Study of the effects of Pb and Hg toxicity using a chronic toxicity reproductive 5-day test with the freshwater rotifer Lecane quadridentata

We have developed chronic toxicity reproductive 5-day tests to study the effects of Pb, as Pb(NO(3))(2), and Hg, as HgCl(2), exposure in the freshwater rotifer Lecane quadridentata. We used "r" (the instantaneous growth rate) as the endpoint. The test was performed using EPA medium at two food levels (10(5) and 10(6) cells/mL of Nannochloris oculata) at a controlled temperature of 25 degrees C and an L/D cycle of 16:8 h. We monitored the levels of both metals, using atomic absorption, at days 0, 2, and 5 of each experiment. Our results showed that rotifers fed at higher food concentrations were capable of withstanding higher levels of metal toxicity than those fed at lower food concentrations (EC50 = 0.704 versus 0.664 mg/L(-1) for lead, P < 0.05; EC50 = 0.057 versus 0.054 for mercury, P < 0.05). Our atomic absorption analysis showed that although 66% of lead nitrate can be taken up by algal cells efficiently and removed from the medium, rotifers also play an important role removing additional lead from the medium (up to 44% in some treatments). In the case of mercuric chloride, most of the mercury is bound by the salts contained in EPA medium or discarded by the organisms, and the remainder is removed by N. oculata in <48 h.     

Using Proales similis (Rotifera) for toxicity assessment in marine waters

There is a need to develop more animal species for assessing toxicity in marine environments. Cyst‐based toxicity tests using invertebrates are especially fast, technically simple, cost‐effective, and sensitive to a variety of toxicants. Over the past 30 years, a variety of toxicity endpoints have been measured using the marine rotifer Brachionus plicatilis hatched from cysts, including mortality, reproduction, ingestion, swimming, enzyme activity, and gene expression. A consensus has developed that the most ecologically relevant toxicity measurements should be made using more than one species. Furthermore, it has been noted that the rotifer species toxicant sensitivity distribution is much broader than which endpoint is measured. This implies that toxicity should be measured with the simplest, fastest, least expensive test available on as many species as feasible. If a battery of test species is to be used to estimate toxicity, diapause egg‐based toxicity tests that do not require culturing of test animals will be key. In this paper, we describe how diapause eggs of a new marine rotifer, Proales similis, can be produced, stored and hatched under controlled conditions to produce animals for toxicity tests. Methods are described for quantifying the toxicity of copper, mercury and cadmium based on mortality, ingestion, reproduction, and diapause egg hatching endpoints. We found that reproduction and ingestion endpoints were generally more sensitive to the metals than mortality or diapause egg hatching. When the copper sensitivity of P. similis was compared to Brachionus manjavacas and B. plicatilis using an ingestion test, similar EC50s were observed. In contrast, the B. rotundiformis ingestion EC50 for copper was about 4× more sensitive. Although diapause egg hatching was not the most sensitive endpoint, it is the most ecologically relevant for assessing sediment toxicity. Our discovery of diapausing eggs in the P. similis life cycle has created a conundrum. We have not observed males or sex in P. similis populations, which is a direct contradiction to the orthodox view of the monogonont rotifer life cycle. Work is needed to clarify how diapause egg production is accomplished by P. similis and whether sexual reproduction is involved.     

Assessing toxicity of nanoparticles using Brachionus manjavacas (Rotifera)

Rotifers are major components of zooplankton in freshwater and coastal marine ecosystems throughout the world and could be useful indicator species, providing valuable insight into the effects of nanoparticles on microinvertebrate grazers. Here we report initial efforts to characterize the immediate and longer‐term effects of nanoparticle exposure on the reproduction of the coastal marine and salt lake rotifer Brachionus manjavacas. We used chemically unreactive fluorescent nanoparticles to probe how size and concentration affects the mode of uptake, distribution within the rotifer body, reproductive rate, feeding behavior, and offspring fitness. Population growth rate (r) was depressed 50% in rotifer populations exposed to 0.30 μg mL^?1 of 37‐nm particles, and 89% in populations exposed to 1.1 μg mL^?1. Larger particles of identical chemical composition, but with diameters up to 3000 nm, caused no reduction in population growth rate. These larger particles remain confined in the gut, implicating nanoparticle size as a critical factor in the ability to penetrate the gut wall and enter tissues. Transfer of the F1 offspring from nanoparticle exposed maternal females into nanoparticle‐free media demonstrated that nanoparticles are rapidly cleared from the animals with no significant residual adverse effects. © 2009 Wiley Periodicals, Inc. Environ Toxicol 26: 146–152, 2011.     

