There’s a particular feeling that comes after you find out something uncomfortable about a product you’ve trusted for years. It’s somewhere between relieved and confused.

Relieved because that fog of reassuring packaging and vague promises has finally cleared, and you’re seeing things more plainly now. But that same clarity brings its own disorientation. You read the Clean Label Project study. You saw the numbers. 

And now you’re standing in the pet food aisle, or staring at the bag on your kitchen floor, and the question hanging there is: what now? Should I continue feeding this one to my buddy, or should I search for a new brand? An if switch brand whats the guarantee that they will holdup gaianst this study findings? 

Here’s where we land on that. The goal isn’t to make you feel terrible about every bowl you’ve already filled. It’s to give you a clearer picture of how the industry actually works, why these gaps exist, and what better actually looks like in practice. Some of what’s needed is on brands. 

How Did We Get Here? The Regulatory Gap Few People Understand

One of the first questions that surfaces is simple.

How did this happen? So let’s see how. Most people assume that if a product is on a shelf, someone tested it.

We have regulatory bodies for almost everything, FDA for human drugs, cosmetics, and food, the EPA for the environment, and it’s reasonable to assume something similar exists for what goes into your dog’s bowl.

That assumption is understandable. It’s also when it comes to dog food contaminants.

The organization most pet parents associate with safety is AAFCO, the Association of American Feed Control Officials. AAFCO sets the nutritional standards that allow a product to be labeled “complete and balanced.” What it doesn’t do is test for heavy metals. It isn’t a regulatory body, it doesn’t certify individual products, it has no enforcement power, and in practical terms, it issues guidelines that manufacturers can choose to follow.

Its framework for heavy metals is based on broad animal feed standards, not research specific to dogs. The data the industry points to when defending current metal levels comes largely from studies conducted decades ago, most of them running 40 weeks or less.

Dr. Nicholas Dodman, former director of the animal behavior program at Tufts University, put it plainly: “It’s not correct on the basis of a 40-week study to extrapolate out for five years. Especially when you know that some of the contaminants are cumulative.”

Nobody lied to get here. The standards were built in an era when testing was expensive, data was limited, and pet food wasn’t held to anything close to the scrutiny applied to human food. The gap is real, it’s been real for a long time, and most brands have operated comfortably inside it. That’s starting to change. Slowly, and not uniformly, but it’s changing.

“Complete and Balanced” Means Less Than You Think

When you see “complete and balanced” on a bag of dog food, it means the product meets AAFCO’s nutrient profile minimums. That’s it. The label doesn’t tell you where those nutrients came from, how the ingredients were sourced, what processing method was used, or what else came along for the ride inside the bag.

AAFCO defines what counts as protein. It doesn’t distinguish between protein derived from high-quality whole meat and protein rendered from animal by-products, which is why two products with identical labels can have very different contamination profiles. Meat by-products, the organs and tissue remaining after human-grade cuts are removed, concentrate heavy metals because those organs spend an animal’s lifetime filtering toxins. When rendered and dried into meal, those metals come along.

Vitamin and mineral premixes present a similar problem. Dogs need supplementation, and premixes are a standard part of most dry food formulas. But trace metals can be present in the raw mineral sources, and the supply chains are complicated enough that tracing exactly what ended up in a specific batch, from which supplier, is genuinely difficult.

The result is a system where a product can be legally sold, labeled as nutritionally complete, and still contain lead levels 12 times higher than what’s found in average human food. All within the rules. All technically compliant. This is less a scandal than a design flaw, and design flaws can be fixed.

What the Research Actually Says, and What It Doesn’t

It’s worth being precise here, because honest communication about this data matters more than alarming headlines.

The Clean Label Project study found significant heavy metal contamination in dry and freeze-dried dog food. An independent 2021 study published in Scientific Reports, which analyzed 100 commercial pet food products, found that 100% of dog foods tested exceeded the maximum tolerated level for lead, and 81% exceeded it for mercury. A separate 2025 study published in the same journal, testing 93 imported products, detected arsenic and chromium in every single sample.

