Regulatory Toxicology and Pharmacology 62 (2012) 125–130

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Regulatory Toxicology and Pharmacology

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Risk assessment of chlorpyrifos on rice and cabbage in China

Chen Chen a, Yongzhong Qian a,⇑, Xianjin Liu b, Chuanjiang Tao c, Ying Liang b, Yun Li a

a Key Lab of Agro-product Quality and Safety, Institute of Quality Standards & Testing Technology for Agro-Products,Chinese Academy of Agricultural Sciences, Beijing 100081, People’s Republic of Chinab Institute of Food Safety, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, People’s Republic of Chinac The Institute for the Control of Agrochemicals, Ministry of Agriculture, Beijing 100125, People’s Republic of China

a r t i c l e i n f o

Article history:Received 11 August 2011Available online 24 December 2011

Keywords:ChlorpyrifosResidueDietary risk assessmentRisk characterization

0273-2300/$ - see front matter � 2011 Elsevier Inc. Adoi:10.1016/j.yrtph.2011.12.011

⇑ Corresponding author. Fax: +86 10 82106551.E-mail address: qyzcaas@yahoo.cn (Y. Qian).

a b s t r a c t

Chlorpyrifos is a widely used organophosphorus insecticide in agricultural pest control. To understandthe residue behavior of chlorpyrifos and to evaluate the dietary risk of chlorpyrifos residue in food inChina, a number of residue studies were conducted on rice and cabbage. The supervised trial median res-idues (STMRs) for rice and cabbage were less than 0.010 and 0.227 mg kg�1, respectively. Only 7.4% and13.3% of acceptable daily intake (ADI) (0–0.01 mg kg�1 bw) of chlorpyrifos is occupied by dietary dailyintake to the Chinese adult and children, respectively, due to the consumption of rice and cabbage. Theseresults on risk assessment were consistent with that of JMPR. Incorporation of market survey residue datagave a 5-fold reduction in the estimated exposures to chlorpyrifos. Concerning the acute exposure, thenational estimated short-term intake (NESTI) represents 0.077% and 10.6% for rice and cabbage, respec-tively, of the acute reference dose (ARfD) (0–0.1 mg kg�1 bw). The application of chlorpyrifos at the rec-ommended dose on rice and cabbage is unlikely to pose any public health issues if it is applied accordingto the good agricultural practices (GAPs) established by each country.

� 2011 Elsevier Inc. All rights reserved.

1. Introduction

Chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosp-horothioate) is an organophosphorus broad spectrum insecticideand one of the most widely-used active ingredients in agriculturalinsect control products in the world. Today, chlorpyrifos is regis-tered in about 100 countries worldwide. It has low solubility inwater and readily partitions from aqueous to organic phases inthe environment (Rack, 1993). It kills insects by disrupting theirnervous system and is effective against both sucking and chewinginsects. Many studies have assessed the effect of chlorpyrifos onthe health and safety of mammals (Dishburger et al., 1997; Johnsonet al., 1998). The presumed mode of toxicity for chlorpyrifos is ace-tylcholinesterase inhibition, which produces accumulation of syn-aptic acetylcholine and cholinergic overstimulation (Taylor, 1985).Suspected effects of chlorpyrifos exposures include birth defects,nervous system disorders and increased rate of leukemia and im-mune system abnormalities (Randhawa et al., 2007). Chlorpyrifosis widely used for pest control and in a number of crops, includingcereals, fruits, and vegetables, as well as for sanitary purposes (Le-mus and Abdelghani, 2000). The extensive agricultural and resi-dential usage of chlorpyrifos increases the potential risk forexposure in human.

ll rights reserved.

