KARYA TULIS
BIOMAGNIFICATION
Oleh :
RAHMAWATY
DEPARTEMEN KEHUTANAN
FAKULTAS PERTANIAN
KATA PENGANTAR
Puji syukur kami panjatkan kepada Tuhan Yang Maha Esa, yang telah memberikan segala
rahmat dan karunia-Nya sehingga KARYA TULIS berjudul “Biomagnification” ini dapat
diselesaikan.
Tulisan ini merupakan suatu hasil pemikiran yang diharapkan dapat memberikan
informasi kepada pembaca mengenai Biomagnifikasi (definisi, bagaimanan terjadinya, dan
cara pencegahan).
Kami menyadari bahwa karya tulis ini masih jauh dari sempurna, oleh karena itu
kami mengharapkan saran dan kritik yang bersifat membangun untuk lebih
menyempurnakan karya tulis ini. Akhir kata kami ucapkan semoga karya tulis ini dapat
bermanfaat.
Medan, Maret 2010
DAFTAR ISI
I. Introduction 1
A. Background 1
B. Objective of the Paper 2
II. Biomagnification: Definition and History 2
A. Biomanification, Bioaccumulation, and Bioconcentration 2
B. History of Biomagnification 7
III. Biomagnification Occurrence 8
A. Process of Biomagnification 8
B. Chemical can be Occurred biomagnification 10
C. Properties of Biomagnification Chemicals 12
D. Case Examples of Biomagnification 13
1. Biomagnification caused by DDT 13
2. Biomagnification caused by Mercury 15
IV. Prevent of Biomagnification 15
A. Pesticide-Producing Establishments 16
B. FDA Monitoring Program 17
BY: Rahmawaty
I. Introduction A. Background
Ecology is the study of the interaction between organisms and their
environment (Odum, 1971). Ecology is derived from the Greek root “oikos”
meaning “house” combined with the root “logy” meaning “the science of” or “the
study of”. Hence, ecology is the study of the earth’s households including plants,
animal, microorganisms, and people that live together as interdependent
components. The German biologist Ernst Haeckel first defined the word
oekologie in 1866 in the context that we use it today. According to Miller (2006),
the science of ecology is also concerned with the study of the interaction
between organisms. It is also concerned with large environmental chemical
processes like oxygen, nitrogen, and water cycles. Ecology is a new science
which seeks to document and answer questions about connections in the natural
world. Its concepts and ideas can explain the mess that we are now in.
With the knowledge of a small number of ecological concepts one can
explain the causes of the major environmental issues we face today. What
follows are the ecological explanations for six severe environmental problems: 1)
Global Warming, 2) Pollution Poisoning, 3) Extinction, 4) Harmful Non-Indigenous
Species, 5) Habitat Destruction, and 6) Overpopulation. Based on the six
environmental problems above, the main focus of this paper is about pollution
poisoning, especially about biomagnification. It is the one of the environmental
problems/international issue that happened all over the world.
Biomagnification is an important concept in ecology, environmental
science, and ecotoxicology. It says that the solution to certain types of pollution
is not dilution, because food chains will concentrate the pollutant
(http://en.wikipedia.org/wiki/Talk). Because of important to know and understand
about environmental problem, especially biomagnification, this paper will try to
explain about definition, history, process, Chemical can be occurred
biomagnification, properties of biomagnification chemicals, cases of
paper can increase our knowledge and give us the information about
biomagnification.
B. Objectives of the Paper
The aims of this paper is giving information about definition, history,
process, chemical can be occurred biomagnification, properties of
biomagnification chemicals, cases of Biomagnification and how to reduce
biomagnification occurrence.
II. Biomagnification: Definition and History
A. Biomagnification, Bioaccumulation, and Bioconsentration
To understanding about the biomagnification, there were two matters that
also related, namely: bioconsentration and bioaccumulation. Therefore, in this
paper also explained the different between biomagnification with bioconcentration
and bioaccumulation.
