The carbon footprint of pathology testing.

OBJECTIVES: To estimate the carbon footprint of five common hospital pathology tests: full blood examination; urea and electrolyte levels; coagulation profile; C-reactive protein concentration; and arterial blood gases. DESIGN,
SETTING: Prospective life cycle assessment of five pathology tests in two university-affiliated health services in Melbourne. We included all consumables and associated waste for venepuncture and laboratory analyses, and electricity and water use for laboratory analyses. MAIN OUTCOME MEASURE: Greenhouse gas footprint, measured in carbon dioxide equivalent (CO2 e) emissions.
RESULTS: CO2 e emissions for haematology tests were 82 g/test (95% CI, 73-91 g/test) for coagulation profile and 116 g/test (95% CI, 101-135 g/test) for full blood examination. CO2 e emissions for biochemical tests were 0.5 g/test CO2 e (95% CI, 0.4-0.6 g/test) for C-reactive protein (low because typically ordered with urea and electrolyte assessment), 49 g/test (95% CI, 45-53 g/test) for arterial blood gas assessment, and 99 g/test (95% CI, 84-113 g/test) for urea and electrolyte assessment. Most CO2 e emissions were associated with sample collection (range, 60% for full blood examination to 95% for coagulation profile); emissions attributable to laboratory reagents and power use were much smaller.
CONCLUSION: The carbon footprint of common pathology tests was dominated by those of sample collection and phlebotomy. Although the carbon footprints were small, millions of tests are performed each year in Australia, and reducing unnecessary testing will be the most effective approach to reducing the carbon footprint of pathology. Together with the detrimental health and economic effects of unnecessary testing, our environmental findings should further motivate clinicians to test wisely.