In supervised field trials, residues of toxicological concern aris-ing from pesticide use according to good agricultural practice(GAP) should be analyzed, enabling estimations for dietary riskassessment. The potential intakes could be compared with theacceptable daily intake (ADI), or other health-based guidance val-ues, such as the acute reference dose (ARfD). The pesticide wouldonly be approved for use under the conditions in which the residuelevels would not exceed the ADI or ARfD, and the maximum resi-due limit (MRL) would be determined from the residue data de-rived from the appropriate supervised field trials. If theestimated intakes would exceed either the ADI or the ARfD, thepesticide would not be approved for use under the conditions ofthe supervised field trials. The applicant should reconsider the con-ditions of the field trial (Renwick, 2002). However, use of data fromsupervised field trials will generally overestimate levels of intakeand the frequency of residues in market samples because in trials,all of the commodity sample will have been treated at the maxi-mum dose when this is very unlikely to be the case in practice(Boobis et al., 2008). Additional information on residue measure-ments is frequently available from special market–basket surveyssponsored by governments. However, it is reasonable to assumethat foods will occasionally contain pesticide residues at concen-trations observed in supervised trials, or even at the MRLs.

Since Chinese government banned five highly toxic organo-phosphorus pesticides, chlorpyrifos has become the dominant spe-cies in the country. More than 20 crops, many of which are dietarystaples for the entire nation, are protected from insect infestation

126 C. Chen et al. / Regulatory Toxicology and Pharmacology 62 (2012) 125–130

with chlorpyrifos products. However, uses of chlorpyrifos on thesecrops were not conducted with risk assessment at the time of reg-istration because the concept of risk assessment was not intro-duced into China until 2004. The aim of the present study was tounderstand the residue behavior of chlorpyrifos on rice and cab-bage, representative models of cereal and vegetable food crops,respectively, and evaluate the chronic and acute dietary risk ofchlorpyrifos in China. The estimated intakes form supervised fieldtrials were compared with that of using residue monitoring datafrom a recent market–basket survey.

2. Materials and methods

2.1. Chemicals and reagents

Chlorpyrifos standards were obtained from the Institute for theControl of Agrochemicals, Ministry of Agriculture (ICAMA), China,and purity was certified by the supplier to be greater than 99%.Stock solutions of 1 mg mL�1 were prepared in acetone and storedat �4 �C. Acetone, n-hexane, acetonitrile, ethyl acetate, dichloro-methane, and anhydrous sodium sulfate were all analytical gradeand obtained from China National Medicines Corporation Ltd.

2.2. Field trials study

The supervised field trials for the determination of chlorpyrifosresidue in rice (Oryza sativa L.) were conducted in Nanjing (118.8E,32.0 N), Chengdu (104.0E, 30.7 N) and Changsha (113.0E, 28.2 N),while the trials in cabbage (Brassica oleracea L.) were carried outin Qingdao (120.2E, 36.0 N) and Taiyuan (112.5E, 37.9 N), whichwere previously investigated to be free of the pesticide. Field trialswere conducted in separate plots measuring 30 m2 each in threereplicates according to the ‘‘Guideline on Pesticide Residue Trials’’(NY/T788-2004).

2.2.1. Field experimental designEach experimental treatment consisted of three replicate plots

and a control plot, a buffer area was used to separate each plot,and the area of each plot was 30 m2. Chlorpyrifos 30% (Larsban40 EC) w/v was sprayed at the recommended dosage of0.63 kg a.i. ha�1 and 1.5 times the recommend dosages of0.945 kg a.i. ha�1 were employed in paddy conditions of mid- andlate-rice planting periods with 3 or 4 treatments of 7 d retreatmentintervals during 2008 and 2009. In a separate experiment, chlor-pyrifos 15% GR was sprayed on cabbages at the recommended dos-age of 2.25 kg a.i. ha�1 and 1.5 times the recommend dosages of3.375 kg a.i. ha�1 with 2 or 3 treatments of 7 d retreatment inter-vals during 2007 and 2008. The spray was carried out with aknap-sack hand sprayer in the absence of precipitation.

2.2.2. Sampling and storageRepresentative rice and cabbage samples were collected from

each plot at 7, 14, 21 days and 7, 14 days, respectively, after the lastapplication of pesticide. Samples were transported at 4 �C and indarkness in labeled polyethylene bags to the laboratory, wheresamples were processed and stored at �20 �C until analysis.

