基于PBPK模型评价三氯乙烯的职业暴露健康风险

三氯乙烯(TCE)作为脱脂和清洗剂被广泛应用于五金、电镀和电子等行业。TCE的职业暴露会产生一系列健康风险,包括过敏症和致癌等。2012年TCE被美国环保局(US EPA)和国际癌症研究机构列为1类致癌物。采用吸附管采样-热脱附/气相色谱-质谱法分析了大连市某企业车间生产工况下空气中TCE浓度。基于生理学的药代动力学(PBPK)模型预测了呼吸暴露途径下TCE在职业工人体内组织中的动态分布、代谢产物生成情况和致癌风险。TCE在不同组织中预测的最大浓度呈现出脂肪肠充分灌注室支气管非充分灌注室肝脏静脉血动脉血的趋势。预测的与致癌有关的代谢产物最大浓度表现为三氯乙酸二氯乙酸三氯乙醛S-二氯乙烯基-L-半胱氨酸。在监测的TCE水平(39.2±24.4)μg·m-3下,暴露8 h·d-1,连续暴露20年,基于外暴露评价的职业工人致癌风险均值为1.31×10-5,该暴露水平下,基于PBPK模型预测的TCE内暴露与外暴露计算的致癌风险水平相近,但基于具有致癌性主要代谢产物的内暴露致癌风险值是外暴露风险值的1.17～1.73倍。TCE的暴露水平越高,基于内暴露方法和外暴露方法的致癌风险评价结果差异越大。敏感性分析表明,心输出血流量和充分灌注室血流量对PBPK模型输出结果具有重要影响。不确定性分析表明,模型参数变化会显著地影响PBPK模型输出结果,但变异在可接受水平。本研究结果说明,评价TCE暴露对人的致癌风险需要考虑其在体内的分布和代谢过程。     

偏钒酸铵对小鼠血清和肝脏转氨酶活力的影响

为了考察偏钒酸铵对小鼠血清和肝脏转氨酶活力的影响,50只小鼠随机分为5组,对照组饮用三重蒸馏水,4个暴露组分别饮用剂量为5、10、15和20 mg·kg-1·d-1的偏钒酸铵,15 d后取血和肝脏样品,测定血清和肝脏中谷丙转氨酶(alanine transaminase,ALT)和谷草转氨酶(aspartate ami...     

生理毒代动力学模型及其在有机污染物水生生态毒理研究中的应用

人类生产和生活使用各种人工合成的化学品,种类和数量急剧增长,对生态系统和人体健康造成了极大威胁。因此,亟需采用高效的方法对数量巨大的化合物进行毒性评价。对生理毒代动力学(PBTK)模型的建立过程及其在污染物生态毒理研究中的应用进行了综述。PBTK模型,又称生理药代动力学(PBPK)模型,是利用生理学和解剖学等原理,将生物体简化为用血流连接的肝、肾和脂肪等各组织器官房室,模拟化合物在生物体内的吸收、分布、代谢和排泄过程。模型参数包括生理参数和生化参数2个部分,可用MATLAB等软件进行模拟。模型已应用于数百余种有机污染物在鱼体等水生生物体的毒代动力学模拟。已有模拟结果能够预测化合物在生物体内的有效剂量,对化合物毒性进行评估,并可用于不同物种、不同剂量和不同暴露途径间的外推,有力推进了污染物生态毒理研究工作的开展。     