1. Biomagnification
There are some definitions about biomagnification. One of the definitions
in Environmental Protection Agency (EPA) glossary (2006), namely:
biomagnification is the increase of tissue accumulation in species higher in the
natural food chain as contaminated food species are eaten. The term
biomagnification refers to the progressive build up of persistent substances by
successive trophic levels, meaning that it relates to the concentration ratio in a
tissue of a predator organism as compared to that in its prey (GreenFacts
Scientific Board, 2006). Wikipedia dictionary also mention about definition of
biomagnification, namely: biomagnification or biological magnification is the
increase in concentration of an element or compound, such as
dichlorodiphenyltrichloroethane (DDT, a type of pesticide) that occurs in a food
chain as a consequence of food chain energetic and lack of or very slow,
excretion or degradation of the substance. Biomagnification describes a process
that results in the accumulation of a chemical in an organism at higher levels than
are found in its food. It occurs when a chemical becomes more and more
single-celled plants and increasingly larger animal species (Extension Toxicology
Network,1993).
Biomagnification is the tendency of pollutants to become concentrated in
successive trophic levels. Often, this is to the detriment of the organisms in which
these materials concentrate, since the pollutants are often toxic. Biomagnification
refers to the tendency of pollutants to concentrate as they move from one tropic
level to the next. Increase in concentration of a pollutant from one link in a food
chain to another. This is a general term applied to the sequence of processes in
an ecosystem by which higher concentrations are attained in organisms of higher
trophic level in the food chain. The process by which xenobiotics increase in body
concentration in organisms through a series of prey-predator relationships from
primary producers to ultimate predators, often human beings. Biomagnification
along a food chain will result in the highest concentrations of a substance being
found at the top of the food chain (Maritta College, 2006).
Biomagnification is the bioaccumulation of a substance up the food chain by
transfer of residues of the substance in smaller organisms that are food for larger
organisms in the chain. It generally refers to the sequence of processes that result in
higher concentrations in organisms at higher levels in the food chain (at higher tropic
levels) (Fig. 1 and Fig. 2). These processes result in an organism having higher
concentrations of a substance than is present in the organism’s food. Biomagnification
can result in higher concentrations of the substance than would be expected if water were
the only exposure mechanism. Accumulation of a substance only through contact with
water is known as bioconcentration.
Source: Is Mercury the Achilles Heel of the Restoration Effort?, South Florida Restoration Science Forum
(http://toxics.usgs.gov/definitions/biomagnification.html).
Fig 1. A hypothetical example of the biomagnification of mercury in water up through the food chain and into a wading bird's eggs.
Source: Ecological and Environmental Learning Services (2006) (http://www.eelsinc.org/id62.html)
B. Bioaccumulation
An important process through which chemicals can affect living organisms
is bioaccumulation. Bioaccumulation means an increase in the concentration of a
chemical in a biological organism over time, compared to the chemical's
concentration in the environment. Compounds accumulate in living things any
time they are taken up and stored faster than they are broken down
(metabolized) or excreted. Understanding the dynamic process of
bioaccumulation is very important in protecting human beings and other
organisms from the adverse effects of chemical exposure, and it has become a
critical consideration in the regulation of chemicals (Extension Toxicology
Network, 1993). Bioaccumulation is a process where chemicals are retained in
fatty body tissue and increase in concentration over time.
(http://www.epa.gov/pesticides/glossary/).
Bioaccumulation refers to how pollutants enter a food chain; is increase in concentration of a pollutant from the
environment to the first organism in a food chain. The accumulation of a
chemical in tissues of an organism to levels greater than in the surrounding
medium. Accumulation may take place by breathing, swallowing or dermal
contact (Marietta College, 2006).
