Bioaccumulation - Sailors for the Sea


By: | May 1, 2010

Are we poisoning ourselves? Can we reverse our course?Throughout the food chain, bioaccumulation – the process by which contaminants such as mercury, arsenic, PCBs, etc. concentrate and magnify as it moves up the chain – is a threat to all species.

Specifically within our ocean environments, as with most ocean pollution, first affected are the littlest of creatures (the phytoplankton). Due to their small size, the amount of pollution absorbed by the phytoplankton is concomitantly small, but when a zooplankton gobbles up 10 of these guys suddenly the pollution swells 10 fold as it rests in the zooplankton’s body. Then, along comes a smelt or a perch which eats 10 zooplankton; the fish now has 100 times the toxic pollution as the tiny phytoplankton. This continues through to sharks, whales, eagles, polar bears, and humans. Finally, the most devastatingly affected are the breast-fed infants who receive the highest dose of all. The bottom line: bioaccumulation affects the entire world ecosystem from oceans to humans. While it is unclear if this trend can be reversed, there are certainly ways to slow its course, some as simple as remaining mindful of the amount of fish you eat.

But where do these toxics come from?

The short answer: each of us. Staggering amounts of plastic debris make its way into our oceans (Algalita Marine Research Foundation puts the figure at over 100 million tons). This debris enters our seas through direct or indirect means -from our homes, offices, schools, boats, movie theaters, gyms, cars and our modern lifestyle right into our waters. This toxic dreck is rife with chemical additives and plasticizers, which, over time, leach into the water with as much vigor as if poured straight in from a tanker. Add to that the centuries of industrial waste dumping that has found its way into our rivers and streams. While there are legal curbs that limit such practice today, an agreed upon universal standard for effective ‘clean’ monitoring systems or measurements is still needed. Finally, one must consider the role of the individual citizen-improperly dumped hazardous waste, chemical-based pharmaceuticals (antibiotics, anti-depressants, hormones, etc.) excreted into the waste stream, overuse of pesticides and herbicides, etc.-to understand fully the causes for the skyrocketing rates of absorption and bioaccumulation.

In 2001, the Centers for Disease Control and Prevention began an “ongoing assessment of the exposure of the U.S. population to environmental chemicals using biomonitoring.” In their Second National Report on Human Exposure to Environmental Chemicals, released in 2003, blood and urine samples collected from the 2,500 participants showed traces of mercury, lead, uranium, dioxins, PCBs, pesticides, herbicides, phytoestrogens and cotinine (a by-product of nicotine). While the third study, released in 2005, found declining levels of some chemicals (blood lead levels in children), exposure to many contaminants persists, and first-time exposure of others (such as widely used synthetic insecticides) has increased.

The Human Food Web

While the Environmental Protection Agency (EPA) agrees that bioaccumulation has integrated itself into the human food web, various schools of thought exist on the dangers this build-up poses to our bodies. Some believe it results in malfunctions of the liver, kidneys, circulatory system, nervous system, and may even contribute to some cancers; others note that the human body is an effective filter capable of handling harmful chemicals and, therefore we should not worry. The truth is scientists do not yet know the long-term effects of these toxics or at what levels irreversible damage occurs. Moreover, it may well be years before conclusive answers are found, as an estimated 75,000 chemicals requiring further research exist in the United States alone.

Knowledge, education, and action are vital to slowing this trend. As humans, we sit at the top of the food chain, and those droplets of toxics in plankton can be quite substantial by the time we ingest them. With this in mind, one should make thoughtful decisions about the types and quantity of seafood consumed. Local health boards provide suggested levels of consumption based upon age, gender, and locale. The EPA link below provides information on a state-by-state basis. It is also important to take preventative measures to reduce the amount of pollution that might find its way in our water system by properly disposing of hazardous waste, using phosphate-free cleaners, and avoiding pesticides. For more suggestions, see our Ocean Trash essay and our Non Point Source Pollution essay. Careful, simple choices made in the grocery store, at restaurants, in our cars and boats, and at home can provide long-term benefits for generations to come, while improving the health of the fish and animals in our grand ecosystem, and possibly reinvigorate our troubled waters.

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