The effect of injection of chlorinated hydrocarbon pesticides on hatchability of eggs

The effects of Dechlorane Plus on toxicity and mRNA expression in chicken embryos: a comparison of in vitro and in ovo approaches

Dechlorane Plus (DP) is an additive chlorinated flame retardant comprising two major isomers, syn- and anti-DP, that is used in a variety of commercial/industrial products. It has been detected in biotic and abiotic matrices including the eggs of herring gulls collected from the Laurentian Great Lakes. However, data on potential toxicological and molecular responses to exposure are lacking, especially for avian species. A combined in vitro/in ovo approach was used to determine concentration-dependent effects of DP in chicken embryonic hepatocytes (CEH) and chicken embryos following injection of DP into the air cell of eggs prior to incubation. Overt toxicity (i.e. cytotoxicity and pipping success) and mRNA expression levels of transcripts previously determined to be responsive to a brominated flame retardant were assessed in CEH and hepatic tissue. DP was not cytotoxic up to a maximum concentration of 3 μM in CEH, and no effects on pipping success were observed up to the highest nominal dose group of 500 ng/g egg. A significant shift in isomeric content of syn- and anti-DP was detected between stock solutions of the commercial mixture and hepatic tissue; the proportion of the syn-DP isomer increased from 0.34 to 0.65 with a concomitant decrease of anti-DP from 0.66 to 0.35. None of the mRNA transcripts changed as a result of in vitro or in ovo exposure to DP indicating that, although there was concordance between the two approaches, DP may evoke its toxicity through other modes of action. At current environmental exposure levels, no adverse effects of DP on embryonic viability or pathways associated with the genes assessed are predicted.

Reevaluation of the developmental toxicity of dieldrin by the use of fertilized Japanese quail eggs

To reevaluate the toxicity of the organochlorine insecticide and persistent organic pollutant dieldrin and confirm its impact on development, an exposure trial using bird eggs was performed. Dieldrin at concentrations of 10-100 microg/g of egg was injected into the yolks of Japanese quail (Coturnix japonica) eggs. Hatchlings from the eggs were raised to sexual maturity and multiple tests to detect the harmful effects of dieldrin were conducted. Dieldrin at 100 microg/g decreased egg hatchability by 50.0% (vehicle control, 86.7%), although embryogenesis even in unhatched eggs treated with high doses of dieldrin was normal. In safely hatched chicks, dose-dependent early death with tonic seizure was observed and all birds exposed to 100 microg/g died within 3 days. Other significant alterations in hatchlings were enlargement of the whole brain, decreases in mRNA expressions of tryptophan hydroxylase in the brainstem and cholesterol side-chain cleavage in the male gonad, and increases in mRNA expressions of cytochrome P450 1A and 2C18 in the liver. For mature birds (males at 5 weeks and females at 10 weeks of age), impairment of eggshell formation such as reduced eggshell mass and eggshell thinning, increases in the body mass of males and the liver mass of females and increases in serum total cholesterol and triglyceride concentrations were observed. The results indicated that not only does the neurotoxicity of dieldrin bring early death, but its effects on reproductive and hepatic functions (detected as gene transcriptional changes in hatchlings) persist harmfully after maturity.

Effects of lindane, paraquat, toxaphene, and 2,4,5-trichlorophenoxyacetic acid on mallard embryo development

The effects were determined of externally treating mallard (Anas platyrhynchos) eggs with two insecticides (lindane and toxaphene) and two herbicides (paraquat and 2,4,5-T) with formulations and concentrations similar to field applications. Paraquat was the most embryotoxic of the four compounds regardless of the type of vehicle. The LC50 for paraquat was 1.5 lb of active ingredient/acre in aqueous emulsion and 0.1 lb/acre in the oil vehicle. The other compounds had LC50's that were several orders of magnitude higher. Both paraquat and toxaphene caused some mortality at 1/2 of the field level of application. Paraquat impaired growth and was slightly teratogenic at 1/2 of the field level of application, but required higher concentrations (1.5 to 3 times the field level) to produce brain and visceral defects. Lindane was teratogenic, resulting in multiple defects but only at doses that were greater than five times the field level of application. Toxaphene resulted in defects of the joints at doses close to or exceeding the LC50. The herbicide 2,4,5-T resulted in few toxic effects and relatively few abnormal survivors with gross defects. The overall embryotoxicity with either vehicle was paraquat greater than lindane greater than toxaphene greater than 2,4,5-T on a lb per acre basis. However the potential hazard at exposures of up to five times the field level of application was paraquat greater than toxaphene; neither lindane nor 2,4,5-T constituted much of a hazard. Both paraquat and lindane were more toxic on lb-per-acre basis when administered in oil vehicle but only paraquat represented a potential hazard at five times the field level of application.

Evaluation of the toxic risk of accumulated DDT in the rat: during fat mobilization

The effects of greatly reduced food intake were investigated in rats which had accumulated three times as much DDT as rats killed with a single dose approaching LD50. DDT and its metabolites mobilized more quickly than the fat deposits. The hypertrophy of the liver due to DDT decreased during food restriction and demonstrated the existence of a large detoxication capacity shown through the high metabolism of the pesticide. The disappearance of p,p' DDE was most rapid, followed by p,p' DDD then p,p' DDT; they did not accumulate in the fat reserves. The half-life of the pesticide, which is normally three months in the rat, was reduced to five days under the experimental conditions. In spite of rapid mobilization, no major toxic signs were detected from either nutritional, physiopathological, or biochemical examinations.