Effect of sulfur dioxide and particulate pollutants on bronchitis in children—A risk analysis

The general morbidity is being influenced to a great extent by diseases of the respiratory tract. Since their incidence and prevalence have been increasing, the identification of causal factors, especially of environmental origin, is of importance, not just in view of implementing preventive control strategies. Primary irritative gaseous [like sulfur dioxide (SO₂)] as well as particulate pollutants (like TSP) can be regarded as causal constituents. Using the opportunity of changing levels of ambient air pollution in East Germany since 1989, the impact of SO₂ and TSP on bronchitis was investigated over the last 10 years as part of several intervention studies in a locally defined homogenous population, children. The data suggest a significant association between SO₂ and the prevalence of bronchitis in children but not for TSP. Considering the findings of other studies with respect to air pollution and the epidemiology of adverse health effects (especially respiratory disease), these results would amend the hypothesis put forward in a review of the literature as TSP<ultrafine particles (SO)=SO₂. Although these data show a significant association with only SO₂, this does not imply that ultrafine particles, such as SO, do not contribute to the association with the observed adverse health effects. Nevertheless, the findings suggest that TSP seems less likely to be a predictor in the association with respiratory diseases, particularly not in the presence of high SO₂. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 269–276, 2001     

Dreams and exposure therapy in PTSD

Exposure therapy is a well-established treatment for PTSD that requires the patient to focus on and describe the details of a traumatic experience. Nightmares that refer to or replicate traumatic experiences are prominent and distressing symptoms of PTSD and appear to exacerbate the disorder. With this apparent paradox in mind, exposure therapy and the literature on sleep and PTSD are reviewed in the context of the relationship between therapeutic exposure and exposure to trauma-related stimuli that occurs in dreams. It is concluded that nightmares that replay the trauma and disrupt sleep do not meet requirements for therapeutic exposure, whereas other dreaming may aid in the recovery from trauma.     

Occupational exposures and cancers of the endometrium and cervix uteri in Finland

BACKGROUND: Endometrial cancer incidence rates are low in Asia and Africa and high in North America and Northern Europe. Cervical cancer is often the most common female cancer in developing countries, and infection with human papillomavirus (HPV) is its main risk factor. However, other factors, such as occupational exposures may modify the HPV-related risk. We conducted an exploratory register-linkage study in Finland to assess the role of occupational exposures on incidence rates of cancers of the endometrium and cervix uteri. METHODS: Occupational risk factors for endometrial and cervical cancers were explored in a 25-year follow-up of female workers born 1906-1945 (N = 413,877) identified through the Population Census of Finland of 1970. Job titles in census records were converted to exposures of 31 occupational agents through a job-exposure matrix. Poisson regression models estimated relative risks (RR) for each agent, standardized for birth cohort, follow-up period, and socio-economic status. For each agent, the product of level and probability of exposure was calculated and subdivided in three categories: zero, low, and medium/high. Adjustment at the job title level was done for the turnover rate (endometrial and cervical cancers), mean parity, and age at first birth (endometrial cancer). RESULTS: Endometrial cancer (2,833 cases) was associated with exposure to animal dust (RR 1.2, low level, 174 cases) and sedentary work (RR 1.3, high level, 145 cases). Cervical cancer (1,101 cases) was associated with exposure to aliphatic and alicyclic (RR 1.3, low level, 91 cases), aromatic (RR 1.2, low level, 318 cases; RR 1.4, high level, 41 cases), and chlorinated hydrocarbon solvents (RR 1.3, low level, 50 cases), silica dust (RR 1.2, low level, 251 cases), and wood dust (RR 1.2, low level, 249 cases). CONCLUSIONS: This study suggests that occupational exposures may be associated with increased risk of endometrial and cervical cancers.     