2种右旋糖酐铁给药后的家兔体内血清铁浓度及毒性比较

目的:比较2种右旋糖酐铁制剂肌内或静脉注射时的血清铁浓度及毒性。方法:家兔给予25mg·kg-1的2种右旋糖酐铁制剂(制剂1,2),隔日1次肌内或静脉注射。分别于给药1,2,4wk处死动物,测给药前后血清铁含量并检查其对脏器的损害。结果:给药后动物血清铁迅速上升,制剂1给药1wk达峰,制剂2达峰略晚。2种途径给药血清铁浓度的变化相似。2种制剂肌内注射均出现肝细胞肿胀和注射局部肌内损伤,制剂2组病变较严重静脉注射时,多种组织出现病理变化,制剂2组的损伤比制剂1组严重。结论:2种右旋糖酐铁给药后血清铁浓度差别不显著,但制剂2组对组织的损害比制剂1组重。     

Freshwater toxicity testing using rehydrated Philodina sp. (Rotifera) as test animals

Rotifers have become widely used in aquatic toxicology as a rapid screening test for toxicity. The commercial availability of diapausing embryos (cysts) have facilitated their popularity because test animals can be obtained without having to master the details of culturing. Other rotifer species have life stages capable of surviving desiccation and also could be used in non‐culture systems for toxicity assessment. In this article, we describe a system for toxicity testing in freshwater based on rehydrating desiccated bdelloid rotifers in the genus Philodina. These animals can remain in this anhydrobiotic state for more than one year and then rehydrate within hours to provide animals for toxicity tests. We describe three endpoints: a 1.5 h ingestion test, a 24 h mortality test, and a five day reproductive test. The latter test requires feeding and a method using a dried commercial product is explained. Using desiccated rotifers and dried food in toxicity tests make this system especially attractive because of its flexibility and low threshold of biological expertise required to execute the tests. The use of the Philodina toxicity test is illustrated with four metals: copper, lead, mercury and cadmium. Reproduction generally was the most sensitive endpoint, with EC50s of 0.33, 0.44, 0.60, and 0.12 mg/L, respectively. Ingestion was a close second with EC50s of 0.13, 1.64, 0.64, and 6.26 mg/L, respectively.     

Inhalation toxicity in mice exposed to sarin (GB) for 20-720 min

Most of the historical data for the toxicity of sarin (GB) was collected for exposure times of <10 min in attempts to establish the utility of and defence against this agent in offensive military use. However, information concerning the toxicity of GB (and other nerve agents) from longer exposures of 1-12 h is critical for all personnel who must work in or close to low-level concentrations of chemical for extended periods and for all personnel, dressed in Individual Protective Equipment, who need to know when, and if, it is safe to take off these cumbersome garments.The data presented for the toxicity of GB to mice for whole-body exposures of 20 min to 12 h are intended to form part of an ongoing, multi-species effort aimed at establishing toxicity estimates for humans for these longer exposure times: LCT50 values of 430, 540, 900, 1210 and 2210 mg.min m(-3) or LC50 values of 21.5, 9.0, 5.0, 3.4 and 3.1 mg m(-3) were obtained for mice for 20-, 60-, 180-, 360- and 720-min exposures to GB, respectively. The data for longer exposures do not follow Haber's rule (LCT50=CT). The 20- and 60-min data fit the 'toxic load model' involving CnT that was established previously from historical data for 0.17-30 min GB exposures to mice. The LCT(50) and LC50 values for 3, 6 and 12 h are progressively higher (toxicity lower) than predicted by either Haber's rule or the toxic load model.     

对氯苯氧异丁酸甲氧基苯丙烯酸酯的小鼠急性毒性和大鼠长期毒性

目的评价对氯苯氧异丁酸甲氧基苯丙烯酸酯(AZ)的安全性。方法 小鼠分别ig给予AZ3000～1001mg.kg-1或ip给予AZ1600～983mg.kg-1,观察14d,测定小鼠的半数致死量(LD50)。大鼠ig给予AZ500,291.7和166.7mg.kg-1(为临床拟用剂量的60倍、35倍和20倍),连续13周,停药2周后,观察大鼠一般状况、体质量增长、血液学、血液生化学和病理组织学等指标的变化。结果小鼠ig及ip给AZ的LD50分别为2053和1254mg.kg-1。大鼠给药13周后,AZ500mg.kg-1组血清转氨酶、尿素氮和肝系数升高(P<0.05),AZ291.7mg.kg-1组血清天冬氨酸转氨酶(AST)和肝系数升高(P<0.05),其他各组各指标与溶媒对照组相比均无显著性差异。病理组织学检查显示,AZ500mg.kg-1有1例肝组织炎细胞浸润,其余组大鼠未见与药物毒性相关的明显病变。停药2周后各异常指标均恢复正常。结论 AZ在规定剂量下使用应有较好的安全性。     

