Lack of Conversion to Inorganic Arsenic after Ingestion of a Monosodium Acid Methanearsonate Herbicide

Background: Monosodium acid methanearsonate (MSMA) is a commonly used herbicide. Reports of human ingestion of organic arsenic (As) compounds have been rare and have not included urine arsenic speciation. Case Report: A 60 year old landscaper was using a commercial MSMA herbicide and mistakenly dran...

Full description

Saved in:
Bibliographic Details
Main Authors: Kleiman, R J, Morgan, B W, Osterloh, J D, Dell'Aglio, D M, Caldwell, K L, Freedman, C G, Verdon, C P, Thomas, J D
Format: Conference Proceeding
Language:English
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Background: Monosodium acid methanearsonate (MSMA) is a commonly used herbicide. Reports of human ingestion of organic arsenic (As) compounds have been rare and have not included urine arsenic speciation. Case Report: A 60 year old landscaper was using a commercial MSMA herbicide and mistakenly drank water from a cup used to mix the product. The patient developed nausea, vomiting, abdominal pain, and green diarrhea within 30 minutes and went to the emergency department. After poison control center consultation, the patient was transferred to a tertiary care facility with a toxicology service. Upon arrival to the tertiary facility the patient was stable and chelation with succimer was recommended. Spot urine was obtained before chelation and was found to have an extremely elevated total urine As level of 2930 ug/L. Speciation showed this was 91% MMA, 7% DMA, 0.3% AS (V), and 1.7% AS(III). Two urine samples obtained after initiation of chelation therapy showed no significant increase in the percentage inorganic As excreted, but did show conversion of MMA to DMA. The patient remained asymptomatic after his initial presentation and was discharged on hospital day 4 to continue 2 weeks of succimer. He remained asymptomatic at 5 months on phone follow up. Case Discussion: Organic As is less toxic than its inorganic forms but few human inges-tions have been fully described. Our patient had an extremely elevated total urine arsenic level which was predominantly MMA, and had a very benign clinical course. Conclusion: Arsenic metabolism in humans is still being defined. Inorganic and organic As ingestions are often treated similarly with chelation. Our case shows a benign course after MSMA ingestion and no evidence of conversion to inorganic As.
ISSN:1556-3650