Meta-analysis of systemic sclerosis and exposure to solvents

BACKGROUND: Although systemic sclerosis is a rare disease, incidence rates have increased recently in the United States. This study investigated the association between systemic sclerosis and exposure to solvents. METHODS: A Medline search of articles published between 1966 and 2000 dealing with solvent exposure and systemic sclerosis identified eight studies that met inclusion criteria of the meta-analysis. The studies included seven case-control studies and one cohort study published between 1989 and 1998. A series of meta-analyses of studies on systemic sclerosis and solvent exposure were performed for all studies and for case-control studies. A random effect model was used to calculate a combined estimator of relative risk. RESULTS: The combined estimator of relative risk for all studies was 2.91, with a 95% confidence interval (CI) of 1.60 to 5.30. The combined estimator of relative risk for the seven case-control studies was 3.14 (95% CI, 1.56-6.33). CONCLUSIONS: A statistically significant increased relative risk for all studies and for case-control studies suggests that exposure to organic solvent may be a risk factor for developing systemic sclerosis. Further studies using other study designs and better control of confounders are needed.     

Cumulative exposure to styrene and visual functions

BACKGROUND: Results from a 1990-1992 longitudinal study of several reinforced plastics plants showed that for those workers whose styrene exposure had decreased, color vision (CV) improved; while near visual contrast sensitivity (CS) was poorer. METHODS: In 1999, we retested these visual functions in 18 workers with good visual acuity. A cumulative exposure index (CEI), corrected for respirator use, was calculated for each worker. RESULTS: Intra-individual comparison of mandelic acid (MA) showed a significant decrease over time (Friedman; P = 0.015), but current values were not related to CEI. For CV, no significant difference was observed between 1992 and 1999; present results were not related to MA or CEI. The CS profile decreased over time, with significant differences at 3 cpd (Friedman; P < 0.05). CS did not vary with MA levels, but was significantly depressed at the intermediate frequencies among those in the upper CEIH category (Kruskal-Wallis; P < 0.05). CONCLUSIONS: These findings suggest that CS loss increases with long-term cumulative exposure, reflecting chronic damage to the neuro-optic pathways.     

Respiratory diseases caused by occupational exposure to 1,5-naphthalene-diisocyanate (NDI): Results of workplace-related challenge tests and antibody analyses

BACKGROUND: 1,5-naphthalene-diisocyanate (NDI) is an aromatic diisocyanate with a very low vapor pressure which is mainly used in the automotive industry. METHODS: In the present study we described five cases with workplace-related asthma and one case with extrinsic allergic alveolitis associated with pulmonary hemorrhage after NDI exposure. RESULTS: Corresponding to case histories, extrinsic alveolitis on asthmatic reactions in three subjects and a rhinitis reaction in one patient could be reproduced by inhalative challenge tests to NDI at a concentration of 10 ppb. Preliminary IgE and IgG antibody analyses in patients' sera did not produce significantly positive results. CONCLUSIONS: According to the outcome of our tests and in comparison with several other studies, we conclude that NDI should be classified as potent airway-sensitizing substance. Improved workplace conditions and decrease in threshold limit values should therefore be recommended.     

Control of chemical risks during the treatment of soil contaminated with chlorophenol, creosote and copper-chrome-arsenic-wood preservatives

BACKGROUND: Exposure to chemicals in polluted soil was studied during the remediation of four polluted sites. They are sawmill areas contaminated with chlorophenols and polychlorinated dibenzo-p-dioxins and furanes (PCDD/F), wood impregnating plants contaminated with polycyclic aromatic hydrocarbons (PAH) from creosote oil, old gas works area contaminated with PAH, and a wood impregnation plant contaminated with copper-chromium-arsenic (CCA) preservative. METHODS: The exposure levels were determined by both air and biological monitoring. RESULTS: Air monitoring showed that the exposure levels were generally well below the current occupational exposure limits. The calculations indicated, however, that the lowest acceptable daily intake value recommended for PCDD/F by the U.S. Environmental Protection Agency was exceeded. Chlorophenol exposure was generally low. Exposure to volatile PAH was 0.038-0.884 mg/m(3) and that to particulate PAH was 0.004-0.183 mg/m(3). The biomonitoring results (urinary 1-pyrenol) suggested that some exposure occurs, probably through the contamination of hands or skin absorption. At the sites contaminated with CCA salts, no exposure limits were exceeded. CONCLUSIONS: The results generally suggest that the exposure of cleanup workers is generally below the current occupational exposure limits but that short-term high exposure cannot be excluded. There was also some indication of poor skin protection, which should be improved when soil contaminated with PAH and creosote oil is handled.     

