Effects on Thyroid Observed Toxicological Effects · Changes in T4 and T3 and increased TSH. ... 4...
10
Perchlorate Perchlorate in Vegetables in Vegetables Page Page 1 Update of Perchlorate in Vegetables Charles Sanchez Charles Sanchez Professor of Soil, Water, and Environmental Professor of Soil, Water, and Environmental Sciences Sciences University of Arizona University of Arizona Robert I. Krieger Robert I. Krieger Extension Toxicologist Extension Toxicologist University of California, Riverside University of California, Riverside Background Background The Colorado River is contaminated with low The Colorado River is contaminated with low levels of perchlorate (ClO levels of perchlorate (ClO 4 - ), a chemical linked to ), a chemical linked to thyroid dysfunction and considered a health threat thyroid dysfunction and considered a health threat to humans. to humans. This contamination is from aerospace and defense This contamination is from aerospace and defense related fuel industries present in the Las Vegas related fuel industries present in the Las Vegas Wash. Wash. It is estimated that more than 20 million people It is estimated that more than 20 million people are exposed to perchlorate in drinking water from are exposed to perchlorate in drinking water from the Colorado River. the Colorado River. There is concern that food in feed crops irrigated There is concern that food in feed crops irrigated with this water may accumulate perchlorate with this water may accumulate perchlorate further enhancing human exposure. further enhancing human exposure. Effects on Thyroid Effects on Thyroid The principal hormones involved are The principal hormones involved are thyroxine (T4) and triiodothyronine (T3) thyroxine (T4) and triiodothyronine (T3) both iodine containing amino acids. both iodine containing amino acids. The molecule responsible for the active The molecule responsible for the active transport of iodine is known as the sodium transport of iodine is known as the sodium- iodine symporter (NIS). iodine symporter (NIS). Perchlorate inhibits this iodine dependent Perchlorate inhibits this iodine dependent transport. transport. Observed Toxicological Effects Observed Toxicological Effects Decreased thyroid uptake of radioactive Decreased thyroid uptake of radioactive iodine iodine Changes in T4 and T3 and increased TSH. Changes in T4 and T3 and increased TSH. Thyroid enlargement (goiter), follicular Thyroid enlargement (goiter), follicular hyperplasia with decreased colloid. hyperplasia with decreased colloid. Half Life Half Life The biological half life of perchlorate The biological half life of perchlorate appears to be less than 12 hours (Lamn et appears to be less than 12 hours (Lamn et al., 1999). al., 1999). However, there is concern that even short However, there is concern that even short term exposure in drinking water may affect term exposure in drinking water may affect sensitive sub sensitive sub- populations. populations. Sensitive Sub Sensitive Sub- groups groups Pregnant women who are marginally iodine Pregnant women who are marginally iodine deficient (Crooks et al. 1967; Glinoer et al., deficient (Crooks et al. 1967; Glinoer et al., 1990; 1992). 1990; 1992). Fetuses and newborns of these pregnant Fetuses and newborns of these pregnant women (Pop et al., 1999; Haddow et al., women (Pop et al., 1999; Haddow et al., 1999). 1999). Individuals suffering from hypothyroidism. Individuals suffering from hypothyroidism.
Transcript of Effects on Thyroid Observed Toxicological Effects · Changes in T4 and T3 and increased TSH. ... 4...
PerchloratePerchlorate in Vegetablesin Vegetables
Page Page 11
Update of Perchlorate in Vegetables
Charles SanchezCharles SanchezProfessor of Soil, Water, and Environmental Professor of Soil, Water, and Environmental
SciencesSciencesUniversity of ArizonaUniversity of Arizona
Robert I. KriegerRobert I. KriegerExtension ToxicologistExtension Toxicologist
University of California, RiversideUniversity of California, Riverside
BackgroundBackgroundThe Colorado River is contaminated with low The Colorado River is contaminated with low levels of perchlorate (ClOlevels of perchlorate (ClO44
--), a chemical linked to ), a chemical linked to thyroid dysfunction and considered a health threat thyroid dysfunction and considered a health threat to humans.to humans.This contamination is from aerospace and defense This contamination is from aerospace and defense related fuel industries present in the Las Vegas related fuel industries present in the Las Vegas Wash.Wash.It is estimated that more than 20 million people It is estimated that more than 20 million people are exposed to perchlorate in drinking water from are exposed to perchlorate in drinking water from the Colorado River.the Colorado River.There is concern that food in feed crops irrigated There is concern that food in feed crops irrigated with this water may accumulate perchlorate with this water may accumulate perchlorate further enhancing human exposure.further enhancing human exposure.
