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Clinical Toxicology: Providing Vital Data in Poisoning Cases


Imagine this scenario: Thirty-three-year-old Marie seeks care at her local health clinic, complaining of symptoms that started a few months ago, including tremors, headache, muscle twitching, foggy thinking, insomnia, and irritability.


The doctor asks Marie about her diet, her overall health, whether she has been exposed to any new chemicals or accidental spills, or whether anything significant has changed in Marie’s lifestyle. Marie says nothing has changed to explain her symptoms. The doctor asks Marie how much fish/seafood she eats, and she tells the doctor she eats one or two servings of fish per week—usually tuna or tilapia.


The doctor runs a series of blood and urine tests, and the lab results show severely elevated levels of mercury in Marie’s urine at 90μg/L (micrograms per liter). Her blood tests show much lower levels of mercury, indicating that Marie’s exposure is most likely to inorganic mercury (such as that found in thermometers, dental amalgam, and creams and ointments used for skin-lightening).


The doctor probes Marie with questions, and eventually Marie mentions that she started using a new skin cream a few months ago. The doctor has Marie retrieve the cream from home for testing. Lab results show that the cream contains levels of mercury thousands of times greater than the threshold allowed by the FDA for cosmetic products. The doctor advises Marie to stop using the cream immediately, and soon thereafter her symptoms improve.


Marie’s case demonstrates the importance of clinical toxicology.


What Is Clinical Toxicology?


Toxicology studies the effects of poisons on living organisms. Clinical toxicology involves measuring and interpreting concentrations of toxic substances in human biological fluids, including blood and urine, as part of patient care.


The important work clinical toxicologists do helps doctors identify a patient’s exposure to toxins that can damage health, as in the scenario above. Clinical toxicology focuses on the diseases associated with short-term and long-term exposure to toxic chemicals.


Clinical toxicology often coincides with other sciences, such as forensic toxicology (measures levels of toxins and drugs in tissues to determine cause of death), biochemistry (the study of chemical processes in the body), and pharmacology (the study of how drugs affect the body).


Toxicologists use a variety of tools and instruments in the course of their work, including syringes and needles to draw patients’ blood, catheters to collect urine for chemical analysis, blood gas analyzers to determine levels of gases like carbon monoxide in the blood, and all of the necessary lab supplies, including reagent alcohol, for tissue preparation and other purposes.


Statistics on Poisoning Cases

The field of toxicology generally doesn’t get much attention unless a celebrity death is involved—the public anxiously awaits the release of toxicology reports that reveal the drug(s) found in celebrity overdose cases. While these incidents get a lot of attention, the majority of toxicology cases involve everyday people. According to the University of California at San Diego:


  • More than two million human exposures are reported to poison control centers every year.
  • Most poisonings are accidental and involve children.
  • 25% of the cases reported to poison control centers are resolved in a health care setting.


According to the National Capital Poisoning Center, the most common poison exposures for young children over age 6 and adults, in 2013, were:


  • Cosmetics/personal care products
  • Cleaners
  • Pain medications
  • Foreign bodies
  • Topical medicines
  • Vitamins
  • Antihistamines
  • Batteries
  • Plants and mushrooms
  • Antimicrobials
  • Pesticides
  • Arts/crafts/office supplies
  • Gastrointestinal preparations


The Explosive Increase in Drug Poisoning Cases


Prescription drug abuse in the United States has increased by epidemic proportions in recent years, according to the Centers for Disease Control (CDC). Forty-four people die in the U.S. each day from prescription drug overdose, and the number of drugs prescribed every year has quadrupled since 1999, even though there have not been documented increases in the amount of pain Americans reported during that period.


Opioids and benzodiazepines are leading the charge in the terms of overdose cases. The most commonly abused opioid drugs are:


  • Hydrocodone (such as Vicodin)
  • Oxycodone (such as OxyContin)
  • Methadone
  • Oxymorphone (such as Ophana)


Opioids and benzodiazepines, such as Valium, are typically used to treat moderate-to-severe pain. They’re often prescribed after a surgery or illness, or to treat pain associated with cancer. In recent years doctors have been more liberal about prescribing these drugs for non-cancer pain, however. In 2013 nearly two million Americans abused prescription painkillers, according to the CDC, and thousands of people wind up in the emergency room every day for using these drugs in a manner other than prescribed.


The good news is painkiller prescription rates have leveled off since 2010, and painkiller-related deaths are declining.


Clinical toxicologists play an important role in identifying which drugs are involved in overdose cases. They work in a variety of settings, including hospitals, and help emergency room physicians save lives.


A Brief History of Toxicology


Toxicology has a colorful history, especially in Medieval and Renaissance Europe. Rulers used royal “tasters” to test their food for poison (which didn’t always turn out well for the tasters!). By the 15th Century, poisoning had become a normal hazard of life—in Italy, Venice’s city council regularly put out poisoning “contracts” on political enemies, and the Borgias practiced “applied toxicology,” killing husbands, wives, lovers, political opponents, etc. Catherine de Medici was known to have poisoned the poor and the sick under the guise of feeding and “assistance.”


“The Dose Makes the Poison”


This quote was made famous by Paracelsus, a Swiss-German Renaissance physician known as the “father of toxicology.” Paracelsus developed the concept of dose and determined that that poison’s effects are a result of “toxicons.”


The “father of modern toxicology” is Orfila, who served as the personal physician to Louis XVIII. Orfila transformed toxicology into a science, compiling chemical and biological information on most known poisons—information that is still used today.


Toxicology in Modern Times


Today our understanding of toxicology has expanded enormously. Toxicology now includes many specialty areas, including clinical toxicology, forensic toxicology, industrial toxicology, environmental toxicology, product development toxicology, and many others. Toxicologists are essential to public health, helping to protect people, animals, and the environment every day.


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