Of the more than 2,000 high-production volume chemicals that are manufactured in or imported into the United States in amounts of one million pounds or more per year (U.S. Environmental Protection Agency 2004), many are widely used in consumer products. Among these chemicals are bisphenol A [BPA; 2,2-bis(4-hydroxyphenyl)propane; CAS no. 80-05-7] and 4-tertiary-octylphenol [tOP; 4-(1,1,3,3-tetramethylbutyl)phenol; CAS no. 140-66-9]. BPA is used in the manufacture of polycarbonate plastic and epoxy resins, which can be used in impact-resistant safety equipment and baby bottles, as protective coatings inside metal food containers, and as composites and sealants in dentistry [Center for the Evaluation of Risks to Human Reproduction (CERHR) 2007; European Union 2003]. Exposure to BPA is thought to result primarily from ingestion of food containing BPA (Kang et al. 2006; Vandenberg et al. 2007). tOP is both a degradation product of and an intermediate in the manufacture of octylphenol ethoxylates, which are nonionic surfactants used in detergents, pesticide formulations, and other applications (Ying et al. 2002). Exposure to tOP may occur from contact with personal care products, detergents, water, and food containing tOP.

Exposures to tOP can result in developmental and reproductive alterations in aquatic species (Segner et al. 2003) and in laboratory animals (Aydogan and Barlas 2006; Bian et al. 2006; Blake et al. 2004; Nagao et al. 2001; Willoughby et al. 2005). At high doses, BPA demonstrates estrogen-like effects on uterine and prostate organ weights in experimental animals. At doses below the putative lowest observed adverse effect level, exposure to BPA has reportedly resulted in decreased sperm production, increased prostate gland volume, altered development and tissue organization of the mammary gland, altered vaginal morphology and estrous cycles, disruption of sexual differentiation in the brain, and accelerated growth and puberty (Durando et al. 2007; Howdeshell et al. 1999; Kubo et al. 2003; Richter et al. 2007; Rubin et al. 2006; Schonfelder et al. 2002; Timms et al. 2005; vom Saal et al. 1998). At present, the interpretation of the evidence related to the low-dose effects of BPA is a subject of scientific debate (European Union 2003; Goodman et al. 2006; Gray et al. 2004; National Toxicology Program 2001; vom Saal and Hughes 2005).

BPA and tOP are of concern to environmental public health because of the high potential for exposure of humans to these phenols and their demonstrated animal toxicity. Information about the concentrations of these compounds in the general population is important for understanding human exposure to BPA and tOP. The National Health and Nutrition Examination Survey (NHANES), conducted continuously since 1999 by the National Center for Health Statistics of the Centers for Disease Control and Prevention (CDC), is designed to measure the health and nutritional status of the civilian noninstitutionalized U.S. population ≥ 2 months of age (CDC 2003). The surveys include household interviews; collection of medical histories; standardized physical examinations; and collection of biologic specimens (e.g., blood and urine from participants ≥ 1 and ≥ 6 years of age, respectively) for clinical chemistry testing, nutritional indicators assessments, and assessment of exposure to environmental chemicals (CDC 2005, 2006).

Previously, we analyzed 394 urine samples collected from adult participants of NHANES III, conducted during 1988–1994, to estimate urinary concentrations of total BPA (free plus conjugated species) in selected demographic groups (Calafat et al. 2005). We now report the first estimate of urinary concentrations of total BPA and tOP in NHANES 2003–2004 participants, a representative sample of the noninstitutionalized U.S. population ≥ 6 years of age.

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Exposure of the U.S. population to bisphenol A and 4-tertiary-octylphenol: 2003-2004

Over the past 30 years, the NCR-13 Soil Testing and Plant Analysis Committee members have worked hard at standardizing the procedures of Soil Testing Laboratories with which they are associated. There have been numerous sample exchanges and experiments to determine the influence of testing method, sample size, soil extractant ratios, shaking time and speed, container size and shape, and other laboratory procedures on test results. As a result of these activities , the committee arrived at the recommended procedures for soil tests. Experiments have shown that minor deviations in procedures may cause significant differences in test results. It is to the advantage of all laboratories that the credibility of soil testing be enhanced. The adoption of these recommended procedures by all laboratories would be a major step toward improving the image of soil testing and, hopefully, the integrity of fertilizer recommendations based on soil tests. Calibration studies conducted by the North Central Agricultural Experiment Stations over the past five decades have been used to calibrate these recommended procedures. NCR-13 wants it clearly understood that the publication of these tests and procedures in no way implies that the ultimate has been reached. Research and innovation on methods of soil testing should continue. The committee strongly encourages increased research efforts to devise better, faster, less expensive and more accurate soil tests. With the high cost of fertilizer , and with the many soil related environmental concerns, it is more important than ever that fertilizer be applied only where needed and in the amount of each element needed for the response goal. The best hope of attaining this goal is better soil tests and better correlations with plant response. NCR-13 stands ready to evaluate promising new soil tests, and with clear justification will move quickly to revise their recommendations. Wisconsin. The 1996-97 official representatives are listed below. The authors and co-authors of the chapters in this edition of Recommended Chemical Soil Test Procedures for the North Central Region are official representatives to the NCR-13 committee with the following exceptions: Authorship This publication was revised in 1980 and 1988 under the leadership of Bill Dahnke who was the North Dakota representative to the NCR-13 committee until his retirement. His introduction to those two revisions is included below without change. The NCR-13 committee on Soil Testing and Plant Analysis asked me to serve as editor for this revision, which I deemed an honor and a …

