Standard Interpretations - Table of Contents
• Standard Number: 1910.1027; 1915.1027; 1926.1127

June 15, 1994

Anton D. Check
Safety and Health Specialist
Degussa Corporation/Metal Group
3900 South Clinton Avenue
South Plainfield, NJ 07080

Dear Mr. Check:

This letter is in response to your questions of June 9, 1994 regarding cadmium biological monitoring. Your questions pertain to accurate urinary sampling. The short answers to your questions are as follow: 1) standard medical practice specifies that when specific gravity is low (e.g., less than 1.008), urine samples are too dilute for accurate laboratory analysis; 2) epidemiological studies of cadmium-induced renal damage, summarized in the preamble to the final cadmium standards, specify that Beta-2 microglobulin (B(2)-M) will degrade in acidic urine, with pH less than 5.5; and, 3) since both cadmium in urine (CdU) and B(2)-M are standardized to grams of creatinine (CRTU), artificially low CRTU will inflate CdU and B(2)-M calculations. Additional information follows.

OSHA has received several questions concerning overhydration and its effects on urinary sample results. In Appendix F of the cadmium standard, OSHA specified a number of sample collection and handling procedures for enhancing the accuracy of blood and urine samples taken as part of the cadmium biological monitoring program. Under section 3.4.1. of Appendix F (57 Federal Register 42424), for example, employees are advised to void, drink a large glass of water, and then provide a urine specimen within an hour. OSHA now believes this prehydration procedure may lead to overhydration in some instances, thereby lowering CRTU levels.

In response to the hydration problem noted in the previous paragraph, OSHA's current rec