Detection of Specific Volatile Organic Compounds in Tribolium castaneum (Herbst) by Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry.

The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a major storage pest that could lead to a wide range of damage. Its secretions have a significant impact on the quality of stored grain and food, leading to serious food safety problems such as grain spoilage and food carcinogenesis. This study investigates new detection techniques for grain storage pests to improve grain insect detection in China. The primary volatile organic chemicals (VOCs) in these secretions are identified using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The specific VOCs that are unique to T. castaneum are selected as criteria for determining the presence of T. castaneum in the granary. To obtain more specific VOCs, experiments were designed for the analysis of T. castaneum samples under different extraction times, two types of SPME fibers and two GC-MS devices of different manufacturers. The experimental results showed that 12 VOCs were detected at relatively high levels, seven of which were common and which were not detected in other grains and grain insects. The seven compounds are 1-pentadecene, 2-methyl-p-benzoquinone, 2-ethyl-p-benzoquinone, 1-hexadecene, cis-9-tetradecen-1-ol, m-cresol and paeonol. These seven compounds can be used as volatile markers to identify the presence of T. castaneum, which could serve as a research foundation for the creation of new techniques for T. castaneum monitoring.

[Determination of 10 organic acids in alcoholic products by ion chromatography-tandem mass spectrometry].

A method was developed for the determination of 10 organic acids in liquor, yellow rice wine, and dry red wine by ion chromatography-triple quadrupole mass spectrometry (IC-MS/MS). First, the liquor samples were diluted with deionized water, degassed with nitrogen, and analyzed by IC-MS/MS. Then, the yellow rice wine and dry red wine samples were purified with different solid-phase extraction cartridges. Finally, the GCB solid-phase extraction cartridge was selected for purification, diluted with deionized water, and analyzed by IC-MS/MS. The samples were separated using a Dionex IonPac AS11-HC anion analysis column with high capacity and strong hydrophilicity, with an KOH aqueous solution as the eluent, which was produced by an automatic generator for gradient elution. After being suppressed using a suppressor, the eluent was injected directly into the electrospray ionization tandem mass spectrometry (ESI-MS/MS), ionized in negative ion mode, detected in multiple reaction monitoring (MRM) mode, and quantified using an external standard method. Oxalic acid, fumaric acid, maleic acid, malic acid, tartaric acid, citric acid, quinic acid, and aconitic acid showed good linear relationships in the range of 0.05-2 mg/L. Succinic acid and lactic acid showed good linearities in the range of 0.05-5 mg/L and 0.05-10 mg/L, respectively. The correlation coefficients (r2) were >0.99. The limits of detection (LODs) and limits of quantification (LOQs) were 1.0-8.0 µg/L and 3.5-26.5 µg/L, respectively. The average recoveries ranged from 83.0% to 112.1%, and the relative standard deviations (RSDs) were <9.1% in spiked samples at three levels. The proposed method allowed easy pretreatment without using organic solvents or derivatization processing. Overall, the proposed method is accurate, rapid, sensitive, and it is suitable for the qualitative and quantitative analyses of the 10 organic acids in three wine samples. Moreover, it can be used for the determination of flavor and quality of alcoholic products.

Exposure to short-, medium-, and long-chain chlorinated paraffins for infant via cow infant formula, goat infant formula and baby food.

Dietary exposure is an important pathway for many pollutants from external exposure to human beings. In this study, we investigated the exposure to short-chain chlorinated paraffins (SCCPs), medium-chain chlorinated paraffins (MCCPs) and long-chain chlorinated paraffins (LCCPs), which are a class of industrial compounds that are of significant concern, in different infant foods (cow infant formula, goat infant formula and baby food are collectively called infant food in this study) in Chinese market. The concentrations of ∑SCCPs, ∑MCCPs and ∑LCCPs in infant foods were in the ranges of 6.22-273 ng/g, 13.1-2020 ng/g and 0.80-1280 ng/g, respectively. Especially, for the first time, we found that the proportion of ∑LCCPs (22.0%) in goat infant formula is almost equivalent to that of ∑SCCPs (25.0%), implying that LCCPs should also be further concerned since the related information is very scarce. There were differences between CP profiles among imported cow infant formula and Chinese cow infant formula due to the different sources of CPs to the infant formula. Imported infant foods were characterized by higher proportion of SCCPs, while Chinese infant foods were characterized by higher proportion on LCCPs. Margin of exposure results demonstrated that there was no significant health concern for the infant, but that large variation of CP concentrations and excessive feeding in practice may cause potential health threats to the infant. LCCPs were detected in all infant food samples, and to our knowledge, this is the first report of LCCPs in cow infant formula, goat infant formula and baby food. This study could provide important data of infant exposure to CPs, especially, LCCPs.

