Associations with known factors such as age, race, and sex were confirmed using this data set. Understanding the prevalence of abnormal thyroid tests among reproductive-aged women informs decisions about screening in this population. The finding that individuals on thyroid hormone replacement medication often remain hypothyroid or become hyperthyroid underscores the importance of monitoring.

Background: Indoor air concentrations of polychlorinated biphenyls (PCBs) in some buildings are one or more orders of magnitude higher than background levels. In response to this, efforts have been made to assess the potential health risk posed by inhaled PCBs. These efforts are hindered by uncertainties related to the characterization and assessment of source, exposure, and exposure-response.Objectives: We briefly describe some common sources of PCBs in indoor air and estimate the contribution of inhalation exposure to total PCB exposure for select age groups. Next, we identify critical areas of research needed to improve assessment of exposure and exposure response for inhaled PCBs.Discussion: Although the manufacture of PCBs was banned in the United States in 1979, many buildings constructed before then still contain potential sources of indoor air PCB contamination. In some indoor settings and for some age groups, inhalation may contribute more to total PCB exposure than any other route of exposure. PCB exposure has been associated with human health effects, but data specific to the inhalation route are scarce. To support exposure–response assessment, it is critical that future investigations of the health impacts of PCB inhalation carefully consider certain aspects of study design, including characterization of the PCB mixture present.Conclusions: In certain contexts, inhalation exposure to PCBs may contribute more to total PCB exposure than previously assumed. New epidemiological and toxicological studies addressing the potential health impacts of inhaled PCBs may be useful for quantifying exposure–response relationships and evaluating risks.Citation: Lehmann GM, Christensen K, Maddaloni M, Phillips LJ. 2015. Evaluating health risks from inhaled polychlorinated biphenyls: research needs for addressing uncertainty. Environ Health Perspect 123:109–113; http://dx.doi.org/10.1289/ehp.1408564

Between April 28 and July 19 of 2010, the U.S. Coast Guard conducted in situ oil burns as one approach used for the management of oil spilled after the explosion and subsequent sinking of the BP Deepwater Horizon platform in the Gulf of Mexico. The purpose of this paper is to describe a screening level assessment of the exposures and risks posed by the dioxin emissions from these fires. Using upper estimates for the oil burn emission factor, modeled air and fish concentrations, and conservative exposure assumptions, the potential cancer risk was estimated for three scenarios: inhalation exposure to workers, inhalation exposure to residents on the mainland, and fish ingestion exposures to residents. U.S. EPA's AERMOD model was used to estimate air concentrations in the immediate vicinity of the oil burns and NOAA's HYSPLIT model was used to estimate more distant air concentrations and deposition rates. The lifetime incremental cancer risks were estimated as 6 × 10(-8) for inhalation by workers, 6 × 10(-12) for inhalation by onshore residents, and 6 × 10(-8) for fish consumption by residents. For all scenarios, the risk estimates represent upper bounds and actual risks would be expected to be less.

Exposures to environmental contaminants can pose risks to pregnant women's health, their developing fetuses, children, and adults later in their lives. Assessing risks to this potentially susceptible population requires a sound understanding of the physiological and behavioral changes that occur during pregnancy and lactation. Many physiological and anatomical changes occur in a woman's organ systems during the course of pregnancy and lactation. For example, blood volume and cardiac output increase during pregnancy, and other metabolic functions are altered to provide for the demands of the fetus. During lactation, nutritional demands are greater than during pregnancy. There are also changes in behavior during both pregnancy and lactation. For example, water consumption during pregnancy and lactation increases. These behavioral and physiological changes can lead to different environmental exposures than these women might otherwise experience in the absence of pregnancy or lactation. This paper provides a summary of information from the published literature related to behavioral and physiological changes in pregnant and lactating women that may affect their exposure or susceptibility to environmental contaminants, provides potentially useful exposure factor data for this population of women, and highlights data gaps.

