Nitrosamines are just one of many emerging classes of nitrogenous disinfection by-products (N-DBPs) of concern.
In another report, Occurrence and Formation of Nitrogenous Disinfection By-Products (2009, order #91250/
project #3014), model compounds and natural organic matter (NOM) were examined as sources of precursors for
NDMA and other N-DBPs. Although carbon-rich NOM fractions can be an important source of precursors for regulated
DBPs (trihalomethanes [THMs] and haloacetic acids [HAAs]), this study demonstrated that it was certain nitrogen-rich
NOM isolates that were important sources of N-DBP precursors. Although algae and treated wastewater were both
found to be sources of precursors for many emerging N-DBPs, treated wastewater was the major source of NDMA
precursors. An important aspect in this project was to show how to best balance the control of regulated DBPs and that
of emerging N-DBPs.
Ongoing research funded by the Foundation continue to provide state-of-the-art information for the water industry.
Currently, researchers have focused on several nitrosamines in water. Project #4089, “Method Development for
Disinfection By-Products Associated With Bladder Cancer,” will examine if there are unidentified DBPs (e.g.,
nitrosamines from alkaloidal material) that may better explain the cancer risk associated with chlorinated drinking water
in epidemiology studies. Another project #4209, “Development and Application of a Total Nitrosamine Assay for
Disinfected Waters,” will develop a method to measure the total amount of nitrosamines in water instead of just one
associated with the few chemicals typically measured.
Because DBP FP tests do not provide a true indication of the likely amount of DBPs formed during actual drinking water
treatment, a new project #4180, “Development of a Protocol to Predict the Formation of Nitrosamines While
Minimizing the Formation of Regulated DBPs,” is developing a bench-scale test to simulate nitrosamine formation
in a distribution system (a simulated distribution system [SDS] test). Moreover, this project is examining the formation
and control of regulated and other emerging DBPs during these tests. As more utilities consider a switch to chloramines
or the use of water from impaired watersheds, this SDS test will provide utilities with a new tool to access how best to
meet existing DBP regulations and that of emerging DBPs that may be regulated in the future.
Metropolitan Water District of Southern California (Metropolitan) and other utilities have benefited immensely
from the Foundation-supported research on nitrosamines. This research has resulted in many utilities, including
Metropolitan, conducting internal studies to better understand the source of NDMA precursors in their waters and
the most cost-effective means of controlling NDMA formation. Although Metropolitan found that their watershed
is impacted to some extent by treated wastewater, the pre-oxidation (e.g., ozone) step was found to destroy NDMA
precursors. At Metropolitan plants, a major source of NDMA precursors was associated with the amine-based
polymer they use. So Metropolitan is examining means of achieving their treatment objectives with a lower polymer
dose and more coagulant. Information from Foundation studies is providing insights on how best to meet potential
future regulatory issues.
Although the UCMR2 will provide the USEPA and stakeholders with a tremendous amount of occurrence data on
NDMA and other nitrosamines, it is well-crafted studies conducted for the Foundation that will provide the water
industry with the type of scientific information upon which a regulation on nitrosamines can be constructed based
on sound science. Metropolitan looks forward to participating in and following up on new Foundation studies that
allow them to best manage their resources to produce water that minimizes the formation of nitrosamines and other
emerging DBPs of health concern.