Occurrence and distribution of polyhalogenated carbazoles in eastern Tibetan Plateau soils along the slope of Mt. Qionglai.

Polyhalogenated carbazoles (PHCZs), are considered as potential persistent organic pollutants (POPs), which have been frequently detected in the environment. However, the altitudinal distribution characteristics and possible sources of PHCZs in high mountain soils are still unknown. The present study was the first to analyze PHCZs in soil samples collected along the eastern slope of Mt. Qionglai (MQ), the east edge of the Tibetan Plateau. The concentration of ΣPHCZs (based on dry weight) ranges from 14.4 to 107 ng/g (median value of 40.9), which was at high end of the range reported in soils and sediments to date in the literature. The composition profiles of PHCZs in the soils of MQ were dominated by 3,6-dichlorocarbazole (36-CCZ), 3-chlorocarbazole (3-CCZ), and 2-bromocarbazole (2-BCZ). The mean TOC-normalized concentrations of ΣPHCZs in soil samples from below-treeline (2092 ng/g TOC) were higher than those from alpine meadow (1124 ng/g TOC), probably due to the forest filter effect. The decreasing trend of the PHCZs TOC-normalized concentrations with altitude shows that accumulation of PHCZs from the alpine meadow samples was not affected by the mountain cold-trapping effect. Significantly positive correlations were observed between the concentrations of more than half of detected PHCZ congeners and TOC. In addition, PHCZs show the potential to represent a class of POPs with the frequent occurrence and wide distribution, as the abundance and environmental behavior of PHCZs are similar to some POPs in MQ.

Occurrence and potential sources of polyhalogenated carbazoles in farmland soils from the Three Northeast Provinces, China.

Polyhalogenated carbazoles (PHCZs) have been detected in various environments frequently and have attracted increasing attention for their multiple toxicities. However, only a few reports record the occurrence of PHCZs in farmland soils, and the sources of which were not yet been implemented. In this study, 12 PHCZs and carbazole (CZ) were screened in farmland soil samples from the Three Northeast Provinces, and the ∑PHCZs were in the range of 18.16-219.67 ng/g dw. 36-CCZ was the dominant congener (40.67%) in farmland soils, followed by 3-CCZ (14.51%), and average percentages of other congeners were lower than 10%. A concrete analysis of the sources of PHCZs in the soil was conducted, revealing the diversity of PHCZs sources. Potential toxic effects associated with the levels of PHCZs were evaluated via the toxic equivalency (TEQ) approach, and the TEQs of PHCZs (TEQPHCZs) were in the range of 2.24-14.06 pg TEQ/g dw. Notwithstanding the 1368-CCZ with a low concentration level, the mean contribution to TEQPHCZs was up to 24.24%, preceded only by 36-CCZ (39.69%), showing the congeners with low concentration also may pose potential risks to the environment. Partial PHCZs congeners (2-BCZ, 3-BCZ, 36-CCZ, 136-BCZ, and 2367-BCZ) showed significant correlations (r = 0.45-0.63, p < 0.05) with the total organic carbon (TOC). Significant correlations were shown between PHCZ congeners replaced by halogens of the same species and quantity (r = 0.40-0.99, p < 0.01). In view of the fact that the high concentration level of PHCZs in the soil and their source diversity, more environmental monitoring and risk assessments of PHCZs should be of particular concern.

Analysis of Organochlorine Pesticide Residues in Various Vegetable Oils Collected in Chinese Markets.