Bioaccumulation is a general term for the accumulation of substances,
such as pesticides (DDT is an example), methylmercury, or other organic
chemicals in an organism or part of an organism. The accumulation process
involves the biological sequestering of substances that enter the organism
through respiration, food intake, epidermal (skin) contact with the substance,
and/or other means. The sequestering results in the organism having a higher
concentration of the substance than the concentration in the organism’s
surrounding environment. The level at which a given substance is
bioaccumulated depends on the rate of uptake, the mode of uptake (through the
gills of a fish, ingested along with food, contact with epidermis (skin)), how
quickly the substance is eliminated from the organism, transformation of the
substance by metabolic processes, the lipid (fat) content of the organism, the
hydrophobicity of the substance, environmental factors, and other biological and
physical factors. As a general rule the more hydrophobic a substance is the more
likely it is to bioaccumulate in organisms, such as fish.
Bioaccumulation is the term bioaccumulation refers to the net
accumulation over time of metals [or other persistent substances] within an
organism from both biotic (other organisms) and abiotic (soil, air, and water)
sources (Fig. 3). (
http://www.greenfacts.org/glossary/abc/bioaccumulation-bioaccumulate.htm)
Source: Wisconsin Department of Natural Resources ( http://www.greenfacts.org/glossary/abc/bioaccumulation-bioaccumulate.htm)
Fig. 3. An example of the Bioaccumulation
C. Bioconcentration
Bioconcentration is the specific bioaccumulation process by which the
concentration of a chemical in an organism becomes higher than its
concentration in the air or water around the organism. Although the process is
the same for both natural and manmade chemicals, the term bio-concentration
usually refers to chemicals foreign to the organism. For fish and other aquatic
animals, bioconcentration after uptake through the gills (or sometimes the skin) is
usually the most important bioaccumulation process (Extension Toxicology
Network, 1993).
Bioconcentration differs from bioaccumulation because it refers only to the
uptake of substances into the organism from water alone. Bioaccumulation is the
more general term because it includes all means of uptake into the organism.
Though sometimes used interchangeably with 'bioaccumulation,' an important
distinction is drawn between the two. Bioaccumulation occurs within a tropic
level, and is the increase in concentration of a substance in an individual's
Bioconcentration is defined as occurring when uptake from the water is greater
than excretion (Landrum and Fisher, 1999). Thus bioconcentration and
bioaccumulation occur within an organism, and biomagnification occurs across
tropic (food chain) levels (http://en.wikipedia.org/wiki/Talk).
B. History of Biomagnification
According to the ISI Science Citation Index, the first use of the term in the
title of a peer-reviewed article was in Johnson & Kennedy (1973). However, the
concept traces back to Rachel Carson's book, Silent Spring, published in 1962. In
Chapter 3 of Silent Spring, he describes the process but does not name it as
biological magnification. Interestingly, she focuses on terrestrial systems, but
most research has been done in aquatic systems. Carson drew attention to the
issue, and other ecologists and toxicologists examined its occurrence in many
systems. As DDT, PCBs, mercury, and other substances were found through the
1970s to occur at strikingly high concentrations in the upper reaches of food
chains, the concept of biomagnification of lipophilic substances became firmly
established. It is presented in most introductory ecology and environmental
science texts.
However, by the 1990s, some researchers began to question the roles of
bioaccumulation versus biomagnification. For one thing, tissue concentrations of
substances did not always increase uniformly with the tropic level (Landrum and
Fisher, 1999). LeBlanc (1995) proposed that what is really bioaccumulation to
different degrees is mistaken as biomagnification, because:
• Lipid contents of organisms increase with the tropic level
• Elimination efficiency of the substances decreases with tropic level
(because the larger organisms have relatively less surface area to
process and excrete substances, for their body size).
Thus the pattern of increased tissue concentration with higher tropic levels could
be due to these differences in bioaccumulation. However, this proposal was
based on rather limited data.
In 1990, Rasmussen et al. compared PCB levels in lake trout sampled
from lakes with different numbers of tropic levels. Inputs to these lakes were
small and relatively constant. The shorter the food chain in the lake, the lower the
concentration of PCBs in the tissue of trout, which feed at the top of the chain (at
occurs. Additionally, they noted that the amount of PCB in tissues increased 3.5
times per tropic level, but the amount of lipids as a proportion of tissues
increases much less, only 1.5 times per tropic level (Rasmussen et al., 1990).
