Residues of DDT in cottonseed after spraying with DDT and torbidan

DDT at 1.12 and 2.24 kg/ha a.i. and Torbidan at 5 and 10 litre formulation/ha (1 and 2 kg DDT/ha) were sprayed five times on cotton over a period of 15 weeks. Seeds from the first pick of the crop were found to contain as residues pp′-DDT and pp′-DDE [1,1-dichloro-2,2-di- (4-chlorophenyl)ethylene]. The highest residue level (0.783 parts/10⁶) was found in seeds from Torbidan 10 litre/ha treatment.     

Accumulation and distribution of pp′-DDT and related compounds in an apple orchard. II. Residues in trees and herbage

DDT residues in or on the roots and leaves of the herbage and the roots, bark, leaves and fruit of the trees are given for an apple orchard sprayed annually (1953–1969). The distribution of DDT in both the grass and the grass roots was in circular areas of residues, with maximum values at each trunk and decreasing radially to each alley. Of the spray applied at the green cluster stage 80% was deposited on the grass sward and very little, if any, directly on the soil surface. The pp′-DDT content of the grass fell rapidly with successive mowings (from which the cuttings remained in situ) from 400 μg/g at spraying to 2 μg/g after nine months. 33 g/ha pp′-DDT was found in the herbage roots (0.87% of the total residues in the soil). The residues in the bark (87.5 g/ha) were much lower than expected after 13 years spray application. There were increased amounts of pp′-DDE, pp′-TDE and pp′-TDEE relative to pp′-DDT, indicating some breakdown on the bark, but the chief losses were attributed to volatilisation and to removal by wind and rain. The residue content of root bark varied from 3 μg/g near the emerging trunk to 0.05 μg/g at a depth of 90 cm. The pp′-DDT content of leaves at leaf fall rose from <1 ng/g after a single spring spray to 8.33 μg/g following an additional spray in late June. There was a large loss of DDT from the canopy between the June spray and leaf fall (440–480 g/ha down to 25 g/ha), attributed to volatilisation. The amount of pp′-DDT on the fruit, after a single spray, was 3 ng/g fresh weight (80.9 mg/ha out of a total of 1.0–1.5 kg/ha used).     

In-vivo and in-vitro studies on DDT uptake and metabolism in susceptible and resistant strains of the mosquito Aedes aegypti L.

Twelve strains of Aedes aegypti have been compared for resistance to pp′-DDT, uptake of pp′-DDT, and dehydrochlorination of pp′-DDT to pp′-DDE in vivo and in vitro both at the larval and adult stages. Resistant larvae were shown to contain significantly more pp′-DDE than susceptible larvae after a standard exposure to pp′-DDT but also substantially more pp′-DDT in an unmetabolised state. There was a small increase in the percentage dehydrochlorinated in vivo in the resistant strains compared with the susceptible strains, but this was not correlated with the level of resistance nor with dehydrochlorination in vitro. However, dehydrochlorination in vitro was correlated with resistance. Adult resistance was correlated positively with dehydrochlorination, both in vivo and in vitro, but the resistant adults did not contain increased levels of unmetabolised DDT. By comparing resistance levels at the two stages, it was found that there were two kinds of resistant strain: four strains of Asian origin and one from West Africa were highly resistant as larvae but showed almost no resistance as adults; five strains from Central and South America were highly resistant at both stages. The different mechanisms of resistance in adults and larvae are discussed in relation to genetic studies.     

Pesticide residues in soil and foodstuff I. Chlorinated pesticides in cattle feed and milk produced in orchard and non-orchard areas

Milk, hay and silage produced in orchard and non-orchard areas have been analysed for their content of chlorinated pesticides. The residue levels in milk produced in orchard areas were about double those in milk produced in non-orchard areas. The levels in hay were much higher (30% up to sevenfold) in the hay produced in orchard areas and the levels in silage from the two areas showed small differences. Milk collected after cattle had been grazing in an orchard for 3 to 4 days contained 10% more pp′-DDT and 2-, 3-, 7- and 15-fold morepp′-DDE, pp′-TDE and heptachlor epoxide, gamma-BHC and pp′-TDE olefin [1-chloro-2,2-bis(p-chlorophenyl)ethylene], respectively, than did the samples collected one day before the cattle grazed in the orchard.     