Effects on ThyroidEffects on Thyroid
The principal hormones involved are The principal hormones involved are thyroxine (T4) and triiodothyronine (T3) thyroxine (T4) and triiodothyronine (T3) both iodine containing amino acids.both iodine containing amino acids.The molecule responsible for the active The molecule responsible for the active transport of iodine is known as the sodiumtransport of iodine is known as the sodium--iodine symporter (NIS).iodine symporter (NIS).Perchlorate inhibits this iodine dependent Perchlorate inhibits this iodine dependent transport.transport.
Observed Toxicological EffectsObserved Toxicological Effects
Decreased thyroid uptake of radioactive Decreased thyroid uptake of radioactive iodineiodineChanges in T4 and T3 and increased TSH.Changes in T4 and T3 and increased TSH.Thyroid enlargement (goiter), follicular Thyroid enlargement (goiter), follicular hyperplasia with decreased colloid.hyperplasia with decreased colloid.
Half LifeHalf Life
The biological half life of perchlorate The biological half life of perchlorate appears to be less than 12 hours (Lamn et appears to be less than 12 hours (Lamn et al., 1999).al., 1999).However, there is concern that even short However, there is concern that even short term exposure in drinking water may affect term exposure in drinking water may affect sensitive subsensitive sub--populations.populations.
Sensitive SubSensitive Sub--groupsgroupsPregnant women who are marginally iodine Pregnant women who are marginally iodine deficient (Crooks et al. 1967; Glinoer et al., deficient (Crooks et al. 1967; Glinoer et al., 1990; 1992).1990; 1992).Fetuses and newborns of these pregnant Fetuses and newborns of these pregnant women (Pop et al., 1999; Haddow et al., women (Pop et al., 1999; Haddow et al., 1999).1999).Individuals suffering from hypothyroidism.Individuals suffering from hypothyroidism.
PerchloratePerchlorate in Vegetablesin Vegetables
Page Page 22
Proposed EPA standardProposed EPA standard
EPA has proposed a drinking water equivalent EPA has proposed a drinking water equivalent (DWEL)levels of 1 ppb.(DWEL)levels of 1 ppb.Largely based on study with rats conducted by Largely based on study with rats conducted by Argus Research Laboratory.Argus Research Laboratory.From these data EPA estimated a “No observed From these data EPA estimated a “No observed adverse effect level” (LOAEL) of 0.0085 adverse effect level” (LOAEL) of 0.0085 mg/kg/day.mg/kg/day.EPA applied an uncertainty factor of 300 to this EPA applied an uncertainty factor of 300 to this LOAEL, an assumed body weight and a drinking LOAEL, an assumed body weight and a drinking water consumption rate of 2 L/day to calculate a water consumption rate of 2 L/day to calculate a DWEL of 1 ppb.DWEL of 1 ppb.
EPA DWEL under review by EPA DWEL under review by NASNAS
The Department of Defense (DOD) has The Department of Defense (DOD) has challenged this proposed DWEL.challenged this proposed DWEL.The Bush administration has asked the The Bush administration has asked the National Academy of Sciences for an National Academy of Sciences for an opinion on the issue.opinion on the issue.An opinion is expected in early 2005An opinion is expected in early 2005
CaliforniaCalifornia
The state of California has chosen to focus The state of California has chosen to focus on human data (Greer et al., 2000, 2002; on human data (Greer et al., 2000, 2002; Lawrence et al., 2000, 2001).Lawrence et al., 2000, 2001).No iodide inhibition was obtained at a dose No iodide inhibition was obtained at a dose of 0.007 mg/kg/day.of 0.007 mg/kg/day.Using this data, an uncertainty factor of 30 Using this data, an uncertainty factor of 30 and a relative source contribution of 60% a and a relative source contribution of 60% a public health goal of 6ppb has been public health goal of 6ppb has been established by OEHHA.established by OEHHA.
