Maximum Contaminant Level Goal Research Articles

Derivation of a drinking water equivalent level (DWEL) related to the maximum contaminant level goal for perfluorooctanoic acid (PFOA), a persistent water soluble compound

Water soluble compounds persistent in humans and the environment pose a challenge for estimating safe levels in tap water. A viable approach to estimate a drinking water equivalent level (DWEL) for perfluorooctanoic acid (PFOA) was applied to its extensive relevant information from human and laboratory animal studies. PFOA has been identified at 3.5 μg/L (mean) in tap water in proximity to a manufacturing facility; however, in most supplies, the levels were below 7.5 ng/L (usual limit of detection). PFOA has an average half-life in humans of 3.5 years. From animal studies, PFOA is considered a possible hepatotoxicant and developmental toxicant for humans. Based on two chronic studies, PFOA was judged to be a possible human carcinogen, whose mode-of-action was likely to be related to receptor activation but not genotoxicity. The Benchmark Dose-Uncertainty Factor approach was selected for dose–response for noncancer and cancer. Based on internal dose of PFOA, the DWEL protective against cancer is 7.7 μg PFOA/L tap water, and the noncancer DWELs range from 0.88 to 2.4 μg/L. These DWELs can be considered a reliable, albeit conservative, basis to set a Maximum Concentration Level Goal under the US Safe Drinking Water Act.

Determination of migration monomer styrene from GPPS (general purpose polystyrene) and HIPS (high impact polystyrene) cups to hot drinks

In this study, 162 samples were analysed for monomer styrene content with using high performance liquid chromatography (HPLC) method in hot tea, milk, cocoa milk. The monomer styrene content, expressed in μg/l of drink and the level of migration of styrene monomer were varied from 0.61 to 8.15 for hot tea, from 0.65 to 8.30 for hot milk, from 0.71 to 8.65 for hot cocoa milk in GPPS (general purpose polystyrene), from 0.48 to 6.85 for hot tea, from 0.61 to 7.65 for hot milk, from 0.72 to 7.78 for hot cocoa milk in HIPS (high performance polystyrene) cups in different temperatures and times. The estimated limit of detection of (HPLC) method for all samples was 0.001 mg/kg. There is linear regression for styrene monomer from 1 to 10 ng/ml. Several samples spiked with a known amount of styrene monomer. The results of the recovery in study for styrene monomer were determinate to be mean, 96.1 ± 1.92 to 99.7 ± 1.15%. The results of this study indicate that styrene monomer from polystyrene disposable into hot and fat drinks was migrated and this migration was highly dependent on fat content and temperature of drinks. The derived concentration of styrene monomer in this study was above the EPA (Environmental protection agency) recommended level, especially in MCLG (Maximum contaminant level goal) standard. More study is needed to further elucidate this finding.

Should Perchlorate in Drinking Water be Regulated?

The rocket fuel ingredient perchlorate has emerged over the past decade as one of the most controversial drinking water regulatory issues. Elevated concentrations have been reported in surface waters and groundwaters and in public water systems in 26 states. Perchlorate was included on the second Contaminant Candidate List (CCL2) for possible regulation under the Safe Drinking Water Act (SDWA). Every five years, the U.S. Environmental Protection Agency (USEPA) is required to determine whether to regulate at least five contaminants from the CCL. A maximum contaminant level goal (MCLG) and National Primary Drinking Water Regulation (NPDWR) are required for a contaminant on the CCL if USEPA determines that: the contaminant may have an adverse effect on the health of people; the contaminant is known to occur or there is substantial likelihood for it to occur in public water systems with a frequency and at levels of public health concern; and, regulation of the contaminant presents a meaningful opportunity for health risk reduction for people served by public water systems. This article briefly reviews a preliminary determination on perchlorate that was issued by the USEPA on Oct. 10, 2008 (USEPA, 2008).

