Table 5.
Summary of low-dose animal studies examining the effects of TCDD on spermatogenesis endpoints
| Study | Administered dose (time of administration) | Animal | Epididymal sperm count | Ejaculated sperm no. | Daily sperm production | Sperm transit rate | % abnormal sperm |
|---|---|---|---|---|---|---|---|
| Mably et al. (409) | 0.064–1 μg/kg (gestational d 15) | Rat | Decreased | NA | Decreased | NA | NA |
| Bjerke and Peterson (402) | 1 μg/kg (gestational d 15) | Rat | Decreased | NA | Decreased | NA | NA |
| Gray et al. (404) | 1 μg/kg (gestational d 8) | Rat | Not significant | Decreased | NA | NA | NA |
| 1 μg/kg (gestational d 15) | Rat | Decreased | Decreased | NA | NA | NA | |
| 1 μg/kg (gestational d 11) | Hamster | Decreased | Decreased | NA | NA | NA | |
| Sommer et al. (408) | 1 μg/kg (gestational d 15) | Rat | Decreased | Decreased | Decreased | Not significant | Not significant |
| Wilker et al. (410) | 0.5, 1 or 2 μg/kg (gestational d 15) | Rat | Decreased | NA | Unaffected | Increased | NA |
| Gray et al. (405) | 0.05–1 μg/kg (gestational d 15) | Rat | Decreased | Decreased | Decreased | NA | NA |
| Faqi et al. (403) | 0.025–0.3 μg/kg (before mating, then 0.005–0.06 μg/kg weekly [to dams]) | Rat | Decreased | NA | Decreased | Increased | Increased |
| Loeffler and Peterson (412) | 0.25 μg/kg (gestational d 15) | Rat | Decreased | NA | Unaffected | NA | NA |
| Ohsako et al. (416) | 0.0125–0.8 μg/kg (gestational d 15) | Rat | Not significant | NA | Unaffected | NA | NA |
| Ohsako et al. (406) | 1 μg/kg (gestational d 15) | Rat | Decreased | NA | Unaffected | NA | NA |
| 1 μg/kg (gestational d 18) | Rat | Unaffected | NA | Unaffected | NA | NA | |
| 1 μg/kg (postnatal d 2 [to pups]) | Rat | Unaffected | NA | Unaffected | NA | NA | |
| Simanainen et al. (407) | 0.03–1 μg/kg (gestational d 15) | Rat | Decreased | NA | Decreased | NA | NA |
| Yonemoto et al. (417) | 0.0125–0.8 μg/kg (gestational d 15) | Rat | Unaffected | Unaffected | NA | NA | Unaffected |
| Yamano et al. (714) | 0.3 or 1 μg/kg (postnatal d 1 and then every week [to dams]) | Rat | Not significant | NA | NA | NA | NA |
| Ikeda et al. (715) | 0.4 μg/kg (before mating, then 0.08 μg/kg weekly [to dams]) | Rat | Unaffected | NA | NA | NA | NA |
| Bell et al. (414) | 0.05–1 μg/kg (gestational d 15) | Rat | Increased (at certain ages) | NA | NA | NA | Increased |
| Bell et al. (415) | 0.0024–0.046 μg/kg (d 12 weeks before pregnancy through parturition) | Rat | Unaffected | NA | NA | NA | Increased |
| Arima et al. (418) | 0.03 or 0.3 μg/kg (gestational d 20, then 5% of dose monthly [to dams]) | Rhesus monkey | Decreased | Not significant | NA | NA | Not significant |
| Yamano et al. (419) | 0.3 or 1 μg/kg (weekly to dams then pups [all postnatal]) | Rat | NA | NA | NA | NA | Increased |
| Jin et al. (411) | 1 μg/kg · d (postnatal days 1–4 [to dams]) | Mouse | Decreased | NA | NA | NA | NA |
| Rebourcet et al. (413) | 0.01–0.2 μg/kg (gestational d 15) | Rat | Decreased (at some ages) | NA | Not significant | NA | NA |
Not significant indicates trend for effect but did not reach statistical significance. Unaffected means assessed, but no differences were observed relative to controls. Here, low doses were considered any at or below 1 μg/kg · d (see text for discussion of how this cutoff was established for rodent studies). NA, Not assessed.