The accumulation and distribution of pp′DDT and related compounds in an apple orchard .I. residues in the soil

Soils from an orchard sprayed annually (1953-1969) with technical DDT (77% pp′DDT and 22 % pp′DDT) were analysed for residues from 1964 until 1969. The amount of DDT found after 17 years was 21 %pp′DDTout of 27.1 kg/ha applied, and 7 % of pp′DDT out of 7.6 kg/ha. The vertical distribution of residues (pp′DDT, pp′DDE, pp′TDE and pp′DDT) showed a linear relationship between log amount and depth, with approximately 80% in the top 10 cm of soil. At depths from 50 to 210 cm, residue values were too small to be determined (i.e. < 1 ng/g dry wt). The surface distribution in the orchard showed a systematic pattern of circular areas of residues, with maximum values centred at each trunk (7.5 μg/g) and decreasing rapidly to each alley (1.9 ug/g). The levels of pp′DDT had reached a steady state (3-4 kg/ha) and the half-life time was calculated as 3.0 j′ears. pp′DDE (1.8 kg/ha) was the main metabolite of pp′DDT. Small amounts of pp′TDE were also found, pp′DDT was less persistent than pp′DDT, with a half-life time of 1.5 years.     

Inhibition of acetyl-coenzyme a carboxylase by coenzyme a conjugates of grass-selective herbicides

A total of 146 samples of different kinds of cheeses produced in Spain were analysed in order to ascertain the specific contamination pattern. The organochlorine compounds studied were those most commonly investigated in previous surveys: α-HCH, β-HCH, γ-HCH (lindane), γ-HCH, chlordane, aldrin, dieldrin, endrin, heptachlor, heptachlor epoxide, and the isomers and metabolites of DDT. α-HCH, β-HCH, γ-HCH, chlordane, p,p′, DDT, and p,p′-DDE were found in more than 76% of samples; p,p′-DDE and γ-HCH were the most frequently detected, with frequencies of 100 and 97.9% respectively. γ-HCH, aldrin, dieldrin, heptachlor, heptachlor epoxide, o,p′-DDT, p,p′-DDD and o,p′-DDD were observed at lower frequencies. No residues of endrin were detected in any sample. Insecticides exceeding the maximum residue limits (MRLs) were chlordane, β-HCH, α-HCH and γ-HCH, with 42, 20, eight and six samples respectively. Mean residues of organochlorines found were as follows (μ kg^?1 butterfat): α-HCH = 46.3; β-HCH = 46.5; γ-HCH = 54.2; δ-HCH = 16.9; aldrin = 16.7; dieldrin = 9.7; heptachlor = 15.9; heptachlor epoxide = 14.8; chlordane = 50.2; o,p′-DDT = 5.1; p,p′-DDT = 12.4; o,p′-DDT = 19.6; p,p′-DDD = 46.7; o,p′-DDE = 6.9; p,p′-DDE = 40.7 (.DDT = 55.0). Estimated dietary intakes (EDIs) from cheese consumption were compared to acceptable daily intakes (ADIs) for the pesticides where residues exceeded the MRL. EDIs calculated were in all cases below ADIs, and, therefore, based on the ADIs, there is no health risk involved in the consumption of cheese from Spain arising from organochlorine residues.     

Residues of some chlorinated hydrocarbon pesticides in milk and milk products after their addition to the feed of cows

Lactating cows fed 0.05 part/million aldrin, 0.2 part/million γ-BHC and 2.0 parts/million pp'-DDT in their concentrate ration gave detectable residues of dieldrin, γ-BHC, pp'-DDE, pp'-TDE and pp'-DDT in the milk and also aldrin in the butter and cheese. The levels found after 28 days of feeding were not significantly greater than those after 14 days. Subsequent increase of the pesticide content of the feed increased the residue content of the milk, butter and cheese. Only a small percentage of pesticide residue was found in the buttermilk, separated milk and the whey.     

高效液相色谱-串联质谱法检测稻田中吡嘧磺隆和苯噻酰草胺残留

采用高效液相色谱-串联质谱法(HPLC-MS/MS),建立了稻田水、土壤、水稻植株、稻秆、稻壳及糙米基质中吡嘧磺隆和苯噻酰草胺的残留分析方法。样品经20 m L V(乙腈)∶V(水)=70∶30的混合溶液提取,提取液用20 mg石墨化碳黑(GCB)与30 mg乙二氨基-N-丙基硅烷(PSA)净化,HPLC-M S/M S检测。吡嘧磺隆在上述各基质中的添加回收率在76%~107%之间,相对标准偏差(RSD)在1.5%~14%之间,定量限为0.004~0.01 mg/kg;苯噻酰草胺的添加回收率在77%~101%之间,RSD在2.4%~13%之间,定量限为0.001~0.01 mg/kg。实现了对两种除草剂同时简便、快速测定的要求。采用该方法测定了26%吡嘧磺隆·苯噻酰草胺水面扩展粒剂在稻田施用后,其有效成分吡嘧磺隆和苯噻酰草胺在实际样品中的残留量。结果表明,两种除草剂均属于易降解农药,在本试验条件下其在糙米中的残留量均低于我国最大残留限量(MRL)(吡嘧磺隆0.1 mg/kg;苯噻酰草胺0.05 mg/kg)。     