Guest Editorial: Biomarkers of Perfluorinated Chemicals and Birth Weight

Guest Editorial: Biomarkers of Perfluorinated Chemicals and Birth Weight

Effect of Copper(II) on Natural Organic Matter Removal During Drinking Water Coagulation Using Aluminum‐Based Coagulants

Coagulation has been proposed as a best available technology for controlling natural organic matter (NOM) during drinking water treatment. The presence of heavy metals such as copper(II) in source water, which may form copper-NOM complexes and/or interact with a coagulant, may pose a potential challenge on the coagulation of NOM. In this work, the effect of copper(II) on NOM removal by coagulation using alum or PAX-18 (a commercial polymerized aluminum chloride from Kemiron Inc., Bartow, Florida) was examined. The results show that the presence of 1 to 10 mg/L of copper(H) in the simulated waters improved the total organic carbon (TOC) removal by up to 25% for alum coagulation and by up to 22% for PAX-18 coagulation. The increased NOM removal with the presence of copper(II) in the waters can most likely be ascribed to the formation copper-NOM complexes that may be more adsorbable on aluminum precipitates and to the formation of copper(II) co-precipitates that may also adsorb NOM. The presence of 1 to 5 mg/L of copper(I) in the waters containing 3 mg/L NOM as carbon was reduced below the maximum contaminant level goal (1.3 mg/L as copper) using either coagulant. The results suggest that the presence of copper(H) in source water may not adversely affect the NOM removal by coagulation. A good linear correlation was observed between the TOC removal efficiency and the log-total moles of the precipitated metals, which include the metal ion from a coagulant and the divalent metal ion(s) in source water.

A drinking water utility's perspective on bromide, bromate, and ozonation

Application of ozone in drinking water treatment plants in the US is growing because of ozone's multiple benefits. Ozone functions as a powerful oxidizing agent and disinfecting agent, it improves finished water quality by reducing turbidity, it reduces the formation of many halogenated disinfection by-products, and it is capable of treating chlorine resistant organisms like cryptosporidia. However, when bromide ion is present, e.g. from the geology, runoff, or sea water intrusion, ozone will convert some of the bromide to bromate depending upon the treatment reaction conditions. Bromate can also be introduced into drinking water as a contaminant in the chlorine used for disinfection. The current maximum contaminant level (MCL) in the USA is 0.010 mg/L, and the maximum contaminant level goal (MCLG) is zero, because of the possibility that bromate may function as a genotoxic carcinogen. The level of the MCL, especially if it is lowered, will significantly impact the ability of many water suppliers to utilize ozone in their water treatment processes and also raise the costs of those applications.

Arsenic Concentrations in the Surface, Well, and Drinking Waters of the Hisarcik, Turkey, Area

ABSTRACT Arsenic is one of the most important water pollutants because of its carcinogenicity. The association between arsenical poisoning and the development of internal malignancies and skin cancer is well known. The U.S. Environmental Protection Agency (USEPA) sets maximum contaminant level goals at zero for carcinogens. In this study are presented groundwater arsenic concentrations in the area of naturally rich boron sources of Turkey. Water samples were collected from the Hisarcik, Turkey, area, which has a large boron mine. An inductively coupled plasma/mass spectrometry method was used to analyze arsenic concentrations in water samples. The arsenic levels in water ranged from no detectable amounts to 3.00 mg As/L (mean: 0.46 ± 0.07SD). This mean As level exceeds by a factor of 10 the USEPA's current Maximum Contaminant Level of 0.05 mgAs/L. Some possible health problems associated with consumption of arsenic-contaminated water are discussed and public health interventions proposed.

