Impact of Red Tides on Human Health in the Philippines

Case Study: Impact of Red Tides on Human Health in the Philippines

Group 8, ABM 11-Q

CHOMI, Samantha S.
FERRER, Angela Mikaella B.
TAJONERA, Justine Nicole Y.
TOLENTINO, Rachel Marie R.

CHAPTER I: ABSTRACT

Many of the red tides that occur in the Philippines are caused by the toxic, Karenia brevis which then produce brevetoxins. These toxins from the K. brevis blooms are mainly responsible for the rise in human health problems (Asai et al., 1982). Two distinct clinical entities are associated with the exposure to the brevetoxins, depending on the route of the exposure – through ingestion or inhalation. As explained by Daniel Baden et al, (1995), the ingestion of brevetoxin-contaminated shellfish may result to gastroenteritis with neurologic symptoms, paralysis or death. On the other hand, with the inhalation of the toxins from the sea spray, there is a high possibility for respiratory irritation in both mammals and humans to occur.Despite many years of community efforts, the processes of initiation, maintenance and eradication of red tide cases and human health problems brought with these are still poorly understood by many. This study aims to review possible human health effects of red tides and further investigate on ways to lessen its impact on coastal areas, mammals and especially humans. Discussions about the factors affecting this phenomenon were also done to properly relate these to the rise of human health problems here in the Philippines.

Keywords: brevetoxins, ingestion, inhalation

CHAPTER II: INTRODUCTION

Only few people – most of which are the scientists and the experts – know the science behind the natural phenomenon, red tide. Presented in this chapter is its definition, an explanation on how it is formed and an overview of its effects, particularly on human health.

1. Red Tide

The Philippine archipelago has its beauty and wonders presently stored in 7,641 islands but just like any other place on Earth, Philippines have its own facets disrupting the productivity of its marine life. One of which is the continuous outbreaks of the red tide phenomenon. Although often heard in news, not everyone knows what red tides really are, where they came from and what effects they have in human health.

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Figure 1. Harmful Algal Bloom/ Red Tide Occurrence in the Sea

Algal blooms cause red tide to occur in the ocean. Discoloration of coastal water is evident due to the numerous algae present.

Source: http://breakthroughstoday.blogspot.com/2010/12/toxins-in-red.html

1. Causes of Red Tide

Red tide is a global occurrence caused by algal blooms during which algae becomes so numerous that they discolor coastal waters. Warm ocean temperatures, calm high nutrient content seas, low salinity and during summer months; rain followed by sunny days are major factors influencing red tide to occur (Bruckner, 2017). As explained by Staugler (2013), the rise in ocean temperature and high nutrient content help the explosive growth of dinoflagellates because heat lets them reproduce very quickly through cell division. To strengthen this fact, Florida Fish and Wildlife Conservation Commission said that harmful algal blooms do not tolerate high salinities in order to maintain their water and salt balance and successfully reproduce. In addition to that, algae that are linked to red tide have the tendency to spread out and be carried wide range and long distances by winds, currents, storms or ships.

1. Effects of Red Tide

When simple plants living in the sea or freshwater grow out of control, they are most likely to produce toxins that are explained to be responsible for the mass mortality of beaucoup marine species such as fish, shellfish, marine mammals and birds. Moreover, this widespread death is what causes the water to change into different colors such as different shades of red, brown or even black depending on the bloom’s cell concentration (Tacio, 2011).

Aside from the fact that red tides greatly contribute to the declining population of marine species, it also put human health in danger. According to Howard Seliger (1989), a marine scientist, in his book Biology, Epidemiology and Management of Pyrodinium Red Tide, red tide is triggered by the increased nutrients in coastal currents. More nutrients are entering coastal waters due to increased charge of industrial and human wastes into waterways and decreased natural filtering due to deforestation. To bolster this idea, much waste becomes conducive to the growth of microorganisms that deplete the oxygen; this then is eaten by the shellfishes and causes red tide incidences. This phenomenon does not just pose great risk to the economic livelihood of people in coastal areas but let human health problems arise.