两种除草剂对蚯蚓的急性毒性及氧化胁迫效应

为评价两种常用除草剂草甘膦和精喹禾灵对土壤动物的影响,以赤子爱胜蚓(Eisenia fetida)为受试生物,采用滤纸接触法和人工土壤法测定了两种除草剂的急性毒性效应。并通过人工土壤染毒法研究了两种除草剂对蚯蚓体内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性和丙二醛(MDA)含量的影响。结果表明,滤纸法染毒48 h,草甘膦和精喹禾灵对蚯蚓为低毒级,其LC50值分别为546.4和638.7μg·cm-2;人工土壤法染毒14 d,草甘膦和精喹禾灵对蚯蚓的LC50值分别为321.4和392.3 mg·kg-1,属低毒级。氧化胁迫试验结果表明,较低浓度草甘膦(≤4 mg·kg-1)和精喹禾灵(≤10 mg·kg-1)对蚯蚓体内抗氧化酶活性影响不显著,而40和80 mg·kg-1草甘膦在暴露7 d内对SOD、CAT和POD活性影响显著,表现为SOD活性显著提高,CAT和POD活性分别呈现降低-提高和提高-降低的变化趋势。暴露7 d内,100 mg·kg-1精喹禾灵对蚯蚓SOD活性表现为先刺激后抑制的变化趋势,CAT和POD活性显著提高。和对照相比,草甘膦污染土壤中蚯蚓体内MDA含量变化不显著,而高浓度精喹禾灵(100 mg·kg-1)污染土壤中,第7和14天时蚯蚓体内MDA含量显著提高。暴露14 d后,草甘膦和精喹禾灵对蚯蚓的氧化胁迫基本消失,说明供试浓度范围内草甘膦和精喹禾灵不会对蚯蚓造成严重的氧化损伤。与急性毒性结果相比,氧化胁迫效应更为敏感,可作为该两种除草剂对土壤生态影响早期预警中的生物标志物。     

乙酰柠檬酸三丁酯围产期暴露对子代小鼠认知能力的影响

研究不同剂量的增塑剂乙酰柠檬酸三丁酯(acetyl tributyl citrate,ATBC)围产期暴露对子代小鼠认知能力的影响及其机制.以C57BL/6小鼠为受试动物,小鼠合笼后,对受孕雌性小鼠进行随机分组,设置对照组、ATBC暴露组(2、20和200 mg·kg-1·d-1),在围产期每天进行灌胃暴露.通过Morris水迷宫实验和跳台实验对子代小鼠的认知能力进行检测,观察子代小鼠脑组织病理变化及胶质细胞激活情况.检测子代小鼠脑组织匀浆中神经递质5-羟基色胺(5-hydroxytryptamine,5-HT)、乙酰胆碱(acetylcholine,ACh)、活性氧(reactive oxygen species,ROS)、丙二醛(malondialdehyde,MDA)和还原型谷胱甘肽(glutathione,GSH)、超氧化物歧化酶(superoxide dismutase,SOD)等的含量或活性以及肿瘤坏死因子α(tumor necrosis factor α,TNF-α)、白介素17(interleukin-17)的水平.结果 显示,200 mg·kg-1 ·d-1的ATBC围产期暴露会导致子代小鼠认知能力下降,脑海马结构出现改变,胶质细胞活化程度增大,脑组织氧化应激水平上升,促炎症因子TNF-α和IL-17含量增加.研究表明,200 mg· kg-1·d-1 ATBC围产期暴露可引起子代小鼠脑组织氧化应激,进而导致其认知能力下降.     

