Today we’re diving into the world of cadmium, a naturally occurring element tucked away in the earth’s crust. This silvery-white metal first made its appearance in 1817 but didn’t make it big in the commercial world until the tail end of the 19th century. Cadmium got its start as a key ingredient in paint pigments and as a stand-in for tin during World War I. Nowadays, you’ll find about 75% of cadmium hanging out in alkaline batteries, with the rest showing up in pigments, coatings, platings, and even as a stabilizer for plastics.
Workers across various industries could come face-to-face with cadmium exposure. The risk is particularly high for folks working in electroplating, metal machining, plastics, ceramics, paint, and welding operations. The primary routes of exposure are inhaling dust and fumes, as well as accidentally ingesting dust from contaminated hands, food, or cigarettes.
Cadmium exposure can also come from smelting and refining metals, or from the air in industrial plants producing batteries, coatings, or plastics. According to the Agency for Toxic Substances and Disease Registry, over half a million workers in the United States encounter cadmium each year.
How OSHA Protects Workers Exposed to Cadmium
Now, let’s talk about how OSHA steps up to the plate to protect workers exposed to cadmium. The top health concerns from long-term cadmium exposure include kidney dysfunction, lung cancer, and prostate cancer. Cadmium can also cause skin or eye irritation and can have lasting effects on health if inhaled or ingested. The risk of cadmium exposure is greater through inhalation than ingestion. Hazardous exposure can occur in jobs where workers come into contact with cadmium dust or fumes, heat compounds or surfaces containing cadmium, or weld or cut materials containing cadmium.
OSHA started shielding workers from cadmium exposure over 30 years ago by adopting the American National Standards Institute’s (ANSI) threshold limit values (TLVs) for cadmium as a national consensus standard under the Occupational Safety and Health Act of 1970, Section 6(a) in 1971. In 1992, OSHA lowered the exposure limits after crunching the numbers on risk assessment and thoroughly evaluating epidemiological studies of lung cancer and renal dysfunction among workers and animal studies. The updated exposure limits made their debut in the Federal Register (Title 29 CFR, Part 1910.1027) and kicked in on December 14, 1992.
You’ll find the full OSHA cadmium standard (applicable to general industry, agriculture, and maritime) in 29 CFR 1910.1027. This summary shouldn’t replace the complete regulatory requirements of the cadmium standard. Keep in mind, the construction industry has its own separate cadmium standard found in 29 CFR 1926.1127.
Exposure Limits for Cadmium
OSHA’s cadmium standard outlines three exposure limits that employers need to keep an eye on. The first is the action level, or AL, which serves as the airborne cadmium level that necessitates airborne exposure monitoring, a medical surveillance program for employees exposed to or above the AL for 30 or more days per year, and respirators upon request. Next up is the Permissible Exposure Limit, or PEL, which sets the maximum level of cadmium exposure allowed in the workplace. Lastly, there’s the Separate Engineering Control Air Limit, or SECAL, which may be one of several distinct exposure limits applying to specific industries and processes. Employers must reach the PEL through engineering controls and work practices in all industries without a separate SECAL.
The action level for workplace cadmium exposure sits at 2.5 micrograms per cubic meter of air (2.5 µg/m³) as an 8-hour time-weighted average (TWA) exposure.
Now, let’s discuss the PEL. This limit is a time-weighted average concentration that must not be surpassed during any 8-hour work shift within a 40-hour work week. The PEL for cadmium is set at 5 micrograms per cubic meter of air (5 µg/m³) for all cadmium compounds, dust, and fumes.
Moving on to SECALs, these separate exposure limits must be achieved in specific processes and workplaces where reaching the PEL of 5 µg/m³ through engineering and work practices alone is not possible. The SECAL for cadmium can be either 15 µg/m³ or 50 µg/m³, depending on the processes involved. Employers subject to the SECAL must achieve that limit through engineering and work practice controls as much as possible, and protect employees from exposures above the PEL using a combination of compliance methods, such as engineering and work practice controls, and respirators.