The metabolism and residues of [14C]Endrin in lactating cows and laying hens

[¹⁴C]Endrin was fed to two lactating cows in a portion of their diet for 21 days. The intake was equivalent to approximately 0.1 mg of endrin per kg of total diet. Excretion of radioactivity in milk, urine and faeces reached equilibrium with intake between 4 and 9 days after starting treatment. Milk residues reached 0.003–0.006 mg/kg, were composed of unchanged endrin and were located in the fat. Muscle residues reached 0.001–0.002 mg/kg. Residues in the fat reached a maximum of 0.1 mg/kg and were due to unchanged endrin. [¹⁴C]Endrin was administered in corn oil to six laying hens for 21 weeks. The intake was equivalent to approximately 0.13 mg/kg of total diet. Ingestion and excretion were almost in balance at 16–20 weeks. Egg residues reached 0.11–0.18 mg/kg, were composed of unchanged endrin and were located in the yolk. Tissue residues were 0.01 mg/kg in breast, 0.1 mg/kg in leg, 0.17 mg/kg in kidney, 0.47 mg/kg in liver and 1.0 mg/kg in fat. The residues were accounted for as unchanged endrin except in liver and kidney in which part was probably due to polar metabolites in the process of excretion. The results show that endrin is much more rapidly metabolised in cows than in hens. The pathways of metabolism were fundamentally the same in both species, the major product being anti-12-hydroxyendrin, which was found un-conjugated in cow urine and faeces and as the O-sulphate conjugate in hen excreta. The only observed difference in primary metabolism was some syfl-12-hydroxyendrin and 12-ketoendrin in cows. This pathway was not detected in hens.     

Comparative excretion of DDT analogues into milk of indian buffalo,Bubalus bubalis L. following oral administration

Four groups of Indian buffaloes were fed daily with 25 mg of p,p′-DDT p,p′-TDE p,p′-DDE or o,p′-DDT for 100 days. Milk was analysed for organochlorine residues during this period and also for 100 days after pesticide administration had been discontinued. For the period showing ‘plateau level’ residues, 17.2% of p,p′-DDE, 17% of p,p′-TDE, 14% of p,p′-DDT as p,p′-DDT (3.5%); p,p′-TDE (10.5%); 3.2% of p,p′-DDT as o,p′-DDT (1.3%) and o,p'-TDE (1.9%) of their administered amounts were excreted in the milk. Since these compounds were excreted at different rates, the residue levels in the milk expected from a given feed would depend on their concentration and proportional distribution in the feed. The maximum tolerable content of DDT analogues in feed was derived to be 0.1 mg kg^?1 (dry weight basis) by using the maximum accumulation coefficient and incorporation of the necessary safety margin. It is concluded that Indian buffaloes fed with rations contaminated with a total of DDT analogues below this limit will yield milk of acceptable quality. Following the termination of feeding with contaminated rations, the elimination of p,p′-DDE in the milk took the longest time and that of o,p′-DDT the shortest. These results suggest that the time required for the initial high residue concentration to decline to less than the legal limit would be determined by the relative amounts of DDE, TDE and DDT in the milk, after elimination of the potent source of contamination.     

露地和大棚条件下啶虫脒在黄瓜和土壤中的残留及消解动态

采用乙腈提取、固相萃取净化和高效液相色谱法,分析测定了啶虫脒在露地和大棚2种种植条件下黄瓜和土壤中的残留及消解动态。结果表明:9%啶虫脒可湿性粉剂同时在露地和大棚中按有效成分30.375 g/hm2剂量(推荐高剂量的1.5倍)施药1次,啶虫脒在露地和大棚黄瓜及其土壤中的原始沉积量分别为0.20、0.13 mg/kg和0.29、0.14 mg/kg,露地黄瓜和土壤中的原始沉积量均分别低于大棚;相应地,啶虫脒在黄瓜和土壤中的半衰期分别为9.7、9.4 d(露地)和10.1、11.9 d(大棚)。9%啶虫脒可湿性粉剂同时在露地和大棚中按有效成分20.25 g/hm2和30.375 g/hm2的剂量施药1次和2次,在相同施药剂量、施药次数和采收间隔期情况下,除个别情况外,露地黄瓜中啶虫脒的最终残留量均低于大棚,分别为0.01~0.05 mg/kg(露地)和0.01~0.09 mg/kg(大棚)。     