III. Biomagnification Occurrence
A.
Process of BiomagnificationAccording to Miller (2006), the chemicals that enter the biosphere of living
systems as a result of industrial processes are not all beneficial or natural.
Plants for instance, need carbon and nitrogen, but there are many things that we
have introduced into the world through industrial processes that are harmful to
ourselves and other living creatures. We have produced dangerous chemicals
that enter living systems and accumulate through the process of
biomagnification, an increase in concentrations in living tissue as one travels up
the food chain. Plants (organisms that can photosynthesize, thereby gaining
energy from sunlight) are consumed higher up the food chain by animals that
cannot photosynthesize, and animals higher up the chain then eat these animals.
At the top of the chain is the apex predator that serves as an indicator species for
the whole ecosystem: an interactive collection of numerous creatures. Food webs
are more complicated than food chains in that the relationships are not linear, but
rather a collection of many interconnections of food chains. The creatures that
eat photosynthesizing bacteria may be eaten by many creatures, but these
critters may also help in the digestion of larger animals which are connected in
webs of relationships rather than a linear chain upwards.
Pollution enters these webs and chains at all levels and the
concentrations increase up the many chains, until it could pose a threat to the
animals at the top of the chain. Human society is often at the top of the food
chain. The animals we eat can potentially pollute us. We have learned that what
we have polluted the environment with can wind up on our dinner plate due to
biomagnification. These pollutants can cause problems and cancer in human
beings as well as creatures in the wild. For example, DDT had a deleterious
effect on brown pelicans by interfering with the production of their eggs, which
were too thin to incubate their young. When the use of DDT was diminished the
brown pelicans made a recovery.
Pollution is also one of the factors that lead to the demise of wildlife
dangerous chemicals. We need to wash the fruit we find at the supermarket
because of pesticides that are used to deter insects that would eat what we grow.
Birds eat these poisoned insects and are poisoned. Excess pesticides wind up in
oceanic and riparian (river system) ecosystems, flowing downstream. Pollutants
have also been dumped into bodies of water resulting in a poisonous harvest. We
as well as the other organisms depend upon these complicated cycles. When
they are disturbed things disappear.
According to Marietta College (2006), the first step in biomagnification; the
pollutant is at a higher concentration inside the producer than it is in the
environment. biomagnification occurs when organisms at the bottom of the food
chain concentrate the material above its concentration in the surrounding soil or
water. Producers, as we saw earlier, take in inorganic nutrients from their
surroundings. Since a lack of these nutrients can limit the growth of the producer,
producers will go to great lengths to obtain the nutrients. They will spend
considerable energy to pump them into their bodies. They will even take up more
than they need immediately and store it, since they can't be "sure" of when the
nutrient will be available again (of course, plants don't think about such things,
but, as it turns out, those plants, which, for whatever reason, tended to
concentrate inorganic nutrients have done better over the years). The problem
comes up when a pollutant, such as DDT or mercury, is present in the
environment. Chemically, these pollutants resemble essential inorganic nutrients
and are brought into the producer's body and stored "by mistake".
The second stage of biomagnification occurs when the producer is eaten.
Remember from our discussion of a pyramid of biomass that relatively little
energy is available from one tropic level to the next. This means that a consumer
(of any level) has to consume a lot of biomass from the lower tropic level. If that
biomass contains the pollutant, the pollutant will be taken up in large quantities
by the consumer. Pollutants that biomagnified have another characteristic. Not
only are they taken up by the producers, but they are absorbed and stored in the
bodies of the consumers. This often occurs with pollutants soluble in fat such as
DDT or PCB's. These materials are digested from the producer and move into
the fat of the consumer. If the consumer is caught and eaten, its fat is digested
and the pollutant moves to the fat of the new consumer. In this way, the pollutant
builds up in the fatty tissues of the consumers. Water-soluble pollutants usually
of the consumer. Since every organism loses water to the environment, as the
water is lost the pollutant would leave as well. Alas, fat simply does not leave the
body (Marietta College, 2006).