Industries with separate SECALs for specific processes include nickel cadmium battery production, zinc/cadmium refining, pigment and stabilizer manufacturing, lead smelting, and plating.
A SECAL of 50 µg/m³ applies to the following industries and processes:
- Nickel cadmium battery industry: Plate making and plate preparation process
- Zinc/cadmium refining: Cadmium refining, casting melting, oxide production, and sinter plant
- Pigment manufacturing: Calcine, crushing, milling, and blending
- Stabilizer production: Cadmium oxide charging, crushing, drying, and blending
- Lead smelting: Sinter plant, blast furnace, baghouse, and yard area
A SECAL of 15 µg/m³ is applicable for the following industries and processes:
- Nickel cadmium battery industry: All processes not listed above
- Pigment manufacturing: All processes not listed above
- Plating manufacturing: Mechanical plating
Communicating Cadmium Hazards to Employees
It’s crucial that employees are informed about the hazards associated with cadmium exposure in the workplace. Employers must adhere to the requirements of the OSHA Hazard Communication Standard (29 CFR 1910.1200), which includes displaying warning signs and labels in visible locations, providing access to material safety data sheets (MSDS), and offering appropriate employee training.
Warning signs must be posted in regulated areas and all approaches to regulated areas (areas where employees may face exposure to cadmium at levels above the PEL). These signs must be well-lit, clean, and maintained so that the legend is easily visible, featuring the following warnings:
- Danger
- Cadmium
- Cancer hazard
- Can cause lung and kidney disease
- Authorized personnel only
- Respirators required in this area
Containers for shipping and storage that hold cadmium, cadmium compounds, or cadmium-contaminated clothing, equipment, waste, scrap, or debris must be labeled with the following information:
- Danger
- Contains cadmium
- Cancer hazard
- Avoid creating dust
- Can cause lung and kidney disease
Where feasible, installed cadmium products should have a visible label or other indication that cadmium is present.
Cadmium Exposure Training for Employees
Before being assigned to a job involving potential cadmium exposure, employees must undergo training and receive additional training at least once a year.
The training should cover the following topics:
- Health hazards associated with cadmium exposure (refer to Appendix A of the cadmium standard at 29 CFR 1910.1027)
- Locations and methods of cadmium usage, storage, and release at the workplace, including processes or operations with potential exposure, especially above the PEL
- Engineering controls and work practices to manage cadmium exposure related to the employee’s job assignment
- Measures employees can adopt to protect themselves, such as adjusting smoking habits, maintaining personal hygiene, and employing suitable work practices
- Emergency procedures
- Purpose, selection, fitting, usage, and limitations of personal protective equipment
- Overview of the medical surveillance program
- Access to a copy of the cadmium standard and its appendices, with the option for employees to request a copy
- Employee rights to access records
Employers must ensure that employees understand they are prohibited from eating, drinking, smoking, chewing tobacco or gum, or applying cosmetics in regulated areas. Carrying or storing such materials or items in a regulated area is also forbidden.
Information about the training program must be available to the Assistant Secretary of Labor for Occupational Safety and Health or the Director of the National Institute for Occupational Safety and Health upon request.
Cadmium Air Monitoring Requirements
If your workplace could potentially expose employees to cadmium, the initial step is to assess if exposure reaches or exceeds the action level of 2.5 µg/m3. Exposure levels are determined by collecting breathing zone air samples, which reflect an employee’s regular, daily TWA exposure over an eight-hour period. The monitoring method and analysis must have an accuracy rate of no less than ±25% with a 95% confidence level.
Breathing zone samples should be collected for every employee on each shift, for each job classification, in each work area. If multiple employees share similar job tasks, job classifications, shifts, work areas, durations, and cadmium exposure levels, a representative fraction of employees can be sampled instead of all employees. Those selected for sampling are expected to have the highest exposure levels.
If air monitoring reveals that employees are exposed at or above the action level, periodic monitoring must occur at least every six months. If periodic air monitoring shows exposure levels below the action level and a repeat test at least seven days later also indicates levels below the action level, the employer may discontinue the semi-annual air monitoring for those employees whose exposures are represented by such monitoring.
