Polybrominated diphenyl ethers (PBDE) in serum: findings from a US cohort of consumers of sport-caught fish

Polybrominated diphenyl ethers (PBDEs) have been used as flame retardants in foams, fabrics and plastics, and are common contaminants of household air and dust and bioaccumulate in wildlife, and are detectable in human tissues and in fish and animal food products. In the Great Lakes Basin sport fish consumption has been demonstrated to be an important source of PCB and DDE exposure. PBDEs are present in the same sport fish but prior to our study the contribution to human PBDE body burdens from Great Lakes sport fish consumption had not been investigated. This study was designed to assess PBDE, PCB and 1,1-bis(4-chlorophenyl)-2,2-dichloroethene (DDE) serum concentrations in an existing cohort of 508 frequent and infrequent consumers of sport-caught fish living in five Great Lake states. BDE congeners 47 and 99 were identified in the majority of blood samples, 98% and 62% respectively. summation operatorPBDE levels were positively associated with age, hours spent outdoors, DDE, summation operatorPCB, years of sportfish consumption, and catfish and shellfish intake, and negatively associated with income and recent weight loss. Other dietary components collected were not predictive of measured summation operatorPBDE levels. In multivariate models, summation operatorPBDE levels were positively associated with age, years consuming sport fish, shellfish meals, and computer use and negatively associated with recent weight loss. Having summation operatorPBDE levels in the highest quintile was independently associated with older age, male gender, consumption of catfish and shellfish, computer use and spending less time indoors. summation operatorPCB and DDE were strongly associated suggesting common exposure routes. The association between summation operatorPBDE and summation operatorPCB or DDE was much weaker and modeling suggested more diverse PBDE sources with few identified multi-contaminant-shared exposure routes. In our cohort Great Lakes sport fish consumption does not contribute strongly to PBDE exposure.     

The value of early third-trimester maternal serum alpha-fetoprotein determination

The value of determination of maternal serum of alpha-fetoprotein (MSAFP) concentration in i he second trimester is well established. In addition to open neural tube defects, pregnancies associated with elevated second-trimester MSAFP have been shown to be at increased risk for a variety of problems, including low birth weight, preterm delivery, and pregnancy-induced hypertension (PIH). We evaluated the potential usefulness of MSAFP in the early third trimester. MSAFP concentration was determined in over 200 women at the time of glucose screening. Results were analysed with regard to gestational age at sampling, maternal weight, race, diabetes, and presence of twins. MSAFP was twice as high in twin gestation, but not affected by race or the presence of diabetes. In contrast to levels in early gestation, third-trimester MSAFP does not appear to be predictive of preterm delivery, low birth weight, or PIH.     

Sampling Airborne Solids in a Duct Following a 90° Bend

Present standardized methods (ASME Power Test Code 27, Western Precipitation Bulletin 50, etc.) of stack sampling usually stress sampling under conditions of steady flow (no variation with time) in order to obtain data representative of the source emissions. On many occasions these standardized methods are applied when the velocity and/or the mass flow rate of pollutants do vary with time, thus impairing the accuracy of the sampling results. In addition, it is difficult to evaluate any inaccuracy of the sampling data. This paper classifies these two source variables into four categories and suggests basic sampling approaches for each type of source condition. Several standardized procedures are evaluated and classified according to the source conditions to which the procedure is applicable. The intent of this paper is to show the most accurate sampling approach for each source condition and thus serve as a guide when planning source sampling programs.     

Statistical Issues for Monitoring Ecological and Natural Resources in the United States

The United States funds a number of national monitoring programs to measure the status and trends of ecological and natural resources. Each of these programs has a unique focus; the scientific objectives are different as are the sample designs. However, individuals and committees, all well aware of the cost of ecological monitoring, have called for more effective monitoring programs. The objective of this paper is to summarize existing programs' statistical designs and discuss potential alternatives for improvement in national monitoring. Can we improve the current situation by providing an overall framework for the design or analysis of data from these disparate surveys? First, the paper summarizes the objectives of these surveys, compares and contrasts their survey designs as currently implemented, and determines what variables they collect. Through this process we identify commonalities and issues that impact our ability to combine information across one or more of the surveys. Three potential alternatives are presented, leading to comprehensive monitoring in the United States.