A peer-reviewed open access journal published by the National Institute of Environmental Health Sciences

The abilities of seven clones of marine phytoplankton, belonging to six different algal classes, to accumulate transuranic elements were evaluated in laboratory culture experiments. Plutonium, americium, and californium were rapidly concentrated by all species, resulting in volume/volume concentration factors generally >10⁵ for all species and all isotopes. Two natural assemblages from the coastal Mediterranean behaved like the algal cultures. Isotopes associated with cells by a passive adsorption to cell surfaces, with equilibrium between cells and water reached in 3–4 days. Uptake of isotope was directly proportional to the number of suspended particles and the isotope concentration in the culture. Equilibrium isotope concentrations differed between species, reflecting different numbers of transuranic binding sites on the cell surfaces. Generally, the green and blue‐green cells had less reactive surfaces than the diatoms. Once accumulated, Am was lost more rapidly by green algae than by diatoms. Elimination proceeded in two phases, a rapid initial loss and then a slower release. The biological half‐life for Am turnover in the slowly exchanging compartment in the diatom was 10–12 days. No substantial differences in uptake were noted between cultures receiving Pu in the III–IV and V–VI oxidation states. In contrast to the other elements, neptunium showed no detectable accumulation by any of the cells. The results suggest that Pu, Cf, and Am would associate with marine particles which could transport them vertically, transfer them into the marine food web, or both, while Np would behave essentially conservatively in seawater.

We present a detailed response to the critique of "State of the Science of Endocrine Disrupting Chemicals 2012" (UNEP/WHO, 2013) by financial stakeholders, authored by Lamb et al. (2014). Lamb et al.'s claim that UNEP/WHO (2013) does not provide a balanced perspective on endocrine disruption is based on incomplete and misleading quoting of the report through omission of qualifying statements and inaccurate description of study objectives, results and conclusions. Lamb et al. define extremely narrow standards for synthesizing evidence which are then used to dismiss the UNEP/WHO 2013 report as flawed. We show that Lamb et al. misuse conceptual frameworks for assessing causality, especially the Bradford-Hill criteria, by ignoring the fundamental problems that exist with inferring causality from empirical observations. We conclude that Lamb et al.'s attempt of deconstructing the UNEP/WHO (2013) report is not particularly erudite and that their critique is not intended to be convincing to the scientific community, but to confuse the scientific data. Consequently, it promotes misinterpretation of the UNEP/WHO (2013) report by non-specialists, bureaucrats, politicians and other decision makers not intimately familiar with the topic of endocrine disruption and therefore susceptible to false generalizations of bias and subjectivity.

The mechanism of sex determination in zebrafish is largely unknown and neither sex chromosomes nor a sex-determining gene have been identified. This indicates that sex determination in zebrafish is mediated by genetic signals from autosomal genes. The aim of this study was to determine the precise timing of expression of six genes previously suggested to be associated with sex differentiation in zebrafish. The current study investigates the expression of all six genes in the same individual fish with extensive sampling dates during sex determination and -differentiation.