Residues of diflubenzuron and two of its metabolites in a forest ecosystem after control of the pine looper moth,Bupalus piniarius L

Diflubenzuron, 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea was used to control the pine looper population in about 1160 ha of Scots pine stand in eastern Finland in summer 1984. The control measure was effective, resulting in the collapse of the population in the treated area. Residues of diflubenzuron and two of its metabolites, 4-chloroaniline and 4-chlorophenylurea, were determined in water, pine needles, litter, humus, boleti and other wild mushrooms, bilberry (Vaccinium myrtillus L.) and cowberry (Vaccinium vitis-idaea L.) samples taken from this area. In water samples taken from the treated area diflubenzuron was still detected at concentrations of 0.1 μg litre^?1 2 months after application. No diflubenzuron was detected in this area the following year, nor outside the treated area. Neither metabolite was detected at any time. The sum of diflubenzuron and its metabolites in the litter layer was, on average, 0.7mg kg^?1 both 1 week and 1 month after the application. The next year, however, it had increased to 1.4 mg kg^?1. Diflubenzuron and its metabolites were not detected in the humus layer. The amount of diflubenzuron residues in the pine needles was, on average, 3.0 mg kg ^?1 1 day after the application, but in 2 months the level had decreased to 0.2-0.3 mg kg ^?1 or was not detectable. The following year the sum of diflubenzuron and its metabolites in two pine-needle samples was 0.3 and 1.6 mg kg ^?1. The sum of diflubenzuron and its metabolites in wild mushrooms was, on average, 0.07 mg kg ^?1 1 week after the application, but the following year no residues were detected. No residues were found in the boletus samples. The residues of diflubenzuron and its two metabolites in bilberries totalled, on average, 0.2 mg kg ^?1 1 day after the application, and 6 μg kg ^?1 the following year. The sum of diflubenzuron and metabolites in cowberries was, on average, 0.2 mg kg ^?1 1 month after application.     

超高效液相色谱-串联质谱法同时检测大米中15种常用农药的残留

建立一种超高效液相色谱-串联质谱同时检测大米中甲氨基阿维菌素苯甲酸盐等15种常用农药残留的方法,考察了基质效应、提取溶剂种类、提取方法以及不同净化方法对15种农药回收率的影响。样品经V (乙腈) : V (丙酮) : V (水) = 16 : 2 : 2混合溶液匀浆提取,分散固相萃取法净化,电喷雾正离子 (ESI+) 模式电离,多反应监测 (MRM) 模式检测,外标法定量。结果表明:在0.005~1 mg/L范围内,甲氨基阿维菌素苯甲酸盐等15种农药的质量浓度与对应的峰面积间线性关系良好,相关系数 (r) ≥ 0.99;在0.01、0.1、1和4 mg/kg 4个添加水平下,15种农药在大米中的平均回收率在82%~116%之间,相对标准偏差在1.2%~12%之间 (n = 5)。方法检出限为0.000 5~0.005 mg/kg,定量限为0.01 mg/kg。用该方法对上海市郊20个批次的大米样品进行测定,均未检出农药残留超标。该方法操作简单、快速、准确,适用于大米中甲氨基阿维菌素苯甲酸盐等15种常用农药残留的同时检测。     

高效液相色谱法检测环氧虫啶在柑橘及土壤中的残留

建立了环氧虫啶在柑橘和土壤中残留量测定的高效液相色谱(HPLC-UVD)分析方法。柑橘样品采用V(蒸馏水):V(二氯甲烷)=1:2提取后经弗罗里硅土柱净化(土壤样品提取后直接测定),HPLC-UVD测定,外标法定量,并运用此方法对田间样品进行了环氧虫啶残留量检测验证。结果表明:在0.05~5mg/L范围内,环氧虫啶质量浓度与对应的峰面积间呈良好线性关系,线性方程为y=10243x+233.0(R2=0.9990);土壤和柑橘中环氧虫啶的最低检测浓度均为0.1mg/kg;在0.1~1mg/kg3个添加水平下,环氧虫啶在土壤和柑橘中的平均回收率在76%~93%之间,相对标准偏差(RSD,n=5)在1.6%~5.8%之间。该方法快速、灵敏、稳定,可用于柑橘和土壤中环氧虫啶残留量的检测。     

