The GEF Small Grant Programme

POPs Awareness Training Module

Read, learn and test your POPs knowledge

Chapter III: Impacts of POPs on Health and Environment

A. Health

Figure 1. Children learning about POPs and the environment, Bulgaria
Figure 1. Children learning about POPs and the environment, Bulgaria
POPs concentrate in the human body and in eco-systems and can cause serious long-term health effects. They can most severely impact those who work or live where POPs are used or produced and who are directly exposed through inhalation, dermal contact and ingestion. The main human exposure pathway to POPs, however, is from general environmental exposure to POPs that is caused by eating fish, meat and dairy products that have been contaminated by POPs in the environment.

When POPs are used as pesticides, the residues contaminate crops and those who eat them. The ability of POPs to travel long distances in the environment causes bioaccumulation in fish, birds and mammals far away from where they are used or produced.1 They enter the aquatic and terrestrial food chain primarily through airborne deposition and become more concentrated as they move up the food chain. This process has been well-documented, especially for the industrial chemical, PCBs. According to a US Government agency, as a result of bioconcentration, “PCB levels in aquatic organisms can be up to 1 million times higher than their concentration in the aquatic environment.”2 POPs pesticides and unintentionally-produced POPs also can greatly bioconcentrate in the environment.

Few countries extensively monitor the POPs content of their food supply, and most never do. Even POPs pesticides that have been banned for decades show up consistently in food. POPs have been found in human blood, fatty tissue, connective tissue, urine, semen and breast milk.

Studies have shown that even low levels of exposure in the womb can cause permanent harm to a developing fetus. POPs are passed to the fetus in the womb through the placenta and cause numerous chronic health impacts, some of which are not expressed until the infant becomes an adult. POPs are also passed from mother to child through breast milk causing harmful effects, though not as severe as fetal exposure. Since breast feeding also has many health benefits for an infant, mothers are strongly encouraged not to discontinue breast feeding.

Research, published in British Medical Journal, The Lancet, reveals a strong link between DDT exposure and the likelihood of pre-term birth: the greater a mother's exposure, the more likely it is that her infant will be born prematurely. Premature birth itself is linked to a wide array of health problems later in life. A study, by scientists at the United States National Institute of Environmental Health Sciences, indicates that DDT's effect on infant mortality, both by increasing preterm birth and by decreasing the length of time that mothers breast feed, is very substantial.3

Acute exposure to POPs pesticides can cause harmful effects whose symptoms can include tremors, headache, dermal irritation, respiratory problems, dizziness, nausea, and seizures.4 Chronic exposure to POPs, the kind often associated with the presence of POPs in the food supply can have long-term health effects such as multiple types of cancer, endocrine system disruption, hormonal disruption, reproductive disorders, neurological and behavior disorders, Parkinson's disease, birth defects, respiratory illness and abnormal immune system function.5

Figure 2.  Burning of waste posed great threat to human health, Cuba
Figure 2. Burning of waste posed great threat to human health, Cuba
A detailed discussion of acute and long-term health effects of the POPs pesticides listed in the Stockholm Convention can be found in Table 6 of the ‘Citizens Guide to the Implementation of the Stockholm Convention,’ page 64.6

PCBs are known to enter marine and aquatic ecosystems in large quantities from the air and then bioaccumulate in fish. This has been well-documented in the Great Lakes of North America. Adverse health effects have been observed in individuals who consume Great Lakes fish, and also in their children. Children of mothers who ate these fish suffered neurobehavioral and developmental deficits that were observed in newborns and that continued in children through at least school-age. Other documented health impacts include systemic effects such as liver disease, diabetes, and effects on thyroid and immune systems; and increased cancer risks.7

Some groups in the Great Lakes region were found to be most effected: sports anglers, Native Americans and the urban poor who all tended to eat large quantities of contaminated fish; and pregnant women, fetuses, nursing infants and the elderly because of higher sensitivity.

Acute PCB exposure can also occur, usually during repair and handling of PCB equipment, through contact with hazardous waste sites, or as a result of leaks from faulty or overheated old electrical transformers, capacitors or other electrical products. (In most countries, this is limited to electrical equipment originally manufactured more than 30 years ago). Individuals acutely exposed to PCBs experience acne, rashes and in some instances liver damage and multiple types of cancer.

Like POPs pesticides and PCBs, human beings are exposed to unintentional POPs such as dioxins and furans primarily through eating fish, meat, eggs and dairy products. Exposure to dioxins in amounts measured in parts per trillion (12 zeros) or even smaller amounts have been associated with health and environmental impairments.

Dioxin exposure appears to affect the growth and development of children, notably the development of the immune, reproductive and nervous systems. Children who are exposed in utero during critical periods of development appear to be the most sensitive and vulnerable to their toxic effects.8 Dioxin exposure has been associated with IQ deficits, increased prevalence of withdrawn/depressed behavior, adverse effects on a child’s ability to pay attention, and an increase in hyperactive behavior. Dioxin exposure has also been associated with diabetes, defects in permanent teeth, adverse effects on thyroid hormones, and increased respiratory infections.

Workers and communities located near dioxin sources can also be exposed. Studies have shown that workers at waste incinerator plants may have higher exposure to dioxins and a higher likelihood of multiple types of cancer, decreased liver functioning, cardiac problems, allergies, chloracne and skin ailments.

Dioxins are classified as human carcinogens by the World Health Organization’s International Agency for Research on Cancer 9 and are considered among the most toxic substances known to science. The toxicity of each PCDD/F congener depends on the number and position of the chlorine atoms. Seventeen of the 210 possible PCDD/F congeners are considered to be highly toxic. The toxicity level of dioxins is expressed in terms of its toxic equivalence (TEQ) to TCDD.