Several researchers have shown that infant exposure to dioxin-like compounds can be significant by the breast milk pathway (1-4). Ayotte et al. (1) used data on the concentrations of dioxin-like compounds [including dioxin and furan congeners as well as the dioxin-like polychlorinated biphenyls (PCBs)] in breast milk of Inuit populations in Nunavik (the Arctic region of Quebec, Canada) with a median concentration of 48 pg dioxin toxic equivalents (TEQ)/g lipid, to calculate an infant dose of 226 pg TEQ/kgday. They applied a pharmacokinetic (PK) model to evaluate the impact of breast-feeding of dioxin TEQs on infant body burdens and on lifetime (up to 75 years) body burdens of TEQs. By studying the accumulation of dioxin-like compounds in humans over time, Patandin et al. (2) showed that 6 months of breast-feeding during the first 25 years of life could contribute 12% of the total dose of these compounds during those 25 years for men and 14% for women. Kreuzer et al. (3) and Lakind et al. (4) combined estimates of 2,3,7,8-tetrachlodibenzo-p-dioxin (TCDD) dose received by the infant via breast-feeding with PK models to demonstrate the initial significant elevation in infant body burdens of TCDD as a result of this exposure. Their models predicted that initially high body burdens declined as a result of infant body weight increases, depuration of residues, and reduced doses due to declines of residues of TCDD in mother's milk.In this paper, we build on the efforts of other researchers (1-4) to model the impacts of breast-feeding on body burdens of dioxinlike compounds. We express body burdens in terms of picograms of dioxin TEQs per gram body lipid or parts per trillion TEQ lipid; these compounds are known to accumulate in lipid, and TEQ concentrations in mother's milk, blood, and other organs are often expressed on a lipid basis.In this paper we focus on dioxin-like compounds expressed as a dose or concentration of dioxin TEQs. The TEQ concentration is the sum of the concentrations of the individual dioxin-like compounds multiplied by their respective toxicity equivalency factors (TEFs). The TEF scheme we used is the one promoted by the World Health Organization in 1998 (5). We use TEQ to signify the 29 compounds assumed to have dioxin-like toxicity, including the 7 polychlorinated dibenzo-p-dioxin (PCDD) and 10 dibenzofuran (PCDF) congeners, as well as the 12 dioxin-like coplanar PCBs, unless otherwise stated. We treat TEQs as a single compound. Even with the principal uncertainty of this approach, the limited validation and general comparison of modeled results with the measured values suggest that this may be a reasonable approach for evaluating trends in exposure to dioxin-like compounds via breast-feeding.In this paper we describe and validate a simple pharmacokinetic model for evaluating the impact of breast-feeding on infant body burdens. We then apply the model to five scenarios: formula only, and nursing times of 6 weeks, 6 months, 1 year, and 2 years. We also performed another sensitivity analysis te...

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Soil and dust ingestion by children may be important pathways of exposure to environmental contaminants. Contaminated soil and dust may end up on children's hands and objects, because they play close to the ground. These contaminants can be ingested by children, because they have a tendency to place objects, including their fingers, in their mouths. Assessing exposure through this pathway requires information about the amount of soil and dust ingested by children. Estimates of soil and dust ingestion and information on the prevalence of the behavior have been published in the literature, but research in this area is generally limited. Three methodologies have been used to quantify soil and dust ingestion rates. In this paper, these are referred to as the tracer element method, the biokinetic model comparison method, and the activity pattern method. This paper discusses the information available on the prevalence of soil and dust ingestion behavior, summarizes the three methodologies for quantifying soil and dust ingestion, and discusses their limitations. Soil ingestion data derived from studies that use these methodologies are also summarized. Although they are based on different estimation approaches, the central tendency estimates of soil and dust ingestion derived from the three methodologies are generally comparable.

The in vitro fibril assembly of calf skin collagen was examined as a function of ionic strength and temperature. In a 0.03 M NaPi, pH 7.0, buffer, fibril assembly required a minimum critical concentration of collagen. At nearly physiological ionic strengths and temperatures, the critical concentration was less than 1 microgram/mL and required a very sensitive method for measurement. Raising the ionic strength of the buffer resulted first in higher and then lower critical concentrations. Raising the temperature led to lower critical concentrations. A van't Hoff plot of the fibril growth constant calculated from the critical concentration gave positive enthalpy changes and positive heat capacity changes which indicate that the fibril growth is driven by both hydrophobic and ionic inter-collagen interactions. Sedimentation equilibrium studies showed the collagen to be monomeric at subcritical concentrations. Differential scanning microcalorimetric studies showed only one very sharp heat absorption peak for the fibril assembly which coincided with the appearance of solution turbidity. Within experimental error, the enthalpy changes of the fibril assembly measured with the microcalorimeter were of the same magnitude as the van't Hoff enthalpy changes. These results are discussed in light of a cooperative nucleation-growth mechanism of collagen fibril assembly proposed earlier.