基于PBPK模型的大鼠体内镉分布的比较:联合暴露及单独暴露

环境中同时存在着多种重金属元素,联合暴露与单独暴露时,重金属在体内的蓄积分布情况也可能有所差异。为探究重金属元素(汞、铬、砷、铅)对镉(Cd)在体内分布的影响,建立了大鼠在Cd暴露下的药代动力学(PBPK)模型,并进行了包括Cd在内5种重金属的联合毒性实验,比较了Cd单独给药与重金属混合物给药2种方式下大鼠肝脏、肾脏中的Cd浓度水平。结果表明,联合暴露高(Hg Cl23.67 mg·kg~(-1),NaAsO_2 3.67 mg·kg~(-1),CdCl_2 10.55 mg·kg~(-1),K_2Cr_2O_7 6.40 mg·kg~(-1),Pb(OOCCH_3)_2·3H_2O 133.33 mg·kg~(-1))、中(HgCl_20.367 mg·kg~(-1),NaAsO_2 0.367 mg·kg~(-1),CdCl_2 1.055 mg·kg~(-1),K2Cr2O70.640 mg·kg~(-1),Pb(OOCCH_3)_2·3H_2O 13.333 mg·kg~(-1))、低(HgCl_2 0.0367 mg·kg~(-1),Na As O20.0367 mg·kg~(-1),Cd Cl20.1055 mg·kg~(-1),K_2Cr_2O_7 0.0640 mg·kg~(-1),Pb(OOCCH3)2·3H2O 1.3333 mg·kg~(-1))剂量组大鼠肝脏中Cd浓度分别为13.37、0.78和0.06μg·g~(-1);肾脏中Cd浓度分别为14.41、1.64和0.15μg·g~(-1)。与对照组相比,暴露组中Cd浓度有显著升高,且不同剂量组之间均有显著性差异。同剂量Cd单独暴露的PBPK模拟结果显示,肝脏及肾脏中的Cd浓度水平落在联合毒性实验结果的浓度范围内,初步推断其他4种重金属的联合暴露并没有影响Cd在大鼠肾脏和肝脏中的浓度分布。     

苯急性暴露对Sprague-Dawley大鼠全基因组DNA甲基化的影响

现有文献表明,DNA甲基化异常与肿瘤的发生密切相关,其中全基因组DNA甲基化水平的改变已经被认为是癌症发生的生物标志物;同时,大量遗传毒理学实验证明苯可以引起DNA突变和断裂,然而苯暴露引起全基因组DNA甲基化异常的现象,目前鲜有文献报道。为了揭示苯引起全基因组DNA甲基化变化的致毒机制,本实验中,Sprague-Dawley（SD）雄性大鼠经口灌胃急性暴露于以500 mg.kg-1（以体质量计）的苯中,在暴露6、12、24、30 h后采集SD雄性大鼠体内血液、肝脏、肾脏和肺,利用高效液相色谱分析方法检测全基因组DNA甲基化水平。结果表明,SD雄性大鼠血液和肝脏的全基因组DNA甲基化水平显著下降,而在肾脏和肺中没有显著地变化,表现出组织特异性。本实验率先报道了苯的暴露可以引起全基因组DNA甲基化水平的异常,从表观遗传学的角度解释了苯影响人体健康的机制。     

近红外长余辉纳米颗粒经小鼠眼部暴露后体内分布和代谢情况

为了研究纳米颗粒通过眼部暴露后进入体内的路径及在体内的分布和代谢情况,实验采用近红外长余辉纳米探针作为示踪剂,对小鼠进行眼部暴露,随后利用活体成像技术观察其进入小鼠体内的过程及分布情况,于暴露第4天收集代谢产物,第7天取重要脏器和血液,并检测纳米探针的存在情况.结果显示纳米探针可由眼经口腔进入胃肠道中,并且纳米颗粒暴露4天后在小鼠的粪便中检测到强荧光信号,而尿液中的荧光信号较弱,暴露7 d后在小鼠的眼睑结膜、胃及眼球中检测到强荧光信号,而其余器官的荧光信号较弱.这表明通过眼部暴露后,纳米颗粒主要分布在眼和消化系统中,最后大部分经消化系统代谢.     

