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Toxic Substances

Toxic SubstancesThe database currently contains scientific papers regarding the following chemical toxic substances:

  • Mercury is commonly known as quicksilver and is the only metal that is liquid at standard conditions for temperature and pressure – a characteristic that facilitates its distribution. Prenatal exposure to methyl-mercury [CH3Hg] is known to impair neurological development (e.g. deficits in attention, cognitive thinking, language, memory, fine motor and visual spatial skills; delayed reaction time). In adults, mercury exposure has been associated with arteriosclerosis, hypertension, memory deficits; Alzheimer and reproductive impairment.  Symptoms for acute intoxication may be impairment of peripheral vision; disturbances in sensations; disordered coordination of movements; and impairment of speech, hearing, and walking.
  • PCBs (polychlorinated biphenyls): The odorless and tasteless PCB congeners (209 in total) have been intensively used in industrial production due to their insulating properties, chemical stability, and low flammability. PCBs are one of the most widely studied environmental contaminants. PCBs have been demonstrated to cause a variety of adverse health effects, e.g. on endocrine system, nervous system, immune systems and reproduction (reduced conception rate and birth weight). PCBs may also be responsible for persistent and significant deficits in neurological development, including visual recognition, short-term memory and learning.  In addition, PCBs are considered human carcinogens.
  • PBDE (polybrominated diphenyl ethers): are used as flame retardants in a number of applications, including textiles, plastics, wire insulation, and automobiles. PBDEs congeners (209 in total) are considered as persistent, bioaccumulative, and biotoxic. Their high lipophilicity and high resistance to degradation processes makes them a persistent threat to humans and wildlife. PBDEs are suspected to have hormone-disrupting effects, in particular, on estrogen and thyroid hormones. Furthermore, PBDE-associated impaired development of the nervous system has been observed, resulting in reduced verbal and full IQ scores in young children.
  • HBCD (hexabromocyclododecane) is a brominated flame retardant. HCBD has 16 possible stereo-isomers with different biological activities and is classified as persistent, bioaccumulative and toxic.  HBCD also undergoes long-range environmental transportation: It is widely present even in remote areas. Medical tests indicate that HBCD has potential reproductive, developmental, and neurological effects. In May 2013, HBCD was banned by the Stockholm Convention on Persistent Organic Pollutants. Countries are urged to phase out this substance – schedule for phase out in the EU is by 2015.
  • PFCs (polyfluoroalkyl compounds) are used to create water and soil repellency. Perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) are the most widely spread PFCs. The bioaccumulating PFCs are associated with reduced female fertility and sperm quality, reduced birth weight, attention deficit hyperactivity disorder (ADHD), increased total and non-HDL (bad) cholesterol levels, changes in thyroid hormone levels and pregnancy-induced hypertension. In addition, they are also correlated with an increased risk of prostate and bladder cancer.
  • Dieldrin is an organochlorine insecticide that is extremely persistent in the environment. Compared to DDT (see below), Dieldrin is more acutely poisonous but tends to be less persistent. Acute symptoms of intoxication include dizziness, hyperirritability, uncontrolled muscle movements, vomiting, headache and even cardiovascular effects; chronic intoxication may result in fainting, muscle spasms, tremors, and weight loss.
  • Chlordane is an organochlorine compound and was used as a pesticide. The compound is bioaccumulating. Acute chlordane exposure may cause neurological effects, such as headache, dizziness, irritability, convulsions, respiratory infections, diabetes, immune-system activation, anxiety, depression, blurry vision, and confusion. As a chronic effect, increased incidence of ovarian and uterine disease is discussed. While not proven yet in humans, animal tests have linked chlordane exposure with cancers of the breast, prostate, brain, and blood cells—leukemia and lymphoma. Accordingly, chlordane is considered a probable human carcinogen.
  • HCH (Hexachlorcyclohexane) is an organochlorine existing in eight chemical forms (isomers); the isomer γ-HCH is better known as lindane, while isomers α- and ß-HCH are by-products of lindane production. HCHs are considered possible human carcinogens.  Exposure to high levels can also cause blood disorders, dizziness, headaches, seizures, and changes in sex hormone levels.
  • HCB (Hexachlorobenzene) is a chlorinated carbon compound (C6Cl6), which is used as a fungicide. It is considered to be a probable human carcinogen, with increased risk for liver, kidney and thyroid cancers. The substance is able to cross the placenta, to accumulate in foetal tissues and to be transferred in breast milk. Chronic oral exposure in humans causes damage to liver tissue, skin lesions, ulceration, photosensitivity, thyroid effects, bone effects, loss of hair and neurological changes. Embryo-lethality and teratogenic effects are also discussed.
  • Toxaphene is a mixture of over 670 chemicals and was widely used as a pesticide in agriculture. The compound stimulates the central nervous system (CNS), leading to convulsive seizures.  Chronic inhalation exposure to toxaphene in humans results in reversible respiratory toxicity, while chronic, oral exposure in animals has resulted in effects on the liver, kidney, spleen, adrenal and thyroid glands, CNS, and the immune system.
  • DDT (dichloro-diphenyl-trichlorethane) is a colorless, tasteless and almost odorless organochlorine insecticide. DDT and also DDE (see below) increase prevalence of diabetes. With its estrogene-like structure DDT has an endocrine disrupting effect and accordingly, a broad negative impact on reproduction. DDT exposure increases the risk for early pregnancy loss, premature birth, and low birth weight. Even a prenatal exposure at low levels is associated with decreased attention cognitive skills in young children.
  • DDE (1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene)) is a metabolite of DDT (see above). Due to results from animal testing, where DDE exposure induced liver and thyroid tumors, health authorities in the United States classified DDE as a probable human carcinogen.
  • Chlorinated paraffins (or chlorinated alkans) are a group of more than 200 polychlorinated compounds with a varying degree of chlorination, which are used for a wide range of industrial applications, such as flame retardants, plasticizers and metal processing. Chlorinated paraffins are considered human carcinogens. Animal tests indicate a correlation with cancer of liver, thyroid gland, and kidney.

In recent years, a number of new chemical compounds that have substantial health risks to both humans and cetaceans have been identified. This database will consider such developments and will seek to include new substantive related papers.
With regards to pathogens related to cetacean meat, the database so far only includes papers on brucellosis, but might, at a later stage, expand that section as well.

  • Brucellosis is an infection caused by the bacteria Brucella that is spread to humans from infected animals. Brucellosis typically starts with flu-like symptoms (fever, headache, weakness, sweating, weight loss, muscle pain, generalized aches). Inflammation of the liver, spleen and testicles, and gastrointestinal or respiratory symptoms are other effects. In cetaceans, Brucella is linked to increased abortion and mortality as well as several infectious diseases. So far, at least in four cases, transfer of Brucella ceti to humans has been documented.

For more information see e.g.