Pregnancy outcomes for mouse preimplantation embryos exposed in vitro to the estrogenic pesticide o,p'-DDT.

Pregnancy outcomes were evaluated following uterine transfer of murine preimplantation embryos exposed in vitro to the estrogenic pesticide o,p'-dichlorodiphenyltrichloroethane (o,p'-DDT). Single-cell embryos were incubated 72 h in medium droplets containing 0.1% ethanol (control) or 0.1 microg/ml o,p'-DDT (pesticide). Morula and preblastocyst embryos were transferred in groups of eight to right uterine horns of pseudopregnant mice (n=111) and pups (n=132) were evaluated at Caesarean-section (C-section). In vitro exposure to o,p'-DDT reduced development to morula (P<0.001) and modestly increased blastomere apoptosis (P=0.05). However, treatment differences were not detected for implantation rates (35% versus 39%; P=0.64), pup numbers per dam (2.3 versus 1.9; P=0.36), transfer efficiencies (16% versus 14%; P=0.53), fetal weights (1.56 g versus 1.57 g; P=0.91), skeletal abnormalities (55% versus 66%; P=0.47), or male ratios (54.8% versus 53.8%; P=1.0). In vitro exposure of preimplantation embryos to 0.1 microg/ml o,p'-DDT for 72 h resulted in no measurable effects on subsequent implantation or pup characteristics at C-section.

Low-dose agrochemicals and lawn-care pesticides induce developmental toxicity in murine preimplantation embryos.

Occupational exposures to pesticides may increase parental risk of infertility and adverse pregnancy outcomes such as spontaneous abortion, preterm delivery, and congenital anomalies. Less is known about residential use of pesticides and the risks they pose to reproduction and development. In the present study we evaluate environmentally relevant, low-dose exposures to agrochemicals and lawn-care pesticides for their direct effects on mouse preimplantation embryo development, a period corresponding to the first 5-7 days after human conception. Agents tested were those commonly used in the upper midwestern United States, including six herbicides [atrazine, dicamba, metolachlor, 2,4-dichlorophenoxyacetic acid (2,4-D)], pendimethalin, and mecoprop), three insecticides (chlorpyrifos, terbufos, and permethrin), two fungicides (chlorothalonil and mancozeb), a desiccant (diquat), and a fertilizer (ammonium nitrate). Groups of 20-25 embryos were incubated 96 hr in vitro with either individual chemicals or mixtures of chemicals simulating exposures encountered by handling pesticides, inhaling drift, or ingesting contaminated groundwater. Incubating embryos with individual pesticides increased the percentage of apoptosis (cell death) for 11 of 13 chemicals (p