SituationSituationApproximately 7.2 Approximately 7.2 million acre feet ( 9 million acre feet ( 9 billion mbillion m33) of ) of irrigation water are irrigation water are diverted from the diverted from the Colorado for use in Colorado for use in Arizona and southern Arizona and southern CaliforniaCaliforniaApproximately 4.2 Approximately 4.2 million acre feet (5 million acre feet (5 billion mbillion m33) diverted at ) diverted at Imperial Diversion Imperial Diversion near Yuma.near Yuma.
Irrigation WaterIrrigation Water
Water samples are Water samples are filtered with Onfiltered with On--Guard Ba/Ag/H Guard Ba/Ag/H cartridges and cartridges and syringe filter.syringe filter.
Dionex 2500Dionex 2500
Used 2mm AG 16/AC16 Used 2mm AG 16/AC16 column pair.column pair.IP 25 isocratic pump, IP 25 isocratic pump, EG50 eluent generator with CREG50 eluent generator with CR--TC, and TC, and conductivity detector.conductivity detector.The columns and suppressor (AMMS III) housed The columns and suppressor (AMMS III) housed in a LC 30 chromatography oven.in a LC 30 chromatography oven.We used 50 mM KOH eluent and 50 mM sulfuric We used 50 mM KOH eluent and 50 mM sulfuric acid suppression acid suppression
PerchloratePerchlorate in Vegetablesin Vegetables
Page Page 33
0.0 1.3 2.5 3.8 5.0 6.3 7.5 8.8 10.0 11.3 12.5 13.8 15.0 16.3 17.5 18.8 20.0-1.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
1 - 040116CAS #72 [modified by UNIVERSITY ARIZONA] CR 1/8/04 ECD_12 - 040116CAS #74 [modified by UNIVERSITY ARIZONA] CR 1/8/04-2 ECD_1µS
min
2
11 - CLO4 - 10.783
0123456789
03/0
3/20
03
04/0
3/20
03
05/0
3/20
03
06/0
3/20
03
07/0
3/20
03
08/0
3/20
03
09/0
3/20
03
10/0
3/20
03
11/0
3/20
03
12/0
3/20
03
01/0
3/20
04
02/0
3/20
04
Date
Perc
hlor
ate
(ug/
L)Perchlorate Dosage Equivalents to Perchlorate Dosage Equivalents to Drinking Water Advisory LevelsDrinking Water Advisory Levels
0.20.2
0.40.4
0.030.03
DosageDosageug/kg bwug/kg bw
66PHGPHGCaliforniaCalifornia
1414HBGLHBGLArizonaArizona
11DEWLDEWLUSEPAUSEPA
LevelLevelDescriptionDescriptionSourceSource
Perchlorate in SoilPerchlorate in Soil
We can measure perchlorate in soils of the We can measure perchlorate in soils of the lower Colorado River region.lower Colorado River region.Amount are low and appear to be Amount are low and appear to be depositional.depositional.Perchlorate is not physically or chemically Perchlorate is not physically or chemically retained by the soil to any significant extent.retained by the soil to any significant extent.
Potential Perchlorate AccumulationPotential Perchlorate Accumulation
Each 10 cm irrigation would Each 10 cm irrigation would include 5 g of ClOinclude 5 g of ClO44 per per hectare.hectare.Total seasonal irrigation for Total seasonal irrigation for lettuce is approximately 40 cm lettuce is approximately 40 cm and a lettuce crop might and a lettuce crop might receive up to 20 g of ClOreceive up to 20 g of ClO44 per per hectare.hectare.Lettuce ET is approximately Lettuce ET is approximately 23 cm and a lettuce crop could 23 cm and a lettuce crop could have a potential ClOhave a potential ClO44accumulation of 11.5 g per accumulation of 11.5 g per hectare.hectare.
