EPA Objectives for Siloxane 

Environmental Monitoring

December 6, 2012

Cathy Fehrenbacher
EPA Objectives for Siloxane Environmental 

Monitoring 

(communicated in writing December 20, 2010 and September 19, 2011, in 

informal pre-ECA process meetings, and during ECA process)

 D4/ D5 Environmental Monitoring

The monitoring program is intended to develop a better understanding of the sources of and 

pathways to the environmental concentrations of D4/D5in environmental media and biota 

associated with industrial releases from manufacturing, processing, formulation (MPF) and highvolume industrial or commercial end users of D4

/D5. The program also intends to include the full 

product life cycle from manufacturing through processing, formulation, high volume industrial or 

commercial end use and disposal as described in the bullets below. The proposed essential 

elements of the monitoring program include:

 Representative Municipal & On-site Industrial Wastewater Treatment Plant (WWTP) Monitoring

– Influent concentrations and flowrates

– Effluent concentrations and flowrates

– Biosolids and their potential migration from land application to water bodies

– Site selection should encompass a representative range of on-site handling and treatment 

practices, for wastes, discharge waters, nearby population centers, and low and high flow.

– Sampling of locations should include points upstream and downstream (progressively 

distant from point of discharge)

– Examination of surface water, suspended solids, bottom sediments, air, biosolids and 

benthic and aquatic organisms
• Monitoring program should include the full product life cycle from manufacturing 

through processing, formulation, end use, and disposal

• Representative watersheds and industrial manufacturing, processing and 

formulating sites

• A representative number of sites would be selected based on information 

obtained from the development of Conceptual Site Models which characterize 

sources and releases for all manufacture, processor, formulator facilities

• The treatment configurations of WWTP must be considered (activated sludge vs

lagoon etc.)

• The population of area that is connected to the facility must be a consideration in 

the selection of sites for both municipal WWTP sites and MPF sites. Geologic, 

geographic, and climatic parameters must also be considered. 

• Characteristics of the receiving water body must also be considered.

• Care also needs to be taken in selecting which POTW will be chosen for a given 

metropolitan area as a large municipality may have facilities of varying sizes.

EPA Objectives - Monitoring Site Selection
• Biota monitoring must support the evaluation of 

bioaccumulation and biomagnification in biota including at 

least 3 replicate samples of specific species per site, with fish 

species selected to represent at least two trophic 

levels/levels of aquatic food web (low and high), and 

additional benthic species, and environmental occurrence 

sampling.

EPA Objectives - Biota Monitoring
EPA Objectives - Existing Monitoring 

Data

• EPA will consider existing monitoring data collected at sites inside and 

outside the US provided they are shown to have similar and 

representative site characteristics. These characteristics include: 

watershed; air-shed; facility production and releases of D4/D5; run-on 

and run-off potential ; waste generation, handling and disposal for onsite waste water treatment facilities; on-site waste disposal units such as 

waste piles, dumps, ponds, pits, landfills, ditches or land applied sludge 

areas; site climate, hydrology, geology, soil type; receiving stream 

morphology, sediments, flow rate, nutrient load, water chemistry, 

aquatic biota on and around the chosen manufacturing facilities. 

• Submission of existing monitoring data is encouraged to further enhance 

the understanding of the behavior of D4/D5 in the environment 

although the EPA will have a high bar for substitution of foreign data for 

monitoring at US sites based on representativeness.
Modifications to EPA Siloxane 

Monitoring Objectives During ECA 

Negotiation

• Intended to focus the monitoring for risk 

assessment purposes

– Fewer MPF monitoring sites 

– Fewer POTW monitoring sites

– Deletion of air monitoring

– Deletion of downstream monitoring

– Biota monitoring has been limited to industrial 

sites