Toluene Diisocyanate (TDI) is an organic chemical compound used extensively in manufacturing. While not a formally defined illness, the term “TDI disease” encompasses a range of health problems that arise from exposure to it. These conditions are primarily occupational hazards, affecting individuals who work in industrial settings where the chemical is present.
Sources of TDI Exposure
Exposure to Toluene Diisocyanate is concentrated in industries that rely on polyurethane chemistry. The primary application of TDI is in the production of flexible polyurethane foams. These foams form the cushioning in furniture, vehicle seats, and mattresses. Workers in manufacturing plants that produce these items are at the highest risk.
The chemical is also a component in coatings, paints, and adhesives. Spray-on insulation can release TDI into the air as an aerosol. The two main pathways for exposure are inhalation of TDI vapors and direct skin contact. Inhalation is the most common route, particularly in poorly ventilated areas or during spray applications.
Skin contact is another significant exposure route. Handling liquid TDI or materials freshly treated with it without proper protective gear can lead to absorption through the skin. This contact can occur during mixing, pouring, or cleaning processes. The risk is heightened for workers involved in maintenance or those who handle spills.
Health Effects of TDI Exposure
Acute exposure to TDI often results in irritation of the surfaces it touches, including the skin, eyes, nose, and throat. Inhaling TDI can directly affect the respiratory tract, causing symptoms like coughing, wheezing, shortness of breath, and a feeling of chest tightness.
A significant long-term consequence of TDI exposure is occupational asthma. As a respiratory sensitizer, TDI can cause a person’s immune system to become reactive after an initial exposure. This sensitization may occur without initial symptoms, but once it develops, any subsequent exposure, even to very low concentrations, can trigger a severe asthmatic attack.
In sensitized individuals, occupational asthma is characterized by inflammation and narrowing of the airways upon re-exposure. Repeated asthmatic episodes can contribute to a persistent state of airway disease. Chronic exposure can also lead to other conditions, such as hypersensitivity pneumonitis, an inflammatory lung disease affecting the air sacs (alveoli).
Diagnosis and Medical Evaluation
Diagnosing a TDI-related health condition begins with a detailed review of the patient’s occupational history to link workplace activities with symptoms. A healthcare provider will inquire about:
- Specific job duties
- Materials handled
- The presence of ventilation systems
- The use of personal protective equipment
This history is complemented by a physical examination with special attention to the respiratory system. A doctor will listen for wheezing or other abnormal breath sounds that could indicate airway obstruction. To measure lung health, pulmonary function tests (PFTs) are commonly administered. Spirometry, a type of PFT, measures how much and how quickly a person can exhale air, providing a baseline of lung function.
To confirm that workplace exposure is the cause of respiratory symptoms, PFTs may be performed before and after a work shift. A significant decrease in lung function over the workday strongly suggests an occupational link. In specialized centers, a specific inhalation challenge test may be conducted. This involves having the patient inhale a small, controlled amount of TDI in a monitored environment to observe for an asthmatic reaction.
Management and Prevention Strategies
The primary step in managing TDI-related health conditions is the cessation of any further exposure to the chemical. For a sensitized worker, this often means removal from the job or work area where TDI is present. Medical treatment focuses on managing occupational asthma symptoms with medications like bronchodilators and inhaled corticosteroids to reduce inflammation.
Preventing initial exposure is based on engineering controls, such as enclosing production processes and installing local exhaust ventilation systems to capture TDI vapors at their source. These systems are designed to keep airborne concentrations below established occupational exposure limits.
When engineering controls cannot sufficiently reduce exposure, administrative controls are implemented, such as limiting the time a worker spends in high-exposure areas. The use of Personal Protective Equipment (PPE) is also required. This includes specialized respirators, chemical-resistant gloves, and protective clothing to prevent skin contact.