Additional monitoring must be performed if new equipment is added, raw materials are changed, new personnel are hired, or work practices and final products are altered, potentially exposing more employees to cadmium at or above the action level. If the employer suspects that cadmium exposure may increase and employees already exposed to cadmium at or above the action level could be exposed above the PEL, additional air monitoring should be conducted.
Employers can rely on “objective data” (industry-wide studies or laboratory product test results resembling conditions in the employer’s facilities) instead of implementing initial monitoring if the data demonstrates that a specific product, material, or process involving cadmium cannot release dust or fumes in concentrations at or above the action level.
Notifying Employees of Monitoring Results Within 15 days of receiving air monitoring results, affected employees must be individually notified in writing, and the results must be posted where all affected employees can view them. Employees exposed to cadmium above the PEL must be informed in writing that the PEL has been exceeded, along with a written explanation of the corrective actions taken by the employer to reduce the exposure level to or below the PEL.
Mechanical Ventilation
If mechanical ventilation is utilized to control exposure, measurements must be taken as necessary to maintain the system’s effectiveness, such as capture velocity, duct velocity, or static pressure. Any changes in production processes or controls that might increase cadmium exposure require the effectiveness of the ventilation system to be reevaluated within five working days of the change.
If air is recirculated from exhaust ventilation into the workplace, the system must be equipped with a high-efficiency filter and monitored periodically to ensure effectiveness.
Compliance Program Requirements
For workplaces experiencing exposure levels above the PEL or SECAL, a written compliance program must be established and implemented to reduce employee exposure to or below the PEL using engineering and work practice controls. If these controls cannot reduce exposure to or below the PEL, the employer must include the use of appropriate respiratory protection in the written compliance program to achieve compliance with the PEL. The written program must be updated at least annually (or more frequently if necessary) and made available for examination and copying to employees as well as the Assistant Secretary of Labor for Occupational Safety and Health and the Director of the National Institute for Occupational Safety and Health upon request.
A written compliance program must contain the following elements:
- Description of each operation involving cadmium emissions, including the type of machinery used, material processed, controls in place, and crew size
- Outline of operating and maintenance procedures and employee job responsibilities
- Explanation of how the employer will achieve compliance, such as engineering plans and studies, and the use of respiratory protection
- Report on the technology used or considered for use to meet the PEL
- Air monitoring data to document the sources of cadmium emissions
- Implementation schedule for the program, including documentation such as copies of purchase orders for equipment and construction contracts
- Emergency plan that covers the use of respirators and personal protective equipment, as well as methods to restrict access to an area for non-essential employees until the problem is resolved
Requirements for PPE
When workers find themselves in environments where cadmium exposure surpasses the Permissible Exposure Limit (PEL) or where skin and eye irritation may occur, it’s crucial that they’re outfitted with appropriate safety gear. This includes respiratory protection and other protective garments that shield both the worker and their clothing from contamination. In cases where eye or skin irritation is a concern, employees should be provided with equipment designed to shield their skin and eyes. Some examples of suitable personal protective equipment are:
- Coveralls
- Gloves
- Headgear
- Boots
- Face shields
- Goggles
Employers are responsible for supplying and maintaining necessary protective equipment at no cost to the employee. In addition, they must also provide changing rooms, handwashing stations, and showers. To keep workers safe, certain precautions must be taken, including:
- Removing all protective clothing and gear in a designated changing area at the end of each shift, avoiding shaking or blowing off any residual cadmium.
- Providing separate storage spaces in changing rooms for street clothes and cadmium-contaminated work attire.
- Ensuring the regular cleaning and upkeep of protective clothing and equipment, including weekly washing, as well as prompt repair or replacement when necessary.
- Mandating that employees exposed to cadmium above the PEL shower at the end of their work shift and refrain from eating, drinking, smoking, or using cosmetics until they’ve washed their hands and face.