B. Chemical can be Occurred Biomagnification
In a review of a large number of studies, Suedel et al (1994) concluded
that although biomagnification is probably more limited in occurrence than
previously thought, there is good evidence that DDT, DDE, PCBs, toxaphene,
and the organic forms of mercury and arsenic do biomagnify in nature. For other
contaminants, bioconcentration and bioaccumulation account for their high
concentrations in organism tissues. More recently, Gray (2002) reached a similar
conclusion. However, even this study was criticized by Fisk et al., (2003) for
ignoring many relevant studies. Such criticisms are spurring researchers to study
carefully all pathways, and Croteau et al. (2005) recently added Cadmium to the
list of biomagnifying metals.
(
http://en.wikipedia.org/wiki/).There are two main groups of substances that biomagnify. Both are
lipophilic and not easily degraded. Novel organic substances are not easily
degraded because organisms lack previous exposure and have thus not evolved
specific detoxification and excretion mechanisms, as there has been no selection
pressure from them. These substances are consequently known as Persistent
Organic Pollutants' or POPs. Persistent organic pollutants (POPs) are those
chemicals that are not materially broken down over a reasonable period of time,
usually measured in decades or more. The POPs of most concern are those that
build up in the environment or are bioaccumulated and/or biomagnified in the
food chain. The realization and importance of persistent environmental chemicals
was first identified in the early 1960s with the publication of Rachel Carson's
seminal work, Silent Spring. Carson wrote of the buildup of pesticides in birds
and hypothesized that this came from direct and indirect (food chain) exposure.
The magnitude of effect from Carson's work can be appreciated when one
considers the breadth of environmental health sciences today and the
international environmental regulations that have been promulgated.
The chemical characteristics of POPs are relatively similar. Many are
polyhalogenated aromatic hydrocarbons (PHAHs), or other polycyclic aromatic
hydrocarbons (PAHs) that are very slowly metabolized or otherwise degraded.
animals, and they build up in the food chain. Some classic examples of POPs are
the pesticides DDT, Dieldrin, Aldrin, Heptachlor, Mirex, and Kepone. Another
group of POPs are the chlorodibenzodioxins, dibenzofurans, and some PCBs.
The pesticides were widely used for several years but eventually discontinued for
toxicological and ecological reasons. Because of their lipid solubility, the
chlorinated compounds are retained and accumulated in the lipids of insects and
other invertebrates that are part of the food chain of higher-order predators, and
they can eventually end up in the diets of humans and feed animals. Several of
these compounds can be sequestered in soil and sediment, such as the PCBs in
the Hudson River bottom sediment, where they can exist for decades.
The health effects of these chemicals, as neat compounds, have been
very well studied. However, low-dose, lifetime exposure studies are lacking.
Many of the organochlorine pesticides cited above are carcinogenic, teratogenic,
and neurotoxic. The dioxins and benzofurans are highly toxic and are extremely
persistent in the human body as well as the environment. Several of the POPs,
including DDT and its metabolites, PCBs, dioxins, and some chlorobenzene, can
be detected in human body fat and serum years after any known exposures.
Lindane (hexachlorocyclohexane), which was used for the treatment of body lice
and as a broad-spectrum insecticide, resulted in very high tissue levels, and in
many cases caused acute deaths when used improperly. Lindane and some of
its isomers have been identified in market-basket surveys and in human fat
samples.
