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Health effects associated with cyanobacteria exposure among beach attendees in Puerto Rico
Citation:
Hilborn, E, C. Lin, E. Sams, A. Chapman, A. Dufour, AND Tim Wade. Health effects associated with cyanobacteria exposure among beach attendees in Puerto Rico. Presented at International Conference on Toxic Cyanobacteria, Johannesburg, SOUTH AFRICA, August 11 - 16, 2013.
Impact/Purpose:
Cyanobacteria and their toxins occur in surface waters worldwide. They may be associated with taste and odor problems in drinking water and have been included in the EPA’s Contaminant Candidate List. They may also contaminate recreational water. This work represents an additional analysis of beach goer health data from a previous EPA field study and now evaluates these health effects in association with low concentrations of cyanobacteria in marine bathing waters. This is the first study to evaluate the health effects associated with low concentrations of cyanobacteria in marine waters.
Description:
Cyanobacteria and their toxins are associated with adverse human health effects, although among marine waters, the pyrrhophyta, including dinoflagellates are more recognized as health hazards. We recruited beach attendees during summer 2009, at Boquerón Beach, Puerto Rico; a locally popular beach. During the day of beach attendance, interviews were conducted and water samples in the swimming area were collected. Samples were analyzed for phytoplankton (counts); lyngbyatoxin and debromoaplysiatoxin (HPLC/MS) and indicators of fecal contamination including enterococci (EPA Method 1600). Interviews were performed 10 – 12 days later and focused on attendee health and development of new symptoms. We used Pearson’s Chi-squared test for the frequency of beach-goers reporting health effects by water contact and phytoplankton exposure levels. Fifteen thousand six hundred ten individuals were included in the analysis. Daily cyanobacteria cell count (cell count) median was 132 cells/mL, range (0 – 1461). Pyrrhophyta counts were low; 0.2 – 106 cells/mL; enterococci CFU were all <35/100mL. Toxin concentrations were below the limit of detection. Cell counts were categorized as: low (<37 cells/mL), medium (37 – 237 cells /mL) and high (>237 cells/mL) . Of the 2995 (19%) persons who reported no water contact, the frequency of respiratory illness (ARI) was 6%, and rash/itchy skin (rash) was 3%; significantly lower compared to those with body immersion, ARI - 7%; rash - 5% (p<0.05). When persons who reported body immersion were evaluated by cell count category, ARI, eye problems and rash frequency were significantly higher among those exposed to higher cell counts. These statistically significant increases in illness frequency were not observed with enterococci or higher pyrrhophyta cell counts. We report a higher frequency of ARI, eye problems and rash among swimmers exposed to higher cell counts. Overall, cell counts were low and did not approach ‘bloom’ status. Increased frequency of illness was not associated with toxins, enterococci, or pyrrhophyta. This is the first study to identify health effects associated with low cyanobacteria cell counts in marine water. This is an abstract of a proposed presentation and does not necessarily represent EPA policy.