Special Cleaning Requirements for Protective Clothing
Cleaning or laundering cadmium-contaminated work attire calls for special care. Employers must make certain that individuals responsible for handling contaminated clothing or equipment are aware of the potential dangers and know how to safely clean or launder these items to prevent cadmium release above the PEL. An essential aspect of this process involves allowing only authorized employees to remove cadmium-contaminated clothing or equipment from the workplace, whether for laundering, cleaning, or disposal. Items taken from the work area must be placed in sealed, impermeable bags designed to prevent the spread of cadmium dust, and these bags should be labeled as outlined in the section on hazard communication to employees.
Types of Respirators
The respiratory protection program must comply with 29 CFR 1910.134 (Respiratory Protection) and include a written respiratory protection program administered by a trained program manager. Respirators are necessary whenever employees are exposed to cadmium levels exceeding the PEL, during both regular operations and maintenance and repair activities. The table below details specific respirator requirements depending on the exposure level, although respirators suited for higher environmental concentrations can also be used at lower exposure levels. Quantitative fit testing is required for all tight-fitting air-purifying respirators when the airborne concentration of cadmium is more than 10 times the PEL. If eye irritation is observed, a full facepiece respirator is necessary.
Table 1: Respiratory Protection for Cadmium
Source: Respiratory Decision Logic, NIOSH, 1987
| Airborne Concentration | Required Respirator Type |
|---|---|
| Less than 10 times the PEL | A half mask, air purifying equipped with a high-efficiency particulate air (HEPA) filter. |
| Up to 25 times the PEL | A powered air-purifying respirator (PAPR) with a loose-fitting hood or helmet equipped with a HEPA filter or a supplied-air respirator with a loose-fitting hood or helmet face piece operated in the continuous flow mode. |
| Up to 50 times the PEL | A full face piece air-purifying respirator equipped with a HEPA filter or a powered air-purifying respirator with a tight-fitting half mask equipped with a HEPA filter or a supplied-air respirator with a tight-fitting half mask operated in the continuous flow mode. |
| Up to 250 times the PEL | A powered air-purifying respirator with a tight fitting full face piece equipped with a HEPA filter or a supplied-air respirator with a tight-fitting full face piece operated in the continuous flow mode. |
| Up to 1,000 times the PEL | A supplied air respirator with half mask or full face piece operated in the pressure demand or other positive pressure mode. |
| More than 1,000 times the PEL | A self-contained breathing apparatus with a full face piece operated in the pressure demand or other positive pressure mode, or a supplied-air respirator with a full face piece operated in the pressure demand or other positive pressure mode and equipped with an auxiliary escape type self-contained breathing apparatus operated in the pressure demand mode. |
| Fire Fighting | A self-contained breathing apparatus with full face piece operated in the pressure demand or other positive pressure mode. |
Requirements for Medical Monitoring
Employers must establish a medical monitoring program for all employees who may be exposed to cadmium at or above the action level for 30 or more days per year (or within a consecutive 12-month period). All medical exams associated with this requirement must be offered at no cost to the employee, at a convenient time and location, and performed by or under the supervision of a licensed physician familiar with the cadmium standard’s regulatory text, including appendices detailing health effects and sample handling and laboratory selection protocols. Biological samples must be collected reliably, and analyses must be carried out in labs with demonstrated proficiency in the tests performed.
Employees must be informed that they have the option to seek a second medical opinion after any employer-provided medical examination or consultation to review findings, determinations, or recommendations, or to conduct additional examinations, consultations, or laboratory tests. The employer can require the employee to notify them of their intention to seek a second opinion and to initiate the process within 15 days of being informed of this option or receiving the physician’s written opinion from an employer-provided examination, whichever occurs later, as a condition for covering the costs of a second medical opinion.