Drawing the Battle Lines: Tracing the "Science War" in the Construction of the Chloroform and Human Health Risks Debate

The United States Environmental Protection Agency (US EPA) and the Chlorine Chemistry Council, the Chemical Manufacturers Association, and others have been embroiled in a legal challenge concerning the US EPA's "reversal" regarding the scientific assessment of chloroform's carcinogenicity. This issue arose during the US EPA's November 1998 promulgation of a Maximum Contaminant Level Goal for chloroform in the Stage 1 Final Rules for Disinfectants and Disinfection Byproducts in drinking water. In this paper we adopt a claimsmaking approach: to trace the development and outcome of the chloroform court challenge in the USA, to examine the construction of scientific knowledge claims concerning chloroform risk assessments, and to investigate how different interpretations of scientific uncertainties regarding the evidence are contested when such uncertainties are brought into a regulatory and judicial arena. This "science war" (Chlorine Chemistry Council and others v. US EPA and others) took place in the US Court of Appeals for the District of Columbia Circuit. The scientific "authority" in the construction of scientific claims in this dispute is based on the International Life Sciences Institute expert panel report on chloroform. Examining these science wars is important because they signal critical shifts in science policy agendas. The regulatory outcome of the chloroform science war in the United States can have profound implications for the construction and acceptance of scientific claims regarding drinking water in other jurisdictions (e.g., Canada). In this challenge, we argue that the actors involved in the dispute constructed "boundaries" around accepted and credible scientific claims.

RETRACTED: Disinfection of Bacillus subtilis spores with chlorine dioxide: a bench-scale and pilot-scale study

Chlorine dioxide (ClO2) inactivation of Bacillus subtilis ATCC 19659 spores was examined at pilot-scale during periods representative of winter and summer temperature extremes at the Britannia Water Treatment Plant in Ottawa, Canada. In addition, bench-scale experiments using the same source water (Ottawa River, Ontario, Canada), as well as buffered and unbuffered laboratory waters were conducted using B. subtilis spores. Bench-scale inactivation of B. subtilis spores by ClO2 was similar to reported values for Cryptosporidium parvum (both organisms being more resistant to ClO2 than Giardia lamblia), suggesting the possibility that these spores may be used as potential indicators for protozoan parasites. Additionally, spore inactivation was observed to be influenced by pH in laboratory (distilled deionised water) water but not in Ottawa River water. At pilot-scale, spore inactivation was influenced by water temperature: a ClO2 dose of 2.5 mg/L resulted in a spore inactivation of approximately 2.0 log10 and 0.5 log10 at water temperatures of 23.2d egrees C and 5.2 degrees C, respectively. Chlorite concentrations remained below both the US EPA maximum contaminant level of 1.0 mg/L and the maximum contaminant level goal of 0.8 mg/L for up to 2.0log10 B. subtilis inactivation.

Chromium VI: a review of recent developments

This article discusses the regulatory fallout for the suddenly high‐profile inorganic contaminant chromium VI, resulting from the popular movie “Erin Brockovich.” Total Chromium was long regulated at 50 ug/L by the US Environmental Protection Agency (USEPA) and states until USEPA in 1991 set a maximum contaminant level goal (MCLG) of 100 ug/L and an MCL to match. When the USEPA set its total chromium MCLG 10 years ago, it rejected public comments claiming ingested chromium VI is carcinogenic and therefore should have its MCLG set at zero. The agency determined that because humans detoxify ingested chromium VI, it only presents a risk of noncancer endpoints if it is ingested at levels high enough to saturate the body's normal detoxification mechanisms.

USEPA's Rule for Chloroform MCLG Vacated

A rule promulgated by the US Environmental Protection Agency (USEPA) setting the maximum contaminant level goal (MCLG) for chloroform was ruled to be arbitrary and capricious and inconsistent with the Safe Drinking Water Act (SDWA).

Chloroform: Science, Policy, and Politics

As part of the Stage 1 Disinfectants/Disinfection Byproducts (D/DBP) Rule, the US Environmental Protection Agency set a maximum contaminant level goal for chloroform at zero. This action touched off a firestorm of criticism, both technical and policy‐related, from several corners. The agency was accused of sacrificing science at the political alter on the one hand and praised for not changing a long‐standing policy on the other. This article discusses how the saga of chloroform regulation mirrors the controversies raised when advances in science collide with traditional policies and national politics.