Cyst-based toxicity tests XIV--application of the ostracod solid-phase microbiotest for toxicity monitoring of river sediments in Flanders (Belgium)

In view of the need for rapid and low-cost solid-phase assays for contaminated sediments, a new 6-day "culture/maintenance-free" microbiotest has been developed with the freshwater ostracod crustacean Heterocypris incongruens at the Laboratory for Biological Research in Aquatic Pollution at the Ghent University in Belgium. The sensitivity of the Ostracodtoxkit F has been compared with that of the 10-day sediment contact test with the amphipod crustacean Hyalella azteca and the two pore water assays (on the anostracan crustacean Thamnocephalus platyurus and the microalgae Raphidocelis subcapitata) selected by the Flemish Environmental Agency for initial hazard assessment of contaminated sediments. The exercise was performed on 26 sediments collected at random from various rivers of the Flemish hydrographic basin in Belgium. The toxicity data ranged from nontoxic to highly toxic for the solid-phase assays and showed that the mortality of the two test biota varied from "nearly identical" to "substantially different," depending on the sediment. The correlation coefficient for the data pairs was weakly positive (r = 0.60), mainly because of 5 samples for which a low mortality had been noted with the ostracod versus a much higher mortality for the amphipod. However, for 4 out of the 5 samples of concern, a substantial growth inhibition was recorded for H. incongruens, showing that this assay eventually performed as did the amphipod test in detecting the toxic character of the sediments. The comparison of toxicity data of the two solid-phase assays with those of the two pore water tests again confirmed that both types of bioassay provided complementary (nonredundant) information. On the basis of its various advantages (independence of stock culturing/maintenance, user-friendliness, precision, and time and cost savings) the new ostracod microbiotest appears to be a promising tool for routine toxicity assessment of contaminated sediments.     

Responses of Chlorella vulgaris exposed to boron: Mechanisms of toxicity assessed by multiple endpoints

Boron (B) has been widely used and contaminated the aquatic ecosystem. However, knowledge of the effects of sodium pentaborate pentahydrate (SPP) on algae remains limited. This study aimed to assess SPP toxicity using multiple endpoints, specially detecting the intracellular metal ion concentrations, malondialdehyde (MDA) content and extracellular polymeric substance (EPS) classes for the very first time during SPP exposure to Chlorella vulgaris (C. vulgaris). Our findings indicated that the inhibitory effects of SPP on C. vulgaris may be related to nutrient absorption and utilization. The changes in intracellular starch grains, MDA and the protein-like substances in EPS probably acted as a defense mechanism, helping to alleviate the toxic effects. This work may contribute to the understanding of the mechanism of SPP toxicity in algae. Further studies may focus on the effects of B on speciation of metallic ions and the interaction of B with metallic ions on aquatic organisms.     

Combined Effects of Food Concentration and the Herbicide 2,4-Dichlorophenoxyacetic Acid on the Population Dynamics of Brachionus patulus (Rotifera)

Herbicides are important in crop protection and management. A number of them including 2,4-D (2,4-dichlorophenoxyacetic acid), however, may reach water bodies and eventually affect the non-target organisms such as rotifers. In the present work, we studied the influence of 6 concentrations viz. 0 (control), 100, 200, 300, 400 and 500 mg l^–1 of 2,4-D on the population growth of the rotifer Brachionus patulus under two algal (Chlorella) food levels (0.5×10⁶ and 1.5×10⁶ cells ml^{– 1}). Regardless of herbicide concentration, the population growth of B. patulus was dependent on the algal food levels, in that an increase in algal food level supported a better population growth. Similarly at any Chlorella density, the herbicide had a negative influence on the population growth of B. patulus. Herbicide level of 500 mg l^–1 inhibited population growth of B. patulus beyond 5 days. Rotifers grown under low food density and high herbicide concentration (300 mg l^–1 or above) were completely eliminated after day 15. The rate of population increase (r) (mean±standard error) in the controls varied from 0.46±0.002 and 0.55±0.004 under 0.5×10⁶ and 1.5×10⁶ cells ml^–1 of Chlorella, respectively. The r values became negative under both, low and high food levels, at or beyond 300 mg l^–1 of 2,4-D. The maximal population abundance (ind. ml^–1) in controls varied from 294±9 to 503±21 under low and high food levels of Chlorella, respectively. The role of algae in mitigating adverse effects of high herbicide concentrations to rotifers has been discussed.     

