Co-carcinogene oder bedingt krebsauslösende Faktoren

Within the last 10 years numerous new and typical exogenous cocarcinogens were identified chemically as well as biologically and characterized biochemically as initiation or tumor promoters. They are highly irritant diterpene esters of plant origin. Promoters of this type were recently detected also in the Euphorbiacea Croton flavens L., the multiple use of which for stimulants according to local habits was previously held responsible for the unusually high rate of esophageal cancer on Curacao. This detection confirms for the first time that in the etiology of human cancer besides solitary carcinogens (first-order carcinogenic risk factors) also cocarcinogens of the promoter type have to be considered (second-order carcinogenic risk factors). — The active principles of the diterpene ester type are the strongest promoters known so far; they are noninitiators and nonmutagens. Of the manyfold biochemical activities of these promoters the three most actual are: the TPA molecule does not require activation by metabolic alteration, it releases very rapidly prostaglandin E₂ from cellular membranes and it activates latent DNA-viral genoms.     

Incubation-derived calcium carbonate equivalence of papermill boiler ashes derived from sludge and wood sources

The burning of a papermill sludge and wood mixture and landspreading the resulting ash is a potential means of disposal of papermill sludge without the use of valuable landfill space. This study evaluated the effectiveness of ashes derived from a mixture of papermill sludge and wood sources to act as an alternative liming agent. The calcium carbonate equivalence of the material was determined using a 91-day laboratory incubation test with three mineral soils and one organic horizon soil. Application rates of soil-incorporated sludge-ash ranged from 2.30 to 32.2 g per kg soil. Soil pH increased linearly with increasing sludge-ash application rate. The calcium carbonate equivalence of the material varied temporally and the average value ranged from 19% to 28%. The fraction of total P, K and Mg added with the sludge-ash and extracted from the ash-amended soils using an NH4OAc based soil test method were 2.6, 3.8 and 17.6%, respectively. The low soil test extractability of ash-derived plant nutrients suggests that this material would provide only a modest increase in plant available nutrient levels in landspread fields.