Predictors of personal polycyclic aromatic hydrocarbon exposures among pregnant minority women in New York City.

As part of a multiyear birth-cohort study examining the roles of pre- and postnatal environmental exposures on developmental deficits and asthma among children, we measured personal exposures to polycyclic aromatic hydrocarbons (PAHs) among 348 pregnant women in northern Manhattan and the South Bronx, New York. Nonsmoking African-American or Dominican women were identified and recruited into the study. During the third trimester of pregnancy, each subject wore a personal air monitor for 48 hr to determine exposure levels to nine PAH compounds. In this study, we examined levels of exposures to PAHs and tested for associations with potential predictor variables collected from questionnaires addressing socioeconomic factors and day-to-day activities during pregnancy as well as activities and environmental exposures during the 48-hr monitoring period. Reliable personal monitoring data for women who did not smoke during the monitoring period were available for 344 of 348 subjects. Mean PAH concentrations ranged from 0.06 ng/m3 for dibenz[a,h]anthracene to 4.1 ng/m3 for pyrene; mean benzo[a]pyrene concentration was 0.50 ng/m3. As found in previous studies, concentrations of most PAHs were higher in winter than in summer. Multiple linear regression analysis revealed associations between personal PAH exposures and several questionnaire variables, including time spent outdoors, residential heating, and indoor burning of incense. This is the largest study to date characterizing personal exposures to PAHs, a ubiquitous class of carcinogenic air contaminants in urban environments, and is unique in its focus on pregnant minority women

Factors contributing to the benefits of foliar nitrogen application for wheat in a sub-tropical winter environment

Beneficial effects of foliar N application to cereal crops have been widely believed to rely on subsequent rainfall or irrigation in the semi-arid region where in-crop rain is insufficient and unreliable. To verify this, factors contributing to the effects of foliar N application were assessed by implementing foliar N application in trials on three farmers' properties in central Queensland, Australia. Solutions of CRN35 (30 kg N ha-1 at 1.94 N % w v_1), urea and UAN (both 26, 2.25%), and urea (20, 20%; 40, 20%) and UAN (20, 20%; 40, 40%), were applied to wheat at anthesis respectively at the three properties (sites). Adjuvant chemical agents were also applied in mixture form with the N at the latter two sites. At the first site, with foliar N (CRN35) application, grain protein content on average increased by 1.07 percentage points, and by 1.6 in the presence of basal superphosphate. Superphosphate alone also increased grain yield. At the second site, while the applications of UAN and urea increased grain protein content by 1.3 and 0.9 percentage points, respectively, UAN showed superiority to urea in N recovery. At the third site, foliar N applications with or without chemical adjuvant did not affect grain protein content, but due to the higher concentration in the N solution, some of them (excluding UAN40) had negative effects on grain yield, compared to the water only control. Based on our data and supporting literature, to ensure the positive effect on wheat grain protein content, subsequent irrigation or rainfall may not be critical provided that foliar N concentration is lower than 5%. It is also suggested that UAN is superior to urea as an N source for foliar application. For alkaline/sodic soils, while the application of basal superphosphate increased grain yield, the added foliar N ensured an increase of grain protein content

Factors contributing to the benefits of foliar nitrogen application for wheat in a sub-tropical winter environment

Beneficial effects of foliar N application to cereal crops have been widely believed to rely on subsequent rainfall or irrigation in the semi-arid region where in-crop rain is insufficient and unreliable. To verify this, factors contributing to the effects of foliar N application were assessed by implementing foliar N application in trials on three farmers' properties in central Queensland, Australia. Solutions of CRN35 (30 kg N ha-1 at 1.94 N % w v_1), urea and UAN (both 26, 2.25%), and urea (20, 20%; 40, 20%) and UAN (20, 20%; 40, 40%), were applied to wheat at anthesis respectively at the three properties (sites). Adjuvant chemical agents were also applied in mixture form with the N at the latter two sites. At the first site, with foliar N (CRN35) application, grain protein content on average increased by 1.07 percentage points, and by 1.6 in the presence of basal superphosphate. Superphosphate alone also increased grain yield. At the second site, while the applications of UAN and urea increased grain protein content by 1.3 and 0.9 percentage points, respectively, UAN showed superiority to urea in N recovery. At the third site, foliar N applications with or without chemical adjuvant did not affect grain protein content, but due to the higher concentration in the N solution, some of them (excluding UAN40) had negative effects on grain yield, compared to the water only control. Based on our data and supporting literature, to ensure the positive effect on wheat grain protein content, subsequent irrigation or rainfall may not be critical provided that foliar N concentration is lower than 5%. It is also suggested that UAN is superior to urea as an N source for foliar application. For alkaline/sodic soils, while the application of basal superphosphate increased grain yield, the added foliar N ensured an increase of grain protein content