Swimming in unsuitable water includes topological, bacteriological, and chemical risks. Topological dangers arise from strong currents and site configurations, leading to accidental drownings. Bacteriological risks from harmful microorganisms peak after heavy rains, causing illnesses. Chemical pollution introduces another layer of risk, often poorly monitored. Lastly, algal and parasitic threats can cause adverse health effects post-swim.
Swimming in water not deemed safe for recreational purposes poses several risks categorized primarily as follows:
1. Topological Risks: This risk is affected by site configuration, including water depth, bank structure, and current strength. Such risks can lead to drowning, especially among youth, with around 1,000 drowning deaths annually in France, particularly in rivers and lakes. Strong currents and areas near engineering structures like bridges and dams are particularly hazardous.
2. Bacteriological Risks: Micro-organisms proliferate in water, especially after heavy rainfall which can overwhelm sewage treatment facilities, contaminating surface waters. Fecal coliforms, such as E. coli, can lead to gastroenteritis and are more concentrated after rains. Health agencies monitor water quality, providing crucial data to avoid swimming in contaminated areas.
3. Chemical Risks: Chemical pollution from human activities impacts water quality, with varying effects based on concentration and specific contaminants. While extreme pollution cases lead to severe health issues, such as those reported in China, in France, pollutants like pesticides are typically at low levels. However, a lack of comprehensive monitoring systems complicates the understanding of chemical safety in recreational waters.
4. Algal and Parasite Risks: Hot weather can enhance the multiplication of harmful algae and parasites in stagnant or slow-moving water. Cyanobacterial blooms can cause skin irritation, digestive problems, and serious health consequences. Additionally, bather’s dermatitis, caused by cercarial larvae from certain waterfowl, can occur post-swim in affected areas. These biological risks are compounded by neglecting post-swim hygiene measures.
5. Injury Risks: Beyond biological concerns, risks of injury from submerged hazards like rocks or sudden currents create additional dangers. Water bodies such as gravel pits and quarries are particularly risky due to potential bottom collapses leading to entrapment. Swimmers are advised to exercise caution and assess site features before entering the water.
Original Source: www.lemonde.fr
