EXPOSURE TO LEAD AND OTHER Objectives: POLLUTANTS · Assessing Human Health Risk Cancer risk...
Transcript of EXPOSURE TO LEAD AND OTHER Objectives: POLLUTANTS · Assessing Human Health Risk Cancer risk...
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Shawn P. McElmurry, Ph.D., P.E.
Assistant Professor
Dept. of Civil & Environmental Engineering
Wayne State University
EXPOSURE TO LEAD AND OTHER POLLUTANTS WHILE GARDENING IN AN URBAN ENVIRONMENT
Michigan Occupational and Environmental Medicine AssociationSeptember 23, 2011
Objectives:
1. Rank potential exposure pathways to urban pollutants resulting from gardening
2. Describe how concentrations of lead found in soil relate to human health risk
3. Identify steps that can be taken to reduce lead exposure via urban gardening
Part 201 (listed) Sites – SE Michigan
http://www.mcgi.state.mi.us/environmentalmapper/
Heavy Metals in an Urban Watershed, SE Michigan
Murray, H., Thompson, K., and Macfie, S. M. (2009).
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10ppm – The average concentration of Pb in agricultural soils in the United States is approximately 10 ppm (Holmgren, Meyer et al. 1993).
17ppm – Crustal average (Hans Wedepohl, 1995)50ppm – Uncontaminated soils contains lead less than 50ppm
(American Academy of Pediatrics 1993) 100ppm – The Minnesota State legislature has stabled a 100
ppm standard for bare in the country based on the assumption that children eating two teaspoons of soil per week would result in blood lead levels that are of concern (Carrington and Bolger 1992; Minnesota Department of Health 1993)
400ppm – The U.S. EPA identifies two maximum concentrations of Pb in bare soil below which action is not required to mitigate human exposure: 400ppm in play areas and 1,200ppm for non‐play areas (U.S. EPA 2001).
Concentrations of Pb in soils
R² = 0.7234
0
2
4
6
8
10
12
1998 2000 2002 2004 2006 2008 2010
BL (ug/dL)
Census Tract 510300
R² = 0.9386
0
2
4
6
8
10
12
1998 2000 2002 2004 2006 2008 2010
BL (ug/dL)
Census Tract 530200
R² = 0.1271
0
2
4
6
8
10
12
1998 2000 2002 2004 2006 2008 2010
BL (ug/dL)
Census Tract 167500
Ryan, et al., 2004
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0
1
2
3
4
5
6
7
8
0 100 200 300 400 500 600 700
Mean
Blood Lead
Concentration (μg/dL)
Mean Measured Soil Lead Concentration (mg/kg)
Geometric Mean Blood Lead BL = 2.038 + 0.172*√SL
R2 = 0.34
Mielke et al. (2007) equation: BL = 2.038 + 0.172(SL)0.5
0
1
2
3
4
5
6
7
8
0 100 200 300 400 500 600 700
Mean
Blood Lead
Concentration (μg/dL)
Mean Measured Soil Lead Concentration (mg/kg)
All whiskers represent 95% confidence of geometric mean by Student's t test
Geometric Mean Blood Lead BL = 0.018*SL + 1
R2 = 0.41
Average Blood Lead Concentration in 2002vs.
