Dioxins and furans in biochars,hydrochars and torreficates produced by thermochemical conversion of biomass: a review

Converting raw biomass into valuable products protects the environment, improves economics, and helps tackle climate change by cutting resource demand and waste production. Thermochemical treatment is a common method for producing biochars, hydrochars and torreficates from biomass and organic wastes, which can also generate dioxins and furans and consequently limit the use of thermochemically converted chars. Here we review the presence of dioxins and furans in chars produced by hydrothermal carbonization, torrefaction, and pyrolysis processes under the influence of temperature, residence time, heating rate, pressure, and feedstock type. Dioxins and furans were mostly below 20 ng total toxic equivalence per kilogram (TEQ kg⁻¹), with the highest level of 113 ng TEQ kg⁻¹ found in over 100 samples of different char types. The most toxic products were hydrochars produced from sewage sludge. Processing temperature and feedstock type were key factors resulting in high dioxin levels in chars, and care should be taken when producing chars at temperatures up to 300 °C or using feedstocks previously contaminated with dioxins or preservatives.

     

Prenatal diagnosis of trisomy 20 by chorionic villus sampling (CVS): a case report with long-term outcome

A case of prenatally diagnosed non-mosaic trisomy 20 in cells cultured from a chorionic villus sample (CVS)is presented. The term placental karyotype was also non-mosaic trisomy 20. The karyotype of thenewborn was 46,XY/47,XY,+20 in foreskin cultures and in a second skin culture; blood lymphocyte culture was 46,XY. Aside from diffuse, hypopigmentary swirls along the lines of Blaschko observed on hisextremities and trunk, referred to as hypomelanosis of Ito, the patient is clinically normal at 8¾ years ofage. In addition, he is one of the oldest reported cases of mosaic trisomy 20 confirmed after birth forwhich the clinical outcome has been monitored. This case demonstrates that these trisomy 20 findings are compatible with normal psychomotor development and phenotype. Copyright © 2001 John Wiley & Sons, Ltd.