Experimental study of clay-hydrocarbon interactions relevant to the biodegradation of the Deepwater Horizon oil from the Gulf of Mexico.

Adding clay to marine oil pollution represents a promising approach to enhance bacterial hydrocarbon degradation in nutrient poor waters. In this study, three types of regionally available clays (Ca-bentonite, Fuller's Earth and kaolin) were tested to stimulate the biodegradation of source and weathered oil collected from the Deepwater Horizon spill. The weathered oil showed little biodegradation prior to experimentation and was extensively degraded by bacteria in the laboratory in a similar way as the alkane-rich source oil. For both oils, the addition of natural clay-flakes showed minor enhancement of oil biodegradation compared to the non-clay bearing control, but the clay-oil films did limit evaporation. Only alkanes of a molecular weight (MW) > 420 showed significant reduction by enhanced biodegradation following natural clay treatment. In contrast, all fertilized clay flakes showed major bacterial degradation of the oil, with a 6-10 times reduction in alkane content, and an up to 8 fold increase in the rate of O2 consumption. Compared to the control, such treatment showed particular reduction of longer chained alkanes (MW > 226). The application of natural and fertilized clay flakes also showed selective reduction of PAHs, mainly in the MW range of 200-300, but without significant change in the toxicity indices measured. These results imply that a large variety of clays may be used to boost oil biodegradation by aiding attachment of fertilizing nutrients to the oil.

Dietary fiber intake and endogenous serum hormone levels in naturally postmenopausal Mexican American women: the Multiethnic Cohort Study.

This study investigated dietary fiber intake in association with serum estrogen levels in naturally postmenopausal Latina women with a wide range of fiber intake. Estrone (E1), estradiol (E2), and sex-hormone-binding globulin (SHBG) were measured in 242 women. Associations between estrogen levels and intake of dietary fiber, including insoluble and soluble fractions, quantified from a food frequency questionnaire, were examined. The biomarker enterolactone was also measured. After adjustment for age, weight, and other nondietary factors, dietary fiber intake was inversely associated with E1 and E2; there was a 22% and 17% decrease (2Ptrend=0.023 and 0.045) among subjects in the highest quintile of intake compared with the lowest. Fitting dietary fiber together with soluble and insoluble nonstarch polysaccharides (NSP) showed a much greater decrease in E1 and E2 (47% and 41%, respectively) while increased soluble NSP intake showed increases in E1 and E2 (64% and 69%, respectively). Two foods, avocado and grapefruit, showed significant positive associations with E1 (2Ptrend=0.029 and 0.015, respectively). This study suggests that different components of dietary fiber may have very significant different effects on serum estrogen levels. The suggestive findings relating increased estrogen levels to avocado and grapefruit intakes need confirmation.

Adherence to the food guide pyramid recommendations among African Americans and Latinos: results from the Multiethnic Cohort.

The objective of the study was to determine the degree of adherence to the Food Guide Pyramid recommendations among African Americans, Latinos born in the United States, and Latinos born in Mexico. Subjects were from the Multiethnic Cohort Study in Hawaii and Los Angeles, and completed a self-administered quantitative food frequency questionnaire at baseline in 1993-1996. Dairy recommendations were the least likely of all the food group recommendations to be followed, with 61% to 99% of individuals in the three ethnic groups not consuming the recommended number of servings. African Americans were less likely to adhere to all of the food group recommendations compared to the two Latino groups. A greater percentage of Latinos born in the United States did not adhere to the food group recommendations compared to Latinos born in Mexico. All three groups would benefit from interventions designed to promote healthy food choices.

Correlation of dietary intake and colorectal cancer incidence among Mexican-American migrants: the multiethnic cohort study.

Studies of migrants, along with geographic and temporal variations in incidence, indicate that colorectal cancer is especially sensitive to changes in environmental factors, including, most importantly, diet. The goal of this research was to examine the changes in dietary practices that may be consistent with the changing incidence of colorectal cancer in the Los Angeles Mexican-American population. Cancer incidence and dietary intake data were available for over 35,000 Latinos of Mexican national origin currently participating in the prospective Multiethnic Cohort Study, representing the largest sample of Mexican-origin Latinos of any such study in the United States. The dataset is unique in that changes in cancer rates and in dietary behaviors across three generations could be examined. Most of the change in colorectal cancer rates occurred between the first and second generations, and, correspondingly, nearly all the dietary change also occurred between the first and second generations. Although some food traditions were retained by Mexican Americans, the dietary changes due to acculturation were significant and support an association between colorectal cancer risk and certain dietary components, notably, alcohol as a risk factor and nonstarch polysaccharides and vegetables as protective factors.