Costco Finds

Costco is a convenient place to buy high-quality foods and household items in bulk, often at lower prices than other retailers. While it offers a variety of organic, non-toxic, and better-for-you products, not everything at Costco is a win for your health. Many everyday products sold in bulk contain hidden toxins, heavy metals, and synthetic chemicals that can negatively impact your well-being over time. Just because it’s available at a warehouse store doesn’t mean it belongs in your home. Knowing what to avoid and why can help you make better choices and minimize your exposure to harmful substances.

My Background in Environmental Science and Toxic Exposure

My perspective on health and consumer products comes from decades of experience in environmental science, where I studied how toxins impact ecosystems and human health. Many of the harmful substances found in everyday products build up in the body over time, contributing to chronic health issues such as hormone disruption, neurological problems, and metabolic disorders. By eliminating or reducing exposure to specific toxins, you can significantly lower your body’s toxic burden and support overall health. Costco has some great options, but I recommend skipping a few key products on your next shopping trip.

Aluminum Foil and Parchment Paper: A Hidden Risk in the Kitchen

Aluminum foil is one of those kitchen staples that many people use without thinking twice. However, aluminum is a known neurotoxin that can leach into food, especially when used at high temperatures. Cooking acidic or salty foods in aluminum increases the amount that transfers into the food, leading to a slow accumulation of aluminum in the body over time.^[1] While the human body can process small amounts, excessive exposure has been linked to neurodegenerative diseases, cognitive decline, and other health concerns. If you use aluminum foil frequently for cooking or food storage, consider switching to safer alternatives like glass containers or parchment paper.

However, not all parchment paper is safe either. Many brands, including some sold at Costco, are coated with silicone, which can release siloxanes when heated. Siloxanes have been associated with hormone disruption, liver toxicity, and potential carcinogenic effects. Some studies suggest that these compounds start breaking down at temperatures as low as 200°F, meaning they may be released even when baking at moderate heat. The best alternative is unbleached, non-coated parchment paper or reusable silicone baking mats made from food-grade silicone.

Tuna and the Problem of Mercury Accumulation

Tuna is a convenient protein and omega-3 fatty acids source, but it often comes with a hidden downside—mercury contamination. Mercury is a heavy metal that can accumulate in the body, affecting brain function, nervous system health, and cardiovascular function. Long-term exposure has been linked to neurological disorders, developmental delays in children, and an increased risk of chronic illness. Large fish like tuna tend to have the highest mercury levels because they absorb mercury from the smaller fish they eat.^[2]

If you eat tuna, you must choose lower-mercury options and consume them in moderation. Brands like Safe Catch test their tuna for heavy metals and offer lower-mercury options. Skipjack tuna is another good choice, as it contains significantly less mercury than larger tuna species like albacore. However, even with lower-mercury possibilities, it’s best to rotate different seafood sources in your diet to minimize exposure. Wild-caught salmon, sardines, and anchovies are excellent alternatives that provide high-quality omega-3s without the same heavy metal risk.

Plug-In Fragrances and Indoor Air Pollution

One of the most toxic products found in many homes is plug-in air fresheners. These products release synthetic fragrance chemicals that can contribute to poor indoor air quality and chronic health issues. Many contain phthalates, volatile organic compounds (VOCs), and other synthetic ingredients that act as endocrine disruptors, interfering with hormone regulation. Studies have linked long-term exposure to artificial fragrances with an increased risk of respiratory problems, cardiovascular issues, and even certain cancers.

Unlike food toxins, which can be reduced through detoxification, airborne toxins from plug-in fragrances are inhaled continuously, making them difficult to avoid once they’re in the home. These synthetic chemicals can also accumulate on furniture, fabrics, and other surfaces, leading to prolonged exposure even after removing the air freshener. Instead of plug-in fragrances, consider natural alternatives like essential oil diffusers, beeswax candles, or simply opening windows for fresh air circulation.

Better Choices for a Non-Toxic Home

Reducing exposure to harmful chemicals doesn’t mean giving up convenience or functionality. There are safer alternatives for nearly every product on this list. Instead of aluminum foil, consider using glass baking dishes and stainless steel storage containers. Switch to unbleached, non-coated parchment paper or reusable silicone mats for baking. If you’re looking for a better seafood option, choose smaller fish like sardines or wild-caught salmon to get the benefits of omega-3s without the heavy metal risk. Opt for pure beeswax candles, simmer citrus peels and spices on the stove, or use high-quality essential oils in a diffuser to freshen your home naturally.

The Importance of Making Informed Choices

While Costco offers plenty of great products, not everything in their inventory meets the standard for a non-toxic home. Knowing what to avoid and what to look for allows you to shop smarter and protect your family’s health. Small changes in daily habits, like swapping out aluminum foil, choosing lower-mercury seafood, and eliminating artificial fragrances, can impact your well-being. By making informed decisions and prioritizing cleaner, safer alternatives, you can reduce exposure to harmful substances and create a healthier living environment.

Final Thoughts: Shop Wisely and Share the Knowledge

The goal isn’t to create fear around shopping but to empower people with the knowledge they need to make healthier choices. Many people assume that because a product is widely sold, it must be safe—but that’s not always the case. Raising awareness about hidden toxins and how they affect long-term health can help more people transition to a cleaner, less toxic lifestyle. If you know someone who regularly buys the products on this list, sharing this information can help them make better home and health decisions. Costco has plenty of non-toxic, high-quality options, but knowing what to avoid makes all the difference in creating a healthier home.

1. Dordevic, Dani, et al. “Aluminum Contamination of Food during Culinary Preparation: Case Study with Aluminum Foil and Consumers’ Preferences.” Food Science & Nutrition, vol. 7, no. 10, Sept. 2019, pp. 3349–60.
2. Bernhoft, Robin A. “Mercury Toxicity and Treatment: A Review of the Literature.” Journal of Environmental and Public Health, vol. 2012, 2012, p. 460508.