2.3. Analytical procedures

2.3.1. Sample extraction and cleanupThe rice grain and cabbage samples were crushed vigorously in

a blender. 10 g of homogenized samples were extracted with60 mL acetone and then sonicated for 15 min. The combined aceto-nitrile phase was centrifuged for 2 min at 3600 rpm and the super-natant carefully transferred in a graduated vial. The supernatant

was partitioned thrice with 60 mL dichloromethane. The dichloro-methane phase was further dried by passing through a 2-cm layerof anhydrous sodium sulfate. The organic solvent was eliminatedby nitrogen evaporation and the extract was redissolved in 1 mLacetone for chlorpyrifos analysis.

2.3.2. Instrumental determinationThe chlorpyrifos concentrations were determined on an Agilent

6890 GC equipped with a flame photometric detector (FPD) and aDB-17 (30 m length, 0.25 lm film thickness, 0.53 mm i.d) capillarycolumn. The gas chromatographic analysis was performed underthe following conditions: detector temperature was 280 �C, inlettemperature was 250 �C, initial oven temperature was 150 �C for2 min, then ramped to 250 �C at 8 �C min�1 and held for 12 min. Ul-tra-pure quality nitrogen was used as carrier gas and injectionswere carried out in splitless mode using 1 lL injection volumes.

The accuracy and precision of the measurements were de-scribed by recovery and relative standard deviation (RSD) at differ-ent concentrations (0.01 and 0.1 mg kg�l) in rice and (0.005, 0.1and 1.0 mg kg�l) in cabbage, respectively. The mean recovery ofchlorpyrifos obtained from rice and cabbage was in the range of88.5–90.6% and 90.3–101.9%, respectively, as shown in Table 2.The RSD for repeatability ranged from 0.68% to 8.5%, which is with-in the acceptable limits for routine analysis of chlorpyrifos resi-dues. Samples were quantified using external standards, with alinear working curve between 0.01 and 1 mg mL�1. The limit ofquantification (LOQ) was established at 0.01 mg kg�1, whichyielded a signal-to-noise (S/N) ratio of 10. The limit of detection(LOD) was 0.003 mg kg�1 at a signal-to-noise ratio of 3.

2.4. Hazard assessment

A number of toxicological studies of chlorpyrifos includingacute, subchronic and chronic studies have been conductedaccording to the guidelines of OECD and US EPA (FAO/WHO,2000). Relevant toxicological end-points of chlorpyrifos are sum-marized in Table 1. The lowest relevant no observed adverse effectlevel (NOAEL) is 1 mg kg�1 bw d�1, based on the inhibition of braincholinesterase activity in rats in a 2-year carcinogenicity study andthe effects in reproductive and developmental toxicity studies. Theestablished ADI for humans was set at 0–0.01 mg kg�1 bw by theWHO/IPCS and by the FAO/WHO JMPR using a 100-fold safety fac-tor in 1999 (FAO/WHO, 2000).

2.5. Chinese food consumption data

Chinese food consumption data were derived from the 2002China National Nutrition and Health Survey (CNNHS) (Jin, 2008),covering residents from 31 provinces, autonomous regions ormetropolises in China (excluding Hong Kong, Taiwan and Macau).The survey was conducted using a multi-stage, random cluster pro-cess over three consecutive days (two weekdays and one weekend,holidays excluded). A total of 23,470 families responded to the sur-vey, in which 7687 families were from urban areas and 15,783were from rural areas. The total of 23,470 families consisted of68,962 individuals being surveyed, 33,551 males and 35,411 fe-males. Detailed records of food consumption were collected by aweighing method combined with a 24 h dietary recall of food con-sumption during these days. Foods consumed outside of the resi-dents were also included into the recall records, from which theaverage nutrients consumed by the individual were calculated(Zhai et al., 2005; Wang, 2006). The food types are categorized intoone of 10 groupings: rice, flour, coarse cereal, pulses, vegetables,fruit, meat, milk, eggs, and aquatic products.

Table 2Analytical recoveries (%) ± RSD of chlorpyrifos in rice (n = 6) and cabbage (n = 5) samples at different fortification levels.