Organochlorine pesticides (OCPs), chemicals frequently used in agriculture, are a group of highly toxic and persistent organic pollutants. This study assesses the distribution and congener profiles of residual OCPs in 11 types of vegetable oils collected from Chinese markets. All samples were extracted using the modified QuEChERS method prior to analysis by gas chromatography-triple quadrupole mass spectrometry. The sesame oil samples had the highest concentration of OCPs, within the range of 15.30-59.38 ng/g, whereas the peanut oil samples had the lowest OCP concentrations, within the range of 10.83-35.65 ng/g. The possible effect of the processing technology on the pesticide residues in these vegetable oils was also evaluated. It was found that the pressing method leaves more OCPs in vegetable oils than the aqueous extraction and cold-pressing, but the result for leaching was not obvious. In light of the obtained results, it was estimated that the average daily intake of different pesticides is between 0.01 and 2.20 ng/kg bw/day for urban and rural households. Hence, it can be affirmed that, given the amount of the concentration of OCPs detected in the vegetable oils collected from Chinese markets, there are no obvious health risks for urban and rural households by intake.

Distributions and Congener Group Profiles of Short-Chain and Medium-Chain Chlorinated Paraffins in Cooking Oils in Chinese Markets.

Chlorinated paraffins (CPs) are organic pollutants that have caused widespread concerns in recent years. Because of their lipophilic characteristics, CPs may enter into the body through diet or other routes and exert adverse effects on human health. In this study, we investigated the occurrence and congener profiles of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in 176 cooking oils and 19 oil containers collected from various markets in China. The concentrations of SCCPs and MCCPs in cooking oils were in the range of not detected (ND) to 16,055 ng/g and ND to 11,612 ng/g, respectively, and the geomean concentrations of MCCPs were lower than those of SCCPs. The concentrations of CPs in sesame oil, rapeseed oil, and camellia oil were higher than those in other types of oils, and different oil processing methods had different effects on the presence of CPs in the oils. CPs were detected in 5 out of 20 oil containers, although their concentrations were much lower than those detected in the oil samples, indicating that containers are not the main sources of CPs detected in the oils. The mean SCCP and MCCP intakes through cooking oils of the general Chinese population were 8.83 and 6.09 µg/kg/d, respectively.

Survey of mineral oil hydrocarbons in infant formula from the Chinese market.

Mineral oil hydrocarbon (MOH) contamination of various foods in the past few decades has raised much concern due to its potential adverse health effects. Since infant formulas (IF) is the major food source for infants, it is necessary to understand MOH contamination level in IF and consequent potential food safety risks. Data on the contamination of IF by mineral oil are lacking in China. On the other hand, the analysis of MOH in food is difficult. There is no harmonised standard analytical method for testing MOHs in IF. GC-FID/MS was chosen as the analytical tool being more convenient for surveys at a national level. Fifty-one IFs comprising dairy milk-based IFs (n = 39) and goat milk-based IFs (n = 12), including different stages (Stage 1, 2 and 3), package type (metal cans and paper boxes) were collected in China market in 2018 for this survey. 17 of 51 IFs were found positive, but trace levels MOAH were found (≤0.7 mg/kg). For the positive samples, all the MOSH and MOAH hump fell into the C16-C25 fraction. MOH humps were found in all the 12 goat milk-based IFs, even 4 samples are reported with quantifiable values which are higher than the method defined LOQ. The highest quantifiable MOH contamination level of goat milk-based IFs were MOSH = 3.5 mg/kg and MOAH = 0.7 mg/kg. Further root cause analysis of contamination is highly recommended to control the MOH contamination for goat milk-based IFs.

Effects of ozone treatment on the antioxidant capacity of postharvest strawberry.

Strawberries are highly popular around the world because of their juicy flesh and unique taste. However, they are delicate and extremely susceptible to peroxidation of their membrane lipids during storage, which induces water loss and rotting of the fruit. This study investigated the effects of ozone treatment on the physiological traits, active oxygen metabolism, and the antioxidant properties of postharvest strawberry. The results revealed that the weight loss (WL) and respiration rate (RR) of strawberry were inhibited by ozone treatment (OT), while the decline of firmness (FIR) and total soluble solids (TSS) were delayed. Ozone also reduced the generation rate of superoxide radical anions , and the content of hydrogen peroxide (H2O2) enhanced the activity of superoxidase (SOD), catalase (CAT), ascorbate peroxidase (APX), and monodehydroascorbate reductase (MDHAR), as well as promoted the accumulation of ascorbic acid (ASA), glutathione (GSH), and ferric reducing/antioxidant power (FRAP). In addition, a total of 29 antioxidant-related proteins were changed between the OT group and control (CK) group as detected by label-free proteomics during the storage time, and the abundance associated with ASA-GSH cycle was higher in the OT group at the later stage of storage, and the qRT-PCR results were consistent with those of proteomics. The improvement of the antioxidant capacity of postharvest strawberry treated with ozone may be achieved by enhancing the activity of the antioxidant enzymes and increasing the expression of the antioxidant proteins related to the ascorbic acid-glutathione (ASA-GSH) cycle.