Average Soil Lead Concentration in 2002
Equation: BL = 0.018 * SL + 1
All Averages are Geometric means
Blood lead data provided by MDCH
Soil lead data published by Detroit Free Press
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1
2
3
4
5
6
7
8
0 100 200 300 400 500 600 700
Mean
Blood Lead
Concentration (μg/dL)
Mean Measured Soil Lead Concentration (mg/kg)
All whiskers represent 95% confidence of geometric mean by Student's t test
Geometric Mean BLL 2002 Geometric Mean BLL 2009 BL = 0.018*SL + 1
510300
167500
530200
Tract 5302 “moved” down and left along the prediction line
Tract 510300 “moved” straight down from above the line to below the line
Tract 167500 did not change position
Characterizing Pb
• Pb is extremely “particle reactive”
• Pb preferentially adsorbs to small particles
• Phosphate precipitates are very stable (Clark et al. 2008)
• Bioavailable: able to be absorbed by a living organism‐ generally assumed to be 30‐50% for humans
Soil tests conducted on urban gardens
2010
Total number of sites tested 100
Sites with concentrations greater than 400ppm 10%
Total number of tests run 201
Tests with concentrations less than 199ppm 77%
Tests with concentrations 200‐399ppm 12%
Tests with concentrations greater than 400ppm 11%
2004‐2009
Total number of sites tested (if available) 353
Sites with concentrations greater than 400ppm 13%
Total number of tests run 466
Tests with concentrations less than 199ppm 67%
Tests with concentrations 200‐399ppm 19%
Tests with concentrations greater than 400ppm 14%
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Uptake through roots
Resuspension of contaminated soil
(splashing)
Atmospheric Deposition
Soil Water Root
Shoot
Leaf
Plant
Water
Water
Water
335 +/‐ 50 mg Pb/kg after 43 days
(Uzu et al. 2010) Deposition
Resuspen
sion
For PbAverage Kd = 10
5 L/kgRange 103‐108 L/kg(Lamba et al. 2009)
L
mg
kg
Lkg
mg
01.010
1000
5
17% Pb, 14% Cd, 41% Zn Translocates to leaves
(Oluwatosin et al. 2010)
Plant uptake:*not linearly correlated
(Chaney et al. 1984)
Pb 0.6% Cu 9.2%Cd 32.0% Ni 27.0%
Zn 32.7% Mn 62.3%
Chaney, R.L., Sterrett, S.B., Mielke, H.W. (1984) Chaney, R.L., Sterrett, S.B., Mielke, H.W. (1984)
Dietary exposure that is estimated to result in blood lead levels of 10µg/dl (Carrington and Bolger 1992):
Children 6 years or younger: 60µg/day
Children 7 years or older: 150µg/day
Pregnant women: 250µg/day
Adults: 750µg/day
(Clark et al. 2008)
Pb exposure via urban gardening depends on:Type of plant grown
Not concerning: most fruits (tomatoes, apples, etc.)
Concerning: root crops (potatoes, carrots, etc.), ferns
Kitchen CleaningAmount of Pb found on mustard leaves after kitchen washing was nearly double the amount observed after laboratory washing (Clark et al. 2008)
Type of soilClay
Sand
Type of amendments added to soilFertilizer
Compost
Gardening habitsTaking shoes off
Washing hands/cloths
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Assessing Human Health Risk
Cancer risk
Non‐cancer risk
Adjustments for contaminant bioavailability
Risk = CDI x SFCDI = chronic daily intakeSF = cancer slope factor
HQ = CDI / RfDHQ = hazard quotientRfD = reference dose
RfDadjusted = RfDIRIS x RBARfDadjusted = RfDIRIS x RBARBA = Relative Bioavailability (0.0 to 1.0)
Measuring BioavailabilityIn Vivo Models In Vitro Models
Examples:Basta and Gradwohl (2000)Ruby et al. (1996)
• strong correlations (r2 = 0.924) between bioaccessibility and bioavailability
• high reproducibility (inter‐ and intra‐laboratory coefficients of variation of 4% and 6%)
(Drexler and Brattin 2007; U.S. EPA 2007
Dependence of soil Pb bioavailability and the total concentration of Pb in soil in determining the amount of Pb absorbed, assuming equal exposure.
Soil Absolute Pb Bioavailability
Total Pb Concentration Soil Ingested Pb Ingested Pb Absorbed
% ppm mg soil/day µg Pb/day µg Pb/day
A 30 400 50 20 6
B 10 400 50 20 2
C 50 400 50 20 10
D 30 1000 50 50 15
E 10 1000 50 50 5
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Chaney, R.L., Sterrett, S.B., Mielke, H.W. (1984)
In Situ Bioremediation
Ca10(PO4)6(OH)2 + Pb2+ Ca10Pb(PO4)6(OH)2 + Ca
2+
Hydroxyapatite + bioavailable Pb = low bioavailable Pb pyromorphite
Formation of Pb pyromophite provides long‐term remediation strategy to reduce Pb
bioavailability
Scheckel and Ryan (2002)
www.epa.gov/brownfields/urbanag
Direct link to Pamphlet:http://www.cec.wayne.edu/gardenpamphletfinal072810.pdf
Wayne State University’s Community Engagement Core (CEC) of the Institute of Environmental Health Sciences
http://www.cec.wayne.edu/communityoutreach.php
Additional Credit:
• Pb in Carrots Grown on Pb‐Rich Soils is mostelywithin the Xylem by Rufus Chaney and Kirk Scheckel presented at the American Society of Agronomy 2010
• U.S. EPA Office of Superfund Remediation and Technology Innovation CLU‐IN Seminar: Bioavailability‐Based Remediation of Metals Using Soil Amendments: Considerations & Evaluation Techniques: Part 2 by Nick Basta and Kirk Scheckel on August 31, 2011 (www.cluin.org)
References:American Academy of Pediatrics (1993). "Lead poisoning: from screening to primary prevention." Pediatrics 92(1): 176‐183.