运用小鼠淋巴瘤细胞基因突变试验测定4,4′-二甲基二苯基碘鎓盐六氟磷酸盐的遗传毒性

目的研究运用小鼠淋巴瘤试验(MLA)对4,4′-二甲基二苯基碘鎓盐六氟磷酸盐(IHT-PI820)作为食品外包装上油墨使用安全性的评价。方法采用L5178Y细胞,处理3h,表达48h后测定突变细胞频率及小集落比例。同时进行添加和未添加代谢活化系统的试验,每个条件下设6个剂量组,阴性(二甲亚砜)、阳性(甲磺酸甲酯或环磷酰胺)对照组及IHT-PI8204个剂量组(37.5,75.0,150.0和300.0mg·L-1),在相同条件下,每组设定两个平行样。结果IHT-PI820各剂量组和阳性对照组的突变频率均显著性高于阴性对照组,并且IHT-PI820各剂量组间存在明确的剂量反应关系,小集落的比例也随剂量的升高呈上升趋势。结论IHT-PI820可以诱发小鼠淋巴瘤细胞Tk基因突变,故将其作为食品外包装上的油墨使用时,应严格按照相关的行业规定操作。     

运用小鼠淋巴瘤细胞基因突变试验测定4,4′-二甲基二苯基

目的研究运用小鼠淋巴瘤试验(MLA)对4,4′-二甲基二苯基碘鎓盐六氟磷酸盐(IHT-PI820)作为食品外包装上油墨使用安全性的评价。方法采用L5178Y细胞,处理3h,表达48h后测定突变细胞频率及小集落比例。同时进行添加和未添加代谢活化系统的试验,每个条件下设6个剂量组,阴性(二甲亚砜)、阳性(甲磺酸甲酯或环磷酰胺)对照组及IHT-PI8204个剂量组(37.5,75.0,150.0和300.0mg·L-1),在相同条件下,每组设定两个平行样。结果IHT-PI820各剂量组和阳性对照组的突变频率均显著性高于阴性对照组,并且IHT-PI820各剂量组间存在明确的剂量反应关系,小集落的比例也随剂量的升高呈上升趋势。结论IHT-PI820可以诱发小鼠淋巴瘤细胞Tk基因突变,故将其作为食品外包装上的油墨使用时,应严格按照相关的行业规定操作。     

A whole sample toxicity assessment to evaluate the sub-lethal toxicity of water and sediment elutriates from a lake exposed to diffuse pollution

The impact of diffuse pollution in aquatic systems is of great concern due to the difficult to measure and regulate it. As part of an ecological risk assessment (ERA), this study aims to use a whole sample toxicity assessment to evaluate the toxicity of water and sediment from Lake Vela, a lake that has been exposed to diffuse pollution. In this way, standard (algae: Pseudokirchneriella subcapitata; cladoceran: Daphnia magna) and local species (algae: Aphanizomenon flos-aquae; cladoceran: Daphnia longispina) were exposed to surface water, and sediment elutriates were collected seasonally from two sites at Lake Vela: one near the east bank (ES), surrounded by agricultural lands; and the other near the west bank (WS), surrounded by a forest. The results confirmed the seasonal contamination of both environmental compartments by pesticides, including organochlorine pesticides, and the presence of high concentrations of nutrients. Although both sites were contaminated, higher levels of pesticides and nutrients were detected in ES, particularly in the sediments. Bioassays showed that water samples (100% concentration) collected in summer and autumn significantly affected the growth rate of P. subcapitata, which could be attributed to the presence of pesticides. Likewise, they revealed an apparent toxicity of elutriates for P. subcapitata and for both daphnids, in summer and autumn. In fact, although pesticides were not detected in elutriates, high levels of un-ionized ammonia were recorded, which is considered highly toxic to aquatic life. By comparing the several species, P. subcapitata was revealed to be the most sensitive one, followed by the daphnids, and then by A. flos-aquae. Results obtained in this study underlined the importance of whole samples toxicity assessment for characterizing the ecological effects of complex mixtures from diffuse inputs, in the ERA processes.     

