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1 概述
敌 敌 畏
1．1基本性质
敌敌畏(Dichlorvos，DDVP)，化学名O，O-二甲基-O(2，2-二氯)乙烯基磷酸酯，分子式为C4H7C12O4P。
敌敌畏纯品在室温下为无色至琥珀色的液体．有芳香气味．对钢和其它金属有腐蚀性。25℃的比重为1．415g／cm2
20℃的蒸气压为0.012mmHg，1mmHg时的沸点为74℃。室温下在水中的溶解度为10g/L，在煤油中的溶解性为2--3％，易与芳香烃、卤代烃和醇类溶剂混溶。
敌敌畏对热稳定，在水溶液中水解。在室温下，饱和的敌敌畏水溶液会分解为磷酸氢二甲酯和二氯乙醛。分解速度约为3％(半衰期为23d)，在碱性溶液中分解更快。
1．2 主要用途
敌敌畏是一种高效、速效、广谱性的有机磷杀虫剂，具有熏蒸、胃毒和触杀的作用。对咀嚼式口器和刺吸式口器的害虫均有良好的防治效果。施药后易分解-残效期短，无残留，因此适用于茶、桑、烟草、蔬菜以及临近收获前的果树以及仓库、卫生害虫的防治。还用作家禽、猪、马、人类的驱虫剂。给牲畜喂食敌敌畏．还可以控制堆肥中的马蝇。由于敌敌畏的蒸气压较高．是一种很好的杀虫熏剂。
把敌敌畏加入到塑料中．可用于飞机等航行器的缓释消毒。
1．3 环境归宿
在土壤中的降解：敌敌畏在土壤中的持久性低，容易水解和生物降解。经测定,在黏土、沙性黏土和松散的沙土中的半衰期为7d。研究发现．没有消毒的土壤中敌敌畏10d后有71％的降解．消毒后的土壤中只有50％的降解。敌敌畏降解的速度受介质的pH值影响，在碱性条件下分解快．而在酸性下分解较慢。pH值为9．1时，敌敌畏的半衰期约为4．5h．而在pH值为1时．半衰期为50h。
敌敌畏不易被土壤颗粒吸附．因此，可能污染地下水。在使用过敌敌畏的土壤中，5天后有18％～20
%的敌敌畏渗透到30cm的土壤深处。
在水中的降解：敌敌畏在水中以溶解的形式存在。不易被吸附到沉积物中·在水中主要通过水解的形式分解。有研究表明，敌敌畏在河水和湖水中的半衰期约为4d。在pH值为9和4时．半衰期分别为20h和80h。敌敌畏在酸性条件下或适合微生物生长的污染水体中会发生生物降解。
敌敌畏从水中的蒸发缓慢，估计从河水中蒸发要57d，从池塘水中蒸发要超过400d。
2环境水平和人体摄入途径
在前苏联4条被敌敌畏污染的河流以及水库中检出过敌敌畏；1988年9～11月，在爱尔兰的Beirtreach Bay的海水中检出了敌敌畏，浓度是0
13μg／L；在加拿大魁北克的Yamaska河及其支流检出过敌敌畏，河口附近两个点的浓度分别为8.2和1.7ng／L；1988年到1990年，日本大阪的检测研究中检测出了敌敌畏，具体浓度没有报道。
美国加利佛尼亚1994～1995年对7个城市的46口饮用水井进行检测-没有检出敌敌畏；
一般人群接触敌敌畏的可能性不大，在一些水果、蔬菜、谷类上发现过敌敌畏·但经过清洗和适当的处理后，可以破坏敌敌畏；生活在含敌敌畏有害废弃物地区的人有可能通过呼吸和接触被污染的土壤而接触到敌敌畏；生产敌敌畏的工人以及使用敌敌畏的人很容易受到敌敌畏的影响；如果在家里喷洒敌敌畏作为卫生防治·则有可能通过呼吸受污染的空气或接触喷洒过敌敌畏的物体的表面而接触敌敌畏。
3 动物实验
急性暴露：敌敌畏通过吸八、皮肤吸收和口服都具有高毒性。由于敌敌畏易挥发-因此．吸人是最普遍的暴露途径。敌敌是急性中毒的症状仅限于胆碱酯酶受抑制产生的影响；由于敌敌畏在体内的代谢和去除快．与其它有机磷农药中毒相比．敌敌畏中毒症状发作快，恢复也快。
小鼠经口摄入敌敌畏的LD50为6l～175mg/kg．狗的LD50为100～1090mg/kg,小鸡的LD50为l5mg/kg，大鼠的LD50为25～80mg/kg，猪的LD50为l57mg/kg，兔子的LD50为11～l2.5mg／kg；
敌敌畏容易被皮肤吸收，大鼠经皮肤摄入的LD50为70.4～250mg/kg，小鼠的LD50。为206mg/kg，兔子的LD50为107mg／kg；大鼠4小时吸人敌敌畏的LD50在0.2mg/L以上。
敌敌畏对皮肤有中等刺激．高浓度的敌敌畏会引起皮肤的灼烧感，甚至烧伤：兔子的眼睛接触1．67mg，kg的敌敌畏，引起了轻度红肿．但对角膜没有损伤。动物实验表明,吸入高剂量的敌敌畏对神经系统有影响，饮用含敌敌畏的水或摄人含敌敌畏的食物都会对动物的神经系统产生影响；
敌敌畏急性中毒引起的胆碱抑制症状与对硫磷、甲基对硫磷等有机磷农药相似.