Basta, N., and Gradwohl, R. (2000). "Estimation of Cd, Pb, and Zn bioavailability in smelter‐contaminated soils by a sequential extraction procedure." Journal of Soil Contamination, 9(2), 149‐164.
Bickel, M.J., Spatial and Temporal Relationships Between Blood Lead and Soil Lead Concentrations in Detroit, Michigan, in Civil and Environmental Engineering. 2010, Wayne State University: Detroit, MI.
Carrington, C. D. and P. M. Bolger (1992). "An Assessment of the Hazards of Lead in Food." Regulatory Toxicology and Pharmacology 16(3): 265‐272.
Chaney, R.L., Sterrett, S.B., Mielke, H.W. (1984) “The Potential for Heavy Metal Exposure from Urban Gardens and Soils” In J.R. Preer (ed.) Proc. Symp. Heavy Metals in Urban Gardens. Univ. Dist. Columbia Extension Service, Washington, DC., pp 37‐84.
Clark, H. F., D. J. Brabander, et al. (2006). "Sources, Sinks, and Exposure Pathways of Lead in Urban Garden Soil." J Environ Qual 35(6): 2066‐2074
Clark, H. F., D. M. Hausladen, et al. (2008). "Urban gardens: Lead exposure, recontamination mechanisms, and implications for remediation design." Environmental Research 107(3): 312‐319.
Drexler, J. W., and Brattin, W. J. (2007). "An in vitro procedure for estimation of lead relative bioavailability: With validation." Human and Ecological Risk Assessment, 13(2), 383‐401.
Hans Wedepohl, K. (1995). "The composition of the continental crust." Geochimica Et Cosmochimica Acta, 59(7), 1217‐1232.
Hettiarachchi, G. M. and G. M. Pierzynski (2004). "Soil lead bioavailability and in situ remediation of lead‐contaminated soils: A review." Environmental Progress 23(1): 78‐93.
Holmgren, G. G. S., M. W. Meyer, et al. (1993). "CADMIUM, LEAD, ZINC, COPPER, AND NICKEL IN AGRICULTURAL SOILS OF THE UNITED‐STATES‐OF‐AMERICA." Journal of Environmental Quality 22(2): 335‐348.
Lamba, D. T., H. Ming, et al. (2009). "Heavy metal (Cu, Zn, Cd and Pb) partitioning and bioaccessibility in uncontaminated and long‐term contaminated soils." Journal of Hazardous Materials 171(1‐3): 1150‐1158
Minnesota Department of Health (1993). Minnesota Rules Chapter 4761.0300. M. D. o. Health. Residential Lead Abatement Standards.
Mielke, H.W., et al., Associations between soil lead and childhood blood lead in urban New Orleans and rural Lafourche Parish of Louisiana. Environmental Health Perspectives, 1997. 105(9): p. 950‐954.
Murray, H., Thompson, K., and Macfie, S. M. (2009). "Site‐ and species‐specific patterns of metal bioavailability in edible plants." Botany‐Botanique, 87(7), 702‐711.
Murray, K. S., D. T. Rogers, et al. (2004). "Heavy Metals in an Urban Watershed in Southeastern Michigan." J Environ Qual 33(1): 163‐172.
Oluwatosin, G. A., O. D. Adeoyolanu, et al. (2010). "Heavy Metal Uptake and Accumulation by Edible Leafy Vegetable (Amaranthus Hybridus L.) Grown on Urban Valley Bottom Soils in Southwestern Nigeria." Soil & Sediment Contamination 19(1): 1‐20.
Ruby, M. V., Davis, A., Schoof, R., Eberle, S., and Sellstone, C. M. (1996). "Estimation of lead and arsenic bioavailability using a physiologically based extraction test." Environmental Science & Technology, 30(2), 422‐430.
U.S. EPA (2001). Lead; Identification of Dangerous Levels of Lead; Final Rule. 40 CFR Part 745. U.S. Environmental Protection Agency. Federal Register: 1206‐1240.
U.S. EPA. (2007). "Estimation of Relative Bioavailability of Lead in Soil and Soil‐like Materials Using In Vivo and In Vitro Methods.", Office of Solid Waste and Emergency Response, ed., United State Environmental Protection Agency, Washington D.C., 1‐74.