Novel organic substances are DDT, PCBs, and Toxaphene and Inorganic
substances are Mercury, Arsenic, and Cadmium. DDT is a colorless contact
insecticide, C14H9Cl5, toxic to humans and animals when swallowed or absorbed
through the skin. It has been banned in the United States for most uses since
1972.A colorless insecticide that kills on contact. It is poisonous to humans and
animals when swallowed or absorbed through the skin. DDT is an abbreviation
for dichlorodiphenyltrichloroethane. Although DDT, when it was first invented,
was considered a great advance in protecting crops from insect damage and in
combating diseases spread by insects, recent discoveries have led to its ban in
many countries. Residue from DDT has been shown to remain in the ecosystem
and the food chain long after its original use, causing harm and even death to
animals considered harmless or useful to man
According to Marietta College (2006), not only DDT is toxin to biomagnify,
but also all of the following have the potential to biomagnify (Table 1).
Table 1. List of Chemical which has Potential to Biomagnify.
Substance Use and Problems Links
PCB's
polychlorinated biphenyls
• insulators in transformers
• plasticizer
• fire retardant
• biomagnifies
• impairs reproduction
• widespread in aquatic systems
• as airborne contaminants
• mercury from gold mining
• many from metal processing
• may affect nervous system
• may affect reproduction
• from an interesting student project
• heavy metals in the
Mississippi River - great source!
C. Properties of Biomagnification Chemicals
In order for biomagnification to occur, the pollutant must be: 1) long-lived,
2) mobile, 3) soluble in fats, and 4) biologically active. If a pollutant is short-lived,
it will be broken down before it can become dangerous. If it is not mobile, it will
stay in one place and is unlikely to be taken up by organisms. If the pollutant is
soluble in water it will be excreted by the organism. Pollutants that dissolve in
fats, however, may be retained for a long time. It is traditional to measure the
amount of pollutants in fatty tissues of organisms such as fish. In mammals, we
often test the milk produced by females, since the milk has a lot of fat in it and
(poisons). If a pollutant is not active biologically, it may biomagnify, but we really
don't worry about it much, since it probably won't cause any problems (Marietta
College, 2006).
D. Case Examples of Biomagnification
1. Biomagnification was caused by DDT
The best example of biomagnification comes from DDT. DDT stands for
dichloro diphenyl trichloroethane. It is a chlorinated hydrocarbon, a class of
chemicals which often fit the characteristics necessary for biomagnification. This
long-lived pesticide (insecticide) has improved human health in many countries
by killing insects such as mosquitoes that spread disease. On the other hand,
DDT is effective in part because it does not break down in the environment. It is
picked up by organisms in the environment and incorporated into fat. Even here,
it does no real damage in many organisms (including humans). In others,
however, DDT is deadly or may have more insidious, long-term effects. In birds,
for instance, DDT interferes with the deposition of calcium in the shells of the
bird's eggs. The eggs laid are very soft and easily broken; birds so afflicted are
rarely able to raise young and this causes a decline in their numbers.
This was so apparent in the early 1960's that it led the scientist Rachel
Carson to postulate a "silent spring" without the sound of bird calls. Her book
"Silent Spring" led to the banning of DDT, the search for pesticides that would not
biomagnify, and the birth of the "modern" environmental movement in the 1960's.
Birds such as the bald eagle have made comebacks in response to the banning
of DDT in the US. Ironically, many of the pesticides which replaced DDT are
more dangerous to humans, and, without DDT, disease (primarily in the tropics)
claims more human lives.