Use of MMT in Canadian gasoline: health and environment issues

BACKGROUND: Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic derivative of manganese (Mn) used in Canadian gasoline since 1976 as an antiknock agent and to improve octane rating. Combustion products of MMT are mainly a mixture of Mn phosphate and Mn sulfate. In 1997, the Canadian federal government adopted a law (C-29) which banned both the interprovincial trade and the importation for commercial purposes of manganese-based substances, including MMT. However, the government reworded this law in July 1998 so that manganese-based fuel additives were not included in the restrictions. MMT is now approved for use in Argentina, Australia, Bulgaria, the United States, France, Russia, and conditionally in New Zealand. Nevertheless, these countries are not using MMT intensively and they are waiting for strong evidence of the absence of effects on human health. Even after several years of use of MMT in Canada, many uncertainties remain. METHODS: Different methods were used in order to assess (1) environmental contamination and human exposure to the parental form of MMT, (2) nitrogen oxides (NO(x)) and carbon monoxide (CO) emissions associated with the use of MMT, and (3) qualitative and quantitative assessments of Mn emissions to the environment. RESULTS: The results provide timely information with regard to the impact of MMT on environmental/ecosystem Mn contamination in abiotic and biotic systems as well as on human exposure. Moreover, results raise major concerns with regard to public health effects related to exposure to Mn. CONCLUSIONS: Obviously, there is still an important lack of adequate toxicological information and further studies are needed to provide successful implementation of evidence-based risk assessment approaches.     

Occupational exposure to airborne mercury during gold mining operations near El Callao, Venezuela

Objective: The National Institute for Occupational Safety and Health (NIOSH) recently conducted a cross–sectional study during gold mining operations near El Callao, Venezuela. The purpose of the study was to assess mercury exposures and mercury-related microdamage to the kidneys. The study consisted of concurrent occupational hygiene and biological monitoring, and an examination of the processing techniques employed at the different mining facilities. Mercury was used in these facilities to remove gold by forming a mercury-gold amalgam. The gold was purified either by heating the amalgam in the open with a propane torch or by using a small retort. Methods: Thirty-eight workers participated in this study. Some participants were employed by a large mining company, while others were considered “informal miners” (self-employed). Mercury exposure was monitored by sampling air from the workers' breathing zones. These full-shift air samples were used to calculate time-weighted average (TWA) mercury exposure concentrations. A questionnaire was administered and a spot urine sample was collected. Each urine sample was analyzed for mercury, creatinine, and N-acetyl-ß-d-glucosaminidase (NAG). Results: The range for the 8-h TWA airborne mercury exposure concentrations was 0.1 to 6,315?μg/m³, with a mean of 183?μg/m³. Twenty percent of the TWA airborne mercury exposure measurements were above the NIOSH recommended exposure limit (REL) of 50?μg/m³, and 26% exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 25?μg/m³. The mean urine mercury concentration was 101?μg/g creatinine (μg/g-Cr), and the data ranged from 2.5 to 912?μg/g-Cr. Forty–two percent of the study participants had urine mercury concentrations that exceeded the ACGIH biological exposure index (BEI) of 35?μg/g-Cr. Urinary NAG excretion is considered a biological marker of preclinical, nonspecific microdamage to the kidney's proximal tubule cells. The mean urine NAG concentration was 3.6 International Units/g-Cr (IU/g-Cr) with a range of 0.5 to 11.5?IU/g-Cr. Three workers had urine NAG levels in excess of the reference values. Correlation analyses found statistically significant correlations between airborne mercury exposure and urine mercury level (P=0.01), and between urine mercury level and urine NAG excretion (P=0.01). In addition, the airborne mercury exposure data and urine mercury data were segregated by job tasks. A Wilcoxon rank sum test revealed significant correlations between tasks and mercury exposure (P=0.03), and between tasks and urine mercury level (P=0.02). Conclusions: The tasks with the highest mean airborne mercury exposures were “burning the mercury-gold amalgam” and “gold refining/smelting”. Recommendations were provided for improving the retort design to better contain mercury, for ventilation in the gold shops, and for medical surveillance and educational programs.