Food Chain Sampling Results (grass, spinach, etc.)

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Radionuclides, once deposited by rainwater or air onto the ground, will find their way through the ecosystem. We are already tracking its path from rainwater to creek runoff to tap water, but we would also like to monitor how much these isotopes that make their way into our food. For example, how much gets taken up by the grass and eventually winds up in our milk?

We have been collecting produce that is as local as possible to test for the radioactive isotopes. We might expect different kinds of plants to take up different quantities of cesium and iodine, so we are trying to measure as many different plants and fruits as we are able to. So far, we have measured:

The Bay Area topsoil, grass, and wild mushroom samples collected all come from the same location, so comparing grass samples to each other is a fair "apples to apples" comparison. For most of the produce, different samples came from different markets and different farms, so there will be many factors influencing the results. This variety of produce helps provide a picture of the food chain as a whole. But for understanding the time-dependence of the food chain results, the grass and soil is what to look at.

In the tables below, we are providing two numbers for each of the isotopes. The first is a standard concentration unit of Becquerel per kilogram (Bq/kg) which is the number of particles decaying per second in each kilogram of the sample. The number in parentheses after the activity is the number of kilograms that one would need to consume to equal the radiation exposure of a single round trip flight from San Francisco to Washington D.C. (0.05 mSv). For more information on how this equivalent dose is calculated, the details are here: How Effective Dose is Calculated

The experimental setup used for the food testing is the same setup used for the Rainwater Collection Experiment.

Topsoil

source: Alameda, CA

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
04/06/2011 10:15 1.04 12.42±1.24
[MDA=0.25]
( 89)		 < MDA
[MDA=0.38]
 		 0.99±0.10
[MDA=0.25]
(2.6E+03)		 1.53±0.15
[MDA=0.33]
(2.4E+03)		 < MDA
[MDA=0.17]
 		 14.74±1.47
[MDA=2.23]
(1.0e+05)		 data
04/08/2011 08:00 0.91 7.55±0.76
[MDA=0.31]
(1.5E+02)		 < MDA
[MDA=0.51]
 		 0.41±0.08
[MDA=0.31]
(6.3E+03)		 0.90±0.12
[MDA=0.39]
(4.1E+03)		 < MDA
[MDA=0.19]
 		 5.21±0.67
[MDA=2.20]
(2.8e+05)		 data
04/13/2011 08:00 1.30 3.79±0.38
[MDA=0.18]
(2.9E+02)		 < MDA
[MDA=0.25]
 		 1.04±0.10
[MDA=0.21]
(2.5E+03)		 1.16±0.12
[MDA=0.26]
(3.2E+03)		 < MDA
[MDA=0.13]
 		 10.06±1.00
[MDA=1.74]
(1.5e+05)		 data
04/21/2011 08:00 1.49 1.41±0.14
[MDA=0.15]
(7.9E+02)		 < MDA
[MDA=0.24]
 		 0.99±0.10
[MDA=0.17]
(2.6E+03)		 1.21±0.12
[MDA=0.20]
(3.1E+03)		 < MDA
[MDA=0.10]
 		 10.92±1.10
[MDA=1.34]
(1.4e+05)		 data
05/02/2011 18:00 1.26 0.60±0.06
[MDA=0.08]
(1.9e+03)		 < MDA
[MDA=0.13]
 		 0.76±0.08
[MDA=0.09]
(3.4e+03)		 1.11±0.11
[MDA=0.10]
(3.3e+03)		 < MDA
[MDA=0.06]
 		 7.05±0.71
[MDA=0.71]
(2.1e+05)		 data
05/18/2011 08:00 1.48 0.14±0.02
[MDA=0.10]
(7.7e+03)		 < MDA
[MDA=0.38]
 		 0.43±0.04
[MDA=0.07]
(6.0e+03)		 0.73±0.07
[MDA=0.08]
(5.1e+03)		 < MDA
[MDA=0.17]
 		 3.59±0.36
[MDA=0.56]
(4.1e+05)		 data
06/03/2011 08:00 0.9 < MDA
[MDA=0.09]
 		 < MDA
[MDA=0.17]
 		 0.58±0.06
[MDA=0.09]
(4.5e+03)		 1.17±0.12
[MDA=0.11]
(3.2e+03)		 < MDA
[MDA=0.07]
 		 6.79±0.68
[MDA=0.76]
(2.2e+05)		 data

