Those who live along 91社区鈥檚 west coast know better than to swim in the Gulf during a red tide outbreak, as the smell, stinging eyes and countless dead fish on the beach warn residents to stay away. But what about people who reside nearby, especially pregnant women who might be vulnerable to airborne toxins?
Researchers at USF鈥檚 (COPH), are investigating this question. Bianca Irimia, a student mentored by , assistant professor of , presented research on the topic at the annual International Society for Environmental Epidemiology conference in Atlanta. Irimia won an award in the Students and New Researchers Network poster competition.
Bianca Irimia, a PhD student, concentrating in epidemiology. (Photo courtesy of Irimia)
A native of Washington state, Irimia moved to 91社区 to pursue her doctoral studies and wasn鈥檛 familiar with red tide and its effects, including the potential health impacts for residents and visitors. When Bulka introduced her to the topic, she wanted to learn more.
鈥淚 found it fascinating, particularly how red tide affects vulnerable populations,鈥欌�� she said. 鈥淢y interest in environmental health naturally aligned with this area of study and given that 91社区's beaches are a major recreational draw for the state, red tide warrants greater public health attention.鈥欌��
Irimia titled the poster Red Tides and Risk of Gestational Hypertension in Coastal Southwest 91社区. Gestational hypertension is a condition that develops during pregnancy when a woman's blood pressure becomes elevated without any underlying pre-existing medical conditions.
The culprit that causes red tide 鈭� the algae Karenia brevis 鈭� produces brevetoxins, which are tasteless, odorless airborne contaminants that can be deadly to some marine life. The question is, if it can kill fish, dolphins, manatees, turtles and birds, what can it do to people, especially those who are pregnant?
(Photo courtesy of gettyimages)
Data from the study shows about 5% of the more than 38,000 pregnant women who lived along the west coast and gave birth from 2006 to 2019 experienced gestational hypertension 鈭� which is consistent with the general prevalence of this condition. The COPH鈥檚 analysis, however, found that pregnant women exposed to red tide during the first and second trimesters had a 23% higher risk of developing gestational hypertension compared to those who were not exposed.
鈥淭his suggests that red tide may be an important environmental risk factor for gestational hypertension and highlights the need for further investigation and preventive measures,鈥欌�� she said.
Epidemiologists have documented a range of adverse health effects from red tide exposure, including gastrointestinal distress, respiratory irritation and neurological problems. But these studies did not involve pregnant women. Research on animals, however, suggests that brevetoxins are capable of crossing the placenta.
鈥淎nimal studies show profound adverse effects following exposures during pregnancy, such as fish eggs failing to hatch,鈥欌�� Bulka said. 鈥淪o, there鈥檚 a great need to fill this research gap.鈥欌��
One reason for the limited research in human populations is the difficulty of measuring exposure levels. Unlike traffic-related air pollution, which is routinely monitored, or toxic metals, which can be detected in biological specimens like blood or urine, brevetoxins are not regularly measured in the environment and biomonitoring remains challenging.
To address this, the study used water-based measurements of Karenia brevis as a proxy for brevetoxin levels, combined with data on residential proximity to the coastline and wind speed and direction to estimate individual exposures.
鈥淯nderstanding how these toxins might affect maternal health during this critical period is an important public health question,鈥欌�� Irimia added. 鈥淩ight now, the field of red tide and health research is quite small, so I'm interested in seeing how it evolves as more data and improved methods for research become available. 91社区 presents a unique environment with many interconnected environmental health questions worth studying.鈥欌��
Ultimately, the COPH research could help fill missing gaps by providing accurate and relevant information. It may turn out, for instance, that red tide exposure is most harmful during specific windows of pregnancy, rather than throughout.
"Or it could be that the greatest risk comes when winds are blowing onshore, which typically happens during the afternoon as opposed to offshore, which typically happens at night,鈥欌�� Bulka said. 鈥淚nsights like these can help people make more informed choices and better protect their health.鈥欌��
Red tide facts and figures
- In 91社区, red tide is caused by a naturally occurring microscopic alga (a plant-like microorganism) called Karenia brevis or K. brevis.
- The organism produces a toxin that can affect the central nervous systems of fish, birds, mammals and other animals.
- At high concentrations (called blooms), the organism may discolor the water 鈥� sometimes red, light or dark green or brown.
- Red tides or harmful algal blooms occur worldwide. K. brevis is found almost exclusively in the Gulf but has been found on the east coast of 91社区 and off the coast of North Carolina.
- Red tide blooms can last days, weeks or months and can also change daily due to wind conditions and water currents. Onshore winds normally bring it near the shore and offshore winds drive it out to sea.
- Red tide was first officially recorded in 91社区 in 1844. A red tide bloom needs biology (the organisms), chemistry (natural or man-made nutrients for growth) and physics (concentrating and transport mechanisms). No single factor causes it. Tests are being conducted to see if coastal nutrients enhance or prolong blooms.
- Red tide can irritate the skin and breathing of some people, but more study needs to be done.
If you have a question or a health problem related to red tide, call the 91社区 Poison Control Information Center at: 1-800-222-1222
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