Uzu, G., S. Sobanska, et al. (2010). "Foliar Lead Uptake by Lettuce Exposed to Atmospheric Fallouts." Environmental Science & Technology 44(3): 1036‐1042.
References:American Academy of Pediatrics (1993). "Lead poisoning: from screening to primary prevention." Pediatrics 92(1): 176‐183.
Basta, N., and Gradwohl, R. (2000). "Estimation of Cd, Pb, and Zn bioavailability in smelter‐contaminated soils by a sequential extraction procedure." Journal of Soil Contamination, 9(2), 149‐164.
Bickel, M.J., Spatial and Temporal Relationships Between Blood Lead and Soil Lead Concentrations in Detroit, Michigan, in Civil and Environmental Engineering. 2010, Wayne State University: Detroit, MI.
Carrington, C. D. and P. M. Bolger (1992). "An Assessment of the Hazards of Lead in Food." Regulatory Toxicology and Pharmacology 16(3): 265‐272.
Chaney, R.L., Sterrett, S.B., Mielke, H.W. (1984) “The Potential for Heavy Metal Exposure from Urban Gardens and Soils” In J.R. Preer (ed.) Proc. Symp. Heavy Metals in Urban Gardens. Univ. Dist. Columbia Extension Service, Washington, DC., pp 37‐84.
Clark, H. F., D. J. Brabander, et al. (2006). "Sources, Sinks, and Exposure Pathways of Lead in Urban Garden Soil." J Environ Qual 35(6): 2066‐2074
Clark, H. F., D. M. Hausladen, et al. (2008). "Urban gardens: Lead exposure, recontamination mechanisms, and implications for remediation design." Environmental Research 107(3): 312‐319.
Drexler, J. W., and Brattin, W. J. (2007). "An in vitro procedure for estimation of lead relative bioavailability: With validation." Human and Ecological Risk Assessment, 13(2), 383‐401.
Hans Wedepohl, K. (1995). "The composition of the continental crust." Geochimica Et Cosmochimica Acta, 59(7), 1217‐1232.
Hettiarachchi, G. M. and G. M. Pierzynski (2004). "Soil lead bioavailability and in situ remediation of lead‐contaminated soils: A review." Environmental Progress 23(1): 78‐93.
Holmgren, G. G. S., M. W. Meyer, et al. (1993). "CADMIUM, LEAD, ZINC, COPPER, AND NICKEL IN AGRICULTURAL SOILS OF THE UNITED‐STATES‐OF‐AMERICA." Journal of Environmental Quality 22(2): 335‐348.
Lamba, D. T., H. Ming, et al. (2009). "Heavy metal (Cu, Zn, Cd and Pb) partitioning and bioaccessibility in uncontaminated and long‐term contaminated soils." Journal of Hazardous Materials 171(1‐3): 1150‐1158
Minnesota Department of Health (1993). Minnesota Rules Chapter 4761.0300. M. D. o. Health. Residential Lead Abatement Standards.
Mielke, H.W., et al., Associations between soil lead and childhood blood lead in urban New Orleans and rural Lafourche Parish of Louisiana. Environmental Health Perspectives, 1997. 105(9): p. 950‐954.
Murray, H., Thompson, K., and Macfie, S. M. (2009). "Site‐ and species‐specific patterns of metal bioavailability in edible plants." Botany‐Botanique, 87(7), 702‐711.
Murray, K. S., D. T. Rogers, et al. (2004). "Heavy Metals in an Urban Watershed in Southeastern Michigan." J Environ Qual 33(1): 163‐172.
Oluwatosin, G. A., O. D. Adeoyolanu, et al. (2010). "Heavy Metal Uptake and Accumulation by Edible Leafy Vegetable (Amaranthus Hybridus L.) Grown on Urban Valley Bottom Soils in Southwestern Nigeria." Soil & Sediment Contamination 19(1): 1‐20.
Ruby, M. V., Davis, A., Schoof, R., Eberle, S., and Sellstone, C. M. (1996). "Estimation of lead and arsenic bioavailability using a physiologically based extraction test." Environmental Science & Technology, 30(2), 422‐430.
U.S. EPA (2001). Lead; Identification of Dangerous Levels of Lead; Final Rule. 40 CFR Part 745. U.S. Environmental Protection Agency. Federal Register: 1206‐1240.
U.S. EPA. (2007). "Estimation of Relative Bioavailability of Lead in Soil and Soil‐like Materials Using In Vivo and In Vitro Methods.", Office of Solid Waste and Emergency Response, ed., United State Environmental Protection Agency, Washington D.C., 1‐74.