Matrix Fortification level (mg kg�1) Recovery (%) Mean recovery (% ±SD) RSD (%)

1 2 3 4 5 6

Rice 0.1 98.4 87.6 83.2 90.4 94.6 89.3 90.6 ± 5.31 5.860.01 80.2 79.4 90.3 91.4 99.3 90.3 88.5 ± 7.52 8.5

Cabbage 0.005 95.5 99.5 104.9 109.1 100.3 101.9 ± 5.25 5.250.1 90.2 92.2 87.9 91.7 89.5 90.3 ± 1.73 1.721 90.2 91.8 90.2 91 90.6 90.8 ± 0.67 0.68

Table 1Relevant toxicological end-points for chlorpyrifos.

Acute toxicityLD50, oral 96 mg kg�1 bw (rats)LD50, dermal >2000 mg kg�1 bw (rats)LC50, inhalation >36 mg/m3 (rats, 4 h, vapor, nose-only exposure)

560 mg/m3 (rats, 4 h, nebulized particles < 5 mm, whole-body exposure)Rabbit, dermal irritation Slightly irritatingRabbit, ocular irritation Slightly irritatingGuinea-pig, dermal sensitisation Not sensitizing

Short-term toxicityTarget/critical effect Inhibition of brain cholinesterase activityLowest critical oral NOAEL 1 mg kg�1 bw d�1 (dogs, 2 years)

1 mg kg�1 bw d�1 (rats, 13 weeks)Lowest relevant dermal NOAEL 5 mg kg�1 bw d�1 (rats, 21 days)Lowest relevant inhalation NOAEL 296 mg/m3 (rats, 13 weeks)

Long-term toxicity and carcinogenicityTarget/critical effect Inhibition of brain cholinesterase activityLowest relevant NOAEL 1 mg kg�1 bw d�1 (rats, 2 years)

0.7 mg kg�1 bw d�1 (rats, 78 weeks)Carcinogenicity Not carcinogenic rats, miceGenotoxicity Not genotoxic

Reproductive toxicityReproductive target/critical effect Neonatal toxicity (reduced pup body weight and survival)Lowest relevant reproductive NOAEL 1 mg kg�1 bw d�1 (rats, two generations)Developmental target/critical effect Fetal and perinatal toxicity at maternally toxic doses (including an increase in delayed ossification, reduced crown-rump

length, reduced pup weight, increased postimplantation loss, delayed sexual maturity)Lowest relevant developmental

NOAEL1 mg kg�1 bw d�1 (rats)

Neurotoxicity/delayed neurotoxicity Reversible neurotoxicity consistent with cholinesterase inhibition. No evidence of delayed neurotoxicity or histopathologicalchanges in nerves of hens (10 mg kg�1 bw d�1) and rats (15 mg kg�1 bw d�1) for up to 13 weeks. At high acute doses (up to150 mg kg�1 bw d�1), significant inhibition of neuropathy target esterase and mild delayed neuropathy in hens, but at thisdose, extensive and aggressive antidote treatments were required for birds’ survival

Other toxicological studies No effect on cognitive function in rat pups in a study of developmental toxicity at doses up to 5 mg kg�1 bw d�1

C. Chen et al. / Regulatory Toxicology and Pharmacology 62 (2012) 125–130 127

2.6. Exposure assessment

2.6.1. Chronic intake assessmentThe NEDI (national estimated daily intake) provides a realistic

estimate of average long-term intakes of pesticide residues fromthe use of pesticides under GAP. The NEDI is the sum for all foodcommodities of the intake of that particular food commodity timesthe appropriate residue level for that commodity. The followingequation was used to calculate the intakes (WHO, 1997; Gaoet al., 2007):

NEDI ¼ STMRi � Ei � Fi ð1Þ

where STMRi is the supervised trial median residue level for a givenfood commodity; Ei is the edible portion factor for that food com-modity; Fi is the national consumption rate of that food commodity.STMR represents the most likely residue level that would resultfrom the use of the pesticide at the maximum approved dosesand timings under GAP.

