some extended analyses. No occupation was a risk factor for NHL. Exposure to phenoxyacetic acids yielded, in the univariate analysis, an odds ratio of 5.5 with a 95% confidence interval of 2.7-11. Most cases and controls were exposed to a commercial mixture of 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. Exposure to chlorophenols gave an odds ratio of 4.8 (2.7-8.8) with pentachlorophenol being the most common type. Exposure to organic solvents yielded an odds ratio of 2.4 (1.4-3.9). These results were not significantly changed in the multivariate analysis. Dichlorodiphenyltrichloroethane, asbestos, smoking, and oral snuff were not associated with an increased risk for NHL. The results regarding increased risk for NHL following exposure to phenoxyacetic acids, chlorophenols, or organic solvents were not affected by histopathological type, disease stage, or anatomical site of disease presentation. Median survival was somewhat longer in cases exposed to organic solvents than the rest. This was explained by more prevalent exposure to organic solvents in the group of cases with good prognosis NHL histopathology.

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.

Cancer in phenoxy herbicide manufacturing workers in Denmark, 1947-87--an update

This report is an update of a cohort study from the two Danish phenoxy herbicide manufacturing plants. The study originally covered the period 1947-82. Data now have been added for the period 1983-87. In 1943-87, the 940 phenoxy herbicide manufacturing and packaging workers experienced the same overall cancer incidence as the Danish population (observed [Obs] = 66; expected [Exp] = 64.27; standardized incidence ratio [SIR] = 1.0; 95 percent confidence interval [CI] = 0.8-1.3). The same was true for the 1,179 workers employed in manual service functions. The data for 1947-82 included five cases of soft tissue sarcoma (STS). One of these patients had his diagnosis changed when he died in 1985. One new STS case was diagnosed during the period 1983-87. This updated study thus includes a total of five STS cases. Four of the STS cases were observed among persons potentially exposed to phenoxy herbicide (Exp = 1.76; SIR = 2.3; CI = 0.6-5.8). Three of the cases occurred among men employed for at least one year in one factory. In this subgroup, an SIR of 6.4 (CI = 1.3-18.7) was observed when a 10-year latency period was taken into account. Based on small numbers, this Danish study thus continues to add to the evidence for a possible association between phenoxy herbicide exposure and risk of STS. Persons potentially exposed to phenoxy herbicide had an incidence of non-Hodgkin's lymphoma close to that of the Danish population (Obs = 4; Exp = 3.08; SIR = 1.3; CI = 0.4-3.3).

Occupational exposure to phenoxy herbicides and chlorophenols and cancer mortality in The Netherlands

As part of the "IARC International Register of Persons Exposed to Phenoxy Herbicides and Contaminants," a cohort of workers who manufacture and prepare chlorophenoxy herbicides was recruited in The Netherlands. The cohort comprised 2,310 workers from two plants, operated by different companies, who were followed during the periods 1955-1985 and 1965-1986, respectively. In 1963, there had been an industrial accident in one factory with concomitant release of dioxin into the environment. Loss to follow-up was 3%. Mortality data on 963 exposed and 1,111 nonexposed men were evaluated by external and internal comparison. Compared with national rates, total mortality (94 deaths, standardized mortality ratio [SMR] = 101; 95% confidence interval [CI], 82-124) and cancer mortality (31 deaths, SMR = 107; 95% CI, 73-152) for exposed workers were not significantly increased. A statistically insignificant increase was observed for non-Hodgkin's lymphoma (2 deaths, SMR = 299; 95% CI, 36-1,078). No cases of soft-tissue sarcoma were encountered. There was no increase in either total mortality (25 deaths, SMR = 111; 95% CI, 72-163) or cancer mortality (10 deaths, SMR = 137; 95% CI, 66-252) among the 139 workers probably exposed to dioxins during the 2,4,5-trichlorophenol production accident or the subsequent clean-up operations. Compared with nonexposed workers, exposed workers did not exhibit a higher total mortality (rate ratio [RR] = 1.28; 95% CI, 0.89-1.82). Mortality due to all cancers (RR = 1.7; 95% CI, 0.9-3.4) and respiratory cancer (RR = 1.7; 95% CI, 0.5-6.3) was insignificantly elevated. These findings suggest that the increases in cancer mortality among workers exposed to phenoxy herbicides and chlorophenols may be attributable to chance. Lack of power prevented evaluation with respect to specific cancers.

Internal exposure to organic substances in a municipal waste incinerator

Fifty-three persons occupied in a municipal waste incinerator were examined with respect to their internal exposure to organic substances which may be produced during pyrolysis of organic matter. For this purpose the levels of benzene in blood, polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) in plasma, and mono- (MCPs), di- (DCPs), tri- (TCPs), tetra- (TCEPs) and pentachlorophenol (PCP) and hydroxypyrene in urine were determined. For control purposes, 431 men and women were examined. Significantly higher values for the workers were found for the excretion of hydroxypyrene [median (m): 0.24 vs 0.11 microgram/l; non-smokers], 2,4/2,5-DCP (m: 10.5 vs 3.9 micrograms/l) and 2,4,5-TCP (m: 1.2 vs 0.8 micrograms/l) and for the HCB level in plasma (m: 4.4 vs 2.8 micrograms/l). For the concentrations of 4-MCP and 2,3,4,6/2,3,5,6-TECP, the controls had significantly higher concentrations in urine than did the workers in the incineration plant (m: 4-MCP 1.7 vs 1.2; 2,3,4,6/2,3,5,6-TECP: 1.2 vs 0.3 micrograms/l). No significant differences between workers and controls were detected with respect to benzene in blood (m: 0.20 vs 0.28 microgram/l; non-smokers), 2,4,6-TCP and PCPs in urine (m: 0.85 vs 0.60 and 2.2 vs 2.2 micrograms/l) or the levels of PCB congeners in plasma (m: sigma 138, 153, 180: 5.6 vs 4.1 micrograms/l). The elevated levels of hydroxypyrene, 2,4/2,5-DCP, 2,4,5-TCP and HCB in biological material may be related to the incineration of the waste. These elevations, however, are very small and are of interest more from the environmental than from the occupational point of view.