Toxicity and distribution of 2-methyl-4-chlorophenoxyacetic acid (MCPA) in developing chick embryos.
The toxicity of the herbicide Erbitox E30, a commercial formulation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) containing 28% MCPA as sodium-potassium salt and 72% of unknown ingredients, was tested on chick embryos. Sterile aqueous solutions of MCPA were injected into the air chamber at doses of 0, 1.5, 3.0, 6.0, 9.0, or 10.5 mg/egg on day 0 or on day 4 of incubation. The mortality rate for the embryos treated on day 0 of incubation was high in the first 5 days, low from 5-12 days and again increased by 15 days. The 15-day LD50 was 4.4 mg/egg (95% C.I. 3.7-5.3 mg/egg). HPLC analysis of albumen and yolk showed that concentrations of MCPA in the albumen were detectable at 5 min, highest at 7 days and markedly diminished by 14 days of incubation; a significantly lower concentration of MCPA was found in the yolk throughout the incubation period, except at 14 days when the yolk concentration was 4 times higher than the albumen concentration. At 15 days of incubation, MCPA was evenly distributed in the tissues of the embryo. MCPA was more toxic to 4-day embryos; concentrations above 6.0 mg/egg were lethal to all embryos within the first week of incubation. The 15-day LD50 for treatment on day 4 of incubation was 2.8 mg/egg (95% C.I. 2.5-3.2 mg/egg). The liver was affected by treatment with MCPA, being green in treated embryos. However, histological examination revealed few changes in the liver parenchyma.
Arias
E
E
Dipartimento di Biologia, Università di Milano, Italy.
Maci
R
R
Santagostino
A
A
D008456:2-Methyl-4-chlorophenoxyacetic Acid / Q000378:metabolism / Q000633:toxicity*; D000653:Amniotic Fluid / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism; D002642:Chick Embryo / Q000187:drug effects* / Q000378:metabolism; D004530:Egg Yolk; D005260:Female; D006016:Glycolates / Q000633:toxicity*; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D014018:Tissue Distribution
D006016:Glycolates; D008456:2-Methyl-4-chlorophenoxyacetic Acid