Lab Science News

By Gregory Salata, Ph.D., Kelso, WA

Many sampling programs include collection and analysis of an equipment blank to ensure there is no contribution of contaminants from the sampling equipment and associated process. To establish that sample collection procedures are contaminant free, an equipment blank is often collected. Equipment blanks are collected by passing water through the sample collection apparatus or utensil and collecting the water into the appropriate containers. To ensure that the water itself is contaminant free, the laboratory will supply the field crew with deionized (DI) water.

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EPA is developing a new approach to managing drinking water and is currently seeking comments by the public and stakeholders, including utilities, rural communities, and states.

The new approach will focus on four areas:

• Address contaminants as a groups rather than one at a time so that enhancement of drinking water protection can be achieved cost-effectively.
• Foster development of new drinking water technologies to address health risks posed by a broad array of contaminants.
• Use the authority of multiple statutes to help protect drinking water.
• Partner with states to develop shared access to all public water systems (PWS) monitoring data.

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By Chris Leaf, Project Chemist, Kelso, WA

Imagine turning on a faucet to get a glass of water and discovering that perfluorooctane sulfonic acid, methyl tert-butyl ether, or chloromethane has flowed into your glass. These chemical compounds represent real threats to the public and are present in many public water supplies today.

In September of 2009, the EPA finalized its Contaminant Candidate List 3 (CCL3), comprised of 116 drinking water contaminants. These contaminants have already been discovered in public water systems or pose the risk of existing in public water supplies. Under the Safe Drinking Water Act (SDWA), the EPA is required to evaluate and determine whether to regulate at least five contaminants from the CCL every five years. The EPA decides if regulations will be required based on the following criteria¹:

• The contaminant may have an adverse effect on the health of persons.
• The contaminant is known to occur, or there is a great likelihood that the contaminant will occur in public water supplies with a frequency and at levels of public health concern.
• In the sole judgment of the EPA Administrator, regulation of the contaminant presents a meaningful opportunity for health risk reduction for persons served by public water systems.

Read more about emerging contaminants and health risks…

by Brian Lewis, Ph. D

On January 15, 2010, the Food and Drug Administration (FDA) reversed its position that exposure to bisphenol-A (BPA) is not harmful, stating that they now “have some concern about the potential effects of BPA on the brain, behavior, and prostate gland in fetuses, infants, and young children”.¹ In the same report, the FDA voiced their support for the food and beverage container industry to halt production of baby bottles and feeding cups in the U.S. that contain BPA.

The FDA’s current position on BPA follows a 2008 draft report by the agency that claimed the no observable adverse effect level (NOAEL) of 5 mg/kg body weight/day was “an adequate margin of safety … for BPA at current levels of exposure from food contact uses,” and that the 2.42 μg/kg body weight/day and 0.185 μg/kg body weight/day exposure levels found in infants and adults, respectively, was safe.² However, when that draft report was submitted to a seven-member panel of experts for peer review, the panel refuted the FDA’s position, stating that “the available qualitative and quantitative information … provides a sufficient scientific basis to conclude that the Margins of Safety defined by FDA as ‘adequate’ are, in fact, inadequate”.³

Read more about Bisphenol-A…

A recent United States Geological Survey (USGS) study of public drinking water wells in California, Connecticut, Nebraska and Florida found that some were contaminated, but in amounts so minimal, human health was unlikely to be affected. The USGS tracked the movement of contaminants in groundwater and public-supply wells in four different aquifers.

According to the USGS, wells are not equally vulnerable to contamination because of differences in three factors: the general chemistry of the aquifer, groundwater age, and direct paths within aquifer systems that allow water and contaminants to reach a well. The importance of each factor differs among the various aquifer settings, depending upon natural geology and local aquifer conditions, as well as human activities related to land use and well construction and operation. However, the USGS feels that the study of the four different aquifer systems can be applied to similar aquifers and wells throughout the nation.

Read more about drinking water contamination…

This article describes the background, stages and the new deadlines for public water systems to comply with the most current disinfectants and disinfection byproducts rule.

By Dr. Harlan H. Bengtson, PE

Background on Disinfection and Disinfection Byproducts

Jersey City, NJ was the first U.S. city to routinely disinfect its municipal water supply, starting in 1908.¹ Soon after, thousands of cities and towns across the country began to do the same and this dramatically decreased the prevalence of waterborne diseases such as cholera and typhoid. To demonstrate, the incidence rate of typhoid fever in the U.S. dropped from about 100 cases per 100,000 people in 1900 to 33.8 cases per 100,000 people in 1920.² By 2006, this rate had dropped to 0.1 cases per 100,000 people.³

Read more about disinfectants rule…

Chlorine has been used to disinfect water for almost a century due to its ability to kill bacteria and viruses in water. The use of chlorine as a disinfectant has been an effective contribution to public health eliminating plagues such as cholera and typhoid, and reducing the incidence of intestinal illness and other health problems caused by waterborne pathogens such as cryptosporidium. The benefits of disinfection, however, do not come without an effect.

Depending on the disinfection procedure used (chlorination, chloramines, bromine, ozone etc.) and the chemical composition of the water prior to disinfection, many different organic chemical disinfection byproducts can form in drinking water. Trihalomethanes (THMs) are a byproduct of chlorine disinfection and to a lesser degree, disinfection using chloroamines. The THMs (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) are formed when free chlorine combines with organic matter, like decaying vegetation commonly found in lakes and reservoirs. Total Trihalomethanes (TTHM) are regulated by the EPA at a maximum allowable annual average of 80 parts per billion. Some of the THMs are very volatile and will vaporize into air easily, so they may be inhaled while showering, however, the EPA has determined that this exposure is minimal compared to that from consumption. The Levels of THMs formed can vary widely on a number of factors including temperature, amount of chlorine used, season, and amount of plant material in the water, among others.

Some drinking water systems use chloroamines as a residual disinfection agent in place of chlorine. Chloroamine is not as reactive as chlorine and less THMs are formed. However, there are also drawbacks to chloroamine use. Chloroamine may cause nitrification and corrosion and may also increase exposure to other disinfection byproducts, such as N-nitrosodimethylamine (NDMA).

EPA Method 524.2 is used to analyze samples for TTHMs. This method involves concentrating the THMs from a water sample using a technique known as purge and trap. This technique isolates the volatile organic compounds (VOCs) from the water. The VOCs are then desorbed into a gas chromatograph/mass spectrometer (GC/MS) where they are separated, their identity is confirmed, and their concentrations are determined. Standard reporting limits for individual TTH with this method are 0.5 µ/L