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Gina Solomon’s Blog

Gulf Shrimp Testing: Is a Dozen Samples in 5000 Square Miles Enough to Reassure You?

Gina Solomon

Posted September 2, 2010 in Health and the Environment

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Today, NOAA reopened 5,130 square miles of Gulf waters to shrimping and fishing. I took a look at the data on which NOAA based their decision and was surprised to find that their data included only 12 samples of shrimp, consisting of a grand total of 73 individual shrimp, caught from an area about the size of the State of Connecticut.

Does that reassure you that they've really found whatever contamination might be out there?

After all of the calls to do more and better testing of Gulf seafood, I am presenting to you below the grand total of publicly-available testing data on Gulf shrimp. After you look at the data below, I'm wondering if you will be confident that it's adequate. In a previous blog, I raised some concerns about the way the FDA was determining the 'safe' levels of contaminants in Gulf seafood. I also raised some general concerns in another blog about the very limited data available on what's actually in the seafood. In this blog, I've summarized all of the data that have been made publicly available to-date on chemical testing of Gulf shrimp.

The bottom line is this, as of September 2nd: 

  • FDA has released data on a total of 42 shrimp samples from Louisiana, 12 from Florida, 7 from Alabama, and 6 from Mississippi. Each sample contained an average of between 1 and 7 shrimp,
  • NOAA has released data on chemical testing of a total of 17 shrimp samples from offshore Gulf waters, containing an average of 6 shrimp each.

Here's a question: Is a total of six samples, containing a total of 21 individual shrimp, enough data on which to base a decision to reopen all of Mississippi's territorial waters to shrimping? Some Mississippi fishermen don't think so, especially since they're still seeing oil in the water. You could ask the same question about each of the other Gulf states.

Even in Louisiana, where more testing has been done, there are still questions: A total of 53 shrimp from Louisiana waters have been chemically analyzed and the levels reported as low. If those 53 shrimp really represent the full extent of the open territory, maybe that's OK, but this oil spill has lots of variability, with pockets of contamination appearing in many locations. As a scientist, I would feel better if I knew there was a robust sampling strategy to address this variability and to take enough samples - maybe several hundred - to assure that if there were contaminated shrimp out there, they would be detected. I'll be meeting with officials from NOAA and FDA on Tuesday and you'd better believe I'll be asking them some questions about their scanty sampling!

Shrimp Sampling in the Gulf Reported by FDA

Louisiana:

Date Tested

# of Shrimp Tested

# of analysis performed (composite samples)

7/22/10

14

14

7/29/10

9

5

8/2/10

13

6

8/11/10

4

4

8/12/10

6

6

8/12/10

7

7

Mississippi:

Date Tested

# of Shrimp Tested

# of analysis performed (composite samples)

7/30/10

9

4

8/2/10

12

2

Alabama:

Date Tested

# of Shrimp Tested

# of analysis performed (composite samples)

8/5/10

26

4

8/13/10

16

3

Florida:

Date Tested

# of Shrimp Tested

# of analysis performed (composite samples)

7/30/10

3

3

8/13/10

39

9

 

NOAA Shrimp Sampling

Chemical analysis of 5 composite samples were reported as of August 27th, they consisted of the following:

Sample #1:  12 shrimp

Sample #2:   2 shrimp

Sample #3:   7 shrimp

Sample #4:   2 shrimp

Sample #5:  4 shrimp

Sampling was not reported by state.

Today, September 2nd, NOAA released results of 12 more composite samples of shrimp. Here's how many were tested in each sample:

Sample 1: 5 shrimp

Sample 2: 1 shrimp

Sample 3: 1 shrimp

Sample 4: 3 shrimp

Sample 5: 2 shrimp

Sample 6: 9 shrimp

Sample 7: 9 shrimp

Sample 8: 9 shrimp

Sample 9: 9 shrimp

Sample 10: 1 shrimp

Sample 11: 1 shrimp

Sample 12: 23 shrimp

What do you think? Is it enough?

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Comments

Carmen ButlerSep 3 2010 11:40 AM

Dear Ms. Solomon,

Thank you for an excellent article in JAMA highlighting the health effects of oil spills, and the Gulf of Mexico oil spill in particular. You mentioned that you and your co-author on the article were surprised at the scarcity of studies on this topic. I wonder if you could tell me what other studies exist, as they could potentially help my work engaging socially responsible investors and oil companies on reducing the health risks posed by many oil companies' operations.

I would be delighted to hear from you.

All the best,
Carmen Butler

Marie CorwinSep 3 2010 01:08 PM

Thanks for the article! such an important subject and brings up so many questions on the importance of scientific method, sample size & data analysis. I would really like to see more on the methodology used in testing the shrimp. Having difficulties finding the actual studies & data. maybe you could help me out or point me in a direction :) thanks
marie

Chuck AndersonSep 3 2010 02:26 PM

I believe that FDA is testing other species besides just shrimp, making the sampling #'s into the hundreds.

I do not know what # makes the sample size strong enough, but you should note that other species being sampled, not just shrimp.

Brian DonovanSep 4 2010 01:39 PM

I would not allow my children to eat Gulf seafood. I do not have a great deal of faith in "sensory experts."

This article briefly discusses BP’s strategy to limit its liability in regard to the Deepwater Horizon blowout. This strategy includes, but is not limited to, intentionally underestimating the rate of flow of oil that’s being released into the Gulf of Mexico, prohibiting independent measurement of the BP oil gusher by unbiased third party scientists and engineers, the excessive and unprecedented use of dispersants (both on the surface and underwater), systematically and intentionally collecting as small an amount of oil as possible from the waters of the Gulf of Mexico, and controlling and restricting media access to the areas affected by the Deepwater Horizon oil gusher.

http://renergie.wordpress.com/2010/07/12/bps-strategy-to-limit-liability-in-regard-to-its-gulf-oil-gusher/

Although this article was published on July 11, 2010, it is still timely.

Sara CrownSep 8 2010 10:27 PM

Gina,

How many shrimp did the NRDC test, and what were your findings?

Be a part of the solution -- talk is cheap.

Gina SolomonSep 10 2010 08:28 PM

Thanks for the comments!

In response to Carmen's question, the main oil spill that has been studied for health effects is the Prestige tanker accident in Spain in 2002. I blogged about the most recent study from that spill here: http://switchboard.nrdc.org/blogs/gsolomon/worker_illness_after_prestige.html. I also summarized previous studies in a blog here: http://switchboard.nrdc.org/blogs/gsolomon/oil_spills_and_human_health_le.html

In response to Marie, the FDA and NOAA methodologies are indeed not easy to find. I added some links into my blog above. Check them out!

Chuck's point is correct - NOAA is testing a lot more fish than shrimp. The reason I focus on shrimp is because crustacea are much less efficient at metabolizing and excreting the PAHs in oil compared to finfish. So we would expect the levels of these chemicals to be higher in shrimp, oysters, and crabs than they are in fish. Most of the oyster fisheries haven't yet reopened, and I don't think people eat a lot of crab, but a lot of shrimping has resumed and it's a popular food, so that is where I have focused my scrutiny.

In response to Sara, NRDC has not - so far - done any independent testing of shrimp. Instead we have been working to make sure that the FDA and NOAA put in place an adequate seafood testing program.

More updates soon!

Comments are closed for this post.

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Switchboard is the staff blog of the Natural Resources Defense Council, the nation’s most effective environmental group. For more about our work, including in-depth policy documents, action alerts and ways you can contribute, visit NRDC.org.

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