Arsenic in the EnvironmentTeresa S. Bowers

Gradient Corporation

Presented at Middleport, New York

October 28, 2008

2

Arsenic Occurs Naturally

• All arsenic in the environment is of natural origin (natural background)

• Human activities redistribute this naturally-occurring arsenic (anthropogenic background)

As33

74.92

3

Arsenic Has Been Used by Man for More Than 5000 Years

• Production of tools, ornaments, pigments, cosmetics

• Backing for mirrors, glass manufacturing• Medicinal uses• Distribution through coal-fired furnaces• Pesticides, including application to fields and

crops, for weed control along railroads, cattle dip vats, additive to poultry and swine feed

• Pressure treating for lumber

4

Arsenic is Everywhere: Soil

1

3.4

7.2

13

0

2

4

6

8

10

12

14

Sandstone Earth'sCrust

SoilAverage

Shale

Concentration of Arsenic in Soil

Ars

enic

Con

cent

ratio

n (m

g/kg

) 10 ppm is 1/8 cup of sand in a 4 cubic yard dump truck

5

Arsenic is Everywhere: WaterConcentrations of Arsenic in Water (µg/L)

0.35 11.5 2.4

10

0

5

10

15

20

Rainwater,median

U.S. Rivers,median

Groundwater,median

U.S. Drinkingwater,average

Drinkingwater

standard (USEPA2006)

Ars

enic

Con

cent

ratio

n (µ

g/L)

10 ppb is1/10 cupof ink in an Olympic-sized pool

Source: ATSDR Tox Profile on Arsenic.http://en.wikipedia.org/wiki/Drop_(unit)

6

Arsenic in Water in the U.S.

7

Arsenic in Water in New York State

8

Arsenic is Everywhere: AirConcentration of Arsenic in Air

1

3

20

100

0 20 40 60 80 100 120 140 160 180 200

Arsenic Concentration (ng/m3)

1 ng/m = 1 TimeMist® sprayin 28x the air volume ofGiants Stadium (1,830,000 m3)

TimeMist® sprayer ~ 0.05 g/spray

(50,000,000 ng)28x

100 ng/m3 = 1 TimeMist® sprayin ¼ of the air volume of Giants Stadium

9

Natural Levels of Arsenic in the Environment are Variable

• Arsenic concentrations vary by rock type– Shales contain more arsenic than granites

• Arsenic concentrations vary by soil type– Clay soils contain more arsenic than sandy soils– Soils high in organic carbon contain more arsenic

• Mineralized rocks and soils (e.g., areas mined for gold, copper, lead) can contain significantly higher arsenic

10

Worldwide Anthropogenic Additions of Arsenic to Soils in 1988

Source: Arsenic in the Environment by Jerome O. Nriagu, 1994.

0%

20%

40%

60%

80%

100%

Mfgr. Urban ForestryAgric.SmeltersMine TailingsAtmos. FalloutCoal AshesComml. Products

11

WIGACAWVTXINILPAMNAZNY

ORAL

ID

0 100,000 200,000 300,000 400,000

Pounds per Year

Remaining States = None reported

Addition of Arsenic to Soil in the U.S.Arsenic Released To Soil in 2004

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Example: Commercially Available

Lawn and Garden Products

Product

Arsenic Concentration

(mg/kg)

Scotts Weed & Feed 27-4-4 8.23Scotts Starter Fertilizer Plus Crabgrass Preventer

18-23-4 7.48Schultz Moisture Plus Potting Mix 0.08-0.12-0.08 19.6Vigoro Ultra Turf Turf Fertilizer with Weed Stop 27.5Source: Washington State Department of Agriculture, 2008. Pesticide Management Database, http://agr.wa.gov/PestFert/Fertilizers/ProductDatabase

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Is it Natural or Did Man Put it There?

• It can be difficult to distinguish between natural and human influences on observed levels of arsenic as there can be significant overlap in their concentration ranges

• It is generally not possible to distinguish between low levels from human sources and natural background levels

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Arsenic in New York State• U.S. Geological Survey studies of apple

orchards and native soils in New York (Shacklette, Boerngen, 1980s)

• Rural lawns (Clark, 1985)• Agricultural and forest areas (Al-Wardy,

2002)• Soils in the lower Hudson Valley

(NYSDEC, 2003)• Statewide Rural Survey of surface soils

(NYSDEC, 2005)

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Summary of Results from Soil Arsenic Background Studies in New York State

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Arsenic in the Middleport Area• Gasport apple orchards (FMC, 1989)• Agencies 1996 background data set• 1993 – 2002 Lyndonville background data

set (DuPont)• 2001 – 2003 Gasport Area Background

Study (FMC + NYSDEC)

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Summary of Results from Soil Arsenic Background Studies in the Middleport Area

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Why is Exposure to Arsenic a Concern?

• Acute toxicity (think Arsenic and Old Lace)• Long-term exposure leading to risk of

vascular, nervous system, reproductive impairment (grouped and assessed as non-cancer effects)

• Cancer risk (skin, bladder)

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How are People Exposed to Arsenic?

