| Organic ultraviolet(UV)filters are substances designed to absorb harmful UV light and are widely used in personal care products(PCPs;e.g.,sunscreens,shampoos,fragrances,cosmetics,soap,etc.)to protect the skin from UV irradiation.According to"Hygienic Standard for Cosmetics"(2007 edition),28 different UV filters,of which 26 organic compounds are permitted.As people become more concerned about the skin problems caused by ultraviolet radiation,there is a huge demand for sunscreen and other skin care products.Recently,the production volume of organic UV filters has increased rapidly.Personal hygiene practices(e.g.,washing,showering and laundering)and sewage treatment plant effluents have led to the great entry of these substances into aquatic environments.One of the most widely used organic UV filters,4-methylbenzylidene camphor(4-MBC),is present at high concentrations in offshore waters.It is difficult to be removed completely by sewage treatment processes and the removal efficiency is only in a range of 38%-77%.The high lipophilic properties make 4-MBC easy to accumulate in the sediment and in the organisms.Various environmental samples in many countries have been frequently found to contain 4-MBC,including the surface waters,wastewaters,sediments and aquatic organismsMarine copepods are the most important class of plankton populations,which Tigriopus japonicas has several advantages as a good model species for estuarine and marine toxicological studies.In the present study,we investigated the acute and multigenerational effects of 4-MBC on the survival,development and reproduction of T.japonicas.The adult copepods were exposed to a series concentrations of 4-MBC for 72 h acute toxicity.The marine copepod T.japonicas was exposed to different concentrations of 4-MBC(i.e.,0,0.5,1,5 and 10 ?g L-1)for four consecutive generations(F0-F3),and they were subsequently resumed under clean environments for two generations(i.e.,F4,F5).Five life history traits(survival rate,time for nauplii to develop to copepodites(N-C),time for nauplii to develop to adults(N-A),number of eggs produced in 10-days per female,hatching rate)were examined for each generation.In addition,the transcription of genes related to oxidative stress,apoptosis and ecdysis was investigated to shed light on the potential toxic mechanisms of 4-MBC in marine copepods.To determine whether 4-MBC poses a potential threat to marine ecosystems,we performed a tentative environmental risk assessment based on the toxicity data.The results showed that:(1)The LC50,LOEC and NOEC(no observed effect concentration)of 4-MBC induced lethal toxicity in the 72 h acute toxicity test were 92.9,10 and<10 ?g L-1,respectively.(2)In the F0 generation,4-MBC caused significant lethal toxicity in T.japonicas at concentrations of 5 and 10 ?g L-1 and the nauplii were more sensitive to 4-MBC toxicity than the adults.However in the F1-F3 generations,4-MBC exposure did not affect the survival rate.(3)The hatching rate and the developmental duration from the nauplii to the copepodite(N-C)and from the nauplii to adult(N-A)decreased significantly in the F1-F2 generations and in the F2-F3 generations,respectively,even at the lowest exposure concentration(0.5 ?g L-1).(4)In the subsequent two generations(i.e.,the F4-F5 generations)of recovery exposure in clean seawater,the growth rates of the original 4-MBC exposure groups were still faster than the control in both the N-C and N-A stages,suggesting possible transgenerational genetic and/or epigenetic changes upon chronic 4-MBC exposure.(5)The expression of the ecdysone receptor gene was up-regulated by 4-MBC,which was consistent with the decrease of the N-C/N-A duration.In addition,4-MBC may induce oxidative stress and trigger apoptosis in T.japonicas,resulting in developmental,reproductive and even lethal toxicity.(6)A preliminary risk assessment suggested that under environmentally realistic concentrations,4-MBC had significant potential to pose a threat to marine crustaceans and marine ecosystems. |
PDF Full Text Request