Grass

source: Alameda, CA

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
04/03/2011 10:00 0.4 9.93±0.99
[MDA=0.31]
(1.1E+02)		 < MDA
[MDA=0.61]
 		 6.99±0.70
[MDA=0.37]
(3.7E+02)		 7.04±0.70
[MDA=0.42]
(5.3E+02)		 < MDA
[MDA=0.26]
 		 68.3±6.8
[MDA=2.8]
(2.2e+04)		 data
04/05/2011 08:30 0.36 6.82±0.68
[MDA=0.54]
(1.6E+02)		 < MDA
[MDA=1.07]
 		 4.39±0.44
[MDA=0.72]
(5.9E+02)		 3.80±0.38
[MDA=0.79]
(9.7E+02)		 < MDA
[MDA=0.34]
 		 48.2±4.8
[MDA=5.3]
(3.1e+04)		 data
04/06/2011 20:00 0.26 6.02±0.60
[MDA=0.65]
(1.8E+02)		 < MDA
[MDA=1.09]
 		 4.61±0.46
[MDA=0.85]
(5.6E+02)		 5.26±0.53
[MDA=0.93]
( 7E+02)		 < MDA
[MDA=0.40]
 		 35.2±3.5
[MDA=6.2]
(4.2e+04)		 data
04/11/2011 07:30 0.51 1.55±0.15
[MDA=0.29]
(7.2E+02)		 < MDA
[MDA=0.38]
 		 1.63±0.16
[MDA=0.30]
(1.6E+03)		 2.20±0.22
[MDA=0.39]
(1.7E+03)		 < MDA
[MDA=0.16]
 		 16.8±1.7
[MDA=2.6]
(8.8e+04)		 data
04/14/2011 08:00 0.45 1.03±0.12
[MDA=0.39]
(1.1E+03)		 < MDA
[MDA=1.19]
 		 1.38±0.15
[MDA=0.48]
(1.9E+03)		 1.24±0.18
[MDA=0.61]
( 3E+03)		 < MDA
[MDA=0.31]
 		 7.1±1.0
[MDA=3.3]
(2.1e+05)		 data
05/02/2011 18:00 0.18 < MDA
[MDA=0.64]
 		 < MDA
[MDA=1.56]
 		 0.92±0.21
[MDA=0.84]
(2.8e+03)		 1.68±0.30
[MDA=1.16]
(2.2e+03)		 < MDA
[MDA=0.47]
 		 9.9±2.0
[MDA=7.9]
(1.5e+05)		 data
06/03/2011 08:00 0.575 < MDA
[MDA=0.17]
 		 < MDA
[MDA=0.52]
 		 < MDA
[MDA=0.14]
 		 < MDA
[MDA=0.19]
 		 < MDA
[MDA=0.23]
 		 5.6±0.6
[MDA=1.3]
(2.6e+05)		 data

Wild Mushrooms

source: Alameda, CA

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
04/02/2011 10:00 0.39 7.35±0.73
[MDA=0.37]
(1.5E+02)		 < MDA
[MDA=1.15]
 		 < MDA
[MDA=0.33]
 		 < MDA
[MDA=0.40]
 		 < MDA
[MDA=0.22]
 		 11.3±1.1
[MDA=3.5]
(1.3e+05)		 data
05/02/2011 18:00 0.49 < MDA
[MDA=0.11]
 		 < MDA
[MDA=0.26]
 		 < MDA
[MDA=0.24]
 		 < MDA
[MDA=0.15]
 		 < MDA
[MDA=0.11]
 		 < MDA
[MDA=0.87]
 		 data