• In order of decreasing importance:– Food consumption– Drinking water consumption– Incidental ingestion of (and dermal exposure

to) soil and dust– Air inhalation

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Exposure Considerations• “The dose makes the poison”• Bioavailability

– Arsenic in water is more bioavailable than arsenic in soil, i.e., more is absorbed by the body

• Inorganic arsenic is more toxic than organic arsenic– Soil and water contain inorganic arsenic– Food contains both organic and inorganic

arsenic

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Arsenic in FoodTotal

Arsenic(mg/kg)

Inorganic Arsenic (mg/kg)

Percent Inorganic

Tuna 1.1 0.025 2%

Rice 0.24 0.1 42%

Rice Bran 1.2 0.9 75%

Meat/Poultry 0.020 0.017 85%

Bread (Wheat) 0.024 0.012 50%Sources: Sun et al., 2008; Yost et al., 2008.

22Arsenic in FoodRice contains an average of 0.1 mg/kg inorganic arsenic. This concentration is equivalent to one grain of in 408 bags of rice weighing 2 pounds each.

How Much Inorganic Arsenic Are We Exposed To?

3.23

0.57

3.2

4

0.28

0

1

2

3

4

5

Child Resident- Intake fromdiet, mean(Yost et al.,

2004 )

Child Resident- Intake from

drinking water

Child Resident- Intake from

soil

Adult Resident- Intake from

diet, mean(Schoof et al.,

1999)

Adult Resident- Intake from

drinking water

Adult Resident- Intake from

soil

Dai

ly In

take

(μg/

day)

An exposure frequency of 350 days/year (USEPA, 1993) was used for exposure to soil and drinking water. Daily intake of arsenic in drinking water was calculated using a national average background concentration of 2 µg/L (ATSDR, 2000), and drinking water

ingestion rates of 1.5 and 2 L/day for the child (ages 1-6 years old) and adult residents, respectively (USEPA, 1997). Daily intake of arsenic in soil was calculated using a soil arsenic concentration of 11.3 mg/kg (USEPA, 1997), soil ingestion rates of 100 mg/day

(Stanek et al., 2001; Stanek and Calabrese, 2000) for the child and 50 mg/day for the adult (Stanek et al., 1997; USEPA, 1997), and a relative bioavailability factor for soil arsenic of 50% (Groen et al., 1994; Rodriguez et al., 1999; Roberts et al., 2002).

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How Do We Know We Are Exposed to Arsenic?

• Everyone has arsenic in their urine• CDC NHANES measured arsenic in urine

of 2557 U.S. residents older than 6 years in 2003-2004– The average person has about 6 µg/L

inorganic arsenic in urine• Arsenic can also be measured in toe nails

and hair

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U.S. EPA did a Risk Assessment for the School Yard in 1998

• Children between ages 5 and 18 years, athletes and non-athletes

• Ingestion and dermal contact with soil, and inhalation of dust, over the school yard as a whole, and in 3 distinct sub-areas

• Evaluated both cancer and non-cancer risks• Based on the risk results, proposed a soil remediation

project in the area of the football field, which was completed by FMC in 1999

• EPA did a subsequent risk calculation based on post-remedy arsenic concentrations, and concluded that the risks of using the school yard did not differ from background risks

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EPA's Risk Assessment was Conservative

• Additional information has been collected in Middleport since 1998 that reduces the uncertainty in risk estimates:– Oral bioavailability study – Dermal absorption study

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EPA's Soil Screening Level (SSL) for Arsenic

• EPA has established default SSLs for a wide variety of chemicals that can be found in soil

• SSLs are used to define areas that require further investigation, and do not automatically equate to unacceptable risk

• EPA's SSL for arsenic of 0.4 ppm is well known to be below natural background levels everywhere

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Reducing Your Exposure to Arsenic in Soil• Wash hands before eating• Wash garden produce

before cooking or eating• Clean dirt from shoes before

entering home• Wear gloves when gardening• Maintain ground cover (grass) in

yard

Arsenic in the Environment�� Teresa S. Bowers�Gradient CorporationArsenic Occurs NaturallyArsenic Has Been Used by Man for More Than 5000 YearsArsenic is Everywhere: SoilArsenic is Everywhere: WaterArsenic in Water in the U.S.Natural Levels of Arsenic in the Environment are VariableWorldwide Anthropogenic Additions of Arsenic to Soils in 1988Addition of Arsenic to Soil in the U.S.Example: �Commercially Available �Lawn and Garden ProductsIs it Natural or Did Man Put it There?Arsenic in New York StateSummary of Results from Soil Arsenic Background Studies in New York StateArsenic in the Middleport AreaSummary of Results from Soil Arsenic Background Studies in the Middleport AreaWhy is Exposure to Arsenic a Concern?How are People Exposed to Arsenic?Exposure ConsiderationsArsenic in FoodHow Much Inorganic Arsenic Are We Exposed To?How Do We Know We Are Exposed to Arsenic?U.S. EPA did a Risk Assessment for the School Yard in 1998 EPA's Risk Assessment was ConservativeEPA's Soil Screening Level (SSL) for ArsenicReducing Your Exposure to Arsenic in Soil