B. Environment
Studies of how individual POPs disrupt ecosystems are difficult because eco-systems and wildlife are generally exposed to multiple POPs at the same time. The effects caused by a given POP may vary according to the animal species, age and gender and the level, extent and duration of exposure. The effect of exposure on an individual organism is also critically influenced by the timing of the exposure relative to the organism's life cycle. There may also be a time delay between exposure and onset of effects.10 Abnormalities may occur in the second or third generation offspring.

Figure 3.  Organic products sold on the market, Thailand
Figure 3. Organic products sold on the market, Thailand
Gross abnormalities in wildlife associated with POP exposure such as crossed bills, club feet, tumors and lesions have been well-reported. On the other hand, a number of other abnormalities that are associated with low level environmental exposure to POPs are subtle and not readily apparent at the individual level, but have serious implications at the population level. For example, the effect of POPs-induced immune system deficiencies may be difficult to detect in an individual amphibian, fish, bird or mammal, but may influence the spread of infectious diseases and may contribute to epidemics and population die-offs. Impairments of reproductive function are also often primarily expressed at the population level. Abnormalities in estrus cycle and sex hormone levels, reduced sperm production, reduced litter size can cause population declines. In some cases total reproductive failure has been reported. There are well-known examples of bird populations exposed to POPs having decreased or retarded egg production, increased embryo mortality, eggshell thinning, embryonic deformities, growth retardation and reduced egg hatchability.

Ecosystem balance can also be negatively impacted by POPs. For example when POPs pesticides are used, they not only kill the organisms for which they are intended, but also kill beneficial insects, birds, fish and other organisms. Extensive pesticide use creates resistance, leading to altered ecological equilibrium 11 and threatens wildlife habitat and the survival of endangered species, for example, amphibians, Pacific salmon, sea turtles and bald eagles.12 The environment may also be impacted by stockpiling of POPs. For example, during the 1960s though 1980s, Africa received thousands of tons of POPs pesticides from the developed world to control pests. They were often not wanted and needed, and so piled up. According to the FAO, 50,000 tonnes of obsolete pesticide stocks and thousands of tons of contaminated soil are now present in African countries and threaten health and the environment. It is estimated that about one/third of the pesticides in these obsolete stockpiles are POPs pesticides. However, since obsolete pesticide stocks are often mixed together, it is generally necessary to treat the entire stockpile as POPs waste. There are more than 50,000 additional tonnes of obsolete pesticide stocks identified in just four of the former Soviet bloc counties: Ukraine, Macedonia, Poland and Moldova.13 The total amount of obsolete pesticide stocks worldwide, including the rest of Eastern Europe plus Asia and Latin America are at least 150,000 tonnes and almost certainly, much more.14 The POPs in these stockpiles leak into the general environment. When they are not properly controlled, children can play near them and farmers can salvage pesticides from the obsolete stockpile for use.

1Id at,pg. 59. Additional information can also be found at: Pesticide Action Network North America, Case Study: Organochlorine Pesticides, available at:
2Department of Health and Human Services; Agency for Toxic Substances and Disease Registry; available at:
3Colburn, Theo, “Out Stolen Future,”
6, pg. 64
7Canadian Environmental Law Association and Great Lakes Centers; Human Health Effects Associated with PCB Exposure; available at:
8Center for Health, Environment and Justice; America's Choice: Children's Health or Corporate Profit, The American People's Dioxin Report, Technical Support Document, November 1999, available at:
9International Agency for Research on Cancer (IARC) - Summaries & Evaluations, Polychlorinated Dibenzo-para-Dioxins; available at:
10Stone, David and Han, Siu-Ling; A case study of POPs concentrations in wildlife and people relative to effects levels, United Nations Environment Programme, Chemicals: Persistent Organic Pollutants;, available at:
11 pg. 63
12Center for Biological Diversity, Environmental Protection Agency Threatened with Lawsuit For Failing to Protect 11 Bay Area Endangered Species from Pesticides, January 10, 2007, available at:; Warning over toxic stockpile, September 18, 2004, available at:
14 , pg. 22

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III Review Quiz:

  1. POPs can be transmitted from mother to child:
    1.   In the womb
    2.   through breast milk
    3.   from the mother’s previous exposure to POPs
    4.   all of the above
  2. POPs are considered an environmental issue of global concern because:
    1.   POPs are the most toxic substances known to science;
    2.   There are high volumes of POPs in global trade and therefore global action is needed to control them
    3.   POPs travel long distances in the environment and can cause harm in countries far distant from their source
    4.   POPs are very harmful to birds, fish and wildlife, but are not as harmful to human health
  3. Exposure to POPs can cause:
    1.   Cancer
    2.   Endocrine, immune system and hormonal disruption
    3.   Reproductive disorders and birth defects
    4.   Neurological and behavior disorders
    5.   All of the above
 Chapter 1: ‘The Dirty Dozen’ and their Characteristics
 Chapter 2: Sources and Uses of POPs
 Chapter 3: Impacts of POPs on Health and Environment
 Chapter 4: Global Institutions and Policies to Reduce and Eliminate POPs
 Chapter 5: Harnessing the Power of NGOs and Communities
 Chapter 6: Case Studies: Local Actions; Global Results
 Chapter 7: Opportunity for National Coordinators and National Steering Committees to Facilitate Results in POPs Focal Area
 Final Quiz: POPs Awareness Self-Test
Quick Reference and Additional Information