Integration of Evidence on Community Cancer Risks from Elongate Mineral Particles in Silver Bay, Minnesota.

The potential for cancer-related risks to community members from ambient exposure to elongate mineral particles (EMPs) in taconite processing has not been formally evaluated. We evaluated 926 ambient air samples including 12,928 EMPs (particle structures with length-to-width ratio ≥3:1) collected over 26 years near a taconite processing facility in Silver Bay, Minnesota. Eighty-two percent of EMPs were ≤3 µm in length and 97% of EMPs had an average aspect ratio <20:1. A total of 935 (7.3%) EMPs had length >5 µm and AR ≥3:1. Average ambient concentration of NIOSH countable amphibole EMPs over all years was 0.000387 EMPs per cubic centimeter (EMP/cm3 ). Of 12,765 nonchrysotile EMPs, the number of amphiboles with length and width dimensions that correlate best with asbestos-related carcinogenicity ranged from four (0.03%) to 13 (0.1%) and the associated ambient amphibole air concentrations ranged from 0.000003 to 0.000007 EMP/cm3 . After 65 years of taconite processing in Silver Bay, evidence of an increased risk of mesothelioma and lung cancer in community members who did not work in the taconite industry is lacking. The absence of an increased risk of asbestos-related cancer in the Silver Bay community is coherent with supporting evidence from epidemiological and toxicological studies, as well as ambient exposure data and lake sediment data collected in Minnesota Iron Range communities. Collectively, the data provide consistent evidence that nonasbestiform amphibole minerals lack the carcinogenic potential exhibited by amphibole asbestos.

Does occupational exposure to formaldehyde cause hematotoxicity and leukemia-specific chromosome changes in cultured myeloid progenitor cells?

Several cross-sectional studies of a single population of workers exposed to formaldehyde at one of two factories using or producing formaldehyde-melamine resins in China have concluded that formaldehyde exposure induces damage to hematopoietic cells that originate in the bone marrow. Moreover, the investigators interpret observed differences between groups as evidence that formaldehyde induces myeloid leukemias, although the mechanisms for inducing these diseases are not obvious and recently published scientific findings do not support causation. Our objective was to evaluate hematological parameters and aneuploidy in relation to quantitative exposure measures of formaldehyde. We obtained the study data for the original study (Zhang et al. 2010 ) and performed linear regression analyses. Results showed that differences in white blood cell, granulocyte, platelet, and red blood cell counts are not exposure dependent. Among formaldehyde-exposed workers, no association was observed between individual average formaldehyde exposure estimates and frequency of aneuploidy, suggested by the original study authors to be indicators of myeloid leukemia risk.

Quantitative estimated exposure to vinyl chloride and risk of angiosarcoma of the liver and hepatocellular cancer in the US industry-wide vinyl chloride cohort: mortality update through 2013.

OBJECTIVE: To evaluate mortality risks of angiosarcoma of the liver (ASL), primary hepatocellular carcinoma (HCC) and other cancers among 9951 men employed between 1942 and 1972 at 35 US vinyl chloride (VC) or polyvinyl chloride plants followed for mortality through 31 December 2013. METHODS: SMR and time-dependent Cox proportional hazards analyses were used to evaluate mortality risks by cumulative VC exposure. RESULTS: Liver cancer mortality was elevated (SMR=2.87, 95% CI 2.40 to 3.40), and ASL and HCC were strongly associated with cumulative VC exposure ≥865 parts per million-years (ppm-years) (ASL: HR=36.3, 95% CI 13.1 to 100.5; and HCC: HR=5.3, 95% CI 1.6 to 17.7 for ≥2271 ppm-years). Excess deaths due to connective and soft tissue cancers (SMR=2.43, 95% CI 1.48 to 3.75), mesothelioma (SMR=2.29, 95% CI 1.18 to 4.00) and explosions (SMR=3.43, 95% CI 1.25 to 7.47) were seen. Mortalities due to melanoma, brain cancer, lung cancer and non-Hodgkin's lymphoma were not increased or associated with VC exposure. CONCLUSION: The association between VC and ASL first reported in this cohort 44 years ago persisted and was strongest among workers most highly exposed. VC exposure also was associated with HCC mortality, although it remains possible that misdiagnosis of early ASLs influenced findings.