Sub samples of crop Sub samples of crop material are chopped material are chopped or diced and frozen.or diced and frozen.Frozen samples are Frozen samples are freeze dried.freeze dried.Freeze dried samples Freeze dried samples are ground for are ground for analysis.analysis.
PerchloratePerchlorate in Vegetablesin Vegetables
Page Page 44
Extraction and cleanExtraction and clean--up up (Ellington and Evans, (2000)(Ellington and Evans, (2000)
Combine 0.6 g of sample and 15 mL Combine 0.6 g of sample and 15 mL of DI water in centrifuge tube and boilof DI water in centrifuge tube and boilfor 30 minutes.for 30 minutes.Place contents in refrigerator for 24 hours.Place contents in refrigerator for 24 hours.Centrifuge and filter for “extract 1”.Centrifuge and filter for “extract 1”.Combine 2 mL of extract 1 and 1 g of Combine 2 mL of extract 1 and 1 g of DDDD--6 alumina and allow to react for 24 hours.6 alumina and allow to react for 24 hours.Add 18 mL of water, filter to complete “extract 2”.Add 18 mL of water, filter to complete “extract 2”.Filter aliquots of extract 2 through OnFilter aliquots of extract 2 through On--Guard RP Guard RP cartridge before loading on IC.cartridge before loading on IC.
0.0 1.3 2.5 3.8 5.0 6.3 7.5 8.8 10.0 11.3 12.5 13.8 15.0 16.3 17.5 18.8 20.0-1.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
1 - 03926CAS #141 [modified by UNIVERSITY ARIZONA] 24A-1 ECD_12 - 03926CAS #142 [modified by UNIVERSITY ARIZONA] 24A-3 ECD_1µS
min
2
11 - CLO4 - 10.000
Perchlorate Distribution in Iceberg Lettuce Perchlorate Distribution in Iceberg Lettuce During Growing SeasonDuring Growing Season
Perchlorate (ug/kg fresh weight) Perchlorate (ug/kg fresh weight)
5353<MRL<MRL46467979108108MatureMature8989<MRL<MRL73738989208208HeadingHeading1021027070100100169169FoldingFolding102102282811011066--7L7L17017022--LL
WholeWholePlantPlant
CoreCore99--12L12L55--9L9L11--4L4LGrowth Growth StageStage
Perchlorate Accumulation in Iceberg Lettuce Perchlorate Accumulation in Iceberg Lettuce During Growing SeasonDuring Growing Season
Perchlorate accumulation (g/ha)Perchlorate accumulation (g/ha)
2.602.60<MRL<MRL0.240.240.740.740.660.66MatureMature1.171.17<MRL<MRL0.300.300.300.300.390.39HeadingHeading0.420.420.1000.1000.1560.1560.1250.125FoldingFolding0.01780.01780.000870.000870.1600.16066--7L7L0.00050.000522--LL
WholeWholePlantPlant
CoreCore99--12L12L55--9L9L11--4L4LGrowth Growth StageStage
NDND5858<MRL<MRL77<MRL<MRL6363272766
23235555303055<MRL<MRL6565222244
NDND4444<MRL<MRL33<MRL<MRL9090323222<MRL<MRL9494373711
HeadHeadFrame & Frame & Wrapper Wrapper LeavesLeaves
Whole PlantWhole PlantSampleSamplePerchlorate (ug/kg)Perchlorate (ug/kg)
Perchlorate in Iceberg Lettuce (2002Perchlorate in Iceberg Lettuce (2002--2003)2003)
<MRL<MRL7474343477<MRL<MRL4444333366
23235555383855<MRL<MRL8989464644<MRL<MRL5555373733<MRL<MRL7777343422<MRL<MRL100100707011
HeadHeadFrame & Frame & Wrapper Wrapper LeavesLeaves
Whole PlantWhole PlantSampleSamplePerchlorate (ug/kg)Perchlorate (ug/kg)
Perchlorate in Iceberg Lettuce (2003Perchlorate in Iceberg Lettuce (2003--2004)2004)
PerchloratePerchlorate in Vegetablesin Vegetables
Page Page 55
Estimated AboveEstimated Above--Ground Ground Perchlorate UptakePerchlorate Uptake
In the spring season of 2002In the spring season of 2002--2003 we estimated 2003 we estimated perchlorate accumulation in the total above ground perchlorate accumulation in the total above ground plant mass of iceberg lettuce was 2.2 g perchlorate plant mass of iceberg lettuce was 2.2 g perchlorate per hectare. Of this, 1.8 g was returned to the soil per hectare. Of this, 1.8 g was returned to the soil in the trimmings.in the trimmings.In fall season of 2003In fall season of 2003--2004 we estimated 2004 we estimated perchlorate accumulation in the above ground perchlorate accumulation in the above ground plant of iceberg lettuce was 2.7 g perchlorate per plant of iceberg lettuce was 2.7 g perchlorate per hectare. Of this, 2.1 g was returned to the soil in hectare. Of this, 2.1 g was returned to the soil in the trimming.the trimming.
