PCDD/F

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PCDD/F, an abbreviation for PCDDs and PCDFs.

Acute toxicity

This is quite variable in different animal species (Table 1). Lethal dose of TCDD to guinea pigs is about 0.001 mg/kg b.w., and to Rhesus monkeys 0.07 mg/kg b.w., but hamsters can tolerate over 1 mg/kg b.w. Even strains within the same species can show a similarly wide difference: the LD50 values for rats vary from 0.010 to >10 mg/kg. Human lethal dose is not known, but human beings are not assumed to be one of the most sensitive species. In Seveso accident, the highest human TCDD concentrations were 56000 ng/kg (in fat), and it can be estimated that the acute dose had been around 0.005 mg/kg b.w. No humans died in the accident, but lots of small animals such as rabbits were found dead at the accident area. No dose will kill the animal immediately, but a high dose causes the so called "wasting syndrome", the animal is anorectic and eats less than a quarter of the normal food intake, and dies after two to three weeks when the body weight has decreased by about 30-40 %. In some animals there may be liver damage including porphyria (disturbance of the synthesis of heme, the pigment of haemoglobin). Other typical features are atrophy of the thymus, disturbances in the levels of some amino acids and lipids, and induction of many oxidative enzymes. Other PCDD/Fs induce similar toxic effects, but they are less potent in line with their TEF (For detailed information, see Pohjanvirta & Tuomisto, Pharmacol. Rev. 1994:46:483-549). See also PCDD/F - toxicity in animals.

Table 1. Acute toxicity (measured as median lethal dose) of TCDD in animal species and strains. The LD50 values (see this) are based on the administered dose in mammals and birds and measured concentrations in fish.

Species (strain)	LD50 (mg/kg)
Lake trout sack fry	0.000074
Guinea pig	0.002
Zebra fish sack fry	0.0025
Rat (Long-Evans)	0.018
Chicken	<0.025
Rat (Sprague-Dawley)	0.06
Rabbit	0.115
Mouse (C57BL/6)	0.182
Mouse (DBA/2)	2.57
Hamster	>3
Rat (Han/Wistar)	>10