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Figure 2. Devastating Effects of Red Tide: Large Fish Kills

One of the environmental effects of red tide is fish kills wherein large amount of dead fishes can be seen floating on coastal waters.
Source: https://start1.org/red-tide/effects/

CHAPTER III: RISKS INVOLVED

This chapter covers the reports in the Philippines regarding the effects of red tides on human health and also in the country’s economy. Cases and risks such as mortality of marine organisms, human poisoning, paralysis and death due to red tide outbreaks are stated under this chapter.

1. Harmful Algal Bloom

"Red tide" is a widespread and commonly used term for a harmful algal bloom. The harmful toxins releasedare Alexandriumfundyense, Alexandriumcatenella, and Karenia brevis (Bruckner, 2017). Karenia brevis has brevetoxin. Brevetoxin affects the nerves. It also affects gills of the fish which causes them to die. One of the few toxins that can become an aerosol is Brevetoxin. It causes upper respiratory irritation with symptoms like a cold, immediately on exposure or inhalation (Mitchell, 2017).

1. Reported Occurrences of Red Tide

Even before the occurrence of agricultural run-off, current observations of global warming and pollution, for centuries, red tide appears to have occurred in many locations. When a person consumes mollusks containing toxic dinoflagellates, Paralytic Shellfish Poisoning develops and occurs. The person could suffer neurological and/or gastrointestinal manifestations. In the early 1980s to early 2000s, a total of 42 toxic outbreaks have resulted to a total of 2,107 paralytic shellfish poisoning cases with 117 deaths. Today, a total of 20 coastal areas are affected. While in the Manila Bay, 38,500 fisher folks were removed from their jobs due to the red tide scare during the 1992 Pyrodinium red tide outbreak (Water Environment Partnership in Asia, 2003). Last April 7, 2017, a red tide outbreak occurred in the waters of the coastal towns Bolinao and Anda in Pangasinan province. The BFAR, Bureau of Fisheries and Aquatic Resources, said that all types of shellfish and Acetes sp. (alamang) gathered from red tide-hit areas were not fit for consumption (Sotelo, 2017). Brand and Compton (2007) recorded the occurrence of red tides around the world between the years 1954-1963 and 1994-2002, it showed that the occurrence of red tides had increased by 13 to 18 times and somehow they also appear more frequently.

1. Economical, Environmental and Health Effects

After these reported red tide outbreaks, consequences were faced by the residences around the coastal areas and consumers of contaminated seafood, particularly shellfish.  A lot suffered from various types of gastrointestinal, respiratory, and neurological disorders and worse, death. These outbreaks can also have an economic impact such as; coastal communities that rely heavily on tourism can lose millions when dead fish wash up on beaches, tourists fall ill, when fisher folks lost their jobs due to the outbreak last 1992 had an economic loss.  The clinical features of red tide poisoning in the Philippines included gastro-intestinal and neurological features with deaths secondary to ventilator failure. In both humans and mammals, the inhalation of aerosolized red tide toxins from sea sprays, respiratory irritation and other health effects are reported. Mortality ranged from 0% to 12% in the different red tide episodes (Hartigan-Go and Bateman, 1994). Reports suggest that red tide occurrence and toxins associated with it may have a greater health impact and effect on local populations than formerly measured. This makes brevetoxin (toxins generated by the marine dinoflagellates) not only an important issue related to food poisoning but an environmental and occupational hazard as well. Mass impact on the marine species is caused by the presence of the algal bloom. Through the depletion of oxygen, the dense red tide kills shellfish and other invertebrates. Thus, making fish kills very common. Fish are harmed the same way brevetoxin affects the human nervous system.

1. Paralytic Shellfish Poisoning

Due to the said red tide occurrences, there had been reported cases of PSP. Paralytic shellfish poisoning (PSP) is a serious illness. It is caused by eating shellfish contaminated with dinoflagellate algae that produce harmful toxins. Some of the toxins are 1,000 times more potent and compulsive compared to cyanide. The toxin levels contained in a single shellfish can be very fatal to humans (World Health Organization Geneva, 1984). PSP toxins can cause paralysis in humans. It blocks sodium channels in neurons which results to preventing neurons from functioning normally.