拟除虫菊酯类杀虫剂在烟叶烘烤过程中的消解动态与最终残留

采用气相色谱-质谱联用技术,测定了良好农业规范(GAP)条件下3种常用拟除虫菊酯类杀虫剂高效氯氟氰菊酯、高效氯氰菊酯及溴氰菊酯在山东、四川、云南、辽宁和江西5地烟叶中的消解动态及最终残留。样品经乙腈提取,SPE-PSA柱净化,气-质联用、选择离子监测模式(GC-MS/SIM)下测定,外标法定量。结果表明:在0.01 ~1 mg/kg添加水平下,3种农药在鲜烟叶和干烟叶中的平均回收率分别在82.9% ~ 110.9%和85.2%~108.3%之间,相对标准偏差(RSD)分别为1.7% ~4.4%和2.3% ~5.7%;3种农药在鲜烟叶和干烟叶中的定量限(LOQ)均为0.01mg/kg;方法的准确度和精密度均符合农药残留检测要求。烘烤过程中残留农药消解明显,高效氯氟氰菊酯、高效氯氰菊酯和溴氰菊酯的消解率分别高达78%、89%和91%。高效氯氟氰菊酯、高效氯氰菊酯和溴氰菊酯乳油分别按有效成分450~675 g/hm2、600~900 g/hm2及450~675 g/hm2于烟叶采 烤初期喷雾施药2次,距末次施药后14d,干烟叶中3种农药的残留量分别为0.022~ 0.50、0.14~0.82和0.046~0.21 mg/kg,均低于国际烟草合作研究中心(CORESTA)提出的指导性农药残留限量标准(GRL)值(0.5、1和1mg/kg),因此建议其安全间隔期可定为14d。     

烯啶虫胺在水稻和稻田环境中的残留及消解动态

采用高效液相色谱-紫外检测器(HPLC-UVD)测定了烯啶虫胺在稻田水、土壤、水稻植株和糙米样品中的消解动态及最终残留。田水样品用二氯甲烷萃取;土壤样品用水提取后经二氯甲烷萃取;水稻植株和糙米样品依次用水、丙酮提取,提取液经液液萃取及柱层析净化;HPLC-UVD检测。当烯啶虫胺在田水和土壤中的添加水平为0.1~5 mg/L和0.1~5 mg/kg,在植株和糙米中的添加水平为0.2~5 mg/kg时,其平均添加回收率在77.2% ~100.3%之间,相对标准偏差 (RSD)在1.9% ~12.9%之间。烯啶虫胺在稻田水、土壤、植株和糙米中方法的定量限(LOQ)分别为0.1 mg/L和0.1、0.2、0.2 mg/kg,检出限(LOD)分别为0.04 mg/L和0.04、0.08、0.08 mg/kg。温室模拟消解动态试验结果显示,以推荐使用高剂量的20倍(有效成分1 500 g/hm2) 施药,烯啶虫胺在稻田水、土壤以及水稻植株中的消解动态规律均符合一级动力学方程,其半衰期分别为0.58、3.31及2.70 d,消解速率较快。最终残留试验表明,于大田分蘖期按推荐使用高剂量的1.5倍(有效成分112.5 g/hm2)分别施药3次和4次,间隔期为7 d,距最后一次施药7 d后采样,糙米中烯啶虫胺的残留量均低于LOD值(0.08 mg/kg)及日本规定的最大残留限量(MRL)值(0.5 mg/kg)。     

QuEChERS-液相色谱-串联质谱法检测糙米中氟唑环菌胺的残留

采用QuEChERS前处理与液相色谱-串联质谱 (LC-MS/MS) 技术,建立了糙米中氟唑环菌胺残留的分析方法。样品采用V(乙腈) : V(水)=80 : 20混合溶液涡旋提取,经PSA分散固相萃取净化,LC-MS/MS测定,外标法定量。结果表明:在0.001~0.1 mg/L范围内,氟唑环菌胺的质量浓度与对应的峰面积间线性关系良好,R2 > 0.996。在0.004、0.01和0.1 mg/kg添加水平下,氟唑环菌胺在糙米中的回收率为83%~95%,相对标准偏差 (RSD) 为3.9%~12%。以最小添加浓度确定氟唑环菌胺在糙米中的定量限 (LOQ) 为0.004 mg/kg,远低于国际食品法典委员会规定的最大残留限量 (MRL) 0.01 mg/kg。所建方法操作简单、准确度和灵敏度高,可用于糙米中氟唑环菌胺残留的检测。对中国6个省 (市) 40个糙米样品进行检测,氟唑环菌胺的残留量均低于LOQ 0.004 mg/kg。膳食风险评估结果表明,氟唑环菌胺目前在中国水稻上使用对一般人群的的健康风险很低。     

