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The memory of crystalline phase in the melt of isotactic polypropylene (iPP) in regiodefective samples of iPP characterized by different concentrations regiodefects, constituted by secondary 2,1 propene units, is studied. The self‐nucleation (SN) experiments have demonstrated that the presence of 2,1 regiodefects produces a strong memory of the crystalline phase in the melt that persists up to temperatures much higher than the melting temperature. The extension of the heterogeneous melt (domain II) containing self‐nuclei increases with increasing the concentration of regiodefects. The higher the concentration of regiodefects the higher the temperature at which the self‐nuclei are dissolved and the homogeneous melt is achieved. This demonstrates that a strong memory of the crystalline phase of iPP in the melt exists not only in copolymers with noncrystallizable bulky comonomeric units rejected from the crystals but even when small defects are largely included in the crystals. [ABSTRACT FROM AUTHOR]

The mechanisms for the formation of N‐substituted hydrazones by coupling of alcohols and hydrazine, achieved by the sequential processes of acceptorless dehydrogenation and borrowing hydrogen, has been unveiled by density functional theory (DFT) calculations. The release of water and molecular hydrogen as subproducts, combined with the Mn‐PNN pincer based catalyst describe a green environment. Mechanistically, apart from describing a complex system of three coupled catalytic pathways, calculations describe the pivotal role of two intermediates, which participate in two catalytic pathways each one. Finally, predictive catalysis plays the role to push forward this reaction toward milder conditions, and thus in line with green chemistry standards. [ABSTRACT FROM AUTHOR]

Glycol ethers (GE) are chemicals used since the 1930s as solvents in paints, inks, varnishes, and cleaning agents, mainly in water-based products, cosmetics, and drugs. World production approximates 1 million tons. Nineteen GE are produced or imported each year; over 1000 tons in European Union (EU) have been classified as high production volume chemicals (HPVCs). First animal data were published in 1971 and 1979 showing severe reprotoxicity for some GE. Two alerts were launched in the United States in 1982 and 1983, but the first partial GE regulation only occurred in 1993 in the EU. Although these chemicals may expose a very large population, basic toxicity data, more especially carcinogenicity, are still lacking (3/32 GE). However, experimental data were sufficient to lead developmental toxicity risk assessment since the early 1980s. Risk indices over 1000 have been calculated for consumers and workers exposed to reprotoxic GE in domestic and industrial activities. The first ban was decided in 1999 in France, but was only for drugs and cosmetics. Not surprisingly, since the late 1980s, human studies have found results similar to those in animal data: spontaneous abortions, malformations, testicular toxicity, and hematotoxicity. Despite this highly coherent set of data, and although substitution products are available, reprotoxic GE have been and still remain widely used in the world. The case of GE shows the failure of the present system based on a posteriori risk assessment. This pleads for the change of paradigm through the European REACH regulation based on the “No data, no market” principle. Ethics in REACH management should also be considered. [ABSTRACT FROM AUTHOR]

Following the wreck of the oil tanker ERIKA off the north-west coast of France in December 1999, cleaning up of the beaches involved considerable work, which in any case could not be perfect. This raised the question of the short- and long-term health risks for the future bathers related to the toxicity of the remaining oil polycyclic aromatic hydrocarbons (PAHs). This risk assessment study was conducted to help health authorities plan risk management policies and inform the public. Thirty-six beaches were selected, representing a sample of the most frequently encountered topographic and beach usage situations; seven “control” beaches, unspoiled by ERIKA, were also investigated. Samples of water and sand were taken from each site, as well as from the surface of rocks. The 16 PAHs selected by the U.S. EPA were quantified in each environment. Several scenarios of exposure were contemplated: (1) a child between 2 and 4 years accidentally ingesting a small ball of fuel, (2) a child daily exposed throughout his holiday-time stay, (3) an adult (including a pregnant woman) spending his/her holidays on the coast, (4) an adult working on the beach, (5) and an adult practicing water sports. Among the available and significant toxicological values, the most conservative ones were selected for computing risks. The sand and water, after decontamination, were slightly polluted (respectively, 7.8 μg/kg and 23.3 ng/l of total 16 PAHs), with values similar to those found in the control beaches. By contrast, the rocky areas in some places were still highly polluted (up to 23 mg/kg on the surface layer). No lethal risk was found for a young child who had accidentally ingested a small ball of fuel. The life-long excess risks for skin cancer and for all other cancers were about 10−5 in scenarios including contact with the polluted rocks. In all other cases, excess risks were considerably lower. The hazard quotient for teratogenic effects was very small, except in scenarios where pregnant women would walk among rocks containing high pollution levels. In conclusion, exposure was mainly associated with polluted water among children, and with spoiled rocks for adults. Despite uncertainties, mainly dealing with the prediction of long-term risks following a short-term exposure, this study showed that beaches where pollution was no longer visible after decontamination did not entail any significant health risks and could be opened to the public. [ABSTRACT FROM AUTHOR]