What the research hasn’t yet established clearly is exactly how these chronic exposure levels affect individual dogs over a full lifespan. Cornell University veterinary nutritionist Dr. Joseph Wakshlag has noted that long-term studies following dogs on different diets are rare. The honest answer is that we have solid evidence of contamination, strong mechanistic reasons to be concerned about accumulation, and an industry-wide gap in longitudinal research that means we’re working with incomplete information.

That incomplete information cuts both ways. It means we can’t say with certainty that current exposure levels cause specific harm. It also means we can’t say they don’t. What we do know is that heavy metals accumulate in tissue and organs over time, that the kidneys and liver bear the bulk of that burden, and that dogs eating the same formula twice a day for years have a fundamentally different exposure profile than humans who eat varied diets.

Uncertainty isn’t a reason to do nothing. It’s a reason to apply better judgment where we can.

Budget Is Real. Here’s How to Think About It Anyway.

Switching entirely to fresh or frozen food is the cleanest option, according to the data. Fresh/frozen products in the Clean Label Project study came in significantly lower than not just dry kibble, but also lower than the benchmark for human consumables. The contamination gap between formats is large enough that it isn’t noise.

But fresh food costs more. Sometimes considerably more, depending on the dog’s size and appetite. And for a lot of families, that’s not a straightforward swap.

A few things worth knowing if a full switch isn’t realistic right now:

Rotating brands and formulas isn’t a perfect solution, but it does reduce consistent daily exposure to the same contamination sources. The Clean Label Project recommends this specifically for owners who continue feeding dry kibble. Different products have different ingredient sources, different suppliers, and different contamination profiles. Rotating adds variety to what is otherwise a fixed daily exposure.

Partial transition is a real option. Some owners add a portion of fresh or minimally processed food to an existing dry food base, not enough to fully shift the contamination profile, but enough to reduce reliance on a single dry formula and add genuine nutritional diversity. Even one fresh meal per day changes the daily exposure math.

Looking for third-party tested products matters. Certifications from organizations like the Clean Label Project mean the product has been independently tested, not just self-reported. That distinction is significant when the regulations themselves don’t require contaminant testing.

Talking to your vet is worth doing, particularly for senior dogs, puppies, or dogs with existing kidney or liver concerns, where accumulated metal exposure over time is a more immediate consideration.

What Better Standards Actually Look Like

This is where we think the conversation needs to go, because individual consumer choices can only move so much.

Brands stepping up means testing their own products proactively, before a study names them. It means publishing those results rather than waiting to be asked. It means sourcing ingredients with enough transparency to know where contaminants might enter the supply chain, and caring enough to address it.

The data from the Clean Label Project showed that fresh/frozen products achieved dramatically lower contamination levels. That’s a manufacturing and sourcing choice, not a coincidence. Minimal processing, real recognizable ingredients, and less reliance on rendered by-product meals, these are choices brands make. They’re not impossible. They’re just different priorities.

The regulatory picture is shifting, too. There’s active discussion about contaminant standards in pet food at both the FDA and AAFCO levels, driven in part by the attention studies like this one have created. That conversation is slow, and its outcome isn’t certain, but consumer awareness is part of what accelerates it.

At Nibble and Wag, our standard is simple, and it doesn’t change: would we feel comfortable feeding this every single day, for the entire life of a dog we love? That question has concrete implications for every sourcing decision we make, every ingredient we include, and every formula we put in front of a dog. We test. We care what the results say. And we think every brand that sells dog food daily should be held to exactly the same question.

Paying Attention Is Enough for Now

The study is uncomfortable reading. So is the regulatory picture. But discomfort and panic are different things, and only one of them is useful.

You now know how the system works, where the gaps are, and what the data actually says versus what’s still uncertain. You know that format matters, that rotation helps, that third-party testing is a meaningful signal, and that asking questions of the brands you buy from is entirely reasonable.

Your dog trusts what’s in the bowl. That trust is worth protecting, not with anxiety, but with the kind of steady attention you’d give anything that matters. Better information leads to better choices, for pet parents and for the brands that should be earning that trust every time they fill a bag.