Update: March 1996
Current Massachusetts Regulatory Limit
MMCL = 0.2 mg/L. ORS adopted the MCL published by the U.S. EPA.
Federal Regulatory Limit
The MCL of 0.2 mg/L is equal to its MCLG of 0.2 mg/L.
Basis for Criteria
The MCLG is derived based on the RfD presented below and assumes that a 70 kg adult ingests 2 L/day of drinking water. A relative source contribution factor of 20% is incorporated into this value.
RfD: 0.025 mg/kg/day
UF: 100 (10 = interspecies; 10 = intraspecies) MF: 1
Confidence in RfD: Medium
Oxamyl is a cholinesterase inhibitor. Clinical signs of acute poisoning include tremors, salivation and lacrimation. The principal adverse effect noted in animal studies is a decrease in body weight.
Groups of 36 weanling rats of each sex were given doses of 0, 2.5, 5.0 and 7.5 mg/kg in the diet daily for two years. Significant decreases in body weight occurred in both males and females at the two highest doses. A NOAEL of 2.5 mg/kg/day was identified from this study (55 FR 30370).
Cancer Assessment: E
The U.S. EPA does not consider oxamyl to be carcinogenic based on evidence from two available studies with rats and mice. U.S. EPA has classified oxamyl in Group E (i.e., no evidence of carcinogenicity).
PQL: 0.02 mg/l
U.S. EPA 531.1 Derivatization/gas chromatography
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 http://www.epa.gov/safewater/methods/methods.html.
Other Regulatory Data
Any Health Advisories, Reference Doses (RfDs), cancer assessments or Cancer Potency Factors (CPFs) referenced in this document pertain to the derivation of the current guidance value. Updated information may be obtained from the following sources:
Health Advisories - The U.S. EPA provides guidance for shorter-term exposures for chemicals based on their non-cancer effects. Current health advisories may be more current than those used to derive MCLs and may be found at http://www.epa.gov/waterscience/drinking/standards/dwstandards.pdf.
RfDs, cancer assessments and CPFs - For specific information pertaining to derivation of drinking water criteria, consult the Federal Register notice that announces the availability of the most current guidance for that chemical. In addition, information on other current RfDs and CPFs as well as cancer assessments for specific chemicals may be found in the U.S. EPA Integrated Risk Information System (IRIS) at http://www.epa.gov/iris/. Please note that the information in IRIS may differ from that used in the derivation process as published in the Federal Register notice.
Federal Register. July 25, 1990. Part II. Environmental Protection Agency. 40 CFR Part 141 et al. National Primary and Secondary Drinking Water Regulations; Synthetic Organic Chemicals and Inorganic Chemicals; Proposed Rule. (55 FR 30370).
Federal Register. July 17, 1992. Part III. Environmental Protection Agency. 40 CFR Parts 141 and 142. National Primary Drinking Water Regulations; Synthetic Organic Chemicals and Inorganic Chemicals; Final Rule. (57 FR 31776).