Science Oddity: The USDA doesn’t regulate sand from ocean beaches

A sandy beach in New Zealand

Moving soil between countries is hard. Back when I worked in a soil microbe lab, my colleagues lamented the effort and paperwork required to import soil samples. If they wanted just the soil, they had to ask the sender to sterilize it using USDA-approved methods to kill any potential nasties that might invade the US and cause trouble. And if they wanted unsterilized soil to study the live soil microbes, they needed to apply for two different USDA permits. That meant taking precious time to submit paperwork justifying why you want the soil, how you’ll use it, and how you’ll keep any microbes in the soil from escaping.

This might sound like an unnecessary burden, but these regulatory hurdles are a vital part of keeping the US safe. Soil harbors microbes, insects, and plant seeds, including those of pests that if introduced could do serious economic and environmental damage. One study found that introduced pests and invasive species cost us nearly $120 billion annually. These include the citrus greening disease, responsible for stunting and killing citrus fruit trees in Florida and costing the state’s iconic industry $4.5 billion between 2007 and 2011. They also include pests like the soybean cyst nematode, which cost soybean growers $500 million a year and originally arrived in the U.S. via imported soil. Then there are the Zika and West Nile viruses, recently introduced diseases transmitted by people and now established on the US mainland. With any pest, it can take as little as one accidental release to unleash destruction. The stakes are high.

So it floored me when during a marine biology project, I learned that mailing ocean beach sand was essentially unregulated by the USDA. At the time, I was researching the effect of agricultural waste on reef health on the Society Islands and spent hours a day snorkeling in a fetid part of Cook’s Bay just below a goat farm. Near the project’s end, I asked our graduate student advisor how to prepare samples to ship back to the U.S. She told me to just seal them in an airtight container and they were good to go. “Do I need to sterilize it?” I asked. “Nope,” she replied, “the USDA doesn’t require it.” I ended up not shipping sand back to the U.S. for analysis, but if I had it would have carried the microbes from the goat farm runoff, potential pests and biohazards and all. Then again, I had just spent six weeks swimming around in diluted goat feces—I was probably a biohazard.

Rocks on a beach in Japan; according to USDA regulations, you can bring these back to the U.S. as long as they’re free of organic matter, though they may still harbor microbes.

To this day, that USDA still technically does not regulate the import of ocean beach sand, so under this loophole you can ship the uncleaned “sediment of saltwater oceans” (i.e. sand) without any permit. Note that this doesn’t apply to the sand/sediment of inland saltwater seas or freshwater lakes. But how could the customs procedures be so different for soil versus ocean beach sand, or beach sand from the Mediterranean Sea vs the Black Sea, separated only by the thin Bosphorous Strait? Ostensibly, the reason is because all of the saltwater oceans in the world are connected, so they already share the same pests and importing beach sand won’t introduce new ones. But this logic ignores the possibility that beaches might harbor different microbes (and potential pests) due to influence from microbes in nearby land soil or human activity (like a goat farm). And while the Customs and Border Patrol (CBP) have tried to discourage people from bringing potentially contaminated sand back to the US, they also acknowledge that due to the USDA’s loophole, you’re free to bring uncleaned ocean sand back with you as long as it doesn’t have visible chunks of organic matter (like twigs or dirt).

But should you? I’m not so sure.

Customs and the USDA won’t allow you to import organic matter, like this dried piece of algae. But they don’t have rules against importing the sand around it.

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