However, it is also important to examine long-term low level effects of hog waste that may enter the environment in a less catastrophic manner. The current treatment method for hog waste is storage in anaerobic lagoons and field spraying. Although field spraying of manure has been a common practice for many decades, the magnitude of the hog industry, coupled with inadequate acreage for spray fields, raises concerns for this method of waste management as an environmental hazard and has increased hog waste inputs into the aquatic environment. Extensive research has been performed to examine high levels of nitrogen and phosphorus in water bodies due to hog waste inputs. However, other, perhaps more subtle, effects of hog waste on aquatic populations have not been investigated.
Estrogens are a group of steroid hormones that primarily control reproduction in vertebrate species.
Current concern has focused on man-made chemicals that mimic or block the action of estrogens and other steroid hormones, therefore causing possible developmental and reproductive abnormalities. Extensive characterization of hog waste has not been performed, although the aforementioned study identified two estrogenic compounds in their analysis of field runoff. The first objective will be to determine the prevalence of estrogenic compounds in hog waste contained in lagoons. Estrogenic effects of hog waste runoff on wild fish populations will be assessed in a similar manner by collecting killifish from streams adjacent to hog farming operations and examining male vitellogenin production. Identification of estrogenic compounds present in the waste will soon be performed, as well as further laboratory exposure studies.