Assessment of blood lead level declines in an area of historical mining with a holistic remediation and abatement program.

UNLABELLED: Lead exposure and blood lead levels (BLLs) in the United States have declined dramatically since the 1970s as many widespread lead uses have been discontinued. Large scale mining and mineral processing represents an additional localized source of potential lead exposure in many historical mining communities, such as Butte, Montana. After 25 years of ongoing remediation efforts and a residential metals abatement program that includes blood lead monitoring of Butte children, examination of blood lead trends offers a unique opportunity to assess the effectiveness of Butte's lead source and exposure reduction measures. This study examined BLL trends in Butte children ages 1-5 (n= 2796) from 2003-2010 as compared to a reference dataset matched for similar demographic characteristics over the same period. Blood lead differences across Butte during the same period are also examined. Findings are interpreted with respect to effectiveness of remediation and other factors potentially contributing to ongoing exposure concerns. REFERENCE POPULATION COMPARISON: BLLs from Butte were compared with a reference dataset (n=2937) derived from the National Health and Nutrition Examination Survey. The reference dataset was initially matched for child age and sample dates. Additional demographic factors associated with higher BLLs were then evaluated. Weights were applied to make the reference dataset more consistent with the Butte dataset for the three factors that were most disparate (poverty-to-income ratio, house age, and race/ethnicity). A weighted linear mixed regression model showed Butte geometric mean BLLs were higher than reference BLLs for 2003-2004 (3.48vs. 2.05µg/dL), 2005-2006 (2.65vs. 1.80µg/dL), and 2007-2008 (2.2vs. 1.72µg/dL), but comparable for 2009-2010 (1.53vs. 1.51µg/dL). This trend suggests that, over time, the impact of other factors that may be associated with Butte BLLs has been reduced. COMPARISON ACROSS BUTTE: Neighborhood differences were examined by dividing the Butte dataset into the older area called "Uptown", located at higher elevation atop historical mine workings, and "the Flats", at lower elevation and more recently developed. Significant declines in BLLs were observed over time in both areas, though Uptown had slightly higher BLLs than the Flats (2003-2004: 3.57vs. 3.45µg/dL, p=0.7; 2005-2006: 2.84vs. 2.52µg/dL, p=0.1; 2007-2008: 2.58vs. 1.99µg/dL, p=0.001; 2009-2010: 1.71vs. 1.44µg/dL, p=0.02). BLLs were higher when tested in summer/fall than in winter/spring for both neighborhoods, and statistically higher BLLs were found for children in Uptown living in properties built before 1940. Neighborhood differences and the persistence of a greater percentage of high BLLs (>5µg/dL) in Butte vs. the reference dataset support continuation of the home lead abatement program. CONCLUSIONS: Butte BLL declines likely reflect the cumulative effectiveness of screening efforts, community-wide remediation, and the ongoing metals abatement program in Butte in addition to other factors not accounted for by this study. As evidenced in Butte, abatement programs that include home evaluations and assistance in addressing multiple sources of lead exposure can be an important complement to community-wide soil remediation activities.

Cohort Study of Carbon Black Exposure and Risk of Malignant and Nonmalignant Respiratory Disease Mortality in the US Carbon Black Industry.

OBJECTIVE: To evaluate lung cancer and respiratory disease mortality associations with cumulative inhalable carbon black exposure among 6634 US carbon black workers. METHODS: This analysis was performed using standardized mortality ratio (SMRs) and Cox regression analyses. RESULTS: Lung cancer mortality was decreased overall (SMR = 0.77; 95% confidence interval [CI], 0.67 to 0.89) but less so among hourly male workers (SMR = 0.87; 95% CI, 0.71 to 1.05). No exposure-response association was observed with time-dependent cumulative inhalable carbon black: hazard ratio [HR] = 1.0 (95% CI, 0.6 to 1.6) for 20 to less than 50 mg/m·yr); HR = 1.3 (95% CI, 0.8 to 2.1) for 50 to less than 100 mg/m·yr; and HR = 1.4 (95% CI, 0.9 to 2.1) for 100 mg/m·yr or more compared with referent (<20 mg/m·yr). No consistent associations were observed between cumulative inhalable carbon black exposure and respiratory disease mortality. CONCLUSION: Quantitative carbon black exposure estimates were not related to lung cancer or nonmalignant respiratory disease mortality.