Comparison of the susceptibility of 22 freshwater species to 15 chemical compounds. I. (Sub)acute toxicity tests

The relative susceptibility of 22 taxonomically different species (bacteria, algae, protozoans, crustaceans, insects, coelenterates, molluscs, fishes and amphibians) to chemicals was determined by comparing the (sub)acute toxicity data of 15 test substances. Marked differences were observed in the susceptibility among the species with respect to the individual test compounds (up to a factor 9000). In contrast to this, differences were small (less than a factor 7) when the relative susceptibilities based on toxicity data on all compounds were taken into account. This tendency was also shown by comparing the susceptibilities based on quantitative structure-activity relationships. Thus, there is no such thing as the most susceptible species to chemicals. As the susceptibility of the species is highly pollutant-specific, at least a set of tests on different species will be required for toxicity screening. However, results indicated that a standard test combination with representative species of green algae, crustaceans and fishes failed to indicate the full toxic potential of chemicals. Since incorporation of a Microcystis aeruginosa test improved the combination in estimating acute toxic levels of chemicals, it is recommended to include this test in both national and international ecotoxicological testing programmes.     

Effect of temperature on heavy metal toxicity to earthworm Lumbricus terrestris (Annelida: Oligochaeta)

Earthworms (Lumbricus terrestris) acclimated at 2 degrees C above their habitat temperature (10-12 degrees C) showed about 5% increase in basal rate of oxygen consumption, which increased to about 38% in 14-16 degrees C- and 40% in 16-18 degrees C-, but decreased by 84% in 20-22 degrees C-acclimated worms. Temperature also increased the blood hemoglobin (Hb) concentration, which decreased slightly in 20-22 degrees C-acclimated worms. The worms acclimated at 20-22 degrees C showed their blood to be hypovolemic than that of 10-12 degrees C worms indicating dehydration. Pre-exposure of 10-14 degrees C-acclimated worms to sublethal concentrations of zinc, copper, and lead did not significantly affect the rate of respiration. However, at higher temperatures all these metals inhibited oxygen consumption; zinc, lead, and cadmium by approximately 11% and copper by approximately 18% of that at 14-16 degrees C. At 20-22 degrees C, the respiration was further inhibited, 36% by copper, 18% by cadmium, and approximately 10% by lead and zinc. Copper, lead, and zinc decreased the temperature-enhanced increase in blood Hb concentration at all temperatures. In 20-22 degrees C-acclimated worms heavy metal exposure slightly lowered the oxygen affinity of Hb as well as caused shifts in carbon monoxide difference spectra. The acute toxicity of these metals was not affected by a 2 degrees C rise in acclimation temperature but increased by 17% (lead), 33% (copper), and 5% (zinc) in 14-16 degrees C- and by 40% (lead), 149% (copper), and 132% (zinc) in 20-22 degrees C-acclimated worms. The increase in toxicity of metals caused by high temperatures may be due to limiting the scope of aerobic metabolism (oxygen extraction, transport, and utilization) via quantitative and qualitative effects on Hb. This terrestrial species appears to be tolerant of slight increases in habitat temperature, such as that expected with current global climate change.     

Effects of Mercury on the Life Table Demography of the Rotifer Brachionus calyciflorus Pallas (Rotifera)

Mercury is highly toxic to a variety of aquatic organisms including zooplankton. The functioning of freshwater ecosystems can be altered if rotifers, being a natural food link between phytoplankton and fish larvae, are contaminated by mercuric compounds. In order to detect age-specific responses of the rotifer Brachionus calyciflorus to mercury toxicity (5 nominal concentrations as chloride viz. 0, 0.000625, 0.00125, 0.0025 and 0.005 mg l(-1)), we used the standard life table method at two different food (Chlorella vulgaris) levels (0.5 x 10(6) and 1.5 x 10(6) cells ml(-1)). Data indicated that increase in mercury concentration had an increasingly intense negative effect on many of the life history variables, while at higher food levels, its impact was less. A nearly rectangular survivorship pattern was obtained in controls, especially at higher food levels. This trend gradually changed to a steep fall as the concentration of the heavy metal in the medium increased from 0 to 0.005 mg l(-1). At any given food density, increase in the mercury concentration resulted in decreased age-specific reproduction. A maximum of 3.5 offspring female(-1) was observed in controls at higher food density. The average lifespan varied from 6 to 8 days at low food level, depending on the heavy metal concentration in the medium. The corresponding values at high food level varied from 8 to 12 days. Regardless of mercury concentration in the medium, gross and net reproductive values varied from 10 to 33 and 4 to 19 offspring female(-1). The longest generation time (about 9 days) of B. calyciflorus was obtained at 1.5 x 10(6) cells ml(-1) food density in control, while the shortest was 5 days at low food level and high (0.005 mg l(-1)) mercury concentration in the medium. Depending on the food level and heavy metal concentration in the medium, the rate of population growth (r) varied from 0.32 to 0.62 d(-1). In general, higher food level resulted in higher r. Except generation time, all other derived variables were significantly influenced by food level and the heavy metal concentration in the medium.     