Sorption behaviors of tris-(2,3-dibromopropyl) isocyanurate and hexabromocyclododecanes on polypropylene microplastics.

In recent years, microplastics in oceans have become a serious environmental problem and the focus of attention. In the present study, the sorption of TBC and HBCDs by microplastics in simulated seawater is examined. The effects of particle size, temperature, salinity, and concentration on the adsorption of TBC and HBCDs by microplastics are studied. Results indicate that the first-order adsorption kinetic model is more suitable than the pseudo-second-order kinetic model to describe adsorption. The equilibrium adsorption times are 15 h and 10 h for TBC and HBCDs, respectively. The adsorption capacity increases with the decrease in particle size. The adsorption capacity gradually increases at first and then decreases with the increase in salinity and temperature. The maximum adsorption capacity is at 15 °C and 14% salinity. Compared with the linear and Freundlich models, the Langmuir model is more suitable; this indicates that the main adsorption mechanism might be chemical adsorption.

High level of tris-(2,3-dibromopropyl) isocyanurate (TBC) and hexabromocyclododecanes (HBCDs) in sediments from the intertidal zone of New River Estuary-a polluted and degraded wetland.

The levels and distribution of tris-(2,3-dibromopropyl) isocyanurate (TBC) and hexabromocyclododecanes (HBCDs) in sediments in the intertidal zone of the New River Estuary were investigated. The concentration of TBC ranged from 2.78 to 35.1 ng·g-1dw, and the concentration of total HBCDs ranged from 10.3 to 43.5 ng·g-1dw. The composition of the three HBCD isomers, α-, ß-, and γ-HBCD, was 6.23%, 8.00% and 85.8%, respectively. Moreover, the mass inventory of TBC, α-, ß-, γ-HBCD, and total HBCDs in sediments were estimated to be about 1465.49, 124.64, 154.98, 1707.54, 1987.16 kg, respectively. Compared to previous studies, the concentrations of TBC and HBCDs in the intertidal zone of the New River Estuary were relatively high. Therefore, more concern of the potential public health and environmental risks of TBC and HBCDs is necessary.

Profiling wines in China for the biogenic amines: A nationwide survey and pharmacokinetic fate modelling.

Biogenic amines (BAs), a class of nitrogenous compounds that are frequently detected in wine, pose adverse effects to humans. However, with the largest red wine consumption in the world, little is known about national profiles correlating BAs in wines to toxicological/health risks in China. In this study, we conducted a nationwide survey of commercially available wines for the occurrence of BAs. Our sampling campaign covered >90% of wine brands (n = 456) in China in a three year span (2014-2016). The target BAs included tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine. In order to quantitatively characterize the potential risk and/or support regulatory decision-making, chronic and acute BA exposure scenarios were developed and simulated with a physiologically based pharmacokinetic model. The model described the fate and transport of BAs within human body using physical descriptions of relevant processes. These results provided baseline data that are needed for the risk assessment of dietary uptake of BAs and evaluating winemaking processes by food safety authorities.

Levels and distribution of tris-(2,3-dibromopropyl) isocyanurate and hexabromocyclododecanes in surface sediments from the Yellow River Delta wetland of China.

The levels and distribution of tris-(2,3-dibromopropyl) isocyanurate (TBC) and hexabromocyclododecanes (HBCDs) of surface sediments in the Yellow River Delta wetland had been investigated. The concentrations of TBC and ∑HBCDs ranged from 0.20 to 29.03ng·g-1dw and below limits of detections (LODs) to 20.25ng·g-1dw. The average composition profile of three HBCDs isomers were 10.1%, 6.1% and 83.8% for α-, ß- and γ-HBCD, respectively. Moreover, correlation analysis indicated there are similar sources among three isomers and positive correlations between total organic carbon (TOC) content and concentrations of TBC and HBCDs. The mass inventory of TBC,α-, ß-, γ-HBCD, ΣHBCDs in surface sediments of Yellow River Delta wetland were estimated about 725.50, 72.76, 44.29, 548.34, 665.39kg. Therefore, further investigations on potential human health and environmental risk assessments of TBC and HBCDs were needed.

