Dieldrin, toxicity

Bandyopadhyay SK, Tiwari RK, Mitra P, et al. 1982. Effects of L-ascorbic acid supplementation on dieldrin toxicity in rats. Arch Toxicol 50 227-232. 

TABLE V Acute/Chronic Ratios for Dieldrin Toxicity to Three Species of Aquatic Animals ... 

Endrin [72-20-8] is l,2,3,4,10,10-hexachloro-l,4,4t ,5,8,8t -hexahydro-6,7-epoxy-l,4- <7o, <7o-5,8-dimethanonaphthalene (35) (mp 245 dec, vp 0.022 mPa at 25°C) and is soluble in water to 23 / g/L. It is produced by a Diels-Alder reaction of hexachloronorbomadiene with cyclopentadiene, followed by epoxidation. This reaction produces the endo,endo isomer of dieldrin, which is less stable and more toxic with rat LD q values of 17.8 and 7.5 (oral) and 15 (dermal) mg/kg. It is used as a cotton insecticide but because of its high toxicity to fish it has been restricted. 

Starvation or disease can lead to rapid release of the stored xenobiotic and to delayed toxic effects. In one well-documented case in the Netherlands (see Chapter 5), wild female eider ducks (Somateria mollissima) experienced delayed neurotoxicity caused by dieldrin. The ducks had laid down large reserves of depot fat before breeding, and these reserves were run down during the course of egg laying. Dieldrin concentrations quickly rose to lethal levels in the brain. Male eider ducks did not lay down and mobilize body fat in this way and did not show delayed neurotoxicity due to dieldrin. 

In predicting the effects of a pollutant on population growth rate, the effects of the chemical on the values of t, I, and n are of central interest. Chemical residue data and biomarker assays that provide measures of toxic effects are relevant here because they can, in concept, be used to relate the effects of a chemical upon the individual organism to a population parameter such as survivorship or fecundity (Figures 4.5 and 4.6). Examples of this are discussed in the second part of the text, including the reduction of survivorship of sparrow hawks caused by dieldrin (Chapter 5), the... 

The cyclodiene insecticides aldrin, dieldrin, endrin, heptachlor, endosulfan, and others were introduced in the early 1950s. They were used to control a variety of pests, parasites, and, in developing countries, certain vectors of disease such as the tsetse fly. However, some of them (e.g., dieldrin) combined high toxicity to vertebrates with marked persistence and were soon found to have serious side effects in the field, notably in Western European countries where they were extensively used. During the 1960s, severe restrictions were placed on cyclodienes so that few uses remained by the 1980s. 

Thus, as with studies on the double-crested cormorant in the Great Lakes (see Chapter 16 in Walker et al. 2006), there is evidence of a continuing (although reduced) effect of p,p -DDE on reproductive success even after environmental levels had fallen and eggshell thinning was much less. This raises the possibility that p,p -DDE may have had toxic effects other than eggshell thinning on these species (Nisbet 1989). There is the further complication that other OCs such as PCBs, dieldrin, and hep-tachlor epoxide were present in the same samples and may have had toxic effects. 

Apart from the oxidations just mentioned, cyclodienes are rather stable chemically. It should, however, be noted that dieldrin can undergo photochemical rearrangement under the influence of sunlight to the persistent and toxic molecule photo dieldrin, which occurs as a residue following the application of this insecticide in the field. 

As mentioned earlier (Figure 5.5), aldrin and heptachlor are rapidly metabolized to their respective epoxides (i.e., dieldrin and heptachlor epoxide) by most vertebrate species. These two stable toxic compounds are the most important residues of the three insecticides found in terrestrial or aquatic food chains. In soils and sediments, aldrin and heptachlor are epoxidized relatively slowly and, in contrast to the situation in biota, may reach significant levels (note, however, the difference between aldrin and dieldrin half-lives in soil shown in Table 5.8). The important point is that, after entering the food chain, they are quickly converted to their epoxides, which become the dominant residues. 

Some data on cyclodiene toxicity is presented in Table 5.9. Aldrin and dieldrin have similar levels of acute toxicity indeed, the toxicity of aldrin has been largely attributed to its stable metabolite, dieldrin. Dieldrin is highly toxic to fish, mammals. 

Because of its lipophilicity and refractory character, the toxic effects of dieldrin may be carried throngh to the next generation. In one example, dosing of female small tortoiseshell bntterhies (Aglais urticae) with dieldrin led to an increased number of deformed adults emerging from pupae (Moriarty 1968). 

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