Developmental studies of hanford miniature swine exposed to 60‐Hz electric fields

Abstract

Evaluations of reproductive and developmental toxicology, including teratology, were included as part of a broad screening study in Hanford Miniature swine (HMS) to detect effects of exposure to electric fields. One group (E) was exposed to a uniform, vertical, 60-Hz, 30-kV/m electric field for 20 h/day, 7 days/week; sham-exposed (SE) swine were housed in a separate, environmentally equivalent building. The first generation (F0) gilts were bred after 4 months of study; some were killed for teratologic assays at 100 days of gestation (dg), and the others produced an F1 generation of offspring. The pooled incidence of terata in these litters (teratologic assays and live births) was similar in the E and SE groups. The F0 females, which produced the F1 generation, were bred again after 18 months of exposure and were killed at 100 dg. Malformation incidence in E litters (75%) was significantly greater than in SE litters (29%). No consistent differences in litter size, fetal mass, or mass of fetal organs were detected. The F1 gilts were bred at 18 months of age; defective offspring were found in significantly more of the E litters (71%) than in SE litters (33%). These F1 females were bred again 10 months later and teratologic assays were performed on their second litters at 100 dg. The percentage of litters with malformed fetuses was essentially identical in the E and SE groups (70% and 73%, respectively). There appears to be an association between chronic exposure to a strong electric field and developmental effects in swine, although the change in incidence of malformations between generations and between the first and second breedings makes it impossible to conclude unequivocally that there is a cause-and-effect relation.

Developmental effects of electromagnetic fields

“…Sikov et al [1987] conducted a three generation study on Hanford Miniature swine. The exposed group was kept in a 60 Hz, 30 kV/m electric field for 20 h/day, 7 days/week.…”

Reproduction, growth, and development of rats during chronic exposure to multiple field strengths of 60-Hz electric fields

“…The teratological assay yields several parallels with results of our previous replicate experiment. In the earlier experiments (Rommereim et al, 1987) incidences of litters with malformed fetuses (combined data from replicate experiments) from 3-month-old F, dams were 5.0% for controls and 9.5% in litters from animals exposed at 65 kV/m. In the results reported here, malformation incidence was doubled in rats exposed at 65 kV/ m as predicted by the statistical model (Fig.…”

“…Subsequently, rats were used to investigate the possible effects of electric field exposure on development and reproduction. Two, essentially identical, multiple-generation rat experiments were conducted (Rommereim et al, 1987). Copulatory behavior, gestational weight gains, pup weights at birth, and their subsequent growth curves were not affected by exposure.…”

Use of Miniature Pig for Biomedical Research, with Reference to Toxicologic Studies

“…When female minipigs were bred after 18 months of uniform exposure to a vertical, 60-Hz, 30-kV/m electric field for 20 h/day, 7 days/week and killed at 100 days of gestation, the malformation incidence in litters (75%) of the exposed females was significantly greater than in litters (29%) of the sham-exposed minipigs. When F1 gilts were bred again at 18 months of age, defective offsprings were found more in litters (71%) of the F1 gilts born from the exposed females than litters of the F1 gilts born from the sham-exposed females, suggesting an association between chronic exposure to a strong electric field and developmental effects in minipigs 51 . Another teratogenicity study was reported for Göttingen minipigs which were given mashed feed mixed with pyrimethamine (PY), an antiparasitic compound.…”