Multi-phase partitioning, ecological risk and fate of acidic pharmaceuticals in a wastewater receiving river: the role of colloids.

The occurrence and multi-phase distribution of five pharmaceutical compounds were investigated in an urban wastewater treatment plant (WWTP) receiving river by analysis of pharmaceuticals in sediment, particulate matter, conventional dissolved phase (>0.7 µm), colloidal phase (5 kDa to 0.7 µm), and truly dissolved phase (<5 kDa) water. Diclofenac was found in all samples, followed by clofibric acid, ibuprofen, ketoprofen, and naproxen with the decreasing detection frequency. All targets in WWTP outfall site were higher than those in the upstream and downstream, indicating that the WWTP is an important input source of pharmaceuticals in the river. The colloidal phase contributed 10-14% of ketoprofen, 8-26% of naproxen, 17-36% of clofibric acid, 22-33% of diclofenac, and 9-28% of ibuprofen in the aquatic system, suggesting the colloids will play an important role as carrier to contaminants in the aquatic environment. Based on truly dissolved concentrations of pharmaceuticals in water, only the risk quotient (RQ) value for diclofenac towards fish was higher than 1, indicating it poses a potential risk to aquatic organisms. Finally, a Level III fugacity model was used to further assess the environmental fate of the selected pharmaceuticals (exemplified for clofibric acid and diclofenac). Both clofibric acid and diclofenac tend to accumulate in water compartment with the percentage of 99.7% and 60.6%, respectively. Advection in river is a significant loss process for clofibric acid (56.4%) and diclofenac (54.4%).

[Direct determination of ethyl carbamate in Chinese rice wine and grape wine by ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry].

An ultra performance liquid chromatography-electrospray ionization tandem mass spectrometric (UPLC-ESI-MS/MS) method was established for the direct determination of ethyl carbamate in Chinese rice wine and grape wine. The Chinese rice wine and grape wine samples were diluted with distilled water, filtered through 0. 22 microm microporous membrane. The LC separation was performed on a Waters Acquity UPLC system with a BEH C18 column, acetonitrile and 0. 1% (v/v) acetic acid aqueous solution as the mobile phase. The ethyl carbamate was determined in the mode of electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM). The butyl carbamate (BC) was used as the internal standard for the quantitative determination. The calibration curve showed good linearity in the range of 2 - 500 microg/L with the correlation coefficient greater than 0.995. The limit of detection (LOD) was 1.7 microg/L and the limit of quantification (LOQ) was 5.0 microg/L. The recoveries of the ethyl carbamate in Chinese rice wine and grape wine was in the range of 90% - 102%. The relative standard deviations (RSDs) of intra-day and inter-day determinations were 0. 8% - 4.5% and 1.4% - 5.6% (n = 6). The results indicated that the proposed method is easy, fast, sensitive, and suitable for the determination of ethyl carbamate in Chinese rice wine and grape wine.

Influence of humic acid on bioavailability and toxicity of benzo[k]fluoranthene to Japanese medaka.

Japanese medakas (Oryzias latipes) and triolein-embedded cellulose acetate membranes (TECAMs) were exposed simultaneously to benzo[k]fluoranthene (BkF) in the static exposure system containing different concentrations of humic acid (HA). The concentration-response relationships of induced hepatic 7-ethoxysorufin-o-deethylase (EROD) activity were established in regard to the nominal water concentration of BkF and the free concentration estimated using TECAM, as well as the body residues, respectively. In general, bioaccumulation of BkF and EROD activity in medaka were reduced with an increase of HA concentration in the exposure medium. The concentration-response relationships varied with HA concentration when expressed in nominal concentration. However, these relationships overlapped completely and partially when expressed in body BkF residue and in free BkF concentration estimated by TECAM, respectively. HA treatments were slightly beyond the 0.95 confidence band of HA-free control thereby indicating the participation of BkF-HA complex to the bioavailability and toxicity. On the basis of the bioavailability model, it was estimated that approximately 17-22% and 13-18% of BkF-HA complex contributed to the bioaccumulation and/or to the induced toxic effect, correspondingly.

Biomimetic accumulation of PAHs from soils by triolein-embedded cellulose acetate membranes (TECAMs) to estimate their bioavailability.

