Environmental and Health Hazards of Chromated Copper Arsenate-Treated Wood: A Review.

Copper chrome arsenate (CCA) water-borne solution used to be widely used to make timber highly resistant to pests and fungi, in particular, wood products designed for outdoor use. Nowadays, CCA is a restricted chemical product in most countries, since potential environmental and health risks were reported due to dermal contact with CCA residues from treated structures and the surrounding soil, as well as the contamination of soils. However, large quantities of CCA-treated timber are still in use in framings, outdoor playground equipment, landscaping, building poles, jetty piles, and fencing structures around the world, thus CCA remains a source of pollutants to the environment and of increasing toxic metal/metalloid exposure (mainly in children). International efforts have been dedicated to the treatment of materials impregnated with CCA, however not only does some reuse of CCA-treated timber still occur, but also existing structures are leaking the toxic compounds into the environment, with impacts on the environment and animal and human health. This study highlights CCA mechanisms and the documented consequences in vivo of its exposure, as well as the adverse environmental and health impacts.

Comparative Cr, As and CCA induced Cytostaticity in mice kidney: A contribution to assess CCA toxicity.

CCA (Chromium Copper Arsenate) treated wood, widely used in outdoor residential structures and playgrounds, poses considerable dangers of leaching of its components to the environment. In this study, mouse kidney samples were used to evaluate the effects of CCA, chromium trioxide (CrO3) and arsenic pentoxide (As2O5) on cell pathophysiology by flow cytometry. Samples were collected after 14, 24, 48 and 96 h of animal exposure. While Cr had no statistically significant cytostatic effects, As2O5 induced a S-phase delay in animals exposed for 24 h, and over time a G0/G1 phase blockage. The effects of CCA in S-phase were similar, but more severe than those of As2O5. Since environmental and public health hazards due to the long durability of CCA-treated wood products, these data confirm that CCA has profoundly toxic effects on cell cycle, distinct from the compounds themselves. These cytostatic effects support cell cycle dynamics as a valuable endpoint to assess the toxicity of remaining CCA-treated infrastructures, and the expected increased waste stream over the coming decades.

Dominance of Paris-type morphology on mycothallus of Lunularia cruciata colonised by Glomus proliferum / Predomínio da morfologia tipo-Paris em talo de Lunularia cruciata colonizado por Glomus proliferum

Microscopic evidence confirms that L. cruciata hosting G. proliferum shows major anatomical traits (arbuscules, coils, arbusculate coils and vesicles) generally associated arbuscular mycorrhizal roots and the anatomical morphology of intra-thalli mycelium is predominantly of the Paris-type. Colonised L. cruciata showed a reduction of biomass when compared with axenic plants suggesting a drain of resources towards the fungus and depletion of nutrients required for optimum plant growth. The behaviour of mycothalli regarding available KH2PO4 indicates that the nutritional stress threshold for phosphorus (P) is above the residual amount of P already present in PhytagelTM and in plant inoculum. These raise the possibility that in certain circumstances the relationship between L. cruciata and G. proliferum be parasitic rather than symbiotic and open the door for future studies to ascertain the nature of liverwort-AM fungi relationships.

Observações de microscopia ótica confirmam que L. cruciata colonizada por G. proliferum apresenta caracteres anatomicos (arbúsculos, hifas novelas, arbúsculos enovelados e vesículas) geralmente associadas a raízes micorrízicas arbusculares em que o micélio intra-tálico apresenta uma anatomia predominantemente do tipo Paris. L. cruciata colonizada apresentou redução de biomassa quando comparada com plantas axenicas, sugerindo dreno de recursos para o fungo e consequente redução de nutrientes necessários para o ótimo crescimento da planta. O comportamento do talo-colonizado em relação à disponibilidade de KH2PO4 no meio indica que o limiar de stress nutricional para fósforo se encontra acima do somatório das quantidades residuais deste elemento presentes no PhytagelTM e no inóculo. Os resultados aqui discutidos sugerem a possibilidade de, em certas circunstâncias, a relação entre L. cruciata e G. proliferum ter características de parasitismo e não de simbiose, abrindo novas perspectivas para futuros estudos na determinação da natureza da relação hepática-fungo arbuscular.

Dominance of Paris-type morphology on mycothallus of Lunularia cruciata colonised by Glomus proliferum.

Microscopic evidence confirms that L. cruciata hosting G. proliferum shows major anatomical traits (arbuscules, coils, arbusculate coils and vesicles) generally associated arbuscular mycorrhizal roots and the anatomical morphology of intra-thalli mycelium is predominantly of the Paris-type. Colonised L. cruciata showed a reduction of biomass when compared with axenic plants suggesting a drain of resources towards the fungus and depletion of nutrients required for optimum plant growth. The behaviour of mycothalli regarding available KH2PO4 indicates that the nutritional stress threshold for phosphorus (P) is above the residual amount of P already present in Phytagel(TM) and in plant inoculum. These raise the possibility that in certain circumstances the relationship between L. cruciata and G. proliferum be parasitic rather than symbiotic and open the door for future studies to ascertain the nature of liverwort-AM fungi relationships.

Does Lunularia cruciata form symbiotic relationships with either Glomus proliferum or G. intraradices?

The present study was undertaken to investigate whether the behaviour in vitro of Lunularia cruciata grown with Glomus intraradices and G. proliferum, on SRV medium with 29.2 mM sucrose satisfies the requirements of Koch' postulates for mutualistic symbiosis. Hyphae emerging from mycothallus were able to grow over a two-compartment Petri dish barrier and capture and translocate phosphorus into the host liverwort. Thus, there were increases in plant dry weight, higher AM fungi spore production, and higher plant total phosphorus content. Moreover, this colonization of L. cruciata reproduces typical symptoms generally associated with mycorrhizae. These results showed that mycothalli of L. cruciata have available functionalities generally associated with mycorrhizal symbiosis in higher plants; however, the energy/photosynthetic carbon requirements to maintain a mutualistic symbiosis may be a limiting factor in vivo. Features here discussed indicate that, at least in tested experimental conditions, the endophytic association of L. cruciata with both G. intraradices and G. proliferum is a parasitic/opportunistic partnership rather than a mutualistic symbiosis.

Lunularia cruciata, a potential in vitro host for Glomus proliferum and G. intraradices.

A study was conducted to define culture conditions for in vitro growth arbuscular mycorrhizal fungi (AMF) with liverworts as hosts. Lunularia cruciata (L.) Dumortier ex. Lindberg developed in vitro monoxenic mycothalli with both Glomus proliferum Dalpé & Declerck (MUCL 41827) and Glomus intraradices Schenck & Smith (MUCL 43204). AMF inoculated plants were co-cultured in plastic Petri dishes with semi-solidified medium supplemented with sucrose and grown under filtered light. Mycothalli of L. cruciata produced external hyphae and spores in quantities equivalent to those obtained with Ri T-DNA transformed root systems.