Seaweed

source: coastal areas of Northern California

Collection Date Sample Mass Species I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg   Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
04/19/2011 0.55 (wet) Porphyra < MDA
[MDA=0.15]
 		 < MDA
[MDA=0.57]
 		 < MDA
[MDA=0.30]
 		 < MDA
[MDA=0.28]
 		 < MDA
[MDA=0.12]
 		 3.16±0.61
[MDA=2.59]
(4.7e+05)		 data
05/18/2011 1.87 (wet) Porphyra < MDA
[MDA=0.17]
 		 < MDA
[MDA=2.23]
 		 < MDA
[MDA=0.11]
 		 < MDA
[MDA=0.09]
 		 < MDA
[MDA=1.01]
 		 0.80±0.16
[MDA=0.66]
(1.9e+06)		 data
05/04/2011 0.50 (dry) Wakame < MDA
[MDA=0.57]
 		 < MDA
[MDA=4.00]
 		 < MDA
[MDA=0.41]
 		 < MDA
[MDA=0.41]
 		 < MDA
[MDA=1.79]
 		 < MDA
[MDA=2.33]
 		 data
05/05/2011 0.11 (dry) Nori < MDA
[MDA=1400]
 		 N/A < MDA
[MDA=0.62]
 		 < MDA
[MDA=0.62]
 		 N/A < MDA
[MDA=13.7]
 		 data
05/05/2011 0.14 (dry) Kombu < MDA
[MDA=2800]
 		 N/A < MDA
[MDA=1.33]
 		 < MDA
[MDA=1.11]
 		 N/A < MDA
[MDA=20.5]
 		 data
06/01/2011 0.15 (dry) Kombu < MDA
[MDA=230]
 		 N/A < MDA
[MDA=0.92]
 		 < MDA
[MDA=0.79]
 		 N/A < MDA
[MDA=12.5]
 		 data
06/08/2012 0.36 (dry) Wakame < MDA
[MDA=0.70]
 		 < MDA
[MDA=4.9]
 		 < MDA
[MDA=0.12]
 		 < MDA
[MDA=0.15]
 		 < MDA
[MDA=4.2]
 		 < MDA
[MDA=1.8]
 		 data
05/21/2012 0.34 (dry) Kombu < MDA
[MDA=57]
 		 N/A
 		 < MDA
[MDA=0.10]
 		 < MDA
[MDA=0.16]
 		 N/A
 		 < MDA
[MDA=2.1]
 		 data
05/24/2012 0.08 (dry) Nori < MDA
[MDA=660]
 		 N/A
 		 < MDA
[MDA=0.30]
 		 < MDA
[MDA=0.33]
 		 N/A
 		 < MDA
[MDA=5.1]
 		 data

Spinach

source: various local organic farms

Collection Date Food Mass I131 I132 Cs134 Cs137 Te132 Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
04/08/2011 (Best By Date) 0.284 1.47±0.15
[MDA=0.50]
(7.5E+02)		 < MDA
[MDA=0.88]
 		 < MDA
[MDA=0.43]
 		 < MDA
[MDA=0.62]
 		 < MDA
[MDA=0.29]
 		 data
04/06/2011 (Purchase Date) 0.30 1.44±0.15
[MDA=0.54]
(7.7E+02)		 < MDA
[MDA=1.66]
 		 < MDA
[MDA=0.89]
 		 < MDA
[MDA=0.60]
 		 < MDA
[MDA=0.28]
 		 data
04/07/2011 (Purchase Date) 0.25 2.50±0.25
[MDA=0.63]
(4.4E+02)		 < MDA
[MDA=0.97]
 		 0.89±0.19
[MDA=0.73]
(2.9E+03)		 1.14±0.25
[MDA=0.96]
(3.3E+03)		 < MDA
[MDA=0.38]
 		 data
04/20/2011 (Purchase Date) 0.56 < MDA
[MDA=0.28]
 		 < MDA
[MDA=0.39]
 		 < MDA
[MDA=0.23]
 		 < MDA
[MDA=0.32]
 		 < MDA
[MDA=0.16]
 		 data
04/28/2011 (Purchase Date) 0.44 < MDA
[MDA=0.27]
 		 < MDA
[MDA=0.46]
 		 < MDA
[MDA=0.34]
 		 < MDA
[MDA=0.37]
 		 < MDA
[MDA=0.20]
 		 data
04/28/2011 (Purchase Date) 0.42 < MDA
[MDA=0.20]
 		 < MDA
[MDA=0.36]
 		 < MDA
[MDA=0.22]
 		 < MDA
[MDA=0.38]
 		 < MDA
[MDA=0.15]
 		 data