2.6.2. Acute intake assessmentDietary intakes of residue levels close to the MRL may occur

periodically following use of the pesticide under GAP. Under thesecircumstances, risk characterization should be based on potential

short-term intakes in comparison with the ARfD (Renwick, 2002).However, the residue data from supervised field trials are basedon composite samples, and variability may exist within the differ-ent units of that composite sample and the use of MRLs as a legallyenforceable limit is based on composite samples. The calculation ofthe national estimated short-term intake (NESTI) requires single-day consumption data for the high-end (the 97.5th percentile) con-sumers and a consideration of variability from unit to unit within acomposite sample.

For rice, the available composite residue data reflect the residuelevels in a meal-sized portion of the commodity as consumed(commodity unit weight is below 25 g). This scenario would arisewhen the commodity was well mixed during processing. Underthese circumstances, the NESTI is calculated simply as the largeportion consumption for the commodity (LP) multiplied by thehighest residue (HR) level detected in the supervised trials dividedby the body weight (BW) (Hamilton et al., 2004).

NESTI ¼ LP�HR=BW ð2Þ

As for cabbage, the available composite residue data do not re-flect the residue level in the food commodity as consumed due tovariability between the individual units within the composite sam-ple. The unit weight of the whole portion is higher than that of the

128 C. Chen et al. / Regulatory Toxicology and Pharmacology 62 (2012) 125–130

large portion. In such cases, the residue level, which is measuredfrom a composite sample, has to be increased by a variability factor(v), which reflects the ratio of a high-level residue to the compositeresidue level (Hamilton et al., 2004).

NESTI ¼ LP� HR� v=BW ð3Þ

2.6.3. Exposure assessment using monitoring dataMeasurements of pesticide residues on foods can come from

different sources (Wright et al., 2002). Supervised field trials areconducted under conditions of the maximum proposed applicationrate and the shortest interval between application and harvest.Additional residue measurements come from monitoring pro-grams, which involve collection and analysis of food samples fromfood distribution centers in a manner that adequately representsthe entire population.

Therefore in a higher level of exposure assessment, market–bas-ket survey data for chlorpyrifos were used in the analysis. Rice is amajor single food of the Chinese diet and it was selected for com-parisons of dietary exposures from two residue data sources. Amarket–basket survey measured residues of chlorpyrifos on 2520samples of milled rice from over 20 provinces throughout Chinaduring 2004–2006 (Chen et al., 2009). Residues of chlorpyrifoswere found in 42 samples in the range of lower than detection lim-it to 0.612 mg kg�l. The dietary exposure to chlorpyrifos was calcu-lated deterministically based on consumption rate and individualbody weights of the Chinese population, and residue measure-ments data. The average residue level was multiplied with the

Table 3Residue data for chlorpyrifos on rice.

Location kg a.i. ha�1 N PHI (d) Concentration (mg kg�1)

Nanjing (2008) 0.63 3 7 0.2114 0.0821 BDL

4 7 0.2414 0.1421 BDL

0.945 3 7 0.3114 0.0921 BDL

4 7 0.4114 0.1621 0.04

Chengdu (2008) 0.63 3 7 0.2814 0.0821 BDL

4 7 0.3214 0.1421 BDL

0.945 3 7 0.3714 0.1221 0.01

4 7 0.3914 0.1521 0.03

Changsha (2008) 0.63 3 7 0.3114 0.1121 BDL

4 7 0.3114 0.1421 BDL

0.945 3 7 0.3614 0.1421 0.01

4 7 0.3914 0.1921 0.05

BDL: below determination limit of 0.01 mg kg�1.a.i., Active ingredient; ha, hectare.PHI, pre-harvest interval.N, No. of applications.

average consumption rate in order to have an idea of the chronicexposure of the population to pesticide residues.

2.7. Risk characterization

Percentage of ADI or ARfD occupied by chronic or acute dietaryintakes was calculated to determine the dietary risk ofchlorpyrifos.

