Concentrations of dialkyl phosphate metabolites of organophosphorus pesticides in the U.S. population

We report population-based concentrations, stratified by age, sex, and racial/ethnic groups, of dialkyl phosphate (DAP) metabolites of multiple organophosphorus pesticides. We measured dimethylphosphate (DMP), dimethylthiophosphate (DMTP), dimethyldithiophosphate (DMDTP), diethylphosphate (DEP), diethylthiophosphate (DETP), and diethyldithiophosphate (DEDTP) concentrations in 1,949 urine samples collected in U.S. residents 6-59 years of age during 1999 and 2000 as a part of the ongoing National Health and Nutrition Examination Survey (NHANES). We detected each DAP metabolite in more than 50% of the samples, with DEP being detected most frequently (71%) at a limit of detection of 0.2 microg/L. The geometric means for the metabolites detected in more than 60% of the samples were 1.85 microg/L for DMTP and 1.04 microg/L for DEP. The 95th percentiles for each metabolite were DMP, 13 microg/L; DMTP, 46 microg/L; DMDTP, 19 micro g/L; DEP, 13 microg/L; DETP, 2.2 microg/L; and DEDTP, 0.87 microg/L. We determined the molar sums of the dimethyl-containing and diethyl-containing metabolites; their geometric mean concentrations were 49.4 and 10.5 nmol/L, respectively, and their 95th percentiles were 583 and 108 nmol/L, respectively. These data are also presented as creatinine-adjusted concentrations. Multivariate analyses showed concentrations of DAPs in children 6-11 years of age that were consistently significantly higher than in adults and often higher than in adolescents. Although the concentrations between sexes and among racial/ethnic groups varied, no significant differences were observed. These data will be important in evaluating the impact of organophosphorus pesticide exposure in the U.S. population and the effectiveness of regulatory actions.     

A revised method for determination of dialkylphosphate levels in human urine by solid-phase extraction and liquid chromatography with tandem mass spectrometry: application to human urine samples from Japanese children

Objectives

Biological monitoring of organophosphorus insecticide (OP) metabolites, specifically dialkylphosphates (DAP) in urine, plays a key role in low-level exposure assessment of OP in individuals. The aims of this study are to develop a simple and sensitive method for determining four urinary DAPs using high-performance liquid chromatography with tandem mass spectrometry (LC–MS/MS), and to assess the concentration range of urinary DAP in Japanese children.

Methods

Deuterium-labeled DAPs were used as internal standards. Urinary dimethylphosphate (DMP) and diethylphosphate (DEP), which passed through the solid-phase extraction (SPE) column, and dimethylthiophosphate (DMTP) and diethylthiophosphate (DETP), which were extracted from a SPE column using 2.5 % NH₃ water including 50 % acetonitrile, were prepared for separation analysis. The samples were then injected into LC–MS/MS. The optimized method was applied to spot urine samples from 3-year-old children (109 males and 116 females) living in Aichi Prefecture in Japan.

Results

Results from the validation study demonstrated good within- and between-run precisions (<10.7 %) with low detection limits (0.4 for DMP and DMTP, 0.2 for DEP and 0.1 μg/L for DETP). The geometric mean values and detection rates of the urinary DAPs in Japanese children were 14.4 μg/L and 100 % for DMP, 5.3 μg/L and 98 % for DMTP, 5.5 μg/L and 99 % for DEP, and 0.6 μg/L and 80 % for DETP, respectively.

Conclusions

The present high-throughput method is simple and reliable, and can thereby further contribute to development of an exposure assessment of OP. The present study is the first to reveal the DAP concentrations in young Japanese children.     

Temporal association of children's pesticide exposure and agricultural spraying: report of a longitudinal biological monitoring study

We measured organophosphorus (OP) pesticide exposures of young children living in an agricultural community over an entire year and evaluated the impact of agricultural spraying on exposure. We also examined the roles of age, sex, parental occupation, and residential proximity to fields. We recruited 44 children (2-5 years old) through a Women, Infants, and Children clinic. We collected urine samples on a biweekly basis over a 21-month period. Each child provided at least 16 urine samples, and most provided 26. We analyzed samples for the dialkylphosphate (DAP) metabolites common to the OP pesticides. DAP concentrations were elevated in months when OP pesticides were sprayed in the region's orchards. The geometric means of dimethyl and diethyl DAPs during spray months were higher than those during nonspray months (p = 0.009 for dimethyl; p = 0.018 for diethyl). Dimethyl DAP geometric means were 0.1 and 0.07 micro mol/L for spray months and nonspray months, respectively (57% difference); diethyl DAP geometric means were 0.49 and 0.35, respectively (40% difference). We also observed differences for sex of the child, with male levels higher than female levels (p = 0.005 for dimethyl; p = 0.046 for diethyl). We observed no differences due to age, parental occupation, or residential proximity to fields. This study reports for the first time the temporal pattern of pesticide exposures over the course of a full year and indicates that pesticide spraying in an agricultural region can increase children's exposure in the absence of parental work contact with pesticides or residential proximity to pesticide-treated farmland.     