A new passive sampling device (PSD), a triolein-embedded cellulose acetate membrane (TECAM), was used to biomimetically accumulate naphthalene, phenanthrene, pyrene and benzo[a]pyrene from ten spiked soils and a soil spiked with different concentrations of these polycyclic aromatic hydrocarbons (PAHs). TECAM exposure conditions were optimized. The quantities of PAHs accumulated by TECAMs were positively and linearly related to their concentrations in the soil. PAHs accumulated by TECAMs were negatively related to soil organic matter (SOM) and positively related to the dissolved organic carbon (DOC) according to the results obtained from ten spiked soils. Aging time (1-150 days) had a significant effect on accumulation of PAHs by TECAMs. A good linear relationship (R2=0.970-0.993) was observed between TECAM-accumulated PAHs and PAHs accumulated by earthworms (Eisenia andrei). The data indicate that TECAM represents a useful surrogate to estimate the bioavailability of PAHs and perhaps other hydrophobic organic contaminants (HOCs) in soils.

Predicting bioavailability and accumulation of organochlorine pesticides by Japanese medaka in the presence of humic acid and natural organic matter using passive sampling membranes.

Adsorption to dissolved organic matter (DOM) may significantly decrease the freely dissolved concentration of many hydrophobic organic compounds and, hence, result in reduced bioavailability to aquatic organisms. Here, the suitability of using triolein-embedded cellulose acetate membrane (TECAM) as a biomimetic surrogate to assess the bioavailability of organochlorine pesticides (OCPs) in water in the presence of DOM was explored. The accumulation of OCPs was measured in TECAM and pelagic Japanese medaka (Oryzias latipes) in the laboratory after 12 h exposure to water containing different levels of Aldrich humic acid. Further, OCP uptake by TECAM and medaka in real aqueous environments was evaluated after 30 d exposures in two sites. Laboratory results showed that OCP uptake by medaka consistently decreased with increasing levels of humic acid in the range of 0-15 mg C/L in sample solutions. This tendency was closely mimicked by OCP accumulation in TECAM under the same conditions. Field results showed that TECAM accumulated similar OCP patterns as medaka (r2 = 0.92 for site 1 and r2 = 0.94 for site 2), although comparison of the in-field eight OCP concentrations in TECAM to those in medaka yielded approximately a factor of 3 (on a wet weight basis). These results suggest that the TECAM method can be used as a simple and useful tool to predict the bioavailability and bioaccumulation potential of poorly biotransformed organic compounds in pelagic fish in aqueous environment.

Using semipermeable membrane devices, bioassays, and chemical analysis for evaluation of bioavailable polycyclic aromatic hydrocarbons in water.

Meiliang Bay is a sublake of Taihu Lake and has been polluted by domestic and industrial effluents. As part of a comprehensive risk assessment project in this region, semipermeable membrane devices (SPMDs) were applied to evaluate the levels and potential toxic potency of polycyclic aromatic hydrocarbons (PAHs) in lakewater, in combination with chemical analysis and in vitro bioassay using H4IIE rat hepatoma cells. In addition, induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity, in crucian carp (Carassius auratus), caged in the vicinity of SPMD sampling sites was also used as a biomarker of exposure to PAHs and related chemicals. The caged crucian carp accumulated similar PAH profile patterns (p < 0.001) but at lower levels compared with SPMDs on a wet-weight basis. Total concentrations of PAHs in crucian carp muscle tissues ranged from 35.6 to 69.1 ng/g after the 32-day exposure, whereas total PAHs in SPMDs ranged from 716.9 to 1007.8 ng/g. Dialysates from SPMDs exposed to Meiliang Bay water caused marked EROD activity in H4IIE cells. Toxic potency of dialysates expressed as bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ) ranged from 3.8 to 6.2 pg TCDD-EQ/g SPMD for 32-day exposure samples. A linear correlation of total amount of PAHs and in vitro TCDD-EQ of SPMD dialysates yielded an R (2) of 0.82. Empirical evidence suggests that aryl hydrocarbon receptor-active PAHs can account for about 42-56% of the potency observed. Significant induction of liver EROD activity was also observed in crucian carp caged alongside SPMDs and there was a good correlation between the results of EROD assays in vivo and in vitro (R (2) = 0.62, p = 0.02). It is, therefore, suggested that the SPMD technique in connection with chemical analysis and specific in vitro bioassays might be a valuable tool to assess the levels and effects of bioavailable hydrophobic pollutants in water.