FITs Offer Lowest Environmental Footprint Among CRC Screening Options

Car-based transportation to and from testing sites drives the environmental impact gap between colorectal cancer (CRC) screening strategies, with annual fecal immunochemical tests (FITs) generating roughly 20% fewer greenhouse gas emissions and causing less health-related harm than colonoscopies over a 10-year period, according to a life cycle assessment recently published in BMJ Public Health.¹

The single-center study, conducted at the University of California, San Francisco (UCSF), is the first to compare FITs, CT colonographies (CTCs), and colonoscopies using life cycle assessment, a gold-standard method for quantifying environmental impact. The findings add an environmental dimension to a body of cost-effectiveness literature already favoring FIT-based screening.

Assessing the Environmental Impact of CRC Screening Methods

Since the health care sector accounts for nearly 10% of US greenhouse gas emissions, investigators argued that high-volume medical services should be evaluated for their climate impact, especially when comparable alternatives are widely available. CRC screening is one such area, as the US Preventive Services Task Force recommends 3 CRC screening pathways for average-risk adults: annual FITs, CTCs every 5 years, or colonoscopies every 10 years.²

Because these tests are considered similarly effective and safe, the researchers set out to determine whether they differ meaningfully in downstream environmental cost.¹ The team performed an on-site audit to document resource use for each screening test at UCSF's Parnassus campus, the site of the main hospital. To estimate the environmental impacts of these procedures, they measured the 3 methods by global warming potential and damage to human health, computing 10-year impacts for each using a Markov model.

FITs Have the Lowest Environmental Impact

The researchers documented 140 unit processes across the 3 tests (33 for FITs, 84 for colonoscopy, and 23 for CTC) and mapped them to the ecoinvent lifecycle inventory database. They found substantial differences in the environmental impact of CRC screening by method: FITs were the most environmentally sustainable screening strategy, with roughly 20% lower impact than colonoscopies, whereas CTC was the least favorable.

A single FIT generated just 0.27 kg of CO₂ equivalents (kgCO₂e) compared with 39.6 kgCO₂e for a colonoscopy and 27.8 kgCO₂e for a CTC when patient transportation was factored in. The environmentally mediated health harms associated with individual tests were also substantially lower for FITs, which were associated with 0.002 disability-adjusted life years (DALYs) lost compared with 0.35 for colonoscopy and 0.25 for CTC.

Transportation was the largest contributor to emissions for colonoscopy and CTC, accounting for 44% to 67% of each test's total footprint and exceeding the next largest contributor, personal protective equipment, by an order of magnitude. For FITs, however, transportation’s contribution to emissions was comparable to that of the paper materials used in mailing.

Because a positive FIT or CTC typically triggers a diagnostic colonoscopy, the researchers built a Markov model projecting outcomes over a 10-year horizon rather than relying on single-test comparisons alone. Still, FIT-based screening demonstrated the greatest advantage, producing 33.9 kgCO₂e with 0.28 DALYs lost over 10 years compared with 41.7 kgCO₂e and 0.34 DALYs lost for colonoscopy and 64.2 kgCO₂e and 0.52 DALYs lost for CTC.

The researchers explained that FITs came out on top because they are the only screening tests that patients can complete without traveling to a health care facility. At the population level, prioritizing FITs by transitioning to 80% FIT-based screening in the US could result in 5.2 million DALYs gained over 10 years, they estimated. In addition, transitioning to electric vehicles (EVs) could reduce the environmental impact of all screening tests by 15% to 20%, with the modeled effect varying according to the extent of EV adoption.

Study Limitations and Implications for Sustainable CRC Screening

The authors acknowledged their study’s limitations, including that it was a single-center assessment, which limits the generalizability of their findings. They also noted that transportation-related impact will vary by geography, likely being worse in rural areas with less connectivity and better in cities with public transportation. Still, the researchers used their findings to make suggestions for future CRC screening methods, emphasizing that FITs are likely more environmentally sustainable than colonoscopies or CTCs.

“Given the similar efficacy and safety of these tests, payers and clinicians should favor FITs for those at low risk for CRC,” they concluded. “Efforts to decarbonize transportation and electric grids, incentivize telehealth, and mandate environmental product declarations and sustainable product design will help curb the unintended harms of health care and promote the health of current and future generations worldwide.”

References

1. Rudrapatna VA, Wang TA, Vazirnia P, et al. Comparative environmental impact analysis of screening tests for colorectal cancer: a single-centre life cycle assessment. BMJ Public Health. 2026;4:e004862. doi:10.1136/bmjph-2025-004862
2. US Preventive Services Task Force, Davidson KW, Barry MJ, et al. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. JAMA. 2021;325(19):1965-1977. doi:10.1001/jama.2021.6238