Biological monitoring survey of organophosphorus pesticide exposure among pre-school children in the Seattle metropolitan area

In this study we assessed organophosphorus (OP) pesticide exposure among children living in two Seattle metropolitan area communities by measuring urinary metabolites, and identified possible exposure risk factors through a parental interview. We recruited children in clinic and outpatient waiting rooms. We obtained spot urine samples in the spring and fall of 1998 from 110 children ages 2-5 years, from 96 households. We analyzed urine samples for six dialkylphosphate (DAP) compounds, the common metabolites of the OP pesticides. Through parental interviews we gathered demographic and residential pesticide use data. At least one of the DAP metabolites was measured in 99% of the children, and the two predominant metabolites (DMTP and DETP) were measured in 70-75% of the children. We found no significant differences in DAP concentrations related to season, community, sex, age, family income, or housing type. Median concentrations of dimethyl and diethyl DAPs were 0.11 and 0.04 micromol/L, respectively (all children). Concentrations were significantly higher in children whose parents reported pesticide use in the garden (0.19 vs. 0.09 micromol/L for dimethyl metabolites, p = 0.05; 0.04 vs. 0.03 micromol/L for diethyl metabolites, p = 0.02), but were not different based on reported pet treatment or indoor residential use. Nearly all children in this study had measurable levels of OP pesticide metabolites. Some of this exposure was likely due to diet. Garden pesticide use was associated with elevated metabolite levels. It is unlikely that these exposure levels would cause acute intoxication, but the long-term health effects of such exposures are unknown. We recommend that OP pesticide use be avoided in areas where children are likely to play.     

沈阳市产妇孕期有机磷农药暴露水平及其影响因素

目的 探讨沈阳市产妇孕期有机磷农药（OPs）暴露水平及相关影响因素,为今后采取健康干预措施提供依据。方法 采用现况调查方法,以2011年3月-2012年3月于沈阳医学院附属中心医院分娩的健康产妇为研究对象,调查其孕期OPs接触情况,收集产妇孕期尿样,采用气相色谱法测定体内有机磷农药5种非特异性代谢产物二烷基磷酸酯类化合物（DAPs）的浓度。结果 249名产妇尿液中5种代谢产物检出率分别为：磷酸二甲酯（DMP）95.6%、二甲基硫代磷酸酯（DMTP）93.6%、磷酸二乙酯（DEP）95.6%、二乙基硫代磷酸酯（DETP）88.8%、二乙基二硫代磷酸酯（DEDTP）6.8%;其几何均数分别为：DMP 13.78 μg/L、DMTP 6.50 μg/L、DEP 5.56 μg/L、DETP 4.00 μg/L、DEDTP来计算;单因素分析比较不同特征产妇尿中OPs代谢产物,≥30岁产妇体内二甲基类代谢产物（DMs）浓度水平高于<30岁组（P<0.05）;家庭内从不使用杀虫剂的产妇体内DMs和DAPs水平均低于偶尔和经常使用杀虫剂的产妇（P<0.05）。多元逐步线性回归分析表明,居住在郊区、年龄越大、家庭杀虫剂使用频率越高的产妇体内DAPs水平越高（P<0.05）。结论 沈阳地区产妇孕期OPs暴露水平较高,且其体内OPs代谢产物水平可能与产妇年龄、居住地和孕期家庭室内杀虫剂使用频率等因素相关。     

Urinary metabolite concentrations of organophosphorous pesticides, bisphenol A, and phthalates among pregnant women in Rotterdam, the Netherlands: the Generation R study