二乙氧基乙醇致小鼠睾丸和精子毒性恢复性研究

目的观察二乙氧基乙醇(2-Ethoxyethanol,2-EE)对小鼠睾丸和精子毒性作用的自然恢复情况,探索其可逆性,为安全性评价和职业健康危险评估提供科学依据。方法选择昆明种小鼠,分别给予剂量100、300和600 mg/kg的2-EE,连续灌胃35 d,观察其毒作用表现。停止染毒后继续饲养35 d,观察毒作用的自然恢复情况。空白对照组以等量生理盐水灌胃。结果染毒组睾丸脏器系数明显下降(0.32±0.08,P<0.01);睾丸生精细胞损伤、分化障碍和精子生成减少。附睾脏器系数、精子数量和精子活性明显下降(P<0.05),精子畸形率明显上升(P<0.05)。恢复组睾丸脏器系数明显回升(0.58±0.09,P<0.01);精子数量和精子活性明显回升(P<0.05),精子畸形率呈明显下降趋势(P<0.05);受损伤的睾丸及精子的各项指标基本恢复至对照组水平。结论2-EE所致的睾丸和精子毒性作用具有明显的可逆性,停止染毒后可以自然恢复到正常水平。     

Effect of temperature on heavy metal toxicity to juvenile crayfish, Orconectes immunis (Hagen)

The acute toxicity of four selected heavy metals to juvenile crayfish Orconectes immunis (Hagen) (1-2 g wet body wt. each) at room temperature increased in the following order: cadmium (x3) < copper (x10) < zinc (x2) < lead. The toxicity of these metals to crayfish acclimated at 17, 20, 23/24, and 27 degrees C increased with temperature (by 7-20% between 20 and 24 degrees C and 14-26% between 20 and 27 degrees C) as judged by the lowering of LT(50) (time to kill 50% of test animals at a fixed concentration) values. A 4 degrees C rise in temperature (from 20 to 24 degrees C), which increased the toxicity of copper by about 7%, increased the rate of oxygen consumption by about 34%. Heavy metals inhibited the rate of oxygen consumption at all temperatures. In 20 degrees C-acclimated crayfish, copper caused about 17% inhibition of oxygen consumption compared to about 7-12% by other metals including the most toxic cadmium. A 3-4 degrees C rise in temperature tripled the inhibitory effect of copper (20%), cadmium and zinc (26 and 18%, respectively), but not of lead, on oxygen consumption. A 7 degrees C-rise in temperature (from 20 to 27 degrees C) increased the inhibitory effect of heavy metals, including lead, on oxygen consumption by up to 54% in the case of copper. The data indicate that rising global temperatures (currently 0.60 degrees C) associated with climate change can have the potential to increase the sensitivity of aquatic animals to heavy metals in their environment.     

Developmental toxicity of polychlorinated biphenyls (PCBs): a systematic review of experimental data

Experimental reproductive and developmental toxicity studies with polychlorinated biphenyls (PCBs) are reviewed in brief to determine their relevance for current environmental exposure of humans during the prenatal and postnatal developmental periods. Additional material is published in electronic form only, which contains graphic overviews on individual PCBs and various mixtures that are linked with the relevant citations. In this comprehensive article we focus on interactions of PCBs with biological substrates that could mediate adverse effects observed in experimental animals and in children, and the shortcomings of many of the animal studies available. A main point of criticism involves the relative lack of animal data on several of those persistent congeners, either as individual compounds or as environmentally relevant mixtures, which are currently used as a measure of human exposure. Experimental studies in animals are frequently conducted with commercial PCB mixtures, a test design that does not reflect the exposure situation in humans. Important improvements of animal experiments could be achieved by more complete reporting of litter data (pre- and post-natal losses, toxic signs in the dam and the offspring, birth weights and postnatal growth data), the inclusion of endpoints that have been found previously to be affected by PCBs, and measurements of internal exposure data.An erratum to this article can be found at