Anion CompetitionAnion Competition
A number of studies indicate uptake of A number of studies indicate uptake of pertechnetate and perchlorate by plants is pertechnetate and perchlorate by plants is affected by other anions including nitrate affected by other anions including nitrate (Echevarria et al., 1998; Krijger 2000), (Echevarria et al., 1998; Krijger 2000), sulfate and phosphate (Cataldo et al., 1978; sulfate and phosphate (Cataldo et al., 1978; 1983).1983).
Typical Anion Composition of Typical Anion Composition of Colorado River WaterColorado River Water
20200.10.1BoronBoron80800.40.4FluorideFluoride
1601600.80.8NitrateNitrate60,00060,000300300SulfateSulfate36,00036,000180180BicarbonateBicarbonate24,00024,000120120ChlorideChloride
Ratio to ClORatio to ClO44Concentration Concentration (mg/L)(mg/L)
AnionAnion
Perchlorate accumulation as Perchlorate accumulation as affected by competing anionsaffected by competing anions
19.419.425825876.976.91.931.93
31.031.035935985.885.81.071.07
29.129.131631692.592.50.610.61
27.427.432332385.185.10.400.40
28.228.234134184.084.00.240.24
28.028.033533583.383.30.180.18
PerchloratePerchlorateUptakeUptake(ug/pot)(ug/pot)
PerchloratePerchlorateConcentrationConcentration
(ng/g)(ng/g)
YieldYield(g/pot(g/pot
WaterWaterECEC
Perchlorate uptake by lettuce as affected by Perchlorate uptake by lettuce as affected by N rate and sourceN rate and source
15.615.630730741.941.9UreaUrea
19.519.527327372.772.7(NH(NH44))22SOSO44
19.819.826726773.673.6Ca(NOCa(NO33))22
22.322.326726780.280.2NHNH44NONO33
N SourceN Source6.36.318518540.740.71.401.4025.925.934134177.477.40.700.7025.725.731131183.283.20.350.359.09.073173112.012.000
PerchloratePerchlorateUptakeUptake(ug/pot)(ug/pot)
Perchlorate Perchlorate ConcentrationConcentration
(ng/g)(ng/g)
Fresh Fresh Weight Weight (g/pot)(g/pot)
N RateN Rate(g/pot)(g/pot)
PerchloratePerchlorate in Vegetablesin Vegetables
Page Page 66
Perchlorate uptake by lettuce as affected by PPerchlorate uptake by lettuce as affected by P
34.634.636036096.296.20.700.70
32.832.834734797.997.90.350.35
28.128.130030093.793.70.170.17
8.68.623223237.337.300
PerchloratePerchlorateUptakeUptake(ug/pot)(ug/pot)
Perchlorate Perchlorate ConcentrationConcentration
(ng/g)(ng/g)
Fresh Fresh Weight Weight (g/pot)(g/pot)
P RateP Rate(g/pot)(g/pot)
Perchlorate Accumulation as Perchlorate Accumulation as affected by N Rateaffected by N Rate
