August / September 2010 Bottled Water Reporter - 32

SOQs, MCLs, MCLGs, PHGs, and Guidelines for Drinking Water:
How Misunderstandings and Misuse Result in Consumer Confusion
By Bob Hirst, IBWA Vice President of Education, Science, and Technical Relations

If you

The drinking water lexicon can be confusing.

monitor the media’s coverage of drinking water matters, including bottled water issues, you probably noticed that the media (and its sources) often reference an assortment of confusing terms during any report on drinking water contaminants. The list below presents a few of the more common terms: • standard of quality (SOQs) • maximum contaminant level (MCL) • maximum contaminant level goal (MCLG) • public health goal (PHG) • guideline. The lexicon can be confusing—not only to the average consumer but also the bottled water professional. That’s where IBWA can help. Provided below is a succinct explanation of the differences and applicability of the terms commonly used when reporting on drinking water issues.

Bottled Water

For food and beverage products—including bottled water—the U.S. Food and Drug Administration (FDA) publishes standards of quality (SOQs). FDA establishes those standards to prevent the public from experiencing an unhealthful exposure to contaminants in food and beverages. For bottled water, most FDA SOQs are based on corresponding U.S. Environmental Protection Agency (EPA) maximum contaminant levels (MCLs ) for public drinking water. In a few cases (such as lead and copper) and in the absence of a corresponding EPA MCL, FDA has established its own SOQs to reduce or eliminate the public’s exposure to those contaminants. Because few FDA SOQs are based on original research within the agency, it’s helpful to understand the concept of the EPA’s maximum contaminant levels.

ESTABLISHING SOQS AND MCLS

In the National Primary Drinking Water Regulations (NPDWRs), the EPA notes that “maximum contaminant level means the maximum permissible level of a contaminant in water which is delivered to any user of a public water system.” But how does the EPA derive the values listed in the NPDWRs? It often requires years of research and health data review to arrive at a value that can reliably protect public health. Given that many of those derived values are often analytically undetectable, the EPA must also develop methods that can reliably detect the contaminants as close to their derived healthbased values as is feasible. Because of analytical limitations, many EPA MCLs (and their corresponding FDA SOQs) may not always be established at the goals derived from toxicological research. Instead, the lowest practical level at which most laboratories can reliably detect a contaminant can become the MCL for that contaminant. That was the case when the EPA established an MCL of 10 parts per billion (ppb) for bromate. However, the EPA periodically reviews contaminant MCLs, at which time advances in analytical technology may permit the EPA to lower an MCL to a point closer to its intended goal, which brings us to the next term: maximum contaminant level goal. In the EPA’s NPDWRs, maximum contaminant level goal (MCLG) is defined as “the maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health of persons would occur, and which allows an adequate margin of safety. Maximum contaminant level goals are nonenforceable health goals.” MCLGs are also known as public health goals (PHGs) in states like California, where PHGs are often established independent of the EPA.
AUGUST/SEPTEMBER 2010

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August / September 2010 Bottled Water Reporter

Table of Contents for the Digital Edition of August / September 2010 Bottled Water Reporter