Formaldehyde Exposure and Mortality Risks From Acute Myeloid Leukemia and Other Lymphohematopoietic Malignancies in the US National Cancer Institute Cohort Study of Workers in Formaldehyde Industries.

OBJECTIVES: To evaluate associations between cumulative and peak formaldehyde exposure and mortality from acute myeloid leukemia (AML) and other lymphohematopoietic malignancies. METHODS: Cox proportional hazards analyses. RESULTS: Acute myeloid leukemia was unrelated to cumulative exposure. Hodgkin lymphoma relative risk estimates in the highest exposure categories of cumulative and peak exposures were, respectively, 3.76 (Ptrend = 0.05) and 5.13 (Ptrend = 0.003). There were suggestive associations with peak exposure observed for chronic myeloid leukemia, albeit based on very small numbers. No other lymphohematopoietic malignancy was associated with either chronic or peak exposure. CONCLUSIONS: Insofar as there is no prior epidemiologic evidence supporting associations between formaldehyde and either Hodgkin leukemia or chronic myeloid leukemia, any causal interpretations of the observed risk patterns are at most tentative. Findings from this re-analysis do not support the hypothesis that formaldehyde is a cause of AML.

Racial differences in gestational weight gain and pregnancy-related hypertension.

PURPOSE: The aim of the study was to examine racial differences in gestational weight gain (GWG) and pregnancy-related hypertension. METHODS: Logistic regression models tested racial differences in adequacy of GWG and pregnancy-induced hypertension in all singleton live births from the South Carolina 2004-2006 birth certificates. RESULTS: Compared with white women, black and Hispanic women had 16%-46% lower odds of gaining weight above the recommendations. However, the odds of inadequate GWG was ∼50% higher in black and Hispanic women with a pregnancy body mass index (BMI) less than 25 kg/m(2). Furthermore, compared with women with adequate GWG, women with excessive GWG had higher odds of pregnancy-related hypertension (underweight: 2.35, 95% confidence interval [CI; 1.66, 3.32]; normal: 2.05, 95% CI [1.84, 2.27]; overweight: 1.93, 95% CI [1.64, 2.27]; obese: 1.46, 95% CI [1.30, 1.63]). Among women with a BMI less than 25 kg/m(2), black women had higher odds of pregnancy-related hypertension than white women (underweight: 1.64, 95% CI [1.14, 2.36]; normal weight: 1.28, 95% CI [1.15, 1.42]), whereas among women with a BMI less than 25 kg/m(2), Hispanic women had 40% lower odds. CONCLUSIONS: Programs are needed to curb excessive GWG in all racial groups and to help some sub-groups ensure adequate GWG. Maternal obesity and GWG are two factors that should be used in combination to reduce racial differences in pregnancy-related hypertension.

Physical activity during pregnancy is associated with reduced fasting insulin--the Pilot Pregnancy and Active Living Study.

OBJECTIVE: To examine the relationship between physical activity during pregnancy and fasting plasma insulin measured in the second trimester. STUDY DESIGN AND METHODS: We conducted a pilot prospective cohort study of 69 overweight or obese women who were enrolled before 20 weeks of gestation at an obstetric clinic in Columbia, South Carolina in 2006-2007. At 24-28 weeks of gestation, fasting blood samples were collected and physical activity from the 3 months prior to the visit was assessed using a validated Pregnancy Physical Activity Questionnaire. RESULTS: Total energy expenditure (EE) in this population was attributable to sedentary activities (24.4%) and to physical activities of different intensities (light: 44.8%, moderate: 30.2%, and vigorous: 0.6%). By type, total EE mainly came from household/caregiving activities (58.9%) with a small proportion from exercise (3.8%). After adjusting for confounders, the mean fasting insulin values across the quartiles of total EE (least to most) were 17.3, 13.0, 12.1, and 9.6 uIU/ml (P for trend=0.01). CONCLUSION: Our findings suggest that increased total physical activity is associated with reduced fasting insulin levels in overweight or obese pregnant women.