Medical monitoring starts with an initial examination for each employee who meets the requirement within 30 days of starting a job that involves cadmium exposure. Exceptions can be made for employees who can prove they’ve had an examination including all required elements within the last 12 months. Results from a qualifying examination during that period must be maintained as part of the employee’s medical record and treated as the initial examination. The examination should include:
- Medical and work history
- Past, present, or anticipated future exposure to cadmium
- History of dysfunction in renal, cardiovascular, respiratory, hematopoietic, reproductive, or musculoskeletal systems
- Current use of medication with potentially nephrotoxic side effects
- Smoking history and current status
- Biological monitoring
- Cadmium in urine (CdU), standardized to grams of creatinine (g/Cr)
- Beta-2 microglobulin in urine (β2-M), standardized to grams of creatinine (g/Cr), with pH specified
- Cadmium in blood (CdB), standardized to liters of whole blood (lwb)
The following trigger levels will determine the extent of medical surveillance following the initial examination. Levels at or below the specified levels require only the minimum level of periodic medical surveillance, which includes a follow-up exam within one year of the initial exam and a periodic exam every two years thereafter. Biological sampling must be provided at least annually.
Trigger levels for medical surveillance:
- CdU level: at or below 3 µg/g Cr
- β2-M level: at or below 300 µg/g Cr
- CdB level: at or below 5 µg/lwb
If an employee’s initial biological monitoring tests reveal levels exceeding any of the aforementioned parameters, the employer must reassess the employee’s occupational exposure to cadmium within two weeks of receiving the test results. This reassessment should include a reevaluation and reexamination of the employee’s work practices, personal hygiene, respirator use (if applicable), respirator program, smoking history and current usage, as well as available hygiene facilities and engineering controls in use. If any deficiencies are identified during this reevaluation, the employer must correct them within 30 days.
An employee with biological test results elevated relative to the trigger levels mentioned above must receive a full medical examination within 90 days after receiving the initial test results. At this point, the examining physician should determine whether the employee should be medically removed from cadmium exposure. If the physician decides against medical removal, biological monitoring must continue semiannually, along with annual medical exams.
If an employee’s biological test results during both the initial and follow-up medical examinations exceed the trigger levels listed below, the employee must be medically removed from exposure to cadmium at or above the action level:
(1) CdU level: above 7 µg/g Cr
or
(2) CdB level: above 10 µg/liter of whole blood
or
(3) β2-M level: above 750 µg/g Cr and
(a) CdU exceeds 3 µg/g Cr
or
(b) CdB exceeds 5 µg/liter of whole blood
Mandatory employee removal is required if the second set of biological monitoring results from the medical examination shows that one of the above mandatory removal trigger levels has been exceeded. The employer must continue to monitor the employee with biological monitoring on a quarterly basis, along with semiannual medical examinations, until the employee’s levels fall within the acceptable trigger levels for medical surveillance.
Employee removal is also necessary if the examining physician determines that the employee needs removal from exposure to cadmium based on other findings from the examination, regardless of the above testing results.
Scheduled Medical Check-ups
Workers exposed to cadmium but not exceeding biological trigger limits must undergo a medical exam within a year after their initial exam, followed by an exam at least every two years. These medical exams should include:
- Comprehensive occupational and medical history.
- Full physical assessment, focusing on blood pressure, respiratory and urinary systems.
- A reasonably-sized posterior-anterior chest x-ray (frequency determined by the physician).
- Lung function tests.
- Bloodwork.
- Urine tests.
- Prostate exams for males over 40.
- Any additional tests deemed necessary by the doctor.
Workers should receive annual biological testing, either as part of their medical exams or as separate periodic monitoring. When an employee leaves the job, voluntarily or otherwise, employers must provide a medical examination that includes a chest x-ray. However, if the employee’s most recent medical exam was less than six months prior, no additional examination is necessary.
Confidentiality and Access to Medical Data
Employers must supply the physician conducting the exam with a copy of OSHA’s cadmium standards and appendices, a description of the employee’s past, present, and anticipated duties and exposure levels related to occupational cadmium exposure, previous medical and biological monitoring results, and a description of the employee’s personal protective equipment.
Employers must also obtain a written medical opinion from the physician for each employee’s medical examination. Physicians should not disclose any unrelated findings or diagnoses to the employer. The written opinion should contain:
- The employee’s diagnosis.
- An evaluation of whether the employee has any medical conditions that increase their risk of health impairment due to further cadmium exposure, including signs of cadmium toxicity.
- Biological test results.
- Any suggested removal or limitations on the employee’s activities, duties, or personal protective equipment usage, such as respirators.