铅暴露与排放对中华鲟幼鱼血液中ALT、AST活力的影响

采用水溶液静态置换法,从中华鲟(Acipenser sinensis)受精卵发育至96 h开始,研究了其在0(对照组)、0.2、0.8和1.6mg·L~(-1) Pb~(2+)水溶液中暴露16周,随后排放6周,对中华鲟幼鱼血液中ALT、AST活力的影响.结果显示:Pb暴露后幼鱼血液中的ALT和AST活力均表现为随Pb暴露剂量增加而升高的趋势,1.6mg·L~(-1)组ALT活力与其它各组比较呈极显著差异(P<0.01);0.8和1.6mg·L~(-1)组AST活力与对照组比较分别呈显著差异(P<0.05)和极显著差异(P<0.01). Pb排放后,各暴露组血液中ALT活力降低至对照组水平(P>0.05);1.6 mg·L~(-1)组的AST活力依然较高.超出对照组近2倍(P<0.01).对照组血液的AST/ALT值在2.24～2.32之间;随Pb质量浓度增加,暴露后AST/ALT值呈增加趋势.Pb排放后AST/ALT值降低,但1.6 mg·L~(-1)组与其余各组比较仍维持较高值(P<0.05).初步认为,0.2 mg·L~(-1)和0.8 mg·L~(-1) Pb~(2+)暴露导致中华鲟幼鱼肝细胞不同程度受损,经Pb排放后,轻度受损的组织细胞能够恢复.血液中的AST/ALT值在判断鱼类组织损伤中也具有重要意义.     

4-硝基酚对大鼠肝脏的毒性及氧化损伤

研究环境内分泌干扰物4-硝基酚(4-nitrophenol,PNP)对大鼠肝脏功能的毒性作用及其对核因子相关因子-2(Nrf2)通路的影响.20只SD雄性大鼠随机分成4个组,分别为对照组、1、10和100 mg·kg-1体重PNP处理组,连续皮下注射28d,检测肝脏的结构变化、氧化损伤和Nrf2及其相关基因的表达情况.结果表明,与对照组相比,100 mg·kg-1PNP处理组大鼠的血清肝功能主要指标ALT、AST、AKP活性和TBIL含量显著性升高p＜005);100 mg·kg-1组肝脏GSH-PX、CAT和SOD活性显著性降低p＜005);大鼠肝脏中Nrf2及其下游基因NQOI和HO-1 mRNA表达水平在1mg·kg-1组显著升高(p＜0.05),10、100 mg·kg-1组有升高趋势;100 mg ·kg-1组肝脏显微和超微结构都发现有不同程度的损伤.结果提示,皮下注射1 mg·kg-1 PNP引起了大鼠肝脏氧化损伤,机体可能通过提高Nrf2及其相关基因mRNA的表达水平来抵抗PNP引起的肝脏损伤;皮下注射100 mg·kg-1 PNP改变了肝脏的正常生理功能,造成肝细胞超微结构病理损伤,引起肝脏毒性.     

Achieving Open Access to Conservation Science

Conservation science is a crisis discipline in which the results of scientific enquiry must be made available quickly to those implementing management. We assessed the extent to which scientific research published since the year 2000 in 20 conservation science journals is publicly available. Of the 19,207 papers published, 1,667 (8.68%) are freely downloadable from an official repository. Moreover, only 938 papers (4.88%) meet the standard definition of open access in which material can be freely reused providing attribution to the authors is given. This compares poorly with a comparable set of 20 evolutionary biology journals, where 31.93% of papers are freely downloadable and 7.49% are open access. Seventeen of the 20 conservation journals offer an open access option, but fewer than 5% of the papers are available through open access. The cost of accessing the full body of conservation science runs into tens of thousands of dollars per year for institutional subscribers, and many conservation practitioners cannot access pay‐per‐view science through their workplace. However, important initiatives such as Research4Life are making science available to organizations in developing countries. We urge authors of conservation science to pay for open access on a per‐article basis or to choose publication in open access journals, taking care to ensure the license allows reuse for any purpose providing attribution is given. Currently, it would cost $51 million to make all conservation science published since 2000 freely available by paying the open access fees currently levied to authors. Publishers of conservation journals might consider more cost effective models for open access and conservation‐oriented organizations running journals could consider a broader range of options for open access to nonmembers such as sponsorship of open access via membership fees. Obtención de Acceso Abierto a la Ciencia de la Conservación     

Some polyphagous Homoptera gain protection from their natural enemies by feeding on the toxic plantsSpartium junceum andErythrina corallodendrum (Leguminosae)

Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.     

Rapid,recurring, structured survey versus bioblitz for generating biodiversity data and analysis with a multispecies abundance model

A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.     