Controversy over chloroform: EPA, industry in legal battle

The Environmental Protection Agency has asked a federal court to let EPA reconsider its year-old drinking water goal for chloroform. The chemical is a probable human carcinogen that is a by-product of drinking water disinfection. But an industry group, which is suing EPA over the chloroform goal, wants the court to overturn the existing goal, which is zero, and order EPA to set the goal above zero. The group says the agency ignored its own scientific conclusions on the level of chloroform in drinking water when it set the goal at zero. They want assurance that the agency will not set the number at zero again. At issue is the December 1998 maximum contaminant level goal (MCLG) for chloroform that the agency set under the Safe Drinking Water Act. An MCLG is not a regulatory standard that water supply utilities must meet Instead, an MCLG indicates the maximum level at which a contaminant in drinking ...

Status of the Drinking Water Standards Program in the United States

The 1996 Amendments to the Safe Drinking Water Act permit standards to be set on a risk management basis. They are driven by: sound peer reviewed science; availability of adequate data and information; prioritized rule making based on risk; increased stakeholder involvement and regulatory negotiations; cost-benefit analysis; better clarity; timely guidance as to provisions of the standards; and implementation assistance though training and guidance materials. The priority rulemaking activities include: standards for harmful microbiological contaminants, disinfectants and disinfectant byproducts; a ground water rule to protect ground water systems from microbiological pathogens; and standards for radon, radionuclides, and arsenic. Additionally, a contaminant candidate list (CCL) must be published every five years to identify potential substances for subsequent regulation. From the CCL, at least five candidates must be identified to consider for regulation within a five year period. A maximum of thirty contaminants for monitoring by water systems must be published by 1999 and every five years thereafter. Monitoring information derived serves as a basis for future standard setting activities. Drinking water standards are set based on health effects and occurrence information through a two step process. First USEPA establishes a non-enforceable maximum contaminant level goal (MCLG) which is the maximum permissible level of a contaminant where no adverse health effects occur. Once the MCLG is established, a maximum contaminant level (MCL) is promulgated as close to the MCLG as feasible.

Chloroform: An EPA Test Case

In March 1998, the U.S. Environmental Protection Agency (EPA) published a proposal to raise the drinking water maximum contaminant level goal (MCLG) for chloroform, a suspected human carcinogen, from zero to 300 parts per billion. The proposal marked a departure from the agency's traditional reliance on linear dose-response models in performing risk assessment, and reflected the new thinking contained in the 1996 draft update to the agency's cancer risk assessment guidelines. The updated guidelines emphasize mechanisms of action and descriptions of the conditions under which carcinogenic hazards are likely to be expressed.

Introducing the New Federal Regulations for Disinfectants, DBPs, and Microbials

This article discusses two rules published by the US Environmental Protection Agency intended to protect customers against harmful levels of disinfectants (D), disinfection byproducts (DBP), and microbial contaminants. Three major components of the Stage 1 D/DBP Rule are discussed: maximum residual disinfectant level goals and maximum residual disinfectant levels for chlorine, chloramines, and chlorine dioxide; maximum contaminant levels for total trihalomethanes at 0.080 mg/L and the sum of 5 haloacetic acids at 0.060 mg/L; and, precursor removal requirements for surface water systems using conventional treatment. Several major components of the Interim Enhanced Surface Water Treatment Rule (IESWTR) are also discussed: a maximum contaminant level goal of zero for Cryptosporidium; increased turbidity performance standards for filtration; individual filter performance requirements; disinfection profiling and benchmarking requirements; prohibition on construction of new uncovered finished water reservoirs; and, requirements that the state conduct sanitary surveys for all systems using surface water or groundwater under direct influence of surface water. Compliance dates for both the Stage 1 D/DBP Rule and the IESWTR are listed.

Defining a Safe Level for Copper in Drinking Water

This article discusses how the scientific basis of the US Environmental Protection Agency's (USEPA's) drinking water regulation for copper has been questioned because of the economic burden it will impose on certain water systems. Topics discussed are: copper as an essential trace element for human nutrition; the susceptibility of children to copper toxicity; the basis of USEPA's maximum contaminant level goal (MCLG); and, the contradictory studies that criticize the current copper MCLG as being either too low or not low enough.

