Photo courtesy NOAA
Persistent Organic Pollutants
Persistent Toxic Substances
Persistent Toxic Pollutants
Persistent Toxic Chemicals
Persistent Bio-accumulative Toxins
Stiff and lean after six months curled in a den, a female polar
bear squeezes herself out of her winter home. Two small cubs emerge tentatively
at her heel for their first view of the world beyond a snow cave. Entirely
dependent on their mother, the cubs follow obediently. Having used up most of
her fat stores, the female scans the sea ice below and ponders a meal of seal
blubber. But her cubs are not yet ready to travel, and her milk will have to
sustain them for some time to come. The milk is rich and nourishing but today it
also harbors a threat. The seals the mother has feasted on in the past, and will
need again soon, are tainted by chemicals from lands far beyond her sea-ice
domain. The chemicals that bind to the fat of the seals have accumulated in her
own fat stores. Unwittingly, the mother passes the toxins to her young in her
fat-rich milk, with effects that are still unclear.
This chapter examines organic chemicals that can affect the
health of animals and people, especially those substances that accumulate in
Arctic food webs and that resist degradation. These are often called persistent
organic pollutants, or POPs. A review of known toxic effects and environmental
levels of POPs forms the basis for evaluating whether Arctic wildlife are
affected by current levels of contamination. A summary of sources and pathways
indicates where the contaminants come from. Many measurements of organic
contaminants have been made because of concern about high intake by people, and
the human health aspects of these substances are discussed in the chapter
Pollution and Human Health.
organic pollutants: a background
Persistent Organic Pollutants
Organic Pollutants (POPs) are chemical substances that persist in the
environment, bioaccumulate through the food web, and pose a risk of causing
adverse effects to human health and the environment. With the evidence of
long-range transport of these substances to regions where they have never been
used or produced and the consequent threats they pose to the environment of the
whole globe, the international community has now, at several occasions called
for urgent global actions to reduce and eliminate releases of these chemicals.
Organic Pollutants & Reproductive Health
The United Nations is currently considering the
elimination or reduction of twelve of some of the most damaging chemicals that
are Persistent Organic Polutants (POPs) through the formulation of an
international, legally binding treaty. Nine of the POPs chemicals under
consideration are pesticides that have been extensively used in both developed
and developing countries. Although many countries have banned these chemicals,
they remain stockpiled, are produced or used illegally, or, because of lenghthy
half-lives, they continue to exist in soil, or other environmental media. In
Geneva, this paper instructed both government delegates and public interest
groups about how these chemicals are particularly injurious to women's bodies.)
Lindane (from: A briefing for UNISON prepared by the Pesticides Trust,
Lindane - g-HCH [hexachlorocyclohexane], is included in the government
"Red List" of dangerous substances. It has been in use as an broad
range insecticide for 50 years, long enough to build up a significant body of
evidence on its toxic and environmental hazards. It has caused deaths and
poisonings in humans and there is authoritative recognition of its long term
health effects including carcinogenic effects. It is a serious environmental
contaminant and as well as being directly toxic to wildlife. It bio-accumulates
along food chains. Scientific and anecdotal evidence links lindane with serious
health problems including aplastic anaemia, the birth disorders C.H.A.R.G.E. and
breast cancer. (See below).
Lindane has been banned or severely restricted in 37 countries. The Advisory
Committee on Pesticides in the UK has so far carried out three reviews of
lindane and continued to recommend its approval. The Pesticides Trust believes
that Lindane should be banned on the basis of existing evidence and as a
precaution to avoid further health and environmental problems which are
suspected of being caused by lindane.
Many other organochlorines which over the years have been linked to major
health and environmental problems have been banned or are no longer used.
Included in this catalogue are aldrin, dieldrin and endrin which have virtually
disappeared, and DDT, heptachlor and toxaphene which have been banned in many
countries but are still used quite extensively particularly in some developing
countries. Lindane is an organochlorine insecticide that is still in relatively
widespread use in developed nations as well as in the third world. It is still
in use in treatment against lice and scabies in humans and also against
ectoparasites in veterinary treatment. In a control study, Davis et al. reported
a statistically significant increase of brain cancer in children following
treatment with lindane shampoo. ("Family Pesticide Use and Childhood Brain
Cancer", 1993). Veterinary use in sheep can cause contamination of wool, as
well of milk and meat.
Lindane is also known as g-HCH since it has to be made up of at least 99% of
the gamma isomer of hexachlorocyclohexane (HCH). Technical HCH can include
varying proportions of alpha, beta, delta and epsilon HCH isomers, but because
these have been shown to have serious short and long term health effects, in the
UK all HCH products containing less than 99% of the gamma isomer are banned.
