Survey of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and non-ortho-polychlorinated biphenyls in US meat and poultry, 2012-13: toxic equivalency levels, patterns, temporal trends and implications.

The US Department of Agriculture (USDA) conducts a statistically based survey of the domestic meat supply (beef, pork, chicken and turkey) to determine current levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and non-ortho-polychlorinated biphenyls (no-PCBs) every 5 years. Fat samples for each slaughter class were collected from US federally licensed slaughter facilities. The samples were processed and analysed for 17 PCDD/Fs and three no-PCBs. The sum of PCDD, PCDF and no-PCB toxic equivalencies (sum-TEQ) calculated using 2005 toxic-equivalency factors for all slaughter classes ranged from non-detect (n.d.) to 6.47 pg TEQ g-1 lipid. The median sum-TEQs, when n.d. = 0.5 LOD, for beef, pork, chicken and turkey were 0.66, 0.12, 0.13 and 0.34 pg TEQ g-1 lipid respectively. A comparison of the current survey with the previous three surveys shows a declining trend, with decreasing differences between medians; differences between the median sum-TEQs from 2007-08 and 2012-13 were -10%, -29%, -33% and -25% for beef, pork, chicken and turkey respectively. Several beef samples underwent further characterisation and congener patterns from these beef samples suggested pentachlorophenol treated wood as the likely exposure source. US consumer exposure to these compounds is relatively low and no slaughter class contributed more than 26% to the US Environmental Protection Agency (USEPA) chronic oral reference dose of 0.7 pg TEQ kg-1 bw day-1.

Cross-cultural comparison of perspectives on healthy eating among Chinese and American undergraduate students.

BACKGROUND: Understanding views about what constitutes a healthy diet in diverse populations may inform design of culturally tailored behavior change interventions. The objective of this study was to describe perspectives on healthy eating among Chinese and American young adults and identify similarities and differences between these groups. METHODS: Chinese (n = 55) and American (n = 57) undergraduate students in Changsha, Hunan, China and Honolulu, Hawai'i, U.S.A. composed one- to two-paragraph responses to the following prompt: "What does the phrase 'a healthy diet' mean to you?" Researchers used content analysis to identify predominant themes using Dedoose (version 5.2.0, SocioCultural Research Consultants, LLC, Los Angeles, CA, 2015). Three researchers independently coded essays and grouped codes with similar content. The team then identified themes and sorted them in discussion. Two researchers then deductively coded the entire data set using eight codes developed from the initial coding and calculated total code counts for each group of participants. RESULTS: Chinese students mentioned physical outcomes, such as maintaining immunity and digestive health. Timing of eating, with regular meals and greater intake during day than night, was emphasized. American students described balancing among food groups and balancing consumption with exercise, with physical activity considered essential. Students also stated that food components such as sugar, salt and fat should be avoided in large quantities. Similarities included principles such as moderation and fruits and vegetables as nutritious, and differences included foods to be restricted and meal timing. While both groups emphasized specific foods and guiding dietary principles, several distinctions in viewpoints emerged. CONCLUSIONS: The diverse views may reflect food-related messages to which participants are exposed both through the media and educational systems in their respective countries. Future studies may further examine themes that may not typically be addressed in nutrition education programs in diverse populations of young adults. Gaining greater knowledge of the ways in which healthy eating is viewed will allow for development of interventions that are sensitive to the traditional values and predominant views of health in various groups.

Biogeochemical impacts of wildfires over four millennia in a Rocky Mountain subalpine watershed.

Wildfires can significantly alter forest carbon (C) storage and nitrogen (N) availability, but the long-term biogeochemical legacy of wildfires is poorly understood. We obtained a lake-sediment record of fire and biogeochemistry from a subalpine forest in Colorado, USA, to examine the nature, magnitude, and duration of decadal-scale, fire-induced ecosystem change over the past c. 4250 yr. The high-resolution record contained 34 fires, including 13 high-severity events within the watershed. High-severity fires were followed by increased sedimentary N stable isotope ratios (δ15N) and bulk density, and decreased C and N concentrations--reflecting forest floor destruction, terrestrial C and N losses, and erosion. Sustained low sediment C : N c. 20-50 yr post-fire indicates reduced terrestrial organic matter subsidies to the lake. Low sedimentary δ15N c. 50-70 yr post-fire, coincident with C and N recovery, suggests diminishing terrestrial N availability during stand development. The magnitude of post-fire changes generally scaled directly with inferred fire severity. Our results support modern studies of forest successional C and N accumulation and indicate pronounced, long-lasting biogeochemical impacts of wildfires in subalpine forests. However, even repeated high-severity fires over millennia probably did not deplete C or N stocks, because centuries between high-severity fires allowed for sufficient biomass recovery.

Dietary estimates of dioxins consumed in U.S. Department of Agriculture-regulated meat and poultry products.

The U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) examined whether levels of dioxin-like compounds (DLCs) measured in FSIS-regulated meat and poultry products indicate possible concern for U.S. public health based on usual and recommended consumption patterns of meat and poultry for the U.S. population. The FSIS estimated daily dietary exposures and compared them with the reference dose (RfD) established by the U.S. Environmental Protection Agency (EPA) for potential noncancer risks from 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), assuming that all measured DLCs were represented by the RfD (i.e., not just TCDD alone). The estimates indicate that a typical U.S. adult daily exposure of DLCs from FSIS-regulated products is below the EPA-established RfD. Only children consuming chronic average daily servings of meat or poultry products containing the highest measured levels of DLCs may exceed the RfD. If one follows the recommendations from the 2010 Dietary Guidelines for Americans, all expected exposures to DLCs from FSIS-regulated products are estimated to be well below the RfD.

Cadmium and lead residue control in a hazard analysis and critical control point (HACCP) environment.

In 2003-2004, the U.S. Department of Agriculture Food Safety and Inspection Service (FSIS) conducted an exploratory assessment to determine the occurrence and levels of cadmium and lead in randomly collected samples of kidney, liver, and muscle tissues of mature chickens, boars/stags, dairy cows, and heifers. The data generated in the study were qualitatively compared to data that FSIS gathered in a 1985-1986 study in order to identify trends in the levels of cadmium and lead in meat and poultry products. The exploratory assessment was necessary to verify that Hazard Analysis and Critical Control Point plans and efforts to control exposure to these heavy metals are effective and result in products that meet U.S. export requirements. A comparison of data from the two FSIS studies suggests that the incidence and levels of cadmium and lead in different slaughter classes have remained stable since the first study was conducted in 1985-1986. This study was conducted to fulfill FSIS mandate to ensure that meat, poultry, and egg products entering commerce in the United States are free of adulterants, including elevated levels of environmental contaminants such as cadmium and lead.