Reproductive viability

Exposure to estrogenic compounds through diet will differ for herbivores and carnivores, the latter being most likely to encounter endogenous steroids in their prey. Efficient uptake of steroids in mammals is illustrated by the use of the contraceptive pill, but routes of absorption in invertebrates remain to be determined. The relationship between endocrine disruption and metabolic toxicity, with reduced reproductive viability a secondary consequence of metabolic disturbance, also merits further study in invertebrate species. 

The main compounds used worldwide to control fouling are organotins as tributyltin oxide (TBTO see Figure 12.1a). They are effective at preventing fouling, but they cause widespread environmental problems due to their persistence in the environment and their toxic effects such as acute toxicity, bioaccumulation, decreased reproductive viability, and increased shell thickness in shellfish. 

Culture a range of invertebrate species from the major phyla, preferably species with short life cycles. The effects of potential endocrine disrupting chemicals on growth rate, reproductive output, viability of offspring and sex ratio, and the vulnerability of different stages of the life cycle, can then be determined. 

Newman B, Ladd P, Brundrett M, Dixon K. Effects of habitat fragmentation on plant reproductive success and population viability at the landscape and habitat scale. Biological Conservation, 2013.159 pp. 16-23. doi 10.1016/j.biocon.2012.10.009... 

In a three - generation reproduction study in rats, Beliles et al. (1980) found that exposure of animals to acrylonitrile in drinking water at 70 mg/kg/day resulted in reduced viability and lactation indices in all generations. The authors considered the reduced pup indices to be the result of maternal toxicity, possibly related to reduced milk production due to decreased water intake by the dams. Fostering of pups on untreated dams lessened pup mortality. Measurement of acrylonitrile in the pups was not performed. 

Drickamer, L.C., Gowaty, P.A. and Holmes, C.M. (2000) Free female mate choice in house mice affects reproductive success and offspring viability and performance. Anim. Behav. 59, 371-378. 

In a 3-generation reproduction study, inbred weanling rats were administered endrin-containing diets at 0, 0.1, 1, or 2 ppm (0.0, 0.005, 0.05, or 0.1 mg/kg/day, respectively) (Eisenlord et al. 1968). There were no effects on indices of fertility, gestation, viability, or lactation. Interpretation of the study results is confounded by the potential presence of infection in controls and, thus, possibly in all animals in the study. 

In a three-generation study of reproductive toxicity no effect was seen on fertility, viability, or litter size in rats fed dietary concentrations of 250ppm." A statistically significant increase in sperm abnormalities was seen in mice after oral administration of ferbam at lOOOmg/kg body weight per day for 5 days. No effects were seen after intraperitoneal administration, indicating that active metabolites were responsible for the teratospermia. 

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