In April 2008, consumeraffairs.com reported multiple cases of diarrhea, vomiting and other intestinal problems in pets fed Nutro products. Nutro stated that their products undergo rigorous safety testing and are 100% safe. Some customers have backed the company, saying that their pets are not having any problems with the food. Veterinarians interviewed stated that it might not necessarily be the food that is causing problems. In September 2008, the Pet Food Product Safety Alliance (PFPSA) tested samples of Nutro dog food in response to the consumer complaints on consumeraffairs.com and found levels of copper in excess of Association of American Feed Control Officials (AAFCO) recommendations. Zinc levels were approximately 2-4 times the minimum recommendation of 120 ppm, but still within the maximum recommendation of 1000 ppm. The PFPSA has criticized the recommended zinc levels as excessive; even the minimum recommended levels are 10 times that of adult human requirements (based on body weight). PFPSA has also stated that the symptoms of zinc toxicity are consistent with consumer complaints regarding Nutro dog food. Nutro rejected PFPSA's claims stating that both zinc and copper levels were within recommended levels, reiterating that their products undergo "rigorous quality assurance testing".