Recreational and occupational field exposure to freshwater cyanobacteria – a review of anecdotal and case reports, epidemiological studies and the challenges for epidemiologic assessment

Table 2 Summary of epidemiological studies investigating recreational exposure to cyanobacteria

Country; year study conducted; study author/s; reference	Study design	Main outcomes reported	Study size (n)	Odds ratio (95% confidence interval)
UK, 1990 Philipp [86]	Cross-sectional	No statistically significant findings	246
UK, 1990 Philipp & Bates [87]	Cross-sectional	No statistically significant findings	363
UK, 1990 Philipp et al [88]	Cross-sectional	No statistically significant findings	246
Australia, 1992 El Saadi et al [89]	Case-control	No statistically significant findings	Approx. 48 (subjects reporting recreational exposure)
Australia, 1995 Pilotto et al [90]	Prospective cohort	Increased symptoms at 7 days following exposure to more than 5,000 cyanobacterial cells/mL for >1 hour vs non-bathers	852 (total) 338 (no prior exposure or symptoms)	1.3 (0.7–2.6) 3.4 (1.1–10.8)
Australia & USA, 1999–2002 Stewart et al [91]	Prospective cohort	Increased reporting of mild respiratory symptoms and any symptom at 3 days following exposure to cyanobacteria cell surface area >12 mm²/mL vs <2.4 mm²/mL	1,331 (total) 1,137 (no prior symptoms) 1,149 (no prior respiratory symptoms)	1.7 (1.0–2.9) (any symptom) 2.1 (1.1–4.0) (respiratory symptoms)