Concern about potential health impacts of low-level exposures to organophosphorus (OP) pesticides, bisphenol A (BPA), and phthalates among the general population is increasing. We measured levels of six dialkyl phosphate (DAP) metabolites of OP pesticides, a chlorpyrifos-specific metabolite (3,5,6-trichloro-2-pyridinol, TCPy), BPA, and 14 phthalate metabolites in urine samples of 100 pregnant women from the Generation R study, the Netherlands. The unadjusted and creatinine-adjusted concentrations were reported, and compared to National Health and Nutrition Examination Survey and other studies. In general, these metabolites were detectable in the urine of the women from the Generation R study and compared with other groups, they had relatively high-level exposures to OP pesticides and several phthalates but similar exposure to BPA. The median concentrations of total dimethyl (DM) metabolites was 264.0 nmol/g creatinine (Cr) and of total DAP was 316.0 nmol/g Cr. The median concentration of mono-ethyl phthalate (MEP) was 222.0 μg/g Cr; the median concentrations of mono-isobutyl phthalate (MiBP) and mono-n-butyl phthalate (MnBP) were above 50 μg/g Cr. The median concentrations of the three secondary metabolites of di-2-ethylhexyl phthalate (DEHP) were greater than 20 μg/g Cr. The data indicate that the Generation R study population provides a wide distribution of selected environmental exposures. Reasons for the relatively high levels and possible health effects need investigation.     

液液萃取-气相色谱质谱法测定饮用水中19种有机磷农药

目的:建立测定饮用水中19种有机磷农药(治螟磷,甲拌磷,内吸磷,二嗪磷,乙拌磷,异稻瘟净,氧化乐果,甲基对硫磷,皮蝇磷,甲基嘧啶磷,杀螟硫磷,马拉硫磷,毒死蜱,倍硫磷,对硫磷,久效磷,溴硫磷,甲基异柳磷,稻丰散)液液萃取-气相色谱质谱(GC-MS)检测方法。方法:二氯甲烷液液萃取(LLE)水样后,浓缩提取液至1 ml后,采用气相色谱-质谱(GC-MS)的选择离子监测(SIM)模式同时定性定量分析。结果:19种有机磷农药的峰面积与其浓度均有良好的线性关系,相关系数均大于0.998;最小检测量为0.14μg/L～0.64μg/L;样品加标回收率为85.2%～97.9%,相对标准偏差为1.9%～9.8%。结论:该方法可对饮用水中有机磷农药同时定量与定性,具有方法简便、准确、可靠等优点。     

全自动固相萃取LC/MS/MS测定水中6种有机磷农药

目的建立水中6种有机磷农药的检测方法。方法利用全自动固相萃取前处理技术,液相色谱串联质谱的方法,选择最佳的仪器条件,同时测定水中6种有机磷农药。结果 6种有机磷农药类线性关系较好,相关系数大于0.999,方法检出限在0.16～63.8 ng/L之间,回收率在84%～117%之间,相对标准偏差小于14%。结论本实验所建立的方法灵敏度好,选择性好,准确度高。     

液相色谱串联质谱法定量检测尿中有机磷农药代谢物

目的建立了液相色谱串联质谱(LC-MS/MS)法测定尿中二乙基磷酸酯、二硫代磷酸二甲酯、二硫代磷酸二乙酯、4-硝基酚、3-氯-4-甲基-7-羟基香豆素和TCPY 6种有机磷农药代谢物含量的方法。方法尿样中加入酶解液,37℃水浴4h后经oasis HLB柱固相萃取,用甲醇洗脱后离心浓缩,乙腈定容;以乙酸铵做缓冲溶液,乙腈和水为流动相等梯度洗脱,经Waters Symmetry C185μm(2.1mm×150mmcolumn)分离,经在线电喷雾离子源(ESI)负离子化后,采用多反应离子监测方式(MRM)选择离子对测定。结果目标化合物的线性范围为0～1000ng/ml,6种化合物的相关系数有5种大于0.990,加标回收率在79%～130%之间,RSD<8.2%;日内、日间相对标准偏差小于15%(n=6)。结论该方法样品采集简单,特异性强,能准确、高效地检测尿样中有机磷农药代谢物。     

Assessment of long-term subacute exposure to dimethoate by hair analysis of dialkyl phosphates DMP and DMTP in exposed rabbits: The effects of dose, dose duration and hair colour