2.22.226262502501.21.215152002002.42.426261501502.62.631311001001.41.4191950502.82.8383800
Above groundAbove groundClOClO44 uptakeuptake
(g/ha)(g/ha)
PerchloratePerchlorateconcentration concentration
(ug/kg)(ug/kg)
N Rate N Rate (kg/ha)(kg/ha)
Perchlorate content of Imperial Valley LettucePerchlorate content of Imperial Valley Lettuce
NDND487.6487.633
<MRL<MRL408.2408.244
NDND578.3578.322NDND499.0499.011BulkBulkNDND691.7691.744NDND589.7589.733
<MRL<MRL589.7589.722NDND646.4646.411WrappedWrappedNDND975.2975.2442323907.2907.233NDND941.2941.2223030952.6952.611NakedNakedIcebergIceberg
PerchloratePerchlorate(ug/kg)(ug/kg)
WeightWeight(g)(g)
SampleSampleTrimTrimTypeType
PerchloratePerchlorate in Vegetablesin Vegetables
Page Page 77
Perchlorate content of Coachella Valley LettucePerchlorate content of Coachella Valley Lettuce
NDND249.5249.533<MRL<MRL283.5283.544
NDND272.2272.222NDND272.2272.211HeartsHearts
<MRL<MRL635.0635.044<MRL<MRL555.7555.733
NDND533.0533.022NDND567.0567.011BulkBulk4747578.3578.3442222589.7589.7332727578.3578.322
<MRL<MRL567.0567.011NakedNakedRomaineRomaine
PerchloratePerchlorate(ug/kg)(ug/kg)
Weight (g)Weight (g)SampleSampleTrimTrimTypeType
0.0230.0231.61.6NDND--104104BostonBoston0.0220.0221.51.5NDND--7171Red leafRed leaf0.0260.0261.81.8NDND--102102Green leafGreen leaf0.0090.0090.610.61NDND--<MRL<MRLRomaine HeartsRomaine Hearts0.0100.0100.720.72NDND--2323Romaine BulkRomaine Bulk0.0220.0221.51.5NDND--128 128 Romaine NakedRomaine Naked0.0060.0060.450.45NDND--<MRL<MRLIceberg BulkIceberg Bulk0.0070.0070.500.50NDND--24 24 Iceberg WrappedIceberg Wrapped0.0120.0120.840.84NDND--3333Iceberg NakedIceberg Naked
AdultAdultMaleMaleDose Dose ug/kgug/kg
Potential Potential Exposure Exposure ug/servingug/serving
ConcentrationConcentrationRange (ug/kg)Range (ug/kg)
Lettuce Type and Lettuce Type and TrimTrim
National SurveyNational Survey
Samples were collected in coastal and Samples were collected in coastal and central valleys of California, New Mexico, central valleys of California, New Mexico, Colorado, Michigan, Ohio, Quebec, New Colorado, Michigan, Ohio, Quebec, New York and New Jersey.York and New Jersey.Of the 440 samples collected 264 were from Of the 440 samples collected 264 were from conventional production systems and 176 conventional production systems and 176 were from organic production systems.were from organic production systems.
