LABORATORY REFERENCE RANGES

FOR TOXIC METALS IN BLOOD AND URINE

ARSENIC

Random urine   < 35 µg/g creatinine  (Not provoked with a chelator)

Whole blood (short half-life in blood)  < 23 µg/L

    (urine is more reliable for long-term exposure)

 CADMIUM

Random urine   < 2.0 µg/g creatinine    (Not provoked with a chelator)

LEAD

Random urine   < 150 µg/g creatinine   (Not provoked with a chelator)

Whole blood         < 19 µg/dL

OSHA upper limit < 40 µg/dL (upper limit for industrial exposure)

Provoked urine < 600 mcg total in 24 hour urine collected

       immediately after 2.0 gm oral    DMSA or 1.0 gm IV EDTA

MERCURY

Random urine    < 5 µg/g creatinine  (Not provoked with a chelator)

Occupational limit in urine of exposed workers < 35 µg/g creatinine (Not provoked with a chelator)

Whole blood    < 8.0 µg/L     Occupational limit in exposed workers  < 15.0 µg/L

 

Hair                <15 µg/g       (µg/g  = ppm)

     Hair mercury is considered a valid test if properly performed. The recent Seychelles Island study showed that hair mercury below 15 µg/g (mean 6.9 ppm, SD 4.5 ppm) did not cause any problems in pregnant mothers or their newborn infants, who were followed with extensive neurological testing for many years from birth onwards. The diet contained ocean fish 12 meals per week. The fish contained the same amount of methyl mercury as found elsewhere in the world.

     The World Health Organization's guidelines maintain that the lowest level that could possibly be harmful to humans is 5 parts per million (ppm). This level is based on scientific results from the 1960s that placed the level at which risk begins at 50 ppm for most people; WHO then applied a safety factor of 10, deciding that a level of 5 or less is safe for even the most vulnerable populations. Now the University of Rochester team has conducted an extensive study in the Seychelles Islands of the most sensitive population -- young children -- where the average level is about 7 ppm, about 10 times the level of the U.S. population. The scientists found no harm from mercury at levels up to 15 ppm, nearly twice the average Seychelles level and about 20 times higher than the average U.S. level.

Environmental exposure: < 8.0 µg/L, individuals consuming large quantities of seafood may have values as high as 200.0 µg/L. Occupational exposure: BEI®: inorganic mercury (sampling time is end of shift at end of work week):  <15.0 µg/L¹

Acute and chronic mercury poisoning affects the kidneys, central nervous system, and the gastrointestinal tract. The three telltale symptoms of mercury poisoning are impaired articulation, irregularity of muscular action, and constricted visual fields. Mercury poisoning through chronic exposure to metallic and inorganic forms of mercury generally produce nervousness, lassitude, tremor, and mucous membrane irritation. Inorganic mercury poisoning is associated primarily with peripheral effects, including gastroenteritis and tubular nephritis, whereas organic compounds predominantly affect the central nervous system (CNS), which may be severe and irreversible.²

Chronic inorganic mercury poisoning is an occupational disease of smelters, mercury miners, gilders, and factory workers. Inhalation of mercury vapors may lead to pneumonitis, cough, fever, and other pulmonary symptoms. The most reliable way to measure exposure to inorganic mercury is to measure urinary mercury levels. Correlation between urine levels and symptoms is poor, however.

The most common nonindustrial source of mercury poisoning is the consumption of methyl mercury-contaminated fish. Organic mercury poisoning is best detected in whole blood, as this form of mercury is located mainly in the RBCs. Organic mercury poisoning may develop quickly and is usually a more serious disease.

BEI® are reference values intended as guidelines for evaluation of occupational exposure. BEI® represent biological levels of chemicals that correspond to workers with inhalation exposure equivalent to the threshold limit value (TLV®) of the chemicals. TLV®s refer to the airborne concentrations of substances and represent conditions under which it is believed that nearly all workers may be repeatedly exposed, day after day, without adverse health effects.³

FOOTNOTES

 1. BEI® (Biological Exposure Indices) based on 2004 Recommendations of the American Conference of Governmental Industrial Hygienists (ACGIH).

2. Baselt RC and Cravey RH, Disposition of Toxic Drugs and Chemicals in Man, 4th ed, Chemical Toxicology Institute, 1995.

3.  TLV®s and BEI®s, Threshold Limit Values for Chemical Substances and Physical Agents and     Biological Exposure Indices 2002, American Conference of Governmental Industrial Hygienists (ACGIH).

 REFERENCES:

Jacobs DS, DeMott WR, Oxley DK, et al, Laboratory Test Handbook With Key Word Index, 5th ed, Hudson, OH: Lexi-Comp Inc, 2001.

 

Baselt RC, Cravey RH: Disposition of Toxic Drugs and Chemicals in Man, 4^th ed, Chemical Toxicology Institute, 1995