The organochlorines in general, and lindane in particular, are characterised
by their broad spectrum insecticidal activity, long persistence in the
environment, and their tendency to bio-accumulate along the food chain.
Several cases of human poisoning by lindane have been reported. Children are
significantly more susceptible to the toxic effects of lindane. In one case a
dose equivalent to 62,5 mg/kg proved fatal, while the LD50 in the rat is above
88mg/kg. In adults, doses above 300 mg/kg ingested orally have proved fatal.
Since lindane has been in very widespread use for several decades, its long
term health effects have been extensively studied. Included among the reported
chronic effects of exposure to lindane are nervous disorders and increased liver
The International Agency of Research on Cancer (IARC) has concluded that
lindane is a possible human carcinogen (class 2B), and the US EPA has classified
it similarly as a class B2/C possible human carcinogen.
Key health issues.
… Aplastic anaemia. Exposure to lindane has been linked with blood
disorders known as blood dyscrasias, and in particular the disorders aplastic
anaemia where the formation of platelets and white cells is disrupted. …
C.H.A.R.G.E. This condition which involves multiple congenital abnormalities has
been linked to exposure of the mothers of CHARGE children to lindane during
early pregnancy. A statistically significant proportion of mothers of CHARGE
children in the UK were exposed to pesticides in early pregnancy, and one of the
most prominent pesticides implicated was lindane.(Blake and others, Child care
health and development, 1993, 19, 395-409) … Breast Cancer. Lindane is an
endocrine disruptor which is capable of imitating hormones in humans and thereby
disrupting the physiological functions which these hormones control. There is a
significant body of evidence which suggests that where lindane is used
extensively, and particularly where cattle are exposed to it, the incidence of
breast cancer is higher. The UK has the highest rate of death from breast cancer
in the world, and in Lincolnshire were lindane is used extensively on sugar beet
crops, the rate of breast cancer is 40% higher than the national average. (Women
Environmental Network, 1994). The presence of lindane in human milk has been
reported in countries throughout the world (Moses, Marion, Pesticides and breast
cancer, Pesticides News 22, December 1993, 3-5).
Environmental effects. Lindane is highly volatile, and when applied to field
crops in particular, a high proportion (up to 90%0 of the pesticide enters the
atmosphere and is later deposited by rain. Lindane is also leached into surface
waters and even into ground water.
The International Conference on the Protection of the North Sea agreed to
reduce emissions from land, rivers and the atmosphere of number of toxic
chemicals including lindane by 50% between 1985 and 1995.
In common with other organochlorine pesticides lindane is fat soluble and
this contributes to its tendency to bio-accumulate through food chains. Residues
have been detected in the kidneys, liver and adipose tissue of a wide variety of
wild animals and birds. It is highly toxic to aquatic invertebrates and fish.
Canada has signed and ratified two international agreements to reduce
atmospheric emissions of 16 Persistent Organic Pollutants (POPs) and three Heavy
Metals (lead, mercury and cadmium). The agreements were negotiated under the
auspices of the United Nations Economic Commission for Europe (UN ECE), which
includes Canada, the United States, European countries, and countries of the
former Soviet Union.
The POPs and Heavy Metals Protocols are the first major multinational,
legally-binding agreements to place controls on emissions of these hazardous air
New Protocol on Persistent Organic Pollutants
Negotiated under the UN Economic Commission for Europe's
Convention on Long-Range Transboundary Air Pollution
PBT pollutants are chemicals that are
toxic, persist in the environment and bioaccumulate in food chains and, thus,
pose risks to human health and ecosystems. The challenges remaining
on PBT pollutants stem from the fact that they transfer rather easily among air,
water, and land, and span boundaries of programs, geography, and generations.
Bioaccumulative and Toxics Initiative
Persistent, Bioaccumulative and Toxic Chemicals in Central and Eastern
European Countries - State-of-the-art Report
Topical Reports Northwest Guide to PBTs
Persistent toxic substances have had disastrous effects in ecosystems.
Studies on human health indicate that people are also being affected through
their food, drinking water and air. Many persistent toxic substances stay in the
environment and food chain for very long periods. Long-term toxic exposures to
fish, wildlife and humans has been linked to various reproductive, metabolic,
neurological and behavioral abnormalities as well as immunity suppression and
other life-threatening problems such as cancer.
Research in the Great Lakes Basin on persistent toxic substances has shown:
- Population decreases in wildlife, increased mortality rates and reproductive
- Congenital malformations/birth defects such as cross-billed ducks and tumors
in fish; and
- Impacts on human health including the presence of toxic substances in breast
milk, increased incidence of cancer and changes to the human reproductive
Research demonstrates that persistent toxic substances are too dangerous
to the ecosystem and to humans to permit their release in any quantity.