慢性暴露：多次重复暴露或长期暴露于有机磷农药产生的影响与急性暴露的症状相似。多次小剂量暴露于敌敌畏对实验动物没有影响。给母牛摄入高达4mg/kg的敌敌畏，没有观察到对母牛明显的不良影响，但血液实验表明这些母牛有胆碱醋酶抑制效应。
饲养研究表明，要产生明显的疾病症状，暴露敌敌畏的剂量必须比产生抑制胆碱的剂量高得多。在大鼠饮食中添加剂量高达62.5mg／kg·d的敌敌畏90d.没有观察到疾病症状；而在剂量只有0
25mg／kg·d，喂养4d时既出现了胆碱酯酶水平降低。大鼠生活在含敌敌畏0．5mg／L的空气中5周，血清、红血球以及大脑中的胆碱酯酶活性明显降低。狗通过食物摄入剂量为1．6和12．5mg／kg·d的敌敌畏达2年，观察到红血球胆碱酯酶活性下降、肝重量增加、肝细胞增大。
猪长期接触大剂量的敌敌畏发生了肝肿大。狗接触高剂量的敌敌畏，产生了对肝的不良影响，还可能引起肺出血。雄大鼠多次接触高剂量的敌敌畏，引起了肺、心脏、甲状腺、肝和肾组织的异常。
生殖毒性：没有证据表明敌敌畏对生殖有不良影响。雌、雄鼠交配前摄入剂量为5mg／kg·d的敌敌畏，雌鼠的摄入直到妊娠期和哺乳期。尽管母体和后代都出现了明显的胆碱酯酶抑制，但对生殖能力以及后代的成活率和生长都没有影响。在另一项对大鼠的三代研究中，饮食中敌敌畏的剂量水平达25mg／kg·d时．也得到了相似的结论。敌敌畏一旦进入血液中，敌敌畏能透过胎盘。
致畸性：没有证据证明敌敌畏是致畸的。剂量为12mg/kg·d的敌敌畏对兔子没有致畸性，也没有对其生殖方面产生任何影响。大鼠和兔子整个妊娠阶段都暴露在含敌敌畏浓度达6．25mg/L的空气中，没有观察到致畸性。大鼠口服敌敌畏也没有发现致畸性。
致突变性：由于敌敌畏能与DNA之类的分子结合．因此对敌敌畏的致突变性进行了广泛的试验。有几项实验证明敌敌畏是致突变的，如有报道说敌敌畏在Ames致突变实验和其它细菌和动物细胞培养的实验结果是阳性的，但没有发现敌敌畏对活的动物具有致突变性的证据，主要是由于敌敌畏在活的动物体内代谢和排泄太迅速。
致癌性：由于在一些实验中对大鼠和小鼠引起了肿瘤的生长．敌敌畏被划分为可能对人类致癌的物质，但还没有对其它种类动物致癌的证据。
器官毒性：敌敌畏主要通过胆碱酯酶抑制影响神经系统。
4对人体的影响
敌敌畏对人体的主要影响在于神经系统，摄人大量的敌敌畏会导致恶心和呕吐、坐卧不宁、盗汗以及肌肉震颤，更大剂量则会引起休克、呼吸困难和死亡。但呼吸含低浓度敌敌畏的车间空气的工人没有表现出任何有害的影响，对于敌敌畏是否会引起人生殖方面的影响，目前尚不太清楚。
尽管动物实验表明敌敌畏可能有致癌性，但是否对人致癌，尚不清楚。国际癌症研究机构(IARC)确定敌敌畏可能对人体致癌．美国EPA将敌敌畏定为一种可能的人体致癌物。
5 在动物和人体内的代谢
在有机磷农药中，敌敌畏在哺乳动物体内代谢和排泄最迅速。大鼠摄入浓度为11mg/L的敌敌畏约4h后．体内检测不出敌敌畏；摄入浓度为50mg/L时，敌敌畏在大鼠’肾内的半衰期为13.5min。敌敌畏迅速消失的原因是由于在组织和血清中有降解酶存在，敌敌畏被摄入并吸收后，迅速到达肝脏并被解毒。因此,非致命剂量的敌敌畏中毒会由于肝的解毒而迅速恢复。大鼠摄入LD50剂量的敌敌畏．可能在1小时内死亡．也可能完全恢复。
敌敌畏不会在身体组织中累积，即使摄入的剂量足以引起严重中毒．在母牛和大鼠的乳汁中也没有检出过敌敌畏。
6我国供水水质中的水平及国内外水质标准的指导值
对我国北京、上海、广州、深圳等lO个城市1999-2000年饮用水的检测结果进行统计，只有一个城市的出厂水中检出了敌敌畏．浓度范围在<O.1～0.4μg／L之间，其它9个城市没有检出敌敌畏(但各城市分析方法的检出限的差别较大。最高的6μg／L．最低的0．005μg／L)。
国内外主要饮用水水质标准敌敌畏的指导值见下表：
国内外主要饮用水水质标准敌敌畏的指导值
┏━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━┓
┃ 标准
┃ 指导值(μg／L) ┃
┃ 欧共体饮用水水质指令(g8/83/EEC) ┃ 0.1(农药单项)
┃
┃ 日本生活饮用水水质标准(1993) ┃ 1 O
┃
┃ 法国生活饮用水水质标准(89-3) ┃ 0.1(有机磷农药)
┃
┃ 澳大利亚饮用水水质准则
┃ 1
┃
┃
┣━━━━━━━━━━┫
┃ 建设部城市供水2000年水质目标规划 ┃ 0.l
┃
┗━━━━━━━━━━━━━━━━━━┻━━━━━━━━━━┛
7 限值
敌敌畏具有很高的急性毒性，而在自然水环境中的持久陛却很低，WHO和美国EPA中都没有将它列入最近的饮用水水质指引或标准中：英国在1990年的“建议的水中敌敌畏临时性环境质量标准”中．确定保护淡水生物的水中敌敌畏临时性水质指标值为lng/L，保护海洋生物的水质指标值为40ng/L；WHO/FAO确定敌敌畏的ADI值为O．004mg，kg(体重)。根据敌敌畏目前分析方法的检测限，参考其它国家和地区的饮用水水质标准，将敌敌畏的指导值定为1.0μg／L。
来源：《城市供水水质标准》检验项目释义
| Synonyms | Dichlorvos |
|---|---|
| Phosphoric acid, 2,2-dichlorovinyl dimethyl ester | |
| DDVP | |
| Vapona | |
| Analytical Method | EPA Method 8141A |
| Molecular Formula | C4H7Cl2O4P |
| Use |
chlorinated organic phosphate insecticide with appreciable vapor pressure. incorporated into plastic strips it slowly releases vapor. has been approved for use in disinfection of aircraft. contact & stomach insecticide with fumigant & penetrant action. used as household & public health fumigant for protection of stored products @ 0.5-1 g ai/100 cu m; for crop protection against sucking & chewing insects @ 300-1000 g/ha. antihelmintic-eg, for swine, dogs, & horses .Controls household, public health, stored product insects. Controls mushrooms, flies, aphids, spider mites, caterpillers, thrips, white flies in glasshouse crops, outdoor fruit, vegetables. |
