The Planetary Cost of Over Testing

We all know that feeling, when we order a test that doesn’t seem entirely warranted but the patient or family is insistent. We do our best to educate them while trying to maintain our working relationship. And often we just end up ordering that investigation. It might also be a way we reduce our own stress about missing a diagnosis; there’s so much uncertainty in the practice of family medicine. The obvious downsides of over testing are the cost and the potential for false positives, which can then lead to a cascade of further testing and treatment.

Choosing Wisely Canada is a resource to help clinicians identify and reduce the use of tests and therapies that provide little or no clinical benefit.

There is an environmental downside to over testing as well. Every test we order has a carbon footprint. A CBC, for instance, emits the equivalent of 332 grams of CO2, maybe not much on its own, but multiplied manyfold over and the impact is huge. These carbon emissions arise from the energy used in laboratories and the lifecycle of materials.

Lab tests are resource-intensive and produce enormous amounts of hazardous and toxic waste. Over testing increases the volume of single-use plastics and other consumables (needles, vials, reagents) that require specialized disposal. The environmental footprint of every test includes the manufacture, packaging, and transport of materials and reagents.

Medical imaging is also a significant contributor to greenhouse gas (GHG) emissions, accounting for some 0.5-1% globally. This is primarily due to the energy consumption of equipment like CT and MRI scanners, and in the manufacture of these machines. A single MRI scan emits an average of 17.5 kg of CO2. CT scans each produce somewhat less carbon, 9.2 kg on average. X-rays have lower emissions, but are numerically far more common and, therefore, have significant cumulative impact.

Cascades Canada’s Toolkit for Primary Care has a section entitled Reducing Unnecessary Care. It’s a useful resource that offers a detailed frame with which to consider the benefits of tests and treatments as well as their unintended harms. Adopting such an approach is both good for the patient, and good for the environment.