3. Results and discussion

3.1. Residue trial results

3.1.1. RiceIn China, chlorpyrifos is registered for use on rice at

0.63 kg a.i. ha�1 with pre-harvest interval (PHI) of 21 days afterthe final application. In 12 trials conducted in China that followedthe above GAP conditions, the concentrations of chlorpyrifos resi-dues in rice were all below the limit of LOQ (0.01 mg kg�1) (Table 3).In one of the trials with higher application rate at 0.945 kg a.i. ha�1

and a PHI of 7 days after the final application, the concentration ofchlorpyrifos residue in rice was 0.46 mg kg�1 (Table 3). As a generalrule, when all residue trials data are below the LOQ, the STMR valuewould be assumed to be at the LOQ (FAO, 2002).

The results indicated that the median residue level should beestimated to be at the LOQ. In this trial, the estimated STMR was0.01 mg kg�1.

Location kg a.i. ha�1 N PHI (d) Concentration (mg kg�1)

Nanjing (2009) 0.63 3 7 0.2514 0.0921 BDL

4 7 0.3414 0.1221 BDL

0.945 3 7 0.3114 0.121 0.01

4 7 0.4614 0.221 0.04

Chengdu (2009) 0.63 3 7 0.2914 0.0921 BDL

4 7 0.3414 0.1721 0.01

0.945 3 7 0.3114 0.1521 BDL

4 7 0.4314 0.221 0.02

Changsha (2009) 0.63 3 7 0.2614 0.1521 BDL

4 7 0.3314 0.1721 0.01

0.945 3 7 0.414 0.1821 0.03

4 7 0.5414 0.2221 0.06

C. Chen et al. / Regulatory Toxicology and Pharmacology 62 (2012) 125–130 129

3.1.2. CabbageChlorpyrifos is registered in China for use on cabbage at

2.25 kg a.i. ha�1 with a PHI of 14 days after the final application.Eight residue trials were conducted under the GAP conditions inChina. The concentrations of chlorpyrifos residues were 0.153,0.157, 0.175, 0.216, 0.237, 0.305, 0.51, and 0.544 mg kg�1 (Table 4).The estimated STMR of cabbage is therefore 0.227 mg kg�1.

FAO/WHO JMPR proposed MRLs for rice and cabbage are 0.5 and1 mg kg�1, respectively (FAO, 2004). Based on our residue results,the highest residue (HR) levels of chlorpyrifos for rice and cabbagefollowing the GAPs in China were <0.01 and 0.544 mg kg�1, respec-tively. Typically, the MRL is set slightly higher than the residuesmeasured in field trials to accommodate the maximum residuesunder the maximum application rates, various weather conditions,and the shortest PHI. Thus we propose 1.0 mg kg�1 as the MRL forchlorpyrifos on cabbage in China.

We found that the STMR for rice adopted by Codex(0.008 mg kg�1) is similar to the STMR of the residue trial resultsin China. The STMR for cabbage derived from the residue trial re-sults in China is higher than the STMR for cabbage adopted by Co-dex (0.15 mg kg�1).

3.2. Exposure assessment and risk characterization

3.2.1. Chronic intake assessmentTable 5 shows a comparison between the dietary exposures to

chlorpyrifos using field trial residues and market survey measure-ments on rice. Incorporation of market survey residue data onrice gave a marked reduction in the estimated exposures to chlor-pyrifos. The estimated exposure was 0.00074 and 0.0013 mg kg�1

bw d�1 for Chinese adult and children, respectively, based onthe Chinese food consumption rate. The incorporation of pesticideresidues measured closer to the point of consumption for thesefoods gave a 5-fold reduction in exposure estimates (Table 5).

Table 4Residue data for chlorpyrifos on cabbage.

Location kg a.i. ha�1 N PHI (d) Concentration (mg kg�1)

Qingdao (2007) 2.25 2 7 0.26314 0.237

3 7 1.0514 0.157

3.375 2 7 1.06514 0.164

3 7 1.8214 0.356

Taiyuan (2007) 2.25 2 7 0.34914 0.153

3 7 0.45214 0.175

3.375 2 7 0.45814 0.185

3 7 0.6514 0.318

Table 5Daily intake a (mg kg�1 bw d�1) of chlorpyrifos residues on rice and cabbage based on Ch

Crop STMR (mg kg�1) Monitoring residue level (mg kg�1) Consump

Adult

Rice 0.01 0.0069 238.3Cabbage 0.227 185.4TotalADI%

a Based on an assumption of average body weight of Chinese adult as 60 kg and childb Calculated from mean monitoring residue level.c Calculated from STMR.

