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The Methylene Chloride Standard, 29 CFR 1910, 1915 and 1926

Introduction

Unfortunately, some of the chemicals used most frequently in industry turn out to be the most harmful to our health. Methylene chloride is one such chemical. Methylene chloride, also known as dichloromethane, is used in many types of industries, including paint stripping, metal cleaning / degreasing, and polyurethane foam production. These industries have been using methylene chloride for years because of its effectiveness.

Since 1991, many studies have been conducted to determine the health effects and dangers associated with methylene chloride use. The studies proved that exposure to methylene chloride involves both acute and chronic hazards. The main routes of entry are inhalation and skin exposure.

Acute inhalation exposure causes an anesthetic effect, light headedness, nausea, vomiting and headaches. In cases of extreme overexposure, methylene chloride can cause unconsciousness and even death. Skin exposure can cause irritation and burning. In long-term tests, methylene chloride has been shown to cause cancer in laboratory animals. Because of these findings, methylene chloride is listed as a suspected carcinogen.

Because methylene chloride is such a health hazard, workers and safety and health advocates have been calling for a new safety standard to address the issue. In fact, in 1986, some industries requested an emergency temporary standard, which OSHA denied. In 1991, OSHA finally issued a notice of proposed rule making. Using exposure data, OSHA published a new methylene chloride standard on January 10, 1997, which became effective April 10, 1997. The new standard, found in the Code of Federal Regulations (CFR) 1910.1052, 1915.1052 and 1926.1152, affects general industry, construction and shipbuilding.

Exposure Limits

The most important change from the previous methylene chloride standard is the lower permissible exposure limit (PEL). The permissible exposure limit is an eight-hour average to which a person can be exposed over a 40-hour work week. The previous exposure limit was set at 500ppm (parts per million), while the new standard lowers the PEL to 25ppm.

In the new standard, OSHA also established a short-term exposure limit (STEL) of 125ppm. A STEL is a 15-minute exposure level that can't be exceeded at any time during the workday.

An action level was also put into effect with the new standard, which is one half of the PEL, or 12.5ppm. This means you must put an air monitoring program into action if your methylene chloride levels exceed 12.5ppm.

Other new requirements of the standard include:

• Establishing a written program that addresses the requirements of the standard;
• Limiting access to areas that exceed the PEL, to trained personnel only;
• Properly marking areas that exceed exposure limits; and
• Prohibiting eating, drinking and smoking in areas that are above the PEL.

Monitoring

Monitoring for methylene chloride is the first step toward complying with the standard. This is the only way to determine the levels of methylene chloride in your workplace. To get an accurate reading, you need to take an air sample that represents the atmosphere in your employees' working environment. You also want to target the person that's most likely exposed to the highest concentration of methylene chloride. If you can document that different shifts experience similar circumstances, you don't need to monitor each shift.

The standard requires an initial monitoring of methylene chloride concentration in your workplace. The exceptions to this rule are:

• If there is objective data showing that methylene chloride air concentrations can't exceed the action level or STEL;
• If monitoring has been done within the last year and the results meet the current standard; or
• If your employees are exposed less than 30 days a year and direct reading monitors are used to determine what control measures are needed to reduce exposure.

Periodic monitoring may be necessary if initial tests show that there are high levels of methylene chloride in your workplace. OSHA has determined how often this monitoring needs to be done based on exposure levels. Refer to the following chart for monitoring frequency information:

Employees have certain rights under the methylene chloride standard, in regards to monitoring:

• They must be notified of the monitoring results within 15 days of the return of the results;
• They must be allowed to observe the monitoring process; and
• Employees who are being monitored in the regulated area must be given the personal protective equipment (PPE) necessary to reduce their methylene chloride exposure.

If any conditions change in the workplace, it's important that you monitor the affected area(s) again to make sure the methylene chloride levels haven't changed. (For more information on air monitoring equipment, see EZ Facts Document #231.)

Medical Surveillance

To ensure that employees aren't adversely affected by exposure to methylene chloride, they must undergo a physical exam. The exception to this rule only applies to employees who will be exposed to methylene chloride for less than 30 days a year and who will not be exposed above the PEL or STEL for more than 10 days a year. However, if an employee has a condition that may be affected by exposure to methylene chloride he/she must still be examined by a qualified physician.

