What is the Difference Between Bioaccumulation and Biomagnification?

In environmental circles, many people confuse the terms bioaccumulatiion and biomagnification. These words are encountered when dealing with issues concerning the gradual build-up of toxic substances in the bodies of organisms; ultimately, in the human body. A certain threshold level will, through time, be reached where some disorder or illness is manifested.

A classic example is the case of mercury dumped into the bay of Minamata in Japan. Nobody knew about the idea of bioaccumulation until it was discovered that gradual ingestion of toxic substances can result to illness and even death.

Bioaccumulation vs. Biomagnification

How is bioaccumulation differentiated from biomagnification? Are these two concepts similar?

1. Bioaccumulation

Bioaccumulation is defined as the increase in concentration of a substance(s) in an organism or a part of that organism.Toxic substances are lipophilic or fat-loving, the reason why these substances are deposited and concentrated in the fat tissues of the organisms. The affected organism has a higher concentration of the substance than the concentration in the organism’s surrounding environment. The toxic substances are very slowly metabolized or excreted so if the organism keeps on consuming prey or food contaminated with toxic substances, the concentration of the substance will further increase in its body, hence, bioaccumulation results. When a certain threshold level is reached, measured in parts per million (ppm), symptoms due to the type of toxin are manifested.

Examples of toxic substances that bioaccumulate are lead, mercury, dichlorodiethyltrichloroethane (DDT), among others (see Reasons Why Used Oil Should Not Be Disposed Of Into the Drain). Lead exposure can be serious for young children because their growing bodies absorb lead more easily than adults. They are more susceptible to its harmful effects. Even low level of lead exposure can harm the intellectual development, behaviour, growth, and hearing of infants. High concentrations of lead in pregnant mothers can cause miscarriages and stillbirths. Mercury, as mentioned above, can cause paralysis. DDT at concentration above 236 mg per kg of body weight, can cause death among humans. Concentration of 6-10 mg/kg leads to such symptoms as headache, nausea, vomiting, confusion, and tremors.

2. Biomagnification

Biomagnification is also called Bioamplification. It is simply the increase in concentration of a substance in a food chain, not an organism. Persistent organic pollutants (POPs) are compounds that biomagnify. Persistent organic pollutants (POPs) are chemical substances that persist in the environment. These substances bioaccumulate through the food web and pose risk not only to humans but also other living organisms because of their adverse effects. These pollutants consists of pesticides (such as DDT), industrial chemicals (such as polychlorinated biphenyls, PCBs) and unintentional by-products of industrial processes (such as dioxins and furans). In essence, biomagnification is similar to bioaccumulation but is descriptive of higher level biological processes, not individual.

Adequate care must therefore be exercised in choosing what to ingest. Foods may be laced with toxic substances that are harmful to the body when consumed in large quantities. It pays to see the labels (see 12 Harmful Ingredients in Power Drinks, Colas, and Artificial Juice Drinks), and be aware of the sources of these toxins.

References

Canada Minister of Health, 2008. Effects of lead on human health. Retrieved on April 21, 2010 at http://www.hc-sc.gc.ca/hl-vs/iyh-vsv/environ/lead-plomb-eng.php#he.

Duke University, n.d. Effects of DDT. Retrieved on April 21, 2010 at http://www.chem.duke.edu/~jds/cruise_chem/pest/effects.html.

Duncan, D. E., 2010. Chemicals within us. Retrieved on April 21, 2010 at http://science.nationalgeographic.com/science/health-and-human-body/human-body/chemicals-within-us.html#page=6.

University of Cincinnati, n.d. Glossary of terms. Retrieved on April 21, 2010 at http://www.eh.uc.edu/growingupfemale/resources_glossary.asp.

Virginia Department of Health, 1999. Biosolids life cycle. Retrieved on April 21, 2010 at http://www.biosolids.state.va.us/research.htm.

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