The field trial results represent the highest residues, while themarket survey levels represent residues resulting from variableapplication rates, storage times, environmental degradation, andfood processing. Market survey measurements realistically esti-mate the magnitude of pesticide residue on food as it is purchasedby the consumer, because samples are taken closer to the pointof consumption, and more accurately represent actual patternsof use and food distribution than measurements from a typicalfield trial.

However, in some rice samples collected from market–basketsurvey, higher residue levels of chlorpyrifos exceeding CodexMRL values (0.5 mg kg�1) was observed. This may be attributedto the fact that farmers are mostly illiterate about the safe andjudicious use of pesticides. Residue level of any pesticide in plantsis primarily dependent on the application rate of the active ingre-dient (Sadlo, 2000). In addition, the repeated use of the pesticide inthe field, particularly closer to harvest significantly contributes to-ward higher residues in food (Dogheim et al., 1996).

3.2.2. Short-term intake assessmentThe NESTI for chlorpyrifos was calculated for rice and cabbage

for which the HR values were estimated and for which data on con-sumption (large portion and unit weight) were available fromGEMS/Food database. The NESTI for rice and cabbage were0.00008 and 0.0106 mg kg�1 bw d�1, respectively.

3.2.3. Risk characterizationComparing estimated daily intake of chlorpyrifos (0.00074 and

0.0013 mg kg�1 bw d�1 for adult and children, respectively) in Chi-na with the ADI (0–0.01 mg kg�1 bw), only 7.4% and 13.3% of ADI isoccupied, respectively. Rice and cabbage are representative modelsof cereal and vegetable in China and contribute 58.4% to the totaldaily food consumption. Intakes of pesticide residues from riceand cabbage may contribute a major part to the total intakes of

Location kg a.i. ha�1 N PHI (d) Concentration (mg kg�1)

Qingdao (2008) 2.25 2 7 0.35914 0.216

3 7 1.9114 0.305

3.375 2 7 2.27514 0.316

3 7 1.6614 0.305

Taiyuan (2008) 2.25 2 7 0.84214 0.51

3 7 0.90614 0.544

3.375 2 7 0.77114 0.654

3 7 1.92414 0.921

inese food consumption data.

tion (g day�1) Daily intakeb Daily intakec

Children Adult Children Adult Children

116.8 2.7 � 10�5 5.4 � 10�5 4 � 10�5 7.8 � 10�5

82.7 7 � 10�4 1.2 � 10�3

7.4 � 10�4 1.3 � 10�3

7.4% 13.3%

ren as 15 kg.

130 C. Chen et al. / Regulatory Toxicology and Pharmacology 62 (2012) 125–130

chlorpyrifos. Data on consumption in GEMS/Food cluster dietswere available for 49 food commodities and were used to calculatedietary intakes, which were calculated as 0.00033–0.0026 mg kg�1 bw d�1 for the five GEMS/Food diets in 2004(FAO, 2004). These results by JMPR are comparative with that inthe present study. Concerning the acute risk, the NESTI of riceand cabbage represents 0.077% and 10.6% of the ARfD (0–0.1 mg kg�1 bw), suggesting that the dietary risk of chlorpyrifosis fairly low for the general Chinese population.

It should be noted that the intake calculations were conserva-tive, as we did not take into account the reduction in residue levelsobtained by processing of these commodities.

4. Conclusion

Based on the supervised residue trials and the risk assessmentresults, the application of chlorpyrifos at the recommended doseon rice and cabbage is quite safe in China from crop protectionand human health point of view. The advantages of the applicationof pesticides in agriculture in producing better crops must beweighed against the possible health hazard arising from the pesti-cide residues in food. Pesticides should be applied according toGAP, using the required amounts.

Conflict of interest statement

We declare that there are none competing interests related toour manuscript.

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