Post on 13-Jan-2016
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Endocrine Disrupting Compounds:
General Overview and Impact on Freshwater Biology
SCAP Water Issues Committee Meeting
May 5, 2011
Photo by Judy Gibson From: Jenkins et al., 2009 P
The Endocrine System
• All vertebrates possess an endocrine system which consists of- Glands: Secrete hormones
- Receptors: Detect and react to hormones
The Endocrine System
• All vertebrates possess an endocrine system which consists of- Glands: Secrete hormones
- Receptors: Detect and react to hormones
• The endocrine system is responsible for biochemical signals that insure proper function of the body throughout the life cycle.
The Endocrine System
• All vertebrates possess an endocrine system which consists of- Glands: Secrete hormones
- Receptors: Detect and react to hormones
• The endocrine system is responsible for biochemical signals that insure proper function of the body throughout the life cycle.
• Endocrine disrupting compounds (EDCs) mimic natural hormones and can bind with hormone receptors – disrupting normal endocrine function
NonylphenolDegradation product of nonionic surfactants (detergents)
17-EstradiolNatural hormone
Endocrine Disrupting Compounds
• Exogenous Compounds-compounds (molecules) that originate outside of living organisms
• Encompass a variety of chemical classes including pesticides, pharmaceuticals, plastisizers, flame retardents, hormones, cleaning products, personal care products
• Many are organic wastewater contaminants (OWCs) and some are contaminants of emerging concern (CECs)
• Primary focus has been on the EDCs “estrogenic effects”-where EDCs mimic the hormone estrogen
• Estrogen receptors are essentially the same among most vertebrates
EDCs Widespread in the Environment
EDC Common Use
Alkylphenol ethoxylates (APEs) and their degradation products
Industrial and household nonionic surfactants (detergents)
Bisphenol-A (BPA) Most widely used plasticizer (softener) in the US
17-ethynyl estradiol (EE2)
Synthetic estrogen used in most birth control and hormone replacement drugs
Organochloride pesticides (OCPs)
Pesticides, herbicides and fungicides used by industry and household consumers (ex: DDT)-banned since
Phthalates Ubiquitous component of leachable plastics
Polyaromatic hydrocarbons (PAHs)
Nonvolatile hydrocarbons present in oils and petroleum-based lubricants
Polychlorinated biphenyls (PCBs)
Oils used primarily in transformers (ex: Aroclor)-banned since 1976
Triclosan and degradation products
Common ingredient of soaps and personal/household disinfectants
EDC Release to Freshwater Systems
• Discharge from wastewater treatment plants (WWTPs)APEs, Hormones (e.g. EE2), Triclosan, BPA, Pharmaceuticals
• Agricultural wastewater dischargesHormones
• Urban and agricultural runoffPAHs, OCPs
• Industrial dischargesAPEs, BPA, Phthalates
Primary release mechanisms:
Impacts on Freshwater Biology
Observations led to years of research to determine cause of abnormalities
Abnormally high incidence of intersex fish observed downstream from WWTPs in late 1970s
Field studies:
• Confirmed correlation between proximity to treated effluent and sexual disruption
• Measured concentrations of EDCs in rivers and treated wastewater effluent-detected at parts per billion (g/L) to parts per trillion (ng/L)
Laboratory studies:
• Examined estrogenic effects of individual EDCs on fish and other biota
• Determined potency (i.e. estrogenic activity) of individual EDCs (e.g. EE2 found to cause feminization at 1.2 ng/L)
Impacts on Freshwater Biology
Rodgers-Gray et al. 2001
− Possession of both male and female germ cells
− Males in possession of “female-like” gonadal tissue and reproductive ducts
− Increased levels of female-specific protein vitellogenin (VTG)
− Reduced sperm density
Evidence of sexual disruption includes:
Impacts on Freshwater Biology
Rodgers-Gray et al. 2001
Exposure of juvenile wild roach to sewage treatment water effluent (STWE) of various dilutions resulted in dose-dependent and sustained feminization of reproductive ducts in males
− Possession of both male and female germ cells
− Males in possession of “female-like” gonadal tissue and reproductive ducts
− Increased levels of female-specific protein vitellogenin (VTG)
− Reduced sperm density
Evidence of sexual disruption includes:
Many EDCs bioconcentration in higher trophic level organisms such as fish, allowing for exposure even when aqueous concentrations are very low
Impacts on Freshwater Biota
• Aqueous concentration
• Partition (i.e. does it prefer to sorb into sediments or does it remain in the aqueous phase?)
• Degree of bioconcentration
• Estrogenic activity
• Degradation pathways
The impact of individual EDCs is primarily a function of the compound’s chemical properties and the extent of its use in human activity
Factors To Consider:
Bisphenol-A
DDTPossible treatment options will also depend on chemical properties
Factors Effecting EDCs’ Biological ImpactComparison of Common EDCs:
EDC Sorption Degradation Bio-concentrationEstrogenic
ActivityPossible
Treatment Options
APEs Moderate Bio-aerobic & anaerobic
Moderate High Sorption, oxidation, reduction
BPA Moderate Bio-aerobic & Photo
Moderate High Biodeg. Photodeg.
EE2 Strong Bio-aerobic Strong Very High Sorption, Oxidation
OCPs Moderate Bio & Photo are minimal
Very Strong Low to Moderate Sorption, Photodeg. Oxidation
Phthaltes Weak Bio-aerobic Weak Moderate Biodeg., Oxidation
PAHs Strong Bio-aerobic & Photo
Highly Variable Moderate to High Sorption, Oxidation
PCBs Strong Bio & Photo are minimal
Strong Moderate to High Sorption, Photodeg. Oxidation
Triclosan Moderate Photo, Bio is disputed
Dioxin biproducts strongly bioconcentrate
Moderate (for Dioxins + Furans)
Sorption, Oxidation, Possibly Reduction
EDCs in the Santa Ana RiverIssue: To what extent to EDCs in the SAR impact the reproductive ability of the Santa Ana Sucker
Gross et al., 2004:
•Measured concentrations of OWCs including APEs and EE2 in effluent of four WWTPs and in river water along the SAR.
•APE metabolites detected in all effluents/at all locations-max concentrations of 19.6 parts per billion (g/L) in effluent upstream of Prado Dam
•EE2 not detected in river or effluent water at detection limit of 2 parts per trillion (ng/L)
•Significant downstream attenuation of compounds observed
Recent studies from the SAR basin provide insight into this issue:
EDCs in the Santa Ana RiverIssue: To what extent to EDCs in the SAR impact the reproductive ability of the Santa Ana Sucker
Jenkins et al., 2009:
•Detected OWCs, including EDCs, in aquatic biota and water in the SAR basin along a gradient of proximity to WWTP effluent (including one control site).
•Conducted in vitro assays of sexual parameters of western mosquitofish (proxy for santa ana sucker)
•Results indicate endocrine disruption in the form of altered hormone ratios in both sexes and secondary sex characteristics in males
Recent studies from the SAR basin provide insight into this issue:
Summary
• EDCs are exogenous compounds that encompass a variety of chemical classes and derive from numerous areas of human activity
• Mimic hormones, in particular estrogen, and bind to endocrine receptors thereby interfering with normal endocrine function
• Treated effluent is an important conduit of EDCs to the environment
• Fate, transport and biological impact is a function of chemical properties and extent of human use
• Large body of evidence that exposure to EDCs causes endocrine disruption in riverine fish, including mosquito fish in the Santa Ana River
• On-going research further investigates link between EDCs and reproductive impairment in aquatic biota