Research Progresson a Novel Brominated Flame Retardant：Tris(2,3-dibromopropyl)Isocyanurate(TBC)

李妍王玲

（青岛大学化学化工与环境学院，山东 青岛266071）

0 Introduction

Brominated flame retardants(BFRs)as the important chemical flame retardants,have been widely used in electronic products,clothing and furniture in daily life articles.However these materials have strong stability and biological aggregation in the environment.[1]Therefore,BFRs are potentially harmful to the ecological system and human health.[2]Since 2006,the production and use of penta-and octa-bromodiphenyl ethers was restricted in Stockholm Convention,and therefore Tris (2,3-dibromopropyl)Isocyanurate (TBC)was used as alternatives for polybrominated diphenyl ethers(PBDEs)in some applications.Due to its significant flame retardant properties,it is therefore used in some glass fiber reinforced plastics.[3]In 1974,the Federal Republic of Germany began to develop TBC,as flame retardant and successfully applied to polyester amine foaming.[4]In China,in 1984,Anhui Institute of Chemical Industry successfully developed the first.[5]In the 1990s,production capacity of TBC achieved more than 500 metric.[6]Although,to date,the total production of TBC is not statistical.With the development of electronic products production,application amount of TBC is bound to increase.[7]As the additive type flame retardant,TBC is easy to precipitate in the use of material and in the process,resulting in environmental pollution.In 2009,TBC was first detected typical industrial pollution of regional environment in Hunan province.[8]Therehave been enough evidences to show that TBC has characteristics of long distance migration,lasting bioaccumulation,causing adverse effects on human health and the environment.

1 The levels of TBC in the environment

TBC as the additive type flame retardant into the environment,through the production,use,processing process.Therefore,we can apply TBC source into the point source pollution and non-point source pollution.In the point source pollution,factory emissions,waste water treatment and waste landfill leachates are sources of TBC.In the nonpoint source pollution,the source of TBC is from the dust with the subsidence of TBC and burning electronic waste and so on.[1]Collected samples from the discharge hole of factory have relatively high TBC contents (163ng/L).In the discharge hole near the river,the content of TBC decrease along the river flowing to the discontinuous.Due to the dilution of the branch water,distance from the discharge hole thousands of meters outside the river water samples,the content of TBC is only 2.3-4ng/L.In the survey area of TBC content sediment surface samples have the highest concentration,followed by the soil and earthworms,the lowest concentration of TBC in water.

TBC can be accumulated in the fatty organ,such as brain,liver,intestine,carp fat etc.Also in the carp intestinal and brain samples with high TBC content,indicating that TBC can be transmitted through blood brain barrier.[7]TBC is mainly concentrated in the carp gills,brain,liver,fat and intestinal tract,which are not only concerned with the physical and chemical properties of TBC,but also with environmental behavior and metabolism of TBC pathway related.However,further research is still needed and enrichment mechanism of metabolic pathways of TBC concrete.

2 Toxic effects of TBC

In order to study reproductive toxicity in zebrafish,female zebrafish were exposed to TBC 14d,then spawn experiments.According to Li Juan for larval zebrafish TBC exposure experiments,we know that TBC can influence the zebrafish hatching rate,cause swim bladder larval zebrafish developmental defects,reduce the swim bladder area.[9]72 hours after fertilization,the swim bladder start expansion of normal zebrafish larvae.However,treatment with TBC of zebrafish larval swimbladder can not develop normally,resulting in the reduction of the survival rate of zebrafish.In addition,the study found that low hatching rate and swim bladder deformity these effects disappear gradually with the extension of recovery time,which showing that the transmission from mother to offspring is TBC one of the major metabolic way of female zebrafish in vivo.In the 4mg/L exposure concentration,liver cell degeneration in zebrafish,and a number of vacuoles appeared.The fish gill biopsy results showed that cells of zebrafish gill filaments in control group arranged in neat uniform,clear cell boundary.The gill filaments cell boundary fuzzy,arranged disorder not neat,accompanied by hyperplasia phenomenon in the treatment group.

Wang studied TBC on the toxicity test of Nannochloropsis oculata.After TBC exposure,Nannochloropsis oculata photosynthetic activity showed an overall decreasing trend.TBC had effect on the expression level of the photosynthetic genes (psaA psbC).With the higher concentration of TBC,psaA and psaC expression level down more obvious.10

In recent years,there are many researches on the toxicology of TBC.And,lot of great progresses had been acquired.[11-12]However,the literature about TBC toxicity mechanism,risk assessment and other aspects is still very scarce.

3 Research prospect

The brominated flame retardant agent TBC has good flame retardancy.It has been widely used in electronic,chemical,textile and other industries,which promoting economic development and social progress.However,there are always two sides to everything.The use of TBC also cause pollution to the environment,threatening the health of the people.TBC has a strong biological enrichment.It has been in various environmental media and biological samples were detected.

TBC a novel brominated flame retardant,has aroused attention.Although the research has achieved certain results,there are a lot of work needs to be done,compared with other brominated flame retardants.The human body can through skin contact,breathing,dietary intake and other ways to absorb exposed to the environment of TBC.At present,the research on TBC main focus in environmental and biological medium distribution level.Related toxicity mechanism of TBC needs further study,as well as the metabolic pathway.The fundamental way to solve the problem is to develop pollution-free flame retardant.

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