Definition and Epidemiology

Chemical exposures can occur by inhalation, ingestion, injection, or absorption through the skin and mucous membranes. Although a chemical exposure can be related to a biologic, radioactive, or chemical toxin, harmful chemicals are ubiquitous and occur at home, at work, and at play. Smoke, pesticides, lead, mercury, phthalates, bisphenol A, and frequently used household and beauty products all have potential long-term health ramifications.^1,2

Common household chemicals that are a more immediate concern include shoe polishes, cosmetics, over-the-counter and prescription medications, alcohols (isopropyl alcohol, methanol, and ethanol), detergents, cleaning products (especially chlorine, ammonia, and lye-containing cleaners), rodent and insect poisons, common yard chemicals, and paints and paint products. Household chemicals are often associated with poisonings in children, but chemical exposures in the home affect people of all ages. Exposure to wood or cigarette smoke, fumes, or other compounds can cause nausea, dizziness, cough, difficulty concentrating, and other symptoms that cause patients to seek care.³

Chemicals also abound in the workplace, and many of these cause irritation or toxicity if the human body is exposed to them. The Occupational Safety and Health Administration (OSHA) requires that all employers and employees be advised of chemical hazards by means of a hazards communication program, which includes having a Material Safety Data Sheet (MSDS) for each chemical used in the workplace. The employer must ensure that MSDSs are readily accessible to employees during each work shift when they are in the work area.⁴ MSDSs are fact sheets provided by chemical manufacturers that list chemical, physical, and health hazard data for a particular substance.⁴ Health hazard data include routes of entry, acute and chronic effects, signs and symptoms of exposure, and emergency and first aid procedures.⁵ For safety reasons and because federal law requires accurate labeling on chemical containers, it is wise to avoid the unnecessary transfer of potentially dangerous chemicals into any other containers. If transfer to another container is necessary, OSHA labeling requirements must be followed.⁴

In 2010, 42,917 people died from poisoning. Many of the deaths were related to opioids, which are increasingly related to overdoses and deaths.⁶ Medication-related poisonings in adults were related to prescription medications (pain medications, sedatives, antipsychotics, hypnotics, antidepressants, cardiac medications, stimulants) and cosmetics and personal care products.⁷ In young children the causes were different; the primary cause of poisoning was related to cosmetics and personal care products, followed by cleaners and pain medications.⁷ Carbon monoxide poisoning is another common cause of poisoning in the United States.^8,9 Newer sources of concern in poison control centers are the growing use of e-cigarettes and the potential for nicotine toxicity, the use of synthetic cannabinoids, the risk of poisoning in children by ingestion of laundry detergent packs, and energy drink toxicity.^10–13

The poisoning statistics are alarming and demonstrate the need for increased patient education by primary care providers to help prevent poisonings and other accidental exposures, because the majority of poisonings are accidental. Prevention is best achieved by keeping cosmetics, personal care products, medications, and cleaners out of the sight and reach of children and by keeping any hazardous material clearly labeled and out of children’s reach.⁴ Parents, grandparents, caregivers, and primary care offices should always have the telephone number of the poison control center readily available.

Immediate emergency department referral, physician consultation, and contact with a poison control center are indicated for chemical exposure.

Pathophysiology

The pathophysiologic and systemic effects of a chemical exposure depend on the characteristics and effects of the substance, the degree and route of exposure, and the patient’s comorbidities.

Clinical Presentation

For poisoning, the history should address the five Ws: who—the patient’s age, weight, sex, and relationship to others present; what—the name and dose of the substance, co-ingestants, and amount ingested; when—the time and date of ingestion; where—both the route of poisoning and the geographic location in which the poisoning occurred; and why—whether the ingestion was intentional or unintentional, plus associated details. A detailed medical history should be obtained, including previous poisonings, comorbid medical conditions, and concurrent medications that might affect the patient’s response to and the metabolism or elimination of ingestants. Additional information should include a history of psychiatric illness, alcohol or substance abuse, and presence of hepatic or renal disease.

The patient who has had a toxic exposure may be affected in many different ways. The presentation of chemical exposures is varied and can be particularly challenging, ranging from a headache to coma or death. With children, there often is physical evidence (e.g., a smell of cleaning products, pill or plant fragments, nonfood stains, open bottles or containers). In acute chemical exposures, adults commonly know the type of exposure unless they are incapacitated by it, in which case witnesses may be able to identify the exposure. If the exposure is occupational, the chemical may be readily identifiable. Review of the MSDS for pertinent information after an occupational exposure may also be helpful.

The clinical presentations of chemical exposures are related to the specific toxins involved. Medications such as dimenhydrinate, diphenhydramine, astemizole, loratadine, meclizine, promethazine, and tricyclic antidepressants and household and wild plants such as mandrake, jimsonweed (“loco weed”), and nightshade are anticholinergics. Anticholinergics cause a syndrome that is best remembered by the mnemonic “hot as Hades, blind as a bat, red as a beet, dry as a bone, mad as a hatter,” which describes, respectively, the following effects: hyperthermia, mydriasis, flushed skin, dry mucous membranes, urinary retention, decreased bowel motility, and hallucinations or frank psychosis.¹⁴

Alkalis are found in numerous household cleaning products (e.g., detergents, drain cleaners, dishwashing fluids), batteries, and other substances and cause irritation to the oral mucosa, esophagus, and stomach. This irritation ranges from mild to extremely severe. Both acids and alkalis cause extensive tissue damage to mucous membranes and the gastric system. The alkalis, however, are associated with a much more serious prognosis because they tend to penetrate tissues more deeply and rapidly than do the acids, particularly if the eye is involved.^14,15

Hydrocarbons and metals are potential toxins that can cause poisoning acutely or chronically. Hydrocarbons are the basis of many industrial chemicals, yet they are also often found in products in many garages and sheds. These substances cause a host of reactions, including coughing, vomiting, a chemical odor to the breath, and, in severe exposure, unconsciousness and coma. Metals such as iron, arsenic, aluminum, lead, mercury, and cadmium also cause poisoning. Aluminum poisoning can affect welders; lead and cadmium are sometimes found in jewelry. Arsenic, mercury, and lead are found almost everywhere in the environment.

Patients with chronic chemical exposure may visit the primary care provider with a variety of complaints, and the cause of the patient’s concerns may not be obvious. Because chemical exposure can be so pervasive, it is always important to consider heavy metals and other sources of poisoning as a potential cause of the patient’s symptoms.

Physical Examination

In acute situations, the initial physical examination for chemical exposure must be rapid, focused, but also comprehensive. Airway, breathing, and circulation must be supported and cardiac function monitored. Temperature, heart and respiratory rates, blood pressure, oxygen saturation, blood glucose concentration, and cardiopulmonary function should be assessed and then frequently reassessed, and a possible deterioration in the patient’s status should be anticipated. The examination must focus on systems (e.g., cognitive status, responsiveness, rest­lessness, agitation, or seizure activity), skin appearance (e.g., needle marks, contusions, petechiae, bullae, skin color, flushed appearance, or diaphoresis), pupil appearance and reactivity, nares, mucous membranes (odor, excessive salivation), cardiac rhythm and rate, pulmonary congestion, bowel sounds or abdominal rigidity, and motor tone to help determine clues to the chemical exposure and on adjuvant diagnostic laboratory studies.^16–18