Developmental Effects of Complex Pollutant Mixtures: Organophosphates, Alkylphenols, and Larval Salmonid Ossification

EPA Grant Number: U915656
Title: Developmental Effects of Complex Pollutant Mixtures: Organophosphates, Alkylphenols, and Larval Salmonid Ossification
Investigators: Amweg, Erin L.
Institution: University of California - Berkeley
EPA Project Officer: Edwards, Jason
Project Period: January 1, 1999 through January 1, 2003
Project Amount: $90,322
RFA: STAR Graduate Fellowships (1999) RFA Text |  Recipients Lists
Research Category: Fellowship - Toxicology , Health Effects , Academic Fellowships


The objective of this research project is to determine whether if estrogenic pollutants alleviate adverse effects of organophosphate pesticides by altering pesticide metabolism. This project study will explore the resultant outcome of combined -contaminant mixtures on biochemical endpoints, and on an ecologically-significant endpoint, larval bone development.


This research will be conducted in three stages: (1) pollutant exposures; (2) in vitro mechanistic experiments; and (3) field measurements of actual contaminant loads in the Sacramento-San Joaquin drain-age basin, in California. 1) Exposures will be conducted using various combinations and dosing regimes of malathion and nonylphenol. Larval fishes will be raised from hatch and exposed through either water or diet for 7-30 days post-hatch, or once via injection into the yolk sac of the developing fry. Carboxylesterase, acetylcholinesterase, and p450 activity will be assessed in liver tissue. Bone precursor cells will be localized during migration and differentiation by in situ immunostaining techniques. Bone density will be measured, and the structural skeletal endpoints will be will be assessed after clearing and staining the fish. 2) The mechanism throughby which malathion and nonylphenolthese two chemicals mediate their effects on the organism will be explored by estrogen receptor and aryl-hydrocarbon receptor binding assays, p450 transactivation assays, and enzymatic analysis, using nonylphenol and malathion as competitive substrates. 3) Finally, chemical analysis of water and sediment samples, prey items, and fish tissue will be conducted along the Sacramento and San Joaquin Rivers and their Delta to quantify levels of several organophosphate pesticides and known environmental estrogens in the aquatic habitat around the San Francisco Bay. Collections of juvenile fall-run chinook and rainbow trout along the estuary, and comparison of skeletal defects to those induced in the laboratory, will allow crude estimates of the current potential impact of pollutants on wild fish populations.

Supplemental Keywords:

fellowship, organophosphates, alkylphenols, larval salmonid ossification, pollutants, pesticides, larval bone development, California, Sacramento-San Joaquin drainage basin.