As more areas of the Gulf are re-opened for fishing and shrimping, I’m hearing more questions about the adequacy of the seafood safety assessments. Contamination from the BP oil spill disaster in the Gulf of Mexico may cause short-term and long-term impacts on seafood safety. Chemicals in the oil, such as polycyclic aromatic hydrocarbons (PAHs) and metals, can build-up in seafood and cause health risks. Pregnant women, young children, and communities that rely on Gulf seafood as their main source of food are most vulnerable to these pollutants. When we reviewed the protocol for determining Gulf seafood safety, developed by the National Oceanic and Atmospheric Administration (NOAA) and the Food and Drug Administration (FDA), we found some flaws that need to be fixed to ensure that vulnerable populations are protected.
Just to be clear, I'm not saying that Gulf seafood isn't safe, or that the areas that have been reopened should be closed. I don't know that. Also, the contaminants we're talking about don't cause acute health risks, nor are they likely to affect health with short-term or moderate consumption -- in other words, don't sweat about where each shrimp you buy came from. The issue here is that FDA and NOAA need to get this right in order to make sure they're on the right track for the longer-term. The seafood safety system in the Gulf needs to be robust and needs to be operating for years into the future, so let's make sure it's set up correctly right now.
Better Protection for Vulnerable Populations
The FDA used faulty assumptions (described below) to determine how much contamination is OK to eat in Gulf seafood. This means that they set the bar too high and lower levels of contaminants could pose a risk to vulnerable populations – like pregnant women, children and communities who eat a lot of Gulf seafood.
- By using an adult average body weight of 176 pounds the FDA does not adequately protect children, or even many women
The average body weight of a 4-6 year old child is about 47 pounds and half of American women weigh less than about 155 pounds. These smaller people would be getting a bigger dose of contaminants per pound of bodyweight than the FDA is estimating they're getting. Not all of us are big men, after all.
- FDA fails to account for the increased vulnerability of the developing fetus and young children
Children are particularly vulnerable to contaminants in seafood because their bodies are still developing, they ingest a larger portion of contaminants relative to their size, and they often don’t process chemicals as well as adults. Human epidemiologic studies have found that fetuses can’t clear the genetic damage from PAHs as easily, and also that babies may be at increased risk of neurological effects from these chemicals.
- Using national seafood consumption rates rather than a survey of local conditions underestimates the hazard to Gulf communities
After the Exxon Valdez, seafood risk assessments used information on local seafood consumption. In this case, ignoring NOAA guidance documents, the FDA relied on national numbers for fish consumption. Here’s a rundown of some of the numbers FDA used:
- 1 meal of shrimp per week
- 2 meals of fish per week
- 3 ounces (less than a quarter of a pound) of shrimp per meal (i.e. 4 jumbo shrimp)
- No more than 16 meals of seafood per month
These numbers don’t match up with the diets of local residents who often report that they eat seafood at every meal and they eat shrimp multiple times a week.
- Assuming a 5 year retention period of contaminants in seafood when studies from other oil spills have documented elevated contaminants in seafood six to seven years following the event.
Although there are many uncertainties in how long seafood may remain contaminated in the Gulf, the quantity of oil suggests that contamination could persist for many years. The FDA risk assessment did not provide a scientific rationale for the choice of only a five-year exposure duration.
Improved Seafood Testing
To ensure the long-term safety of, and confidence in, Gulf seafood, there needs to be a robust and comprehensive seafood monitoring program. NOAA should:
- Test for toxic metals known to be present in the crude oil
Cadmium, copper, lead and mercury have all been detected in studies of crude oil. Given the public health impact of exposures to low levels of these metals and their potential to bio-accumulate in seafood, chemical analyses of seafood should include metals.
- Assess the potential for contamination of seafood by dispersant chemicals
The BP oil disaster clean-up has involved an unprecedented volume of use of dispersant chemicals. NOAA should assess the potential for dispersant chemicals to contaminate seafood, and whether dispersants may enhance the uptake of oil.
- Evaluate the presence of subsurface oil in addition to surface sheens
The use of dispersants has increased the presence of subsurface plumes. Therefore, monitoring of oil in the water column must be conducted in order to determine whether an area is truly “free of oil”.
- Conduct representative sampling that ensures adequate coverage of highly affected areas
Due to the immense quantity of oil spilled and the complexity of the oil dispersion patterns, sampling needs to be conducted in a manner that will assure adequate coverage of sensitive areas. The minimum sampling frequency cited in the NOAA protocol of “6 sub-samples per species (3 sub-samples for oysters) from each sampling location” seems inadequate unless the sampling locations are very numerous.
Public Disclosure of Test Results and Methods
To improve transparency and improve public confidence, the testing methods and all of the results need to be posted on the NOAA website.
- Ensure consistency between States and Federal Waters
Given the large area that was impacted by oil and the variety of state and federal jurisdictions governing the re-opening of oil-affected areas, the FDA should be playing a strong role in ensuring the protection of public health across the Gulf Coast. This entails careful scrutiny of state and local decisions. Inconsistencies among states could quickly erode public confidence in the seafood testing program and put vulnerable populations at risk.