FAQs
14. May I have information on the uses, toxicity profiles and guidance levels of the Stockholm Convention POPs?
The uses, toxicity profiles and guidance levels of the 12 Convention POPs are summarised below.
Reference Sources:
United Nations Environment Programme (UNEP) Chemicals World Health Organization (WHO) Food and Agriculture Organization (FAO) Codex Maximum Residue Level (MRL) Database International Programme on Chemical Safety (IPCS) Database US National Library of Medicine Databases (Hazardous Substances Data Bank and TOXNET) US Environmental Protection Agency (EPA) Integrated Risk Information System (IRIS) US Food and Drug Administration (USFDA)
| Aldrin | |
| Use: | Insecticide used on crops such as corn and termites in agricultural soils. |
| Toxicity in humans: | The lethal dose for an adult has been estimated to be about 80 mg/kg body weight (bw). Mainly affects the central nervous system. Classified as a B2 carcinogen by the USEPA Weight-of-Evidence Cancer Classification. A B2 carcinogen is defined as a "probable human carcinogen", i.e. a chemical showing sufficient evidence of carcinogenicity in animals,but no direct evidence of being cancer causing in humans. |
| Toxicity in laboratory animals: | The acute oral LD50 (the lethal dose administered that kills half the test population) in the guinea pig and the hamster is 33 and 320 mg/kg bw, respectively. |
| Toxicity in wildlife: | The toxicity in aquatic organisms is quite variable, with aquatic insects being the most sensitive invertebrates. |
| The maximum residue limits (MRLs) in food recommended by the FAO/WHO vary from 0.006 mg/kg milk fat to 0.2 mg/kg meat fat. The USFDA guideline action level in all fish is 0.3 mg/kg wet weight (ww). WHO guideline value of health significance in drinking-water is 0.03 µg/litre (L). Water quality criteria in the range of 0.1 - 180 µg/L have been published. | |
| Chlordane | |
| Use: | A broad-spectrum insecticide used on a variety of agricultural crops including vegetables, fruits and cotton; used extensively to control termites; and on home lawn and garden pests. |
| Toxicity in humans: | Evidence of endocrine disruption in an intact organism. Classified as a B2 carcinogen by the USEPA Weight-of-Evidence Cancer Classification. |
| Toxicity in laboratory animals: | The acute oral LD50 in the rat is 200-590 mg/kg bw. |
| Toxicity in wildlife: | The toxicity in aquatic organisms is variable. LC50 (the lethal concentration administered that kills half the test population) of 0.4 (pink shrimp) to 90 (rainbow trout) mg/L has been reported. |
| The MRLs in food recommended by the FAO/WHO vary from 0.002 mg/kg milk fat to 0.5 mg/kg poultry fat. The USFDA guideline action level in all fish is 0.3 mg/kg ww. WHO guideline value of health significance in drinking-water is 0.2 µg/L. Water quality criteria in the range of 1.5 - 6 µg/L have been published. | |
| DDT (1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane) | |
| Use: | Insecticide used on agricultural crops, primarily on cotton; used extensively to control insects that carry diseases such as malaria and typhus. |
| Toxicity in humans: | DDT has been shown to have an estrogen-like activity. Classified as a B2 carcinogen by the USEPA Weight-of-Evidence Cancer Classification. |
| Toxicity in laboratory animals: | The acute oral LD50 in the rat is 113-118 mg/kg bw. |
| Toxicity in wildlife: | Egg shell thinning of birds (black duck) has been shown at DDT dietary concentration of 0.6 mg/kg bw. The toxicity in aquatic organisms is variable, LC50 of 1.5 - 56 mg/L in the fish has been reported. |
| The MRLs in food recommended by the FAO/WHO range from 0.02 mg/kg milk fat to 5 mg/kg meat fat. The USFDA guideline action level in all fish is 5 mg/kg ww. WHO guideline value of health significance in drinking-water is 1.0 µg/L. | |
| Dieldrin | |
