US EPA

2202193 

Technical Report 

Effects of chemicals on egg shell formation 

Mueller, WJ; Leach RMJr 

1974 

PESTAB/75/0573 

Rev 

REF:142 

289-303 

PESTAB. Among the chemicals which affect egg shell formation are substances which may affect matrix formation (lathrogens and Mn), substances that affect calcification (calcium, phosphorus, magnesium, strontium, Vitamin D), substances that may affect carbonate deposition (carbonic anhydrase inhibitors, zinc, and factors altering acid-base balance). A review of the evidence that DDT causes eggshell thinning is given, with a table describing species differences. Some evidence suggests that DDT effect depends on method of administration and age of the bird. Methoxychlor, lindane, and PCBs do not seem to affect eggshell formation, while dieldrin and parathion have caused shell thinning above certain feeding levels. DDT may interfere with the reproductive endocrinology of birds. It is similar in structure to diethyl stilbestrol and the estrogenic activity of the o,p'-isomer has been demonstrated in chickens and quails. Other biochemical effects of DDT observed in avian species have been increased breakdown of blood estradiol concentrations, decreased (SUP)45Ca accumulation in bone, hyperthyroidism, hypothyroidism, and inhibition of carbonic anhydrase activity in blood.