Compliance with and ecosystem function of biodiversity offsets in North American and European freshwaters

Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.     

Sequestration of cucurbitacin analogs by New and Old World chrysomelid leaf beetles in the tribe Luperini

Summary Two South American polyphagous leaf beetles,Diabrotica speciosa andCerotoma arcuata, selectively accumulated the bitter tasting compound 23,24-dihydrocucurbitacin D in their body after ingesting root tissues of cucurbit plants. Similarly, three Asian Cucurbitaceae-feeding specialists in the genusAulacophora were found to sequester the same compound. Cucurbitacin analogs were shown to deter feeding by a bird predator, indicating an allomonal role for these compounds in cucurbitacin-associated chrysomelid leaf beetles both of New and Old Worlds. The strong affinity to cucurbitacins, selective sequestration of the analogs and consequent protection from predators suggested an ecological adaptation mechanism developed in common among these two geographically isolated subtribes in the Luperini.     

Effects of Controlled Fire and Livestock Grazing on Bird Communities in East African Savannas

Abstract: In East Africa fire and grazing by wild and domestic ungulates maintain savannas, and pastoralists historically set fires and herded livestock through the use of temporary corrals called bomas. In recent decades traditional pastoral practices have declined, and this may be affecting biodiversity. We investigated the effects of prescribed fires and bomas on savanna bird communities in East Africa during the first and second dry seasons of the year (respectively before and after the rains that mark the onset of breeding for most birds). We compared abundance, richness, and community composition on 9‐ha burned plots, recently abandoned bomas, and control plots in the undisturbed matrix habitat over a 3‐year period. Generally, recently burned areas and abandoned bomas attracted greater densities of birds and had different community assemblages than the surrounding matrix. The effects of disturbances were influenced by interactions between primary productivity, represented by the normalized difference vegetation index, and time. Bird densities were highest and a greater proportion of species was observed on burned plots in the months following the fires. Drought conditions equalized bird densities across treatments within 1 year, and individuals from a greater proportion of species were more commonly observed on abandoned bomas. Yearly fluctuations in abundance were less pronounced on bomas than on burns, which indicate that although fire may benefit birds in the short term, bomas may have a more‐lasting positive effect and provide resources during droughts. Several Palearctic migrants were attracted to burned plots regardless of rainfall, which indicates continued fire suppression may threaten their already‐declining populations. Most notably, the paucity of birds observed on the controls suggests that the current structure of the matrix developed as a result of fire suppression. Traditional pastoralism appears critical to the maintenance of avian diversity in these savannas.     

A palaeo-hydrogeological model for arsenic contamination in southern and south-east Asia

An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.     

Threats to intact tropical peatlands and opportunities for their conservation

Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.     

What Every Conservation Biologist Should Know about Economic Theory

Abstract: The last century has seen the ascendance of a core economic model, which we will refer to as Walrasian economics. This model is driven by the psychological assumptions that humans act only in a self‐referential and narrowly rational way and that production can be described as a self‐contained circular flow between firms and households. These assumptions have critical implications for the way economics is used to inform conservation biology. Yet the Walrasian model is inconsistent with a large body of empirical evidence about actual human behavior, and it violates a number of basic physical laws. Research in behavioral science and neuroscience shows that humans are uniquely social animals and not self‐centered rational economic beings. Economic production is subject to physical laws including the laws of thermodynamics and mass balance. In addition, some contemporary economic theory, spurred by exciting new research in human behavior and a wealth of data about the negative global impact of the human economy on natural systems, is moving toward a world view that places consumption and production squarely in its behavioral and biophysical context. We argue that abandoning the straightjacket of the Walrasian core is essential to further progress in understanding the complex, coupled interactions between the human economy and the natural world. We call for a new framework for economic theory and policy that is consistent with observed human behavior, recognizes the complex and frequently irreversible interaction between human and natural systems, and directly confronts the cumulative negative effects of the human economy on the Earth's life support systems. Biophysical economics and ecological economics are two emerging economic frameworks in this movement.