- A statement confirming that the physician has thoroughly and clearly explained the medical examination results to the employee, including biological test results.
Employees must receive a copy of this written opinion and the biological monitoring test results (with an explanation) within two weeks after the employer receives it. If the employee requests access to the information provided by the employer to the physician, this information must be provided within 30 days.
Emergency Exposure Situations
In case of emergencies that could result in acute cadmium exposure, employers must provide a medical examination equivalent to the standard periodic medical exam as soon as possible, with particular emphasis on the respiratory system, other relevant organ systems, and monitoring for overexposure symptoms.
Employee Removal Procedures
Employers must temporarily remove any employee from work with excessive cadmium exposure if biological monitoring tests indicate that the employee has reached specific trigger zones or if a physician determines in a written medical opinion that the employee needs removal. The employer must reassign the employee to a position with cadmium exposure below the action level. If such a position is not immediately available, the employer must provide one as soon as it becomes available.
An employee must also be removed from excessive cadmium exposure if a physician recommends it based on biological monitoring results, the employee’s inability to wear a respirator, evidence of illness or other signs of cadmium-related dysfunction, or any other medically appropriate reason. Inability to wear a respirator requires removal from work with cadmium exposure above the PEL; any other reason for removal requires moving the worker to a position with exposure below the action level.
Follow-up biological monitoring must be provided for any employee removed from duty at least every three months, with follow-up medical examination semiannually until the examining physician provides a written opinion that the employee may return to their former job status or must be permanently removed from excessive cadmium exposure.
Employers must provide Medical Removal Protection Benefits (MRPB) for up to 18 months each time an employee is temporarily medically removed from a position due to excessive cadmium exposure. This requires employers to maintain the employee’s normal earnings, seniority, and all other employee rights and benefits, including the right to their former job status during this period. In return, employers may require the employee to participate in medical surveillance. If an employee is unable to return to their former position by the end of the 18-month period, the employer must provide the employee with a medical examination to obtain a final medical determination regarding whether the employee can return to their former position or requires permanent removal from excessive cadmium exposure.
Recordkeeping Requirements
Employers operating facilities with potential occupational exposure to cadmium must maintain three types of records: air monitoring, medical surveillance, and training records.
Air Monitoring Records Air monitoring records must include:
- The date, duration, and results of air monitoring tests, expressed as an 8-hour TWA for each sample.
- The name, social security number, and job classification of monitored employees and those they represent.
- A description of sampling and analytical methods used, along with evidence of their accuracy.
- The type of respiratory protection, if any, worn by monitored employees.
- A notation of any conditions that may affect monitoring results.
Employers must retain these records for 30 years.
Employers can use “objective data” to be exempt from initial monitoring requirements under the OSHA standard. “Objective data” is defined as information showing that a specific product, material containing cadmium, or process, operation, or activity involving cadmium cannot release dust or fumes at or above the action level, even under worst-case conditions. This information may come from industry-wide studies or laboratory test results conducted under conditions similar to the employer’s current operations. If an employer opts to use objective data, records supporting this decision must be kept for 30 years.
Medical Surveillance Records
Employers must maintain records for every employee subjected to medical surveillance, including:
- The employee’s name and social security number.
- A description of the employee’s duties.
- A copy of the physician’s written opinions and an explanation sheet for biological monitoring results.
- A copy of the employee’s medical history, physical examination results, and all test results.
- A description of any employee symptoms potentially related to cadmium exposure.
- A copy of the information provided to the physician.
These records must be maintained for the duration of the employee’s employment with the company plus 30 years. Upon request by the employee, their designated representative, anyone with written consent from the employee, or the employee’s family members after the employee’s death or incapacitation, the employer must provide copies of these records within 15 days.
Training Records Employers must create a certification record indicating that employees have received training. This record should include the employee’s identity, the trainer or employer’s signature, and the training completion date. These records must be retained for one year after the training.
If an employer ceases operations and no successor employer is available to retain the required records, the employer must comply with the record transfer requirements outlined in 29 CFR 1910.1020 (h).
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