| Consumption Patterns | ESSENTIALLY 100% AS A PESTICIDE |
| Apparent Color | COLORLESS TO AMBER LIQUID |
| Odor | Mild chemical odor ; Aromatic odor |
| Boiling Point | 140 DEG C @ 20 MM HG |
| Molecular Weight | 220.98 |
| Density | 1.415 @ 25 DEG C/4 DEG C |
| Sensitivity Data | Dichlorvos is not known to be an eye irritant. |
| Environmental Impact | Dichlorvos may be released to the environment during its production, disposal and use as an insecticide in households and on crops and livestock. Dichlorovos is one of the more volatile organophosphates. If released into water it will hydrolyze with a half-life of approximately 4 days although its half-life varies considerably between pH 4 and 9. It will degrade very slowly at pH 4 and quite rapidly at pH 9. Biodegradation may aid in its disappearance, particularly when acclimated colonies of microorganisms exist or under more acidic conditions when hydrolysis is slower. Bioconcentration in fish will not be significant. The Henry's Law constant indicates that volatilization of dichlorvos from environmental waters and moist soil should generally be slow. The volatilization half-lives from a model river and a model pond, the latter considers the effects of adsorption, have been estimated to be 57 and over 400 days, respectively. If released on land, dichlorvos will leach into the ground water where it will hydrolyze and also degrade through chemical and biological processes with reported half-lives ranging from 1.5-17 days. If released into the atmosphere, dichlorvos is expected to exist almost entirely in the vapor phase in ambient air. In air, vapor phase dichlorvos will react with photochemically generated hydroxyl radicals and ozone with estimated half-lives of 2 and 320 days, respectivley. Human exposure will be primarily from indoor air where dichlorvos is used as an insecticide and from food which has been prepared where it is used. |
| Environmental Fate | TERRESTRIAL FATE: When spilled on soil, dichlorvos leached into the ground with 18-20% penetrating to 30 cm within 5 days of spraying in one experiment. It will degrade by both hydrolysis and biodegradation. Half-lives of 7 days were obtained in clay, sandy-clay, and loose sandy soil . A half-life of 1.5 days was obtained in field plots on chestnut soil and 17 days in an unidentified soil . It disappeared from soil as well as foliage when sprayed on a vineyard in the USSR . Dissipation rates on lawns were measured with