Recreational exposure to low concentrations of microcystins during an algal bloom in a small lake.
We measured microcystins in blood from people at risk for swallowing water or inhaling spray while swimming, water skiing, jet skiing, or boating during an algal bloom. We monitored water samples from a small lake as a Microcystis aeruginosa bloom developed. We recruited 97 people planning recreational activities in that lake and seven others who volunteered to recreate in a nearby bloom-free lake. We conducted our field study within a week of finding a 10-microg/L microcystin concentration. We analyzed water, air, and human blood samples for water quality, potential human pathogens, algal taxonomy, and microcystin concentrations. We interviewed study participants for demographic and current health symptom information. Water samples were assayed for potential respiratory viruses (adenoviruses and enteroviruses), but none were detected. We did find low concentrations of Escherichia coli, indicating fecal contamination. We found low levels of microcystins (2 microg/L to 5 microg/L) in the water and (<0.1 ng/m(3)) in the aerosol samples. Blood levels of microcystins for all participants were below the limit of detection (0.147 microg/L). Given this low exposure level, study participants reported no symptom increases following recreational exposure to microcystins. This is the first study to report that water-based recreational activities can expose people to very low concentrations of aerosol-borne microcystins; we recently conducted another field study to assess exposures to higher concentrations of these algal toxins.
Backer
Lorraine C
LC
National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway NE, Chamblee, Georgia 30341, USA. lbacker@cdc.gov
Carmichael
Wayne
W
Kirkpatrick
Barbara
B
Williams
Christopher
C
Irvin
Mitch
M
Zhou
Yue
Y
Johnson
Trisha B
TB
Nierenberg
Kate
K
Hill
Vincent R
VR
Kieszak
Stephanie M
SM
Cheng
Yung-Sung
YS
D000293:Adolescent; D000328:Adult; D000336:Aerosols; D000368:Aged; D002648:Child; D004781:Environmental Exposure / Q000032:analysis*; D004784:Environmental Monitoring; D005068:Eutrophication; D005260:Female; D005618:Fresh Water / Q000382:microbiology*; D006801:Humans; D008297:Male; D052998:Microcystins / Q000008:administration & dosage / Q000097:blood / Q000633:toxicity*; D046931:Microcystis / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism; D008875:Middle Aged; D011634:Public Health; D011998:Recreation; D014481:United States; D014919:Wind; D055815:Young Adult
D000336:Aerosols; D052998:Microcystins