The above studies refer to aquatic systems. In terrestrial systems, direct
uptake by higher trophic levels must be much less, occurring via the lungs. This
critique of the biomagnification concept does not mean that we need not be
concerned about synthetic organic contaminants and metal elements because
they will become diluted. Bioaccumulation and bioconcentration result in these
substances remaining in the organisms and not being diluted to non-threatening
concentrations. The success of top predatory-bird recovery (bald eagles,
peregrine falcons) in North America following the ban on DDT use in agriculture
DDT has a half-life of 15 years, which means if you use 100 kg of DDT, it
will break down as follows (Table 2):
Table 2. A half-life of 15 years using 100 kg of DDT
Year Amount Remaining
0 100 kg
15 50 kg
30 25 kg
45 12.5 kg
60 6.25 kg
75 3.13 kg
90 1.56 kg
105 0.78 kg
120 0.39 kg
This means that after 100 years, there will still be over a pound of DDT in
the environment. If it does bioaccumulate and biomagnify, much of the DDT will
be in the bodies of organisms. DDT actually has rather low toxicity to humans
(but high toxicity to insects, hence its use as an insecticide). Because it could be
safely handled by humans, it was extensively used shortly after its discovery just
before WW II. During the war, it was used to reduce mosquito populations and
thus control malaria in areas where US troops were fighting (particularly in the
tropics). It was also used on civilian populations in Europe, to prevent the spread
of lice and the diseases they carried. Refugee populations and those living in
destroyed cities would have otherwise faced epidemics of louse-born diseases.
After the war, DDT became popular not only to protect humans from
insect-borne diseases, but to protect crops as well. As the first of the modern
pesticides, it was overused, and soon led to the discovery of the phenomena of
insect resistance to pesticides, bioaccumulation, and biomagnification (Marietta
College, 2006).
By the 1960's, global problems with DDT and other pesticides were
becoming so pervasive that they began to attract much attention. Credit for
sounding the warning about DDT and biomagnification usually goes to the
scientist Rachel Carson, who wrote the influential book Silent Spring (1962). The
silent spring alluded to in the title describes a world in which all the songbirds
have been poisoned. Her book of course was attacked by many with vested
B. Biomagnification was caused by Mercury
Another example of biomagnification comes from mercury. Chan, et al
(2003) reporting about impacts of mercury on freshwater fish-eating wildlife and
humans. This following is the abstract from their report:
“This paper reviews the current state of knowledge of the toxic effects of mercury on fish-eating birds, mammals, and humans associated with freshwater ecosystems, including new information on the relative risk of elevated methyl Hg exposure for fish-eating birds inhabiting aquatic ecosystems impacted by mining/smelting activities and areas characterized by high geological sources of Hg. The influence of various environmental conditions such as lake pH, DOC, and chemical speciation of Hg, on fish-Hg concentrations and Hg exposure in fish-eating wildlife, are discussed. Although a continuing global effort to decrease the release of this non-essential metal into the environment is warranted, Hg rnethylation and biomagnification may be limited in some environments due to chemical speciation of mercury in soils and sediments (e.g., HgS) and water quality conditions (e.g., high alkalinity and pH) that do not facilitate high methylation rates. We have shown such limitations for a lake where historic Hg mining greatly increased sediment-Hg loadings, yet Hg increases in small fish of various species are currently lower than expected, and top predators (bald eagles), despite having elevated concentrations of Hg in their blood compared with individuals from nearby lakes, exhibit no Hg-related reproductive impairment or other signs of MeHg intoxication. Recent epidemiological studies have shown that fish-eating human populations may be exposed to Hg sufficient to cause significant developmental effects. However, for humans, we conclude that the current USEPA reference dose for MeHg may be too restrictive, particularly for the less sensitive adult. The health status of indigenous peoples relying on the subsistence harvest of wild foods may be negatively affected by such restrictions”.
V. Prevent of Biomagnification
International efforts to minimize exposure to these compounds include the
banning of their use except in emergency situations where it has been determined that no
other chemical is efficacious. With the exception of DDT, few, if any, of these
compounds have been authorized for use. PCBs, which were widely used in capacitors,
transformers, and lubricating oils, have not been manufactured for several decades but
linger in the environment. Chlorinated dibenzodioxins and dibenzofurans were never
products per se, but are byproducts of products made from chlorophenols. The processes
by which these final products are manufactured have been altered to minimize the
unwanted dioxins. The other source of dioxins is the chlorine bleaching of paper pulp.