Strawberries

source: various local organic farms

Purchase Date Food Mass I131 I132 Cs134 Cs137 Te132 Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
04/01/2011 1.23 0.21±0.03
[MDA=0.10]
(5.3E+03)		 0.35±0.07
[MDA=0.29]
(4.3E+05)		 0.71±0.07
[MDA=0.13]
(3.6E+03)		 0.72±0.07
[MDA=0.15]
(5.1E+03)		 < MDA
[MDA=0.07]
 		 data
04/07/2011 1.06 0.32±0.04
[MDA=0.15]
(3.5E+03)		 < MDA
[MDA=0.41]
 		 0.50±0.06
[MDA=0.19]
(5.2E+03)		 0.48±0.07
[MDA=0.23]
(7.7E+03)		 < MDA
[MDA=0.10]
 		 data
04/20/2011 1.08 < MDA
[MDA=0.11]
 		 < MDA
[MDA=0.40]
 		 0.49±0.05
[MDA=0.15]
(5.3E+03)		 0.64±0.06
[MDA=0.21]
(5.8E+03)		 < MDA
[MDA=0.077]
 		 data
04/20/2011 1.20 < MDA
[MDA=0.073]
 		 < MDA
[MDA=0.13]
 		 0.27±0.03
[MDA=0.10]
(9.5E+03)		 0.26±0.03
[MDA=0.10]
(1.4E+04)		 < MDA
[MDA=0.060]
 		 data
04/28/2011 1.08 < MDA
[MDA=0.09]
 		 < MDA
[MDA=0.21]
 		 0.23±0.03
[MDA=0.11]
(1.1e+04)		 0.42±0.05
[MDA=0.18]
(8.7e+03)		 < MDA
[MDA=0.06]
 		 data
04/28/2011 1.02 < MDA
[MDA=0.08]
 		 < MDA
[MDA=0.14]
 		 0.29±0.03
[MDA=0.12]
(8.9e+03)		 0.44±0.04
[MDA=0.15]
(8.4e+03)		 < MDA
[MDA=0.06]
 		 data
05/19/2011 0.905 < MDA
[MDA=0.10]
 		 < MDA
[MDA=0.32]
 		 0.15±0.03
[MDA=0.11]
(1.7e+04)		 0.15±0.03
[MDA=0.13]
(2.4e+04)		 < MDA
[MDA=0.14]
 		 data
06/09/2011 0.80 < MDA
[MDA=0.38]
 		 < MDA
[MDA=4.60]
 		 < MDA
[MDA=0.09]
 		 < MDA
[MDA=0.20]
 		 < MDA
[MDA=0.79]
 		 data
06/30/2011 0.99 < MDA
[MDA=0.08]
 		 < MDA
[MDA=0.16]
 		 < MDA
[MDA=0.19]
 		 < MDA
[MDA=0.11]
 		 < MDA
[MDA=0.07]
 		 data

Cilantro

source: various local organic farms

Purchase Date Food Mass I131 I132 Cs134 Cs137 Te132 Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
04/04/2011 0.50 < MDA
[MDA=0.34]
 		 < MDA
[MDA=0.41]
 		 < MDA
[MDA=0.34]
 		 < MDA
[MDA=0.56]
 		 < MDA
[MDA=0.15]
 		 data

Kale

source: various local organic farms

Purchase Date Food Mass I131 I132 Cs134 Cs137 Te132 Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
04/06/2011 0.34 < MDA
[MDA=0.64]
 		 < MDA
[MDA=0.81]
 		 < MDA
[MDA=0.87]
 		 0.65±0.17
[MDA=0.62]
(5.7E+03)		 < MDA
[MDA=0.34]
 		 data
04/07/2011 0.38 0.93±0.13
[MDA=0.47]
(1.2E+03)		 < MDA
[MDA=0.64]
 		 1.14±0.20
[MDA=0.80]
(2.3E+03)		 0.59±0.15
[MDA=0.57]
(6.2E+03)		 < MDA
[MDA=0.28]
 		 data
04/20/2011 0.50 < MDA
[MDA=0.28]
 		 < MDA
[MDA=0.44]
 		 < MDA
[MDA=0.30]
 		 < MDA
[MDA=0.49]
 		 < MDA
[MDA=0.20]
 		 data
04/20/2011 0.34 < MDA
[MDA=0.35]
 		 < MDA
[MDA=0.64]
 		 < MDA
[MDA=0.47]
 		 < MDA
[MDA=0.56]
 		 < MDA
[MDA=0.25]
 		 data
04/28/2011 0.60 < MDA
[MDA=0.23]
 		 < MDA
[MDA=0.55]
 		 < MDA
[MDA=0.26]
 		 < MDA
[MDA=0.30]
 		 < MDA
[MDA=0.18]
 		 data
04/28/2011 0.41 < MDA
[MDA=0.19]
 		 < MDA
[MDA=0.39]
 		 0.39±0.07
[MDA=0.26]
(6.6e+03)		 0.52±0.09
[MDA=0.34]
(7.1e+03)		 < MDA
[MDA=0.15]
 		 data
05/19/2011 0.555 < MDA
[MDA=0.19]
 		 < MDA
[MDA=1.70]
 		 < MDA
[MDA=0.25]
 		 < MDA
[MDA=0.19]
 		 < MDA
[MDA=0.50]
 		 data