The physician should be given pertinent information on methylene chloride, including the following:

• A copy of the standard
• A description of the employee's history of exposure
• The frequency at which the employee will be exposed
• The personal protective equipment to be used
• Any other information pertinent to the exposure

The physician should also examine the employee's complete work history, perform a complete physical and request the appropriate lab tests based on the employee's history. the physician must supply a written opinion to the employer within 15 days of completing the employee evaluation and within 30 days of the physical exam.

Under the methylene chloride standard, employees require periodic medical exams depending on their age. If the employee is 45 years or older, medical evaluations should be done every 12 months. For employees younger than 45 years old, a medical evaluation is needed every 36 months. In both cases, if the employee warrants it based on their medical and work history, a medical exam should be done more frequently.

Methods of Control

To control overexposure to any chemical, OSHA offers the following recommendations to eliminate or reduce your exposure:

• Implement engineering controls
• Develop administrative controls
• Use personal protective equipment

Engineering Controls: Engineering controls include the use of ventilation systems to lower the ambient concentration. These systems include fans or fume hoods. another type of engineering control is the use of an isolation device that keeps the methylene chloride in a small area, minimizing the number of employees affected. However, engineering controls are often not feasible due to high costs, or are not possible because of the building's structure.

Administrative Controls: Administrative control measures include the substitution of a less hazardous chemical, and/or limiting exposure of high concentrations of methylene chloride to a small number of employees. Even though it's a widely accepted administrative control paractice in industry, the methylene chloride standard doesn't allow rotation of employees, because more employees would then be exposed to the chemical. The standard does call for washing facilities so that employees are not exposed after leaving the workplace.

PPE to eliminate or reduce chemical exposure should be considered after engineering and administrative controls have failed to produce effective results or if they aren't feasible options. Too often, PPE is chosen first because it's fairly easy to use and is usually the least expensive option.

Respirators and Personal Protective Equipment

When engineering and administrative controls aren't adequate to reduce overexposure to chemicals, personal protective equipment is an alternative control method. If respirators are used to control methylene chloride exposure, they must be used according to 29 CFR 1910.134 (see EZ Facts Document #275). According to the OSHA standard, cartridge respirators aren't allowed for exposures above the PEL.

According to the 3M 2007 Respirator Selection Guide (3M Occupational Health and Environmental Safety Division), the permissible exposure limit (PEL) for Methylene Chloride is 25 parts per million (ppm). If the concentration (in air) of Methylene Chloride is above 25 ppm proper respiratory protection is required.

If respiratory protection is required, the NIOSH recommendations are:

• Self-contained breathing apparatus (SCBA) with full facepience, pressure demand or other positive-pressure mode.
• Supplied air respirator with full facepiece, pressure demand or other positive-pressure mode.

Escape only: Any air purifying, full facepiece respirator (gas mask) with a chin-style, (front or back-mounted) organic vapor cartridge or canister, or any appropriate escape-type, self contained breathing apparatus.

If skin contact is a possibility, you need to provide your employees with chemical-resistant gloves and aprons or coveralls. There are several types of methylene chloride-resistant gloves available - OSHA suggests Silvershield or PVA. PVA is a glove material that holds up well to methylene chloride, but being soluble in water, it isn't the best choice for every situation.

For protective clothing, the best materials to use against methylene chloride are Tychem BR, Tychem LV, Responder, Tychem TK and Reflector by DuPont.

Recordkeeping

According to OSHA, employers are required to retain records relating to the methylene chloride standard, such as medical and air monitoring records. You must keep any such records for at least 30 years after the employee's employment has terminated. The records must be accessible to both current and past employees.

If it's been determined that monitoring isn't necessary, you need to keep a record of this information as well. Records will be required if your facility is ever inspected.

Records regarding exposure monitoring should include the dates and times the monitoring was done, name and critical information of the employee exposed to methylene chloride, the operation affected by the methylene chloride, number of samples taken, sampling methods used and type of personal protective equipment used.

For medical surveillance, records should include the name and critical information of the employee, name of the physician and their written opinion, and the employee's condition relating to the methylene chloride.

Training

Employee training is covered by the Hazard Communication Standard (see EZ Facts Document #150). Some additional training topics include:

• Requirements of the methylene chloride standard, including where employees can get a copy of the standard; and
• Information on how methylene chloride is used in the workplace, as well as exposure levels for each area of your workplace.

Refresher training should be done on a regular basis as needed. This is a good way to ensure that employees are safe and are following the proper procedures for handling methylene chloride.

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Please Note: The information contained in this publication is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the cited regulation or consult with an attorney.