This bleaching process has been altered to eliminate chlorine, and thereby to eliminate the
possibility of dioxins. Several combustion processes also result in the formation of
dioxins and benzofurans. Municipal and chemical waste incinerators can be sources of
these unwanted by-products. Engineering controls have been put in place in modern
facilities to minimize production. However, older and less controlled processes may
A. Pesticide-Producing Establishments
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) require
that production of pesticides and pesticidal devices be conducted in a registered
Pesticide-Producing Establishment. ("Production" includes formulation,
packaging, repackaging, and relabeling.) Production in an unregistered
establishment is a violation of the law. EPA issues Pesticide-Producing
Establishment numbers for facilities where pesticides or pesticide devices are
produced. These facilities include foreign establishments that import pesticides
and/or devices to the United States.
The use and regulation of pesticides has a significant international
component. The goals and benefits of International Pesticide Activities (EPA)
range from protecting the U.S. food supply to assisting developing countries to
develop appropriate pesticide regulatory programs. International agreement;
Environmental Protection Agency EPA works closely with U.S. agencies, foreign
countries, and international organizations to develop or strengthen international
standards and legal mechanisms related to the sound management of chemicals.
Quite a few international agreements have been developed on different aspects
of pesticides (Environmental Protection Agency, 2006), including: ¾ Stockholm Convention on Persistent Organic Pollutants (POPs)
¾ Convention on Long-Range Transboundary Air Pollutants (LRTAP), Protocol on Persistent Organic Pollutants (POPs)
¾ Rotterdam Convention on the Prior Informed Consent (PIC) Procedure for Certain Hazardous Chemicals and Pesticides in International Trade ¾ Globally Harmonized System (GHS) for Classification and Labelling of
Chemicals
¾ North American Agreement on Environmental Cooperation (NAAEC) ¾ North American Free Trade Agreement (NAFTA), Technical Working
Group on Pesticides
¾ Canada-United States Strategy for the Virtual Elimination of Persistent Toxic Substances in the Great Lakes
¾ International Convention on the Control of Harmful Anti-fouling Systems on Ships
¾
The Vienna Convention for the Protection of the Ozone Layer & the Montreal Protocol on Substances that Deplete the Ozone Layer.Three federal government agencies share responsibility for the regulation
of pesticides. The Environmental Protection Agency (EPA) registers (i.e.,
approves) the use of pesticides and sets tolerances (the maximum amounts of
residues that are permitted in or on a food) if use of a particular pesticide may
result in residues in or on food (1). Except for meat, poultry, and certain egg
Department of Agriculture (USDA) is responsible, FDA is charged with enforcing
tolerances in imported foods and in domestic foods shipped in interstate
commerce. FDA also acquires incidence/level data on particular
commodity/pesticide combinations and carries out its market basket survey, the
Total Diet Study. Since 1991, USDA's Agricultural Marketing Service (AMS),
through contracts with participating states, has carried out a residue testing
program directed at raw agricultural products and various processed foods. FSIS
and AMS report their pesticide residue data independently.
B. FDA Monitoring Program
Food and Drug Administration (FDA) participates in several international
agreements in an effort to minimize incidents of violative residues and to remove
trade barriers. A standing request for information from foreign governments on
pesticides used on their food exported to the U.S. exists, a provision of the
Pesticide Monitoring Improvements Act.
FDA samples individual lots of domestically produced and imported foods
and analyzes them for pesticide residues to enforce the tolerances set by EPA.
Domestic samples are collected as close as possible to the point of production in
the distribution system; import samples are collected at the point of entry into
U.S. commerce. Emphasis is on the raw agricultural product, which is analyzed
as the unwashed, whole (unpeeled), raw commodity. Processed foods are also
included. If illegal residues (above EPA tolerance or no tolerance for a given
food/pesticide combination) are found in domestic samples, FDA can invoke
various sanctions, such as a seizure or injunction. For imports, shipments may be
stopped at the port of entry when illegal residues are found. "Detention without
physical examination” (previously called automatic detention) may be invoked for
imports based on the finding of one violative shipment if there is reason to
believe that the same situation will exist in future lots during the same shipping
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