Accumulation of endosulfan residues in fish and their predators after aerial spraying for the control of tsetse fly in Botswana

Residues of endosulfan insecticide (α- and β-isomers, and ‘endosulfan sulphate’) in fish and their predators were measured during and after operations to control tsetse fly in the Okavango Delta, Botswana. Six ultra-low-volume doses of endosulfan 35% e.c. (6–12 g a.i. ha^?1) were applied from the air in a period of 12 weeks over 2500 km². The concentration of residues found in living fish was up to 0.19 mg kg^?1 wet wt in caudal muscle, and usually < 0.8 mg kg^?1 wet wt in pooled viscera (maximum 2.8 mg kg^?1). These values returned to near-normal within 3 months after cessation of spraying, but residues were still detectable after 12 months. By comparison, fish killed by spraying contained a maximum residue level (whole-body) of 1.5 mg kg^?1 wet wt. The residue level in fish was approximately proportional to their fat content. Lean fish were more susceptible to poisoning than fat fish. The proportion of the ‘endosulfan sulphate’ metabolite in fish increased at least six times with respect to the parent isomers (α+β) during the period of spraying, but more advanced stages of metabolic breakdown were not monitored. Residue levels in fish predators (fish-eating birds and crocodiles) were similar to those in their prey, and the risk to them was consequently low.     

丁虫腈在玉米和土壤中的残留及消解动态

建立了丁虫腈在土壤、玉米植株及玉米籽粒中残留的气相色谱分析方法。玉米植株和籽粒样品用乙腈提取,经Oasis HLB固相萃取柱净化;土壤样品用丙酮提取,经液-液萃取净化,气相色谱-电子捕获检测器(GC-ECD)检测,外标法定量。结果表明:在0.01、0.05和0.5 mg/kg 3个添加水平下,丁虫腈的回收率为80%~86%,相对标准偏差(RSD)为5.1%~8.0%;其在土壤、玉米植株及籽粒中的定量限(LOQ)均为0.01 mg/kg。采用所建立的方法对丁虫腈在玉米和土壤中的残留及消解动态进行研究的结果表明:丁虫腈在土壤和玉米植株中的半衰期分别为6.77和2.44 d。采用5%的丁虫腈乳油按推荐高剂量(有效成分)37.5 g/hm2及其1.5倍该剂量(56.25 g/hm2)于玉米苗后茎叶初期施药1次,在玉米乳熟期和成熟期时,玉米籽粒中丁虫腈的最终残留量均低于定量限;玉米收获时(距施药90 d),籽粒中丁虫腈的残留量均低于参考的MRL值(0.02 mg/kg,氟虫腈在谷物中的最大残留限量)。     

Fonofos residues in an organic soil and vegetable crops following treatment of the soil with the insecticide

Fonofos (O-ethyl S-phenyl ethylphosphonodithioate) was applied to an organic soil as band treatment at the rates of 1.12 and 2.24 kg/ha. The persistence of the insecticide and its translocation into onions and two rotation crops (lettuces and carrots) was studied under field conditions. Proportionally more residues persisted in the soil from the higher rate of application. In autumn, 4 months after soil treatment, about 40-48 % of the initially recovered levels of fonofos remained in soil. However, the amount of fonofos present at the harvest time, during the second growing season was only 16–26% of the insecticide concentration found in spring. Onions harvested 4 months after application of fonofos had no detectable residue (> 0.005 mg/kg) whereas lettuces and carrots grown in the following year contained fonofos in various amounts. At the lower rate of application the insecticide residues in lettuces and carrots were < 0.005 and 0.025 mg/kg, respectively, and those from the higher application rate were 0.012 and 0.036 mg/kg. About 72–80% of the residue could be removed by peeling the carrots. No residue of the oxygen analogue, O-ethyl S-phenyl ethylphos-phonothioate (I) was detected in any soil or crop samples.