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Update: May 2004

Current Massachusetts Regulatory Limit
MMCL = Treatment Technique. (Refer to 310 CMR 22.20.) ORS has adopted the MCL published by the U.S. EPA.

Federal Regulatory Limit
The MCL for Giardia lamblia is a Treatment Technique. Under U.S. EPA's Surface Water Treatment Rule, systems using surface water or groundwater under the direct influence of surface water must achieve a 99.9% removal/inactivation of Giardia lamblia. The MCLG for Giardia lamblia is zero.

Basis for Criteria
The MCL for Giardia lamblia is based on a Treatment Technique as described above.

Critical Effects
Giardia lamblia is a waterborne protozoan parasite that can be transmitted via the fecal-oral route and can cause waterborne illness. Although 50-75% of giardiasis cases can be asymptomatic, symptoms of giardiasis can include chronic diarrhea, abdominal cramps, weight loss, nausea, vomiting, and malabsorption of fats, among other symptoms. Transmission via water, especially in unfiltered water systems is one way in which Giardia is spread.

Cancer Assessment: 

Biological Pathogen

Analytical Information
: See U.S. EPA Method 1623 (U.S. EPA, 2001)

Analytical Methods
U.S. EPA Method 1623

PQLs and analytical methods may have been updated since this guidance value was last revised. Updated analytical methods for drinking water and their associated PQLs may be found at US EPA Drinking Water Analytical Methods .

Federal Register. January 14, 2002. Environmental Protection Agency. Parts 9, 141 and 142. National Primary Drinking Water Regulations: Long Term 1 Enhanced Surface Water Treatment Rule. Final Rule. (67 FR 1811).

U.S. Environmental Protection Agency (U.S. EPA). November 1999. Giardia: Drinking Water Health Advisory. EPA-822-R-99-008. Office of Science and Technology. Office of Water.

U.S. Environmental Protection Agency (U.S. EPA). April 2001. Method 1623: Cryptosporidium and Giardia in Water by Filtration/IMS/FA. EPA-821-R-01-025. Office of Water.

U.S. Environmental Protection Agency (U.S. EPA). July 2002. List of Contaminants and Their MCLs. EPA 816-F-02-013.