01020304050607080
ND<M
RL
20-30
ppb
30-40
ppb
40-50
ppb
50-10
0ppb
>100
ppb
Range
Pere
cent
age
of T
otal Conventional
Organic
Estimated average exposure from Estimated average exposure from national surveynational survey
0.030.031.861.86OrganicOrganic
0.010.010.730.73ConventionalConventional
DoseDose((ugug/kg /kg bwbw))
ExposureExposure((ugug/serving)/serving)
ProductionProductionSystemSystem
Survey of Perchlorate Content of Vegetable and Survey of Perchlorate Content of Vegetable and Fruit Crops Irrigated with Colorado River Fruit Crops Irrigated with Colorado River
WaterWater
PerchloratePerchlorate in Vegetablesin Vegetables
Page Page 88
Survey of Selected VegetablesSurvey of Selected Vegetables
NDND1111SquashSquash
44
1818
1010
1010
Number of Number of SamplesSamples
NDNDSnap beansSnap beans
NDNDSweet Corn Sweet Corn
NDNDOnionsOnions
NDNDCarrotsCarrots
ResultResultCropCrop
Perchlorate content of MelonsPerchlorate content of Melons
Perchlorate (Perchlorate (ugug/kg)/kg)TypeType
<MRL<MRLHoney DewHoney Dew<MRL<MRLHoney DewHoney Dew<MRL<MRLHoney DewHoney Dew
NDNDGalliaGalliaNDNDGalliaGalliaNDNDCantaloupeCantaloupe
<MRL<MRLCantaloupeCantaloupe<MRL<MRLCantaloupeCantaloupe<MRL<MRLCantaloupeCantaloupe<MRL<MRLCantaloupeCantaloupe
NDNDCantaloupeCantaloupe
Perchlorate Content of Lemon Perchlorate Content of Lemon Trees Trees
699 to 4930 ug/kgLeaves
Below DetectionFruit
67 to 357 ug/kgBranches
Below Detection to 262 ug/kgTrunk
12,813 to 33,715 ug/kgRoots
Perchlorate Range (dry weight)Perchlorate Range (dry weight)Tree PartTree Part
Fruit and Vegetable ExposuresFruit and Vegetable Exposures
If produce all contains 20 ppb perchlorateIf produce all contains 20 ppb perchlorateAnd we eat our recommended “5And we eat our recommended “5--AA--Day”Day”Hypothetical perchlorate exposure would beHypothetical perchlorate exposure would be
5 x 80 g each = 400 grams produce5 x 80 g each = 400 grams produce20 nanograms/gram x 400 grams = 8,000 ng20 nanograms/gram x 400 grams = 8,000 ng
8 ug/day8 ug/day
Perchlorate is not the only Perchlorate is not the only competitive inhibitor of iodide competitive inhibitor of iodide
uptake by the NISuptake by the NISHow do trace levels of perchlorate in food compare How do trace levels of perchlorate in food compare to natural occurring goitrogens in food?to natural occurring goitrogens in food?Both nitrate and thiocyanate are known NIS iodine Both nitrate and thiocyanate are known NIS iodine uptake inhibitors and occur at high concentrations uptake inhibitors and occur at high concentrations in many food crops.in many food crops.The relative potency of ClOThe relative potency of ClO44
--, NO, NO33--, and SCN, and SCN-- are are
well established from previous evaluations.well established from previous evaluations.Typically the relative potency of ClOTypically the relative potency of ClO44
-- to inhibit Ito inhibit I--
uptake is 15 and 250 times that of SCNuptake is 15 and 250 times that of SCN-- and NOand NO33--,,respectivelyrespectively
Nitrate content of Imperial Valley LettuceNitrate content of Imperial Valley Lettuce
11601160487.6487.633
12981298408.2408.244
12841284578.3578.32213601360499.0499.011BulkBulk13771377691.7691.74413601360589.7589.73312981298589.7589.72212181218646.4646.411WrappedWrapped18021802975.2975.24415631563907.2907.23314881488941.2941.22212751275952.6952.611NakedNakedIcebergIceberg
NitrateNitrate(mg/kg)(mg/kg)
WeightWeight(g)(g)
SampleSampleTrimTrimTypeType
PerchloratePerchlorate in Vegetablesin Vegetables
Page Page 99
Relative Relative Iodide Iodide Uptake Uptake
Inhibition Inhibition Potential Potential NONO33:ClO:ClO33
RatioRatioNitrateNitrate(ppb)(ppb)
Perchlorate Perchlorate (ppb)(ppb)
LocationLocation
5505501.4 x 101.4 x 10552.2 x 102.2 x 10661616CoachellaCoachella3503508.8 x 108.8 x 10441.4 x 101.4 x 10661616YumaYuma
RomaineRomaine5005001.3 x 101.3 x 10552.0 x 102.0 x 10661616ImperialImperial4004009.6 x 109.6 x 10449.6 x 109.6 x 10551010YumaYuma
