Drinking Water Notification Level for Manganese
The Division of Drinking Water's (DDW's) drinking water notification level for manganese is 0.5 milligram per liter (0.5 mg/L). When manganese is present in water served to customers at concentrations greater than the notification level, certain requirements and recommendations apply, as described below.
The notification level applies to all public water systems, whether or not they are covered by the current regulation of manganese.
Current Regulation of Manganese
Manganese is regulated by a 0.05-mg/L secondary maximum contaminant level (MCL) (see drinking water regulations), a standard established to address issues of aesthetics (discoloration), not health concerns. In California secondary MCLs are enforceable. (USEPA's 0.05-mg/L federal secondary standard for manganese is a non-enforceable guideline.)
Secondary MCLs are enforceable standards in California, but are applicable only to community systems. Thus, noncommunity systems, particularly nontransient noncommunity (NTNC) systems such as schools and workplaces, do not receive the benefits of the secondary standard.
Although the aesthetic effects related to elevated manganese in drinking water are likely to be encountered at concentrations below the notification level, the notification level provides an extra layer of protection to consumers of water from systems subject to the secondary MCL requirements.
Manganese is a required nutrient. Table 2.1 in ATSDR (2008) has a table of adequate intake levels for manganese, which range from 1.2 mg/day for 1- to 3-year-old infants, to 1.8 -2.3 mg/day for female and male adults. Values are lower for infants and higher for the pregnant or lactating woman. A healthful diet provides adequate manganese for good nutrition (US EPA, 2003). Reviews of typical Western and vegetarian diets showed typical manganese intakes of 0.7 to 10.9 mg/day (WHO, 2004).
However, manganese at very high levels can pose a neurotoxic risk (ATSDR, 2008; US EPA, 1996, 2003, 2004; WHO, 2004). For example, neurologic damage (mental and emotional disturbances, as well as difficulty in moving—a syndrome of effects referred to as "manganism") has been reported to be permanent among manganese miners and other workers exposed to high levels of airborne manganese for long periods of time. Lower chronic exposures in the workplace resulted in decrements in certain motor skills, balance and coordination, as well as increased memory loss, anxiety, and sleeplessness (ATSDR, 2008). USEPA (1996), in developing an oral reference dose for manganese based on dietary intake, mentions an epidemiological study in Greece that showed an increase in neurologic effects such as weakness and fatigue, disturbances in gait, and neuromuscular effects, in people whose drinking water contained 1.6 to 2.3 mg/L. Uncertainties about the levels of dietary manganese and the amount of drinking water consumed did not enable USEPA to use these data for risk assessment purposes.
ATSDR (2008) reports several studies that showed decreased ability in neurobehavioral performance testing and in several educational parameters, in children exposed to high level of manganese in drinking water and diet for at least several years.
Children are considered to be particularly susceptible to possible effects of high levels of manganese exposure because they absorb and/or retain more manganese than adults (ATSDR, 2008; USEPA, 1996).
Attention to the potential health concerns of high levels of manganese in drinking water is appropriate, as the 0.5-mg/L notification level provides, given the possibility of neurologic effects at very high concentrations. Similar advisory levels for manganese have been established by the US EPA , which has a manganese health advisory level of 0.3 mg/L (USEPA, 2004), and the World Health Organization, which has a manganese health guideline level of 0.4 mg/L (WHO, 2004).
Benefits of a Notification Level for Manganese
A health-based notification level for manganese is helpful in addressing high manganese levels in drinking water sources, in several ways:
- It provides guidance and information to systems with manganese above the secondary MCL, as they deal with the regulatory requirements associated with exceeding the secondary standard (PDF) , such as addressing costs associated with treatment.
- It provides guidance to DDW staff in evaluating waivers from treatment requirements to meet the secondary MCL. Currently, consumers are to be surveyed about their acceptance of exceeding a secondary MCL. A notification level allows health-based considerations to enter into the consumer survey and waiver from treatment process.
- It allows consumers of water from NTNC systems to be informed about the potential for health concerns associated with sources that have high levels of manganese.
Requirements and Recommendations
When manganese is present in concentrations greater than the notification level, the following requirements and recommendations apply:
- Systems with drinking water sources with manganese concentrations greater than the notification level are required to notify local city and county governing bodies, just as for other contaminants with notification levels and for contaminants that exceed MCLs.
- Consumer notification is recommended at levels greater than the notification level. This may be handled through the water systems' annual consumer confidence reports. Other means could be used as well, if more appropriate, such as direct mailing, or posting a notice. These should be coordinated with the local DDW district office.
- Source removal is recommended at ten times the notification level.
Monitoring for manganese is required within the framework of secondary MCL regulations, but generally not outside that framework. For sources not subject to the secondary MCL requirements, DDW recommends analyses of sources that are near other sources that have very high manganese levels.
In 2003, when the California Department of Health Services' Drinking Water Program (DDW) established the 0.5-mg/L notification level (then called an "action level") for manganese, we recommended follow-up monitoring for those systems that historically had shown manganese higher than the 0.5-mg/L concentration, but which lacked recent data. Current monitoring allows water systems to confirm earlier values, and to allow them to meet the requirement for notifying its local government body with timely information. If a water system chose not to take a contemporary follow-up sample for manganese analysis, then we recommended notification of the governing body based on prior data. Consumer notification should follow the recommendations mentioned above.
For community systems subject to the secondary MCL monitoring and compliance requirements (22 CCR §64449) with manganese greater than the notification level, DDW recommends that information about the health concerns associated with high manganese exposures be provided to consumers as part of the required consumer dissatisfaction determination.
Manganese Detections Greater Than 0.5 mg/L
There are ~12,000 sources belonging to ~4,400 community and NTNC systems in California. Historically, about 30 percent of drinking water sources monitoring for manganese have reported manganese detections, reflecting its natural occurrence. The detection limit for purposes of reporting (DLR), the level at which DDW is confident about the quantification of manganese's presence in drinking water, is 0.02 mg/L.
A number of sources have reported detections greater than the 0.5-mg/L notification level, as shown in the table below for the periods of January 2006-June 2011 and July 2011 to March 2019. Sources with a detection above 0.5 mg/L occurred in 46 of the state's 58 counties, most often in the counties of Sonoma (61 sources), Napa (23), San Diego (21), Santa Barbara (18), Lake (16), and San Luis Obispo (15).
Drinking Water Sources with Manganese Detected above 0.5-mg/L*
|Date Range||No. of Sources||No. of Systems||No. of Counties|
|Jan 2006-Jun 2011||384||272||46|
|Jul 2011- Mar 2019||435||322||47|
In determining the number of sources for this table, inactive wells, abandoned and destroyed wells, agricultural wells, and monitoring wells were excluded.
2 These data are from manganese detections above 0.5 mg/L (Excel) (July 2011 – Mar 2019).
- ATSDR, 2008, Toxicological Profile for Manganese, Agency for Toxic Substances and Disease Registry, September 2008.
- US EPA, 1996, Manganese, Integrated Risk Information System, US Environmental Protection Agency, Reference Dose last updated May 1, 1996.
- US EPA, 2003 (PDF), Health Effects Support Document for Manganese, February 2003.
- US EPA, 2004 (PDF), Drinking Water Health Advisory for Manganese, January 2004.
- WHO, 2004 (PDF), Manganese in Drinking-water, Background document for development of WHO Guidelines for Drinking-water Quality, World Health Organization, 2004. See also: WHO, Chemical Hazards in Drinking Water - Manganese.
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