Uzu, G., S. Sobanska, et al. (2010). "Foliar Lead Uptake by Lettuce Exposed to Atmospheric Fallouts." Environmental Science & Technology 44(3): 1036‐1042.
LE
AD
SA
FE
GA
RD
EN
INGFOR MORE
INFORMATION CONTACT:
CLEARCorps/Detroit11148 Harper Avenue
Detroit, MI 48213(313) 924-4000
www.clearcorpsdetroit.org/Brochure designed by CLEARCorps/Detroit
1418 Michigan AvenueDetroit, MI 48216(313) 285-1249
www.detroitagriculture.org
Shawn P. McElmurry, Ph.D., P.E.(313)577-3876
www.cee.eng.wayne.edu
Mary O. Dereski, Ph.D.(313)577-5597
www.iehs.wayne.edu
WHY IS LEAD A CONCERN?
• 1 in 20 children in Detroit is lead poisoned• Children with lead levels higher then 10
ug/dL* have lead poisoning• Lead poisoning can cause learning and
speech problems, hyperactivity and nerve damage that cannot easily be reversed and are likely to last a lifetime
• The effects of lead poisoning cannot always be seen
• A healthy diet high in vitamin C & D, calcium, zinc and iron can help reduce lead poisoning
• Children become lead poisoned by eating dust, dirt, and paint that contain lead
• All children under 6 should be tested yearly
WHAT IS LEAD?Lead is a naturally occurring metal that can be hazardous to human health, especially for children under 6 years of age
WHY IS THERE LEAD IN THE SOIL?
• Lead is found naturally in the soil in low amounts
• Most houses built before 1978 have leaded paint inside and outside
• Soil (mainly in large cities) may have high lead levels because of heavy industry and exhaust from leaded gas (banned in 1986)
* ug/dL = microgram lead per deciliter of blood
GET YOUR SOIL TESTED!
The suggested local source is the professional gardening group The
Greening of Detroit (see back)www.detroitagriculture.org
Other ResourcesMichigan Dept. of Community Health
www.michigan.gov/mdchUniversity of Massachusetts
Soil and Plant Tissue Testing Laboratorywww.umass.edu/soiltest
Accurate Analytical testing LLCwww.accurate-test.com
WHERE CAN LEAD BE FOUND IN YOUR YARD?• Lead may be found in the top 4 inches of
soil around your yard• Soil lead is found in highest amounts near
the walls of buildings, especially if they were painted prior to 1978
• Soil lead levels can be higher close to roads• Large cities tend to have higher soil lead
levels than suburbs
CLEANING UP AFTER GARDENING
• Wash hands after working in the garden• Remove shoes/boots before coming into
your home• Keep a separate set of clothes for gardening• Wash gardening clothing separately
BEST GARDENING PRACTICESYearly Upkeep
• Treat soil with clean compost• Till soil as deeply as possible (at least 4 in.)• Plant your garden away from buildings,
garages and the street• Keeping your soil pH above 6.5 will help
limit the amount of lead entering plants
WHERE IS LEAD IN THE GARDEN?
• Lead is not usually found in the fruit of the plant like cucumbers, tomatoes, or strawberries
• Lead is most often found in the root of plants like carrots, beets, turnips, potatoes
• Soil with lead can collect on leafy vegetables (collards, kale, turnip greens) especially those close to the ground
WHEN SHOULD YOU BE WORRIED?
When your yard has a soil testing level of• Below 100 ppm*: safe range, no action
needed• 100-400 ppm*: level of concern, use Best
Gardening Practices• 400-2,000 ppm*: no gardening before
contacting a professional gardening group like The Greening of Detroit
• Above 2000 ppm*: gardening of any kind is not recommended
* ppm = Parts-Per-Million (soil testing levels)
Before/During Gardening• Wear gloves and wash up after gardening• Keep a layer of mulch around plants to stop
soil from splashing onto leaves during rain• Do not eat or smoke while gardening• Wet the soil before working in the garden
to keep soil dust down• Keep children under 6 years old out of
gardens with soil lead levels above 100 ppm* as they may eat dirt
After Harvesting/Before Eating• Wash all vegetables with soap and water or
a vinegar water mixture (1 part vinegar to 9 parts water)
• Throw away outer leaves of leafy vegetables, and wash inner leaves well
• Peel and wash root vegetables well (if your soil lead levels are higher then 400 ppm* you should not plant root crops before consulting a professional gardening group)