IcebergIceberg
Perchlorate Loading (12-Month Rolling Average) - Las Vegas Wash - Northshore Road Sampling Point
Real-Time Flow Values
0
100
200
300
400
500
600
700
800
900
1,000
1,100
1,200
1,300
1,400
Perc
hlor
ate
Load
ing
(lbs/
day)
Notes: * Perchlorate concentration sampled on or about the 28th of each month. Approximate Location: 36°07' 20" N by 114°54' 15" W . * Northshore Road sampling point positioned approximately one-half mile upstream from confluence of Las Vegas Wash and Lake Mead
Perchlorate Concentration & Specific Conductance Colorado River - Willow Beach AZ Sampling Point
0.01.02.03.04.05.06.07.08.09.0
10.011.012.013.014.015.016.017.018.019.020.0
Perc
hlor
ate
Con
cent
ratio
n,µg
/L
0601201802403003604204805406006607207808409009601020108011401200
Spec
ific
Con
duct
ance
, µS
/cm
Perchlorate Concentration Perchlorate Detetion Limit Specific Conductance
Notes: * Perchlorate concentration & Specif ic Conductance sampled on or about the 8th of each month. * Willow Beach AZ sampling point is located along the east bank of the Colorado River approximately 11 miles dow nstream from Hoover Dam (Lake Mead)
0
2
4
6
8
10
10-Dec 28-Jun 14-Jan 01-Aug 17-Feb
Date
Perc
hlor
ate
ug/L
STEP II: GELA SITE 6 (0-2ft)
-0.100
-0.050
0.000
0.050
0.100
0 50 100 150 200
Ce, ppb
Q, u
g/g
STEP II: WELLTON SITE 4 (0-1ft)
-0.100
-0.050
0.000
0.050
0.100
0 50 100 150 200
Ce, ppb
Q, u
g/g
STEP II: YUMA VALLEY (53M)
-0.100
-0.050
0.000
0.050
0.100
0 50 100 150 200
Ce, ppb
Q, u
g/g
STEP II: YUMA MESA (54F)
-0.100
-0.050
0.000
0.050
0.100
0 50 100 150 200
Ce, ppb
Q, u
g/g
SummarySummary
Perchlorate is accumulating in lettuce and Perchlorate is accumulating in lettuce and other leafy vegetables.other leafy vegetables.Data suggest exposure from lettuce small Data suggest exposure from lettuce small relative to harmful effects.relative to harmful effects.Accumulation in fruit crops less Accumulation in fruit crops less problematic but more data are needed.problematic but more data are needed.Additional work is needed to identify all Additional work is needed to identify all natural and anthropogenic sources of natural and anthropogenic sources of perchlorate entering the food chainperchlorate entering the food chain
PerchloratePerchlorate in Vegetablesin Vegetables
Page Page 1010
SummarySummary
Concern over Concern over perchlorateperchlorate in Lower in Lower Colorado River region will decline as river Colorado River region will decline as river clean up continues, soil mitigation occurs clean up continues, soil mitigation occurs concurrently, and crop accumulation concurrently, and crop accumulation continues to decline. continues to decline.
OnOn--going workgoing work
Expanded survey work (USDA and Kerr Expanded survey work (USDA and Kerr McGee).McGee).Exposure and risk assessment (CLRB and Exposure and risk assessment (CLRB and USDAUSDA--NIFSP).NIFSP).Evaluation of uptake and factors affecting Evaluation of uptake and factors affecting uptake (AILRC).uptake (AILRC).
Work NeededWork NeededStudies aimed at gaining an understanding Studies aimed at gaining an understanding of factors affecting the transport, of factors affecting the transport, transformations, and distribution of transformations, and distribution of perchlorate in water and soils.perchlorate in water and soils.Status of regional ground water sourcesStatus of regional ground water sourcesOther sources of perchlorate (CDFAOther sources of perchlorate (CDFA--FREP).FREP).
AcknowledgementAcknowledgement
We gratefully acknowledge the support of We gratefully acknowledge the support of the Arizona Iceberg Lettuce Research the Arizona Iceberg Lettuce Research Council, the California Lettuce Research Council, the California Lettuce Research Board, the USDABoard, the USDA--ARS, Kerr McGee Corp., ARS, Kerr McGee Corp., and the USDAand the USDA--NIFSP.NIFSP.