| Use: | Insecticide used primarily to control termites and textile pests; also used to control insects living in agricultural soils. |
| Toxicity in humans: | Mainly affects the central nervous system. Classified as a B2 carcinogen by the USEPA Weight-of-Evidence Cancer Classification. |
| Toxicity in laboratory animals: | The acute oral LD50 in the mouse and rat ranges from 40 - 70 mg/kg bw. Adverse effects on the survival rate have been reported at a daily dose of 0.6 mg/kg bw in the rabbit. |
| Toxicity in wildlife: | The acute toxicity in aquatic organisms is high; LC50 in the fish between 1.1 - 41 mg/L has been reported. |
| The MRLs in food recommended by the FAO/WHO vary from 0.006 mg/kg milk fat to 0.2 mg/kg poultry fat. The USFDA guideline action level in all fish is 0.3 mg/kg ww. WHO guideline value of health significance in drinking-water is 0.03 µg/L. Water quality criteria in the range of 0.1 - 18 µg/L have been published. | |
| Endrin | |
| Use: | Insecticide used on agricultural crops such as cotton and grains; also used to control rodents. |
| Toxicity in humans: | Mainly affects the central nervous system. An oral dose of 0.2 - 0.25 mg/kg bw is known to produce convulsions while a high dose of 1 mg/kg bw may result in repeated seizures. The chemical is not classifiable as to the carcinogenicity for humans. |
| Toxicity in laboratory animals: | The acute oral LD50 values are between 3-43 mg/kg bw. For long term toxicity in the rat, No-Observed-Effect-Level (NOEL) of 0.05 mg/kg bw/day has been reported. |
| Toxicity in wildlife: | Highly toxic to fish, aquatic invertebrates and phytoplankton; the LC50 values are mostly less than 1 µg/L. |
| The MRLs in food recommended by the FAO/WHO are 0.05 mg/kg for fruiting vegetables and cucurbits, and 0.01 mg/kg for poultry meat. WHO guideline value of health significance in drinking-water is 0.6 µg/L. | |
| Heptachlor | |
| Use: | Insecticide primarily used to kill soil insects and termites; also widely used on agricultural crops such as cotton; and used to kill malaria-carrying mosquitoes. |
| Toxicity in humans: | Limited information is available on the effects in humans; studies are inconclusive regarding heptachlor and cancer. Classified as a B2 carcinogen by the USEPA Weight-of-Evidence Cancer Classification. |
| Toxicity in laboratory animals: | The acute oral LD50 values are between 40-119 mg/kg bw. |
| Toxicity in wildlife: | Highly toxic to aquatic organisms; LC50 value as low as 0.11 µg/L has been reported in the pink shrimp. |
| The MRLs in food recommended by the FAO/WHO vary from 0.006 mg/kg milk fat to 0.2 mg/kg meat or poultry fat. | |
| Hexachlorobenzene (HCB) | |
| Use: | Fungicide used on food crops and for seed treatment. Also used as an industrial chemical, e.g., in making fireworks, ammunitions, synthetic rubber and as a raw material for the production of many agricultural chemicals. Also produced as an unintentional POPs by-product from combustion and/or as an intermediate during industrial processes. |
| Toxicity in humans: | Known to cause liver disease in humans; Classified as a B2 carcinogen by the USEPA Weight-of-Evidence Cancer Classification. |
| Toxicity in laboratory animals: | The acute toxicity is low; oral LD50 value of 3.5 mg/g bw in the rat has been reported. |
| Toxicity in wildlife: | The reported LC50 values in the fish vary between 50-200 µg/L. |
| The MRL in food recommended by the European Union (EU) is 0.01 mg/kg. | |
| Mirex | |
| Use: | Insecticide used mainly to combat fire ants, other types of ants and termites. |
| Toxicity in humans: | There is evidence of its potential for endocrine disruption. Classified as a Group 2B carcinogen by International Agency for Research on Cancer (IARC), i.e. the chemical is possibly carcinogenic to humans. |
| Toxicity in laboratory animals: | The acute oral LD50 in the rat is 235 mg/kg bw. |