Hair analysis for dialkyl phosphates’ (DAPs) residues could provide a measure of chronic exposure to organophosphate pesticides (OPs). The aim of this study was to determine whether these metabolites can be internally incorporated into the hair of rabbits exposed to dimethoate and also to investigate the influence of dose and dose duration of this OP, as well as the effect of hair colour on the concentrations of its DAPs in hair. Two-coloured rabbits were daily exposed to dimethoate (0, 12 or 24 mg kg⁻¹ body weight) via their drinking water. Hair samples of both colours were obtained 4 and 6 months after the beginning of exposure from the back of all treated rabbits, and each hair colour sample was analyzed for dimethyl phosphate (DMP) and dimethyl thiophosphate (DMTP) by gas chromatography-mass spectrometry (GC-MS). Analysis revealed the incorporation of these metabolites into the rabbit hair in a dose-dependent manner. The mean concentrations found ranged from 0.18 to 0.77 ng mg⁻¹ for DMP and from 0.43 to 1.53 ng mg⁻¹ for DMTP. Mixed results for the significance of the relationship between dose duration and the levels of the two DAPs in hair are observed. Hair pigmentation does not appear to affect the concentration values of DMTP, whereas it seems to be a critical factor in the incorporation of DMP into hair. These data confirm the ability of hair testing to assess chronic OP exposure by the detection of DAPs.     

Evaluation of take-home organophosphorus pesticide exposure among agricultural workers and their children

We analyzed organophosphorus pesticide exposure in 218 farm worker households in agricultural communities in Washington State to investigate the take-home pathway of pesticide exposure and to establish baseline exposure levels for a community intervention project. House dust samples (n = 156) were collected from within the homes, and vehicle dust samples (n = 190) were collected from the vehicles used by the farm workers to commute to and from work. Urine samples were obtained from a farm worker (n = 213) and a young child (n = 211) in each household. Dust samples were analyzed for six pesticides, and urine samples were analyzed for five dialkylphosphate (DAP) metabolites. Azinphosmethyl was detected in higher concentrations (p < 0.0001) than the other pesticides: geometric mean concentrations of azinphosmethyl were 0.53 micro g/g in house dust and 0.75 micro g/g in vehicle dust. Dimethyl DAP metabolite concentrations were higher than diethyl DAP metabolite concentrations in both child and adult urine (p < 0.0001). Geometric mean dimethyl DAP concentrations were 0.13 micro mol/L in adult urine and 0.09 micro mol/L in child urine. Creatinine-adjusted geometric mean dimethyl DAP concentrations were 0.09 micro mol/g in adult urine and 0.14 micro mol/g in child urine. Azinphosmethyl concentrations in house dust and vehicle dust from the same household were significantly associated (r2 = 0.41, p < 0.0001). Dimethyl DAP levels in child and adult urine from the same household were also significantly associated (r2 = 0.18, p < 0.0001), and this association remained when the values were creatinine adjusted. The results of this work support the hypothesis that the take-home exposure pathway contributes to residential pesticide contamination in agricultural homes where young children are present.     

Method for determination of acephate, methamidophos, omethoate, dimethoate, ethylenethiourea and propylenethiourea in human urine using high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry

Because of increasing concern about widespread use of insecticides and fungicides, we have developed a highly sensitive analytical method to quantify urine-specific urinary biomarkers of the organophosphorus pesticides acephate, methamidophos, omethoate, dimethoate, and two metabolites from the fungicides alkylenebis-(dithiocarbamate) family: ethylenethiourea and propylenethiourea. The general sample preparation included lyophilization of the urine samples followed by extraction with dichloromethane. The analytical separation was performed by high-performance liquid chromatography (HPLC), and detection by a triple quadrupole mass spectrometer with and atmospheric pressure chemical ionization source in positive ion mode using multiple reaction monitoring and tandem mass spectrometry (MS/MS) analysis. Two different Thermo-Finnigan (San Jose, CA, USA) triple quadrupole mass spectrometers, a TSQ 7,000 and a TSQ Quantum Ultra, were used in these analyses; results are presented comparing the method specifications of these two instruments. Isotopically labeled internal standards were used for three of the analytes. The use of labeled internal standards in combination with HPLC-MS/MS provided a high degree of selectivity and precision. Repeated analysis of urine samples spiked with high, medium and low concentration of the analytes gave relative standard deviations of less than 18%. For all compounds the extraction efficiency ranged between 52% and 63%, relative recoveries were about 100%, and the limits of detection were in the range of 0.001-0.282 ng/ml.     