Arugula

source: various local organic farms

Purchase Date Food Mass I131 I132 Cs134 Cs137 Te132 Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
04/07/2011 0.38 0.41±0.07
[MDA=0.24]
(2.7E+03)		 < MDA
[MDA=1.11]
 		 < MDA
[MDA=0.35]
 		 0.66±0.12
[MDA=0.45]
(5.6E+03)		 < MDA
[MDA=0.19]
 		 data
04/20/2011 0.36 < MDA
[MDA=0.32]
 		 < MDA
[MDA=0.90]
 		 < MDA
[MDA=0.49]
 		 < MDA
[MDA=0.51]
 		 < MDA
[MDA=0.25]
 		 data
04/28/2011 0.313 < MDA
[MDA=0.31]
 		 < MDA
[MDA=0.57]
 		 < MDA
[MDA=0.37]
 		 < MDA
[MDA=0.41]
 		 < MDA
[MDA=0.25]
 		 data

Carrots

Source: a local organic farm

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
08/11/2011 0.63 < MDA
[MDA=0.17]
 		 < MDA
[MDA=0.90]
 		 < MDA
[MDA=0.21]
 		 < MDA
[MDA=0.15]
 		 < MDA
[MDA=0.28]
 		 < MDA
[MDA=1.20]
 		 data

Cherry Tomatoes

Source: a local organic farm

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
08/11/2011 0.83 < MDA
[MDA=0.072]
 		 < MDA
[MDA=0.28]
 		 < MDA
[MDA=0.082]
 		 < MDA
[MDA=0.079]
 		 < MDA
[MDA=0.109]
 		 < MDA
[MDA=0.55]
 		 data

Hay

Source: Northwest Nevada, irrigated with reservoir water

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
07/15/2011 0.16 < MDA
[MDA=0.61]
 		 < MDA
[MDA=2.48]
 		 < MDA
[MDA=0.42]
 		 < MDA
[MDA=0.72]
 		 < MDA
[MDA=1.46]
 		 41.7±4.2
[MDA=5.1]
(3.5e+04)		 data

Topsoil from San Diego

source: San Diego, CA

Top layer of soil (top 3–4 inches)

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
Never placed outside 0.54 < MDA
[MDA=2.33]
 		 < MDA
[MDA=226]
 		 < MDA
[MDA=0.33]
 		 < MDA
[MDA=0.26]
 		 < MDA
[MDA=87]
 		 < MDA
[MDA=2.43]
 		 data
06/29/2011 0.52 < MDA
[MDA=2.36]
 		 < MDA
[MDA=157]
 		 0.96±0.10
[MDA=0.32]
(2.7e+03)		 1.55±0.16
[MDA=0.37]
(2.4e+03)		 < MDA
[MDA=77]
 		 9.81±0.98
[MDA=3.63]
(1.5e+05)		 data

Next lower layer of soil (under 3–4 inches)

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
Never placed outside 0.55 < MDA
[MDA=4.22]
 		 < MDA
[MDA=850]
 		 < MDA
[MDA=0.33]
 		 < MDA
[MDA=0.24]
 		 < MDA
[MDA=380]
 		 < MDA
[MDA=2.54]
 		 data
06/29/2011 0.60 < MDA
[MDA=3.51]
 		 < MDA
[MDA=1040]
 		 < MDA
[MDA=0.21]
 		 < MDA
[MDA=0.31]
 		 < MDA
[MDA=280]
 		 < MDA
[MDA=2.34]
 		 data

Soil and Manure from Sacramento

Source: Farm in the Sacramento Area

Topsoil sample

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
08/16/2011 0.93 < MDA
[MDA=0.138]
 		 < MDA
[MDA=0.845]
 		 0.147±0.015
[MDA=0.055]
(1.8e+04)		 2.590±0.259
[MDA=0.072]
(1.4e+03)		 < MDA
[MDA=0.567]
 		 0.974±0.121
[MDA=0.532]
(1.5e+06)		 data

Dried manure sample — was produced about one year ago, left outside exposed to rain after Fukushima

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
08/16/2011 0.56 < MDA
[MDA=0.53]
 		 < MDA
[MDA=6.41]
 		 5.18±0.52
[MDA=0.14]
(5.0e+02)		 7.93±0.79
[MDA=0.17]
(4.7e+02)		 < MDA
[MDA=3.37]
 		 16.6±1.7
[MDA=1.5]
(8.9e+04)		 data