and without postspray irrigation, and it was not detected 24 hrs after application (detection limit 0.003 ug/sq cm) . AQUATIC FATE: When released into water, dichlorvos will remain in the aqueous phase since it will not adsorb appreciably to sediment. It will degrade primarily by hydrolysis although biodegradation may be important where acclimated microorganisms may exist such as some polluted waters or where the water is more acidic and hydrolysis slower. One investigator reported 64% disappeared in 24 hr at pH 8.7 and only 8% at pH 6. Half-lives in lakes and rivers are reported to be approximately 4 days . The Henry's Law constant indicates that volatilization of dichlorvos from environmental waters should generally be slow . Based on the Henry's Law constant, the volatilization half-life from a model river has been estimated to be 57 days(2,SRC). The volatilization half-life from a model pond, which considers the effects of adsorption, has been estimated to be over 400 days(3,SRC). ATMOSPHERIC FATE: Based upon the vapor pressure, dichlorvos is expected to exist almost entirely in the vapor phase in ambient air . In the atmosphere, vapor phase reaction with photochemically produced hydroxyl radicals may be important fate processes. Vapor phase reactions with ozone may also occur. The rate constant for the vapor-phase reaction of dichlorvos with photochemically produced hydroxyl radicals has been estimated to be 9.24X10-11 cu cm/molecule-sec at 25 deg C, which corresponds to an atmospheric half-life of about 2 days at an atmospheric concentration of 5X10 5 hydroxyl radicals per cu cm . The rate constant for the vapor-phase reaction of dichlorvos with ozone has been estimated to be 3.58X10-11 cu cm/molecule-sec at 25 deg C which corresponds to an atmospheric half-live of about 320 days at an atmospheric concentration of 7X10 11 molecules per cu cm . Dichlorvos will not directly photolyze in the atmosphere. Octanol water partition coefficients and air water partition coefficients were obtained for 10 organochlorine pesticides (including dichlorvos) as basic data for predicting their fate in the environment. The octanol water partition coefficient is 1.45X10 1 for dichlorvos. These values approximately correlated with the solubilities of these pesticides in water. The air water partition coefficient is 5.0X10-3 for dichlorvos. |
| Drinking Water Impact | Dichlorvos has been detected in a water reservoir and water supply-irrigation system in the USSR and in 4 polluted rivers . On September 9 to 11, 1988, dichlorvos was detected in marine waters of Beirtreach Bay, Ireland at concentrations up to 0.13 ug/L . EFFL: Dichlorvos was detected in wastewater from a dichlorvos production plant in Bulgaria 16 g/l . |