中毒污染事件中常见农药、鼠药及其他化学品的现场快速样品处理及GC-MS定性\半定量检测程序

目的:为快速响应食物中毒、环境污染等突发公共卫生事件,建立中毒污染事件中常见农药、鼠药和其他有毒化学品的现场快速样品处理及GC-MS定性\半定量检测程序。方法:用多种有机溶剂同时提取食物中毒、环境污染样品中常见农药、鼠药,气相色谱-质谱联用仪(GC-MS)定性\半定量快速检测。结果:运用该程序,可实现食物中毒、环境污染样品中有机磷、有机氯、氨基甲酸酯、拟除虫菊酯、鼠药及其他有毒化学品等在到达事发现场后2～3个小时内快速检测。结论:本方法原理可靠,样品处理与检测时间周期短,覆盖毒物范围广,结果准确度高,适用于突发食物中毒、环境污染样品的现场快速检测。     

分散固相萃取-气相色谱串联质谱法测定菊花茶中的56种农药残留

目的 建立菊花茶中56种农药残留的分散固相萃取（QuEChERS） - 气相色谱串联三重四级杆质谱（GC - MS/MS）测定方法。方法 样品用乙腈提取,PSA+C18+GCB混合型分散固相萃取剂净化,DB - 5MS色谱柱分离,多反应监测模式（MRM）检测,外标法定量。结果 在0.005～500 mg/L范围内,56种农药的线性相关系数均≥0.995,方法定量限为0.002～0.057 mg/kg,平均回收率为60.0%～118.0%,相对标准偏差（RSD）为0.53%～20.09%。结论 该方法简单快速灵敏,可以实现菊花茶中农药残留的快速高通量检测。     

血清中16种有机磷农药GC/MS/MS检测方法的研究

目的应用GC/MS/MS建立测定血清中敌敌畏、氧化乐果等16种有机磷农药的分析方法。方法首先做GC/MS全扫描分析,确定16种化合物的母离子,然后比较不同碰撞诱导裂解(CID)电压时二级质谱中特征离子的峰面积大小以及信噪比,对CID电压进行优化,从而确定各化合物的色谱质谱条件。样品用Oasis HLB小柱进行固相萃取后,用乙酸乙酯洗脱,浓缩后再用乙酸乙酯定容后上机测定。结果在0～1000ng/ml范围内,16种化合物的线性相关系数均大于0.995,加标回收率在75%～129%之间,RSD<10%;日内和日间相对标准偏差小于15%(n=6)。除敌敌畏的检测限为55ng/ml外,其余待测物均检出限均小于2ng/ml。结论该方法灵敏度高、准确性好,适合于血清中有机磷农药的分析测定。     

饮用水中多种有机磷农药残留的气相色谱-三重四极杆质谱测定法

目的建立一种同时测定饮用水中7种有机磷农药残留量的气相色谱-三重四极杆质谱（GC-MS/MS）方法。方法采用液-液萃取方法,用二氯甲烷对水样中7种有机磷农药进行提取,无水硫酸钠脱水,滤液在40℃水浴中旋转蒸发近干,用二氯甲烷定容,GC-MS/MS测定,外标法定量。结果 7种有机磷农药在21 min内分离,在0.01-10 mg/L范围内相关系数r2均在0.99以上,在0.05、0.25和0.45 mg/L 3个水平加标回收率在78.9%-99.3%之间,相对标准偏差均小于10%,检出限为0.02-0.06μg/L。结论该方法操作简单,准确度和精密度高,消除了其他有机磷农药的干扰,避免假阳性的出现,适用于饮用水中7种有机磷农药残留量的检测和确证。     

悬浮固化分散液液微萃取-气相色谱-质谱法测定水中10种有机磷农药

目的 建立水中10种有机磷农药的悬浮固化分散液液微萃取-气相色谱-质谱法(DLLME-SFO-GC-MS)。 方法 取10mL水样于离心管中,加0.8g氯化钠,振荡溶解,加入20μL十二醇和500μL乙腈涡旋1 min,4 000 r/min离心5min后,于冰浴中浸泡,待十二醇凝固后转移,室温融化后进行气相色谱-质谱分析。 结果 10种有机磷农药在0.2μg/L～8.0μg/L范围内线性良好,相关系数≥0.996,检出限为0.015μg/L～0.047μg/L,回收率在85.3%～103.6%,相对标准偏差为3.9%～10.5%。 结论 本法操作简单,灵敏快速,绿色环保,可满足水样中有机磷农药的检测要求。     