Soil from Sonoma County

Source: Farm in Sonoma County

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
04/27/2011 2.21 N/A N/A 0.347±0.035
[MDA=0.056]
(7.5e+03)		 1.905±0.190
[MDA=0.057]
(1.9e+03)		 N/A 3.436±0.493
[MDA=2.138]
(4.3e+05)		 data

Soil from Oakland

Source: a grassless, treeless front yard

Collection Date Sample Mass Sample depth Sample dimensions I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg cm cm × cm Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
09/08/2011 2.03 0–2 25 × 38 < MDA
[MDA=0.037]
 		 < MDA
[MDA=0.105]
 		 0.087±0.010
[MDA=0.046]
(3.0e+04)		 2.46±0.25
[MDA=0.05]
(1.5e+03)		 < MDA
[MDA=0.057]
 		 0.441±0.088
[MDA=0.402]
(3.4e+06)		 data
09/08/2011 1.25 2–4 16.5 × 33 < MDA
[MDA=0.095]
 		 < MDA
[MDA=0.47]
 		 < MDA
[MDA=0.083]
 		 4.91±0.49
[MDA=0.09]
(7.5e+02)		 < MDA
[MDA=0.264]
 		 < MDA
[MDA=0.474]
 		 data
09/08/2011 1.08 4–6 15 × 28 < MDA
[MDA=0.173]
 		 < MDA
[MDA=1.31]
 		 < MDA
[MDA=0.119]
 		 3.62±0.36
[MDA=0.13]
(1.0e+03)		 < MDA
[MDA=0.694]
 		 < MDA
[MDA=0.769]
 		 data
09/08/2011 1.23 6–9 14 × 22 < MDA
[MDA=0.372]
 		 < MDA
[MDA=16.7]
 		 < MDA
[MDA=0.075]
 		 2.74±0.27
[MDA=0.08]
(1.4e+03)		 < MDA
[MDA=9.18]
 		 < MDA
[MDA=0.55]
 		 data
09/08/2011 1.37 9–14 13 × 15 < MDA
[MDA=1.147]
 		 < MDA
[MDA=79.5]
 		 < MDA
[MDA=0.051]
 		 3.06±0.31
[MDA=0.09]
(1.2e+03)		 < MDA
[MDA=62.8]
 		 < MDA
[MDA=0.91]
 		 data

Sand from Palo Alto

Source: Yard

For comparison, the activity concentration of Potassium-40 (K-40) in this sample was 730±73 Bq/kg.

Collection Date Sample Mass I131 I132 Cs134 Cs137 Te132 Be7* Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
05/29/2012 2.6 < MDA
[MDA=0.26]
 		 < MDA
[MDA=5.1]
 		 0.129±0.013
[MDA=0.030]
(2.0e+04)		 0.181±0.018
[MDA=0.032]
(2.0e+04)		 < MDA
[MDA=4.0]
 		 1.29±0.13
[MDA=0.31]
(1.2e+06)		 data

Soy Sauce

Source: Product of Japan, purchased in local grocery store

For comparison, the activity concentration of Potassium-40 (K-40) in this sample was approximately 100 Bq/L.

Collection Date Sample Volume I-131 I-132 Cs-134 Cs-137 Te-132 Data
  L Bq/L (L**) Bq/L (L**) Bq/L (L**) Bq/L (L**) Bq/L (L**)  
08/21/2012 1.08 < MDA
[MDA=0.027]
 		 < MDA
[MDA=0.044]
 		 < MDA
[MDA=0.029]
 		 < MDA
[MDA=0.032]
 		 < MDA
[MDA=0.065]
 		 data

Salmon

Source: Pacific Northwest, purchased in local grocery store

Collection Date Sample Mass I-131 I-132 Cs-134 Cs-137 Te-132 Data
  kg Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**) Bq/kg (kg**)  
01/31/2013 1.36 < MDA
[MDA=0.085]
 		 < MDA
[MDA=0.25]
 		 < MDA
[MDA=0.049]
 		 < MDA
[MDA=0.056]
 		 < MDA
[MDA=0.39]
 		 data

* Be-7 is observed normally due to its being produced by cosmic rays interacting with the atmosphere.

** The number in parentheses is the number of kilograms of the item that one would need to consume to equal the radiation exposure of a single round trip flight from San Francisco to Washington D.C. (0.05 mSv). To see how we calculate these numbers, please visit our explanation of the equivalent dose calculation.

Note: "MDA" is the estimated minimum detectable activity for a given isotope in the detector.