Use of the reference dose in risk characterization of drinking water contaminants

Abstract Regulatory decisions should be made in the most expert and informed way since they are precipitated by real and perceived threats to public health, under the glare of public scrutiny. The development of environmental regulations require a three‐step paradigm, collectively called risk analysis. This paper will address the risk assessment practices required under the Safe Drinking Water Act (SDWA) Amendments of 1986 to determine a Maximum Contaminant Level Goal (MCLG, nonenforceable health goal) which should result in no known or anticipated health effects, and allows adequate margin of safety. The end product of this risk assessment, risk characterization, and risk management encompassing control options and nonrisk analysis are combined to derive the Maximum Contaminant Level (MCL, enforceable standard). Furthermore, this paper discusses the U.S. Environmental Protection Agency's efforts in exploring new and improved noncancer risk assessment approaches providing the basis for MCLGs for the prote...

Need to Revise the National Drinking Water Regulation for Copper

Copper is an essential micronutrient and a potential toxic metal. The USEPA current maximum contaminant level goal (MCLG, a nonenforceable aspirational health goal) and the required treatment technique action level, both set at 1.3 mg/liter of copper are not adequately protective for infants and children under 10 years of age. Infants and children up to 10 years of age have increased susceptibility to copper toxicity. The two main reasons for the high sensitivity in this population subgroup are the presence of a normally high concentration of copper in the liver during early life and the lack of a fully developed homeostatic mechanism of copper in children under 10 years of age. This sensitive group of infants and children represents approximately 17% of the total U.S. population. The adverse health effects caused by drinking water contaminated with copper are abdominal pain, nausea, vomiting, diarrhea, headache, and dizziness. The proposed drinking water guideline of 0.3 mg/liter for copper was derived by the application of the risk assessment procedures approved by the USEPA. Drinking water containing 0.3 mg/liter of copper will provide approximately 26% of the nutritional requirement of copper. This proposed drinking water guideline (0.3 mg/liter) for copper will adequately protect health of infants, children, and adults.

Potential Regulatory Problems Associated with Atrazine, Cyanazine, and Alachlor in Surface Water Source Drinking Water

Post-application seasonal (May-July) average concentrations of atrazine, cyanazine, and, to a lesser extent, alachlor sometimes exceed their Maximum Contaminant Levels (MCLs) (3 ug/L for atrazine and 2 ug/L for alachlor) or Maximum Contaminant Level Goal (MCLG) (1 ug/L for cyanazine) in surface waters of the Mississippi and Great Lakes Basins. These three chemicals are among the primary pre-emergent herbicides applied to corn. MCLs and MCLGs are compared to annual average concentrations for regulatory purposes. However, annual average concentrations are much less frequently reported than post-application seasonal averages. In most cases, both seasonal and annual average concentrations are substantially less than the MCLs or MCLG. However, actual and estimated annual mean concentrations occasionally exceed the MCLs or MCLG. Actual or estimated exceedences occur more frequently for atrazine and cyanazine than for alachlor, and may occur more frequently in lakes or reservoirs with long retention times than in streams and rivers. Additional year round data, and data for lakes and reservoirs, are needed to determine the extent to which such exceedences occur throughout the corn belt. The American Water Works Association (AWWA) believes that substantial numbers of Community Water Systems (CWSs) within the corn belt are currently, or will be, in violation of the revised Safe Drinking Water Act (SDWA) with respect to atrazine and cyanazine. They are concerned that such violations could result in numerous CWSs having to implement expensive tertiary treatment systems such as granular activated carbon to decrease herbicide concentrations. The United States Environmental Protection Agency, (US EPA) is continuing to review data on the pesticide concentrations in reservoirs and lakes that registrants have been submitting over the last 18 mo under the 6(a)(2) adverse impact provision of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). The US EPA is also currently using computer modeling and other methods to evaluate potential alternative and/or supplemental herbicides to reduce atrazine use. In June 1992, the US EPA approved revised labeling that is designed to reduce indirect atrazine loadings to surface waters. Additional mitigation methods have been proposed and are being considered.