2014 - 2017年西安市蔬菜有机磷农药残留状况调查

目的 了解西安市蔬菜中有机磷农药残留情况。方法 2014年3月 - 2017年12月随机抽样检查西安市各大农贸市场及超市的蔬菜。采用气相色谱-质谱仪法对20种蔬菜中13种有机磷农药残留量进行测定。结果 2014-2017年共采集蔬菜样品506 份,检出有机磷农药的样品数为92份,农药超标的样品数为23份,共有10种农药不同程度的检出,其中毒死蜱和氧化乐果检出率较高,依次为10.27%（52/506）和2.37%（12/506）,有6份蔬菜样品检出禁用农药水胺硫磷。结论 西安市市售蔬菜有一定程度的有机磷农药残留污染,相关部门应继续采取有效的措施加强监督和检测。     

Assessment of the exposure of pest control operators to organophosphorus pesticides. Organophosphorus pesticides in blood and alkyl phosphate metabolites in urine

Pest control operators usually spray pesticides in small areas such as a kitchen in a restaurant and are exposed to various pesticides, especially those of the organophosphorus (OP) type. In order to evaluate their occupational exposure to OP pesticides during the work, OP pesticides in blood and alkyl phosphate metabolites in urine of these operators were analyzed and the relationship between pesticide exposure and analytical results were studied. OP pesticides in blood were analyzed by gas chromatography with flame photometric detector (FPD-GC) after separation of phospholipid in blood with silicagel column chromatography. OP pesticides were not detected in any blood samples (the limit of detection was 1 ng/ml). Dimethylphosphate (DMP) and dimethylthiophosphate (DMTP), being urinary metabolites of OP pesticides, were analyzed by FPD-GC after benzyl derivatization. This method eliminated interfering peaks in gas chromatograms. The ratio of two isomeric derivatives of DMTP was found to be constant. Both DMP and DMTP of the exposed group were significantly higher than those of the non-exposed group, DMP being higher than DMTP. The ratio of DMP to DMTP in the fenitrothion-dichlorvos-exposed group was significantly higher than that in the fenitrothion-exposed group. It was considered that the ratio might reflect a result of pesticide exposure. The urinary metabolites of OP pesticides tended to become lower with the lapse of time since the last exposure. However, small amounts were detected in a few samples even 5 days after the last exposure.     

Early-life Exposure to Organophosphate Pesticides and Pediatric Respiratory Symptoms in the CHAMACOS Cohort

Background: Although pesticide use is widespread, the possible effect of early-life exposure to organophosphate (OP) on pediatric respiratory health is not well described.Objectives: We investigated the relationship between early-life exposure to OPs and respiratory outcomes.Methods: Participants included 359 mothers and children from the CHAMACOS birth cohort. Dialkyl phosphate (DAP) metabolites of OP pesticides, specifically diethyl (DE) and dimethyl (DM) phosphate metabolites, were measured in urine from mothers twice during pregnancy (mean = 13 and 26 weeks gestation) and from children five times during childhood (0.5–5 years). Childhood DAP concentrations were estimated by the area under curve (AUC). Mothers reported their child’s respiratory symptoms at 5 and 7 years of age. We used generalized estimating equations (GEE) to examine associations of prenatal and childhood DAP concentrations with repeated measures of respiratory symptoms and exercise-induced coughing at 5 and 7 years of age, adjusting for child’s sex and age, maternal smoking during pregnancy, secondhand tobacco smoke, season of birth, PM_2.5, breastfeeding, mold and cockroaches in home, and distance from highway.Results: Higher prenatal DAP concentrations, particularly DE, were nonsignificantly associated with respiratory symptoms in the previous 12 months at 5 or 7 years of age [adjusted odds ratio (aOR) per 10-fold increase = 1.44; 95% CI: 0.98, 2.12]. This association was strongest with total DAP and DE from the second half of pregnancy (aOR per 10-fold increase = 1.77; 95% CI: 1.06, 2.95; and 1.61; 95% CI: 1.08, 2.39, respectively). Childhood DAP, DE, and DM concentrations were associated with respiratory symptoms and exercise-induced coughing in the previous 12 months at 5 or 7 years of age (total DAPs: aOR per 10-fold increase = 2.53; 95% CI: 1.32, 4.86; and aOR = 5.40; 95% CI: 2.10, 13.91, respectively).Conclusions: Early-life exposure to OP pesticides was associated with respiratory symptoms consistent with possible asthma in childhood.Citation: Raanan R, Harley KG, Balmes JR, Bradman A, Lipsett M, Eskenazi B. 2015. Early-life exposure to organophosphate pesticides and pediatric respiratory symptoms in the CHAMACOS cohort. Environ Health Perspect 123:179–185; http://dx.doi.org/10.1289/ehp.1408235