Recommended Chemical Soil Test Procedures for the North Central Region

Modern research in atmospheric chemistry requires highly sensitive techniques for the measurement of concentrations of free radicals which determine the rate of photochemical destruction of most atmospheric pollutants. Tunable diode-laser absorption spectroscopy (TDLAS) has already been successfully used for measurements of very low concentrations of stable gases, but further improvement in its sensitivity by signal averaging has been limited by the stability of the instrument. In this paper the concept of the Allan variance is utilized to analyze the stability of an existing frequency-modulated (FM) TDLAS instrument leading to a detection limit for NO2 of 34 pptv at 6 Hz detection bandwidth. The stability of the instrument allows averaging over 60 s. Taking into account the measuring cycle consisting of the determination of the sample spectra and zero air spectra as well as gas exchange in the absorption cell, the detection limit achievable with this particular instrument was 10 pptv within 25 s under laboratory conditions. Possibilities of further improvement of the detection limit are discussed.

The limits of signal averaging in atmospheric trace-gas monitoring by tunable diode-laser absorption spectroscopy (TDLAS)

Oil spill identification

Polyfluoroalkyl compounds (PFCs) comprise a class of man-made, fluorinated organic compounds that have been used in a variety of consumer and industrial applications. Although these have been produced for many years, only recently have reports surfaced suggesting widespread exposure in wildlife and humans (Butenhoff et al. 2006; Calafat et al. 2007; Giesy and Kannan 2001; Houde et al. 2006; Kannan et al. 2004). Two of the most widely detected and studied compounds in this class are perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA). PFOS and related compounds (polyfluorinated sulfonamides) are surfactants used in applications ranging from oil and water repellents for fabrics, apparel, carpets, and paper coatings to specialty chemical applications such as insecticides and fire fighting foams (3M Company 1999). PFOA and its salts are used as chemical intermediates and processing aids in the production of fluoropolymers and fluoroelastomers.

Both PFOS and PFOA have shown the potential for developmental toxicity in animal studies. PFOS has been shown, in rats and mice, to induce developmental and reproductive effects, such as reduced birth weight, decreased gestational length, structural defects, developmental delays, and increased neonatal mortality (Fuentes et al. 2006; Grasty et al. 2003; Lau et al. 2003; Luebker et al. 2005a, 2005b; Thibodeaux et al. 2003). Recent studies have also reported developmental toxicity from PFOA in rodents, including pregnancy loss, reduced fetal weight, reduced postnatal survival, and delays in postnatal growth and development in offspring (Butenhoff et al. 2004; Lau et al. 2004, 2006). However, such studies of PFOS and PFOA have been conducted using doses that produce serum concentrations much higher than general population human exposures. There are limited epidemiologic data on the potential impacts of PFC exposure on fetal growth and development. However, one recent occupational study found no association between employment in jobs with high exposure to PFOS before the end of pregnancy and maternally reported birth weight (Grice et al. 2007).

PFOS and PFOA have also been shown to cause reductions in serum cholesterol and/or triglycerides in several animal species (Haughom and Spydevold 1992; Seacat et al. 2002, 2003; Thibodeaux et al. 2003). Conversely, a few cross-sectional occupational studies conducted among fluorochemical production employees have reported positive relationships between PFOS and/or PFOA concentrations and serum lipid levels (Gilliland and Mandel 1996; Olsen et al. 1999, 2003). The fetus is likely to be sensitive to the availability of cholesterol and triglycerides, which support cellular growth, differentiation, and adipose accumulation (Woollett 2001). Disruptions to normal fetal growth and development have been associated with effects across the lifespan, including adverse neonatal and childhood outcomes (Hofman et al. 1997; Kramer et al. 1990) and metabolic diseases in adulthood (Barker 2006).

In a previous report, we documented factors associated with cord serum concentrations of PFOS and PFOA in a population of newborn deliveries known as the Baltimore THREE study (Apelberg et al. 2007). In this study, we examined the relationship between these concentrations and gestational age, birth weight, and measures of birth size, including head circumference, length, and ponderal index (a measure of body mass at birth).

J.K. Taylor

Papers

Quality assurance of chemical measurements