| Toxicity in wildlife: | Toxic to the fish and can affect their behaviour; reported LC50 values vary between 0.2 (rainbow trout) to 30 (bluegill) mg/L. Delayed mortality of crustaceans is observed at 1 µg/L exposure level. |
| The USFDA guideline action level in all fish is 0.1 mg/kg ww. | |
| Toxaphene | |
| Use: | Insecticide used on a wide variety of agricultural crops such as cotton, cereal grains, fruits, nuts and vegetables; also used to control ticks and mites in livestock. |
| Toxicity in humans: | Strong evidence of an endocrine disruption potential. The chemical is carcinogenic in mice and rats, and classified as a B2 carcinogen by the USEPA Weight-of-Evidence Cancer Classification. |
| Toxicity in laboratory animals: | The acute oral toxicity ranges from 49 (dogs) to 365 (guinea pigs) mg/kg bw. For long term toxicity in the rat, NOEL of 0.35 mg/kg bw/day has been reported. |
| Toxicity in wildlife: | Highly toxic to the fish; reported LC50 values vary between 1.8 (rainbow trout) to 22 (bluegill) µg/L. Long term exposure to chemical concentration of 0.5 µg/L has been shown to reduce egg viability to zero. |
| The MRL in food recommended by the EU is 0.1 mg/kg. | |
| Polychlorinated biphenyls (PCBs) | |
| Use: | Industrial chemical widely used as heat exchange/insulating fluids in electric transformers and capacitors and other electrical equipment, and as additives in paint, carbonless copy paper, sealants and plastics. Also produced as an unintentional POPs by-product during combustion processes. |
| Toxicity in humans: | Evidence of endocrine disruption in an intact organism. Classified as a B2 carcinogen by the USEPA Weight-of-Evidence Cancer Classification. |
| Toxicity in laboratory animals: | The acute toxicity is generally low; oral LD50 value of 1 g/kg bw in the rat has been reported. |
| Toxicity in wildlife: | Highly toxic to the fish; in the larval fish (rainbow trout), LD50 and NOEL of 0.32 and 0.01 µg/L, respectively, has been reported. |
| The USFDA guideline action level in all fish is 2 mg/kg ww. | |
| Polychlorinated dibenzo-p-dioxins (PCDDs/Dioxins) and polychlorinated dibenzofurans (PCDFs/Furans) | |
| Sources: | Dioxins/furans are unintentional by-products of industrial and thermal processes involving organic matters and chlorine, formed and released as a result of incomplete combustion or chemicals reactions. Dioxins are also produced by natural processes such as forest fires and volcanic eruptions. |
| Toxicity in humans: | Dioxin exposures to humans have been reported to be associated with increased risk of severe skin lesions (chloracne and hyperpigmentation). Other possible adverse effects include: altered liver function and lipid metabolism, depression of the immune system, reproductive and developmental abnormalities and endocrine disruption. The most sensitive groups are fetus and neonatal infants. Classified as a B2 carcinogen by the USEPA Weight-of-Evidence Cancer Classification. |
| Toxicity in laboratory animals: | Effects on the immune system in the mouse have been reported at 10 ng/kg bw/day, while reproductive effects have been seen in rhesus monkeys at 1-2 ng/kg bw/day. Biochemical effects have been demonstrated in the rat at a very low dose of 0.1 ng/kg bw/day. |
| Toxicity in wildlife: | Adverse impacts of dioxins on the hatching of reptiles and birds have been reported. |
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The Tolerable Daily Intake (TDI) recommended by the WHO for dioxins is 1- 4 pg TEQ/kg bw/day*. The EU has set a limit of 4 pg WHO-TEQ /g† for PCDDs/PCDFs for fish and fish products on whole weight basis. |
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* pg TEQ/kg bw/day = picogram toxicity equivalent per kilogram body weight per day
† pg WHO-TEQ/g = picogram World Health Organisation toxicity equivalent per gram fish and fish products
