That's definitely what you're looking at. Unfortunately this is an issue with kava, not just in the drying phase, but in growing as well. Kava is often grown where animals roam freely, so there is bacteria in the soil. It's actually quite difficult to avoid when dealing with agricultural products. Washing isn't enough to get rid of bacteria. The best way to get rid of bacteria is with heat. Most is killed at 140 degrees fahrenheit, though most processors don't have the ability to bring kava to that temperature. The UV in sunlight probably isn't enough to kill most bacteria, but concentrated UV-C light may be.
Contamination is a bigger problem than people realize and I'm happy to see the Fijian government acknowledging it, though it will be tough for most processors to invest in procedures that will fix the issue. At least for now, the retailers will be the ones making sure kava is clean. I'm currently working with the FDA on getting a reconditioning plan approved. This will ensure that importers can sterilize kava in a way that is acceptable to the FDA. There's quite a bit of red tape involved in the process.