PDF Version of Hazard Info Bulletin 397 pdf format of hib397.pdf

The Massachusetts Right to Know Law applies to all public sector employees working in State, county and municipal workplaces in the Commonwealth with the exception of those employed in police stations, public armories where ammunition is stored and public sector research labs (if granted an exemption by the Department of Public Health). The Massachusetts Right to Know Law became effective in 1984. Federal OSHA regulates private sector workplaces under the Hazard Communication Standard (CFR 1910.1200) with similar requirements. The Workplace portion of the Mass Right to Know law requires that information on chemical hazards be given to employees. This is accomplished by requiring that employees, who have been, are or may be exposed to toxic/hazardous chemicals in the workplace, are provided with the following:


  • access to Material Safety Data Sheets (MSDSs),
  • labeling on containers of chemicals, and,
  • written instructions or training on chemical hazards and safe work procedures.

Chemicals Covered

All products which contain 1% or more (2% if an impurity) of one or more ingredients listed on the Mass Substance list are covered by the Right to Know Law. In order to determine this, it is necessary to get a copy of the list and request an MSDS from the manufacturer so that the ingredients can be compared to the chemicals on the list.

Alternatively, as a matter of DLS policy, it is acceptable for a municipal, county or state employer to assume that all chemicals for which a manufacturer has prepared a MSDS are covered by the Right to Know Law.

Employers have no obligations under the Right to Know Law with respect to certain items, including food, alcoholic beverages, and some consumer items, regardless of their contents. A detailed list of exempt items is set forth in the Right to Know Law (Mass General L. ch. 111F, sec. 1) and the regulations promulgated there under (454 CMR 21.00).


A material safety data sheet (MSDS) is a document, which provides important information on the ingredients and hazards of and protective equipment and practices needed to work safely with a product. The MSDS is developed by the product manufacturer. An employer who has not received an MSDS from the manufacturer must request it from the manufacturer.

An MSDS must be requested for each chemical used in the workplace in order to determine which chemicals are covered by the Law. MSDSs should be filed in an organized manner at a central location in the workplace, so that the employer can easily provide an MSDS if an employee requests one.

Labeling Requirements

Employers must label all substances subject to the RTK Law, which are in containers of more than 1 gallon or more than 5 pounds. The labels must include the chemical name of such substances. Chemical names must be used with all of the substances listed on the Mass Substance List if they are present in the container at quantities greater than 1% (2% if impurity).

Containers, which contain more than five gallons or thirty pounds of materials to which National Fire Protection Association (NFPA) Code 49 applies, must also be labeled with the proper NFPA Code.

As a matter of DLS policy, containers, which are labeled in accordance with the OSHA Hazard Communication Standard, will also be considered to satisfy the labeling requirements of the Right to Know Law. Under the OSHA Hazard Communication Standard, containers must be labeled with the name of the product as listed on the MSDS, the health hazard warnings (including target organ health effects) and physical hazard warnings (such as flammable or corrosive). Most manufacturers label containers in accordance with this Standard, since this is a Federal law applying to all private sector workplaces.

Training/Written Instruction Requirements

Employees who are or may be exposed to chemical hazards must be trained or instructed in writing annually. The initial training or instruction for new employees must be provided within 30 days of employment. A record including a description of the training given, the date of the training and the names of both the instructor and employees who received training or instruction must be kept for the duration of employment.

The training or written instruction must include a summary of the employee's rights under the law. It must also include information on how to read an MSDS. Finally, the most critical aspect of the training is informing employees of the specific hazards and safe work practices for preventing these hazards.

Posting a Workplace Notice

A Right to Know Workplace Notice must be posted in a central location at all workplaces which are covered by the RTK Law (Contact DLS at (617) 969-7177 for current workplace notices). Which can be Downloaded HERE pdf format of rtk-poster.pdf

Employee Rights

Employees have rights under the law, which include the right to request a copy of an MSDS and in certain circumstances, the right to refuse to work if a MSDS is not provided. More detailed information on employees' rights is given on the required workplace notice and in the RTK Law and the regulations.

Law and Regulation Reference

The Right to Know Law -MGL Ch.111F (Sections 1 -21)

Department of Labor Standards (DLS) - Workplace Regulation-454 CMR 21.00

Two other sets of regulations have been promulgated by other agencies under the Right to Know Law:

  • Mass Dept of Public Health (105 CMR 670.000) (promulgated under sec. 4 - 6; 12 and 20 of Ch. 111F).
  • Dept of Environmental Protection (310 CMR 33.00) (promulgated under sec. 16 - 19 of Ch. 111F).

Registration of Third Party Trainers

The Massachusetts Right to Know Law provides for the registration of Third Party Trainers by the DLS. To obtain copies of the necessary documents or to obtain a list of current registrants, please contact the DLS at 617-969-7177.

Further Information

If you have questions, or, would like to ask for an inspection or consultation, contact the DLS Workplace Safety and Health Program/Indoor Air Quality Program at 617-969-7177. 

Right to Know Documents

1. Right to Know Booklet

This booklet contains all official State documents pertaining to the Right to Know Law. It includes a copy of the Law and regulations of the Department of Labor Standards (DLS), Department of Public Health and Department of Environmental Protection. The Mass Substance List is included in the booklet. The booklet can be obtained from the Statehouse Bookstore.

2. Massachusetts Right to Know: Employer Assistance Manual

This manual reviews employers' responsibilities under the Law and is written in easily understood language. It provides a step by step process for complying with the law and provides tips for accomplishing the required tasks. It is currently being updated.

3. Chemical Hazards on the Job: Your Right to Know

This booklet gives a detailed explanation of worker rights under the Mass Right to Know Law. Topics covered include Material Safety Data Sheets, container labeling, training, and filing complaints. It is available at the Statehouse bookstore.

4. Right to Know Poster

This required poster has recently been updated to provide the most current contacts for Right to Know. It is available online HERE. pdf format of rtk-poster.pdf

5. Understanding Material Safety Data Sheets (MSDSs)

This four page document explains the terms on a Material Safety Data Sheet in easy to understand language. It is available free of charge by calling DLS at 617-969-7177.

There are two Statehouse Bookstores:

Massachusetts State House Bookstore
State House, Room 116
Boston, MA 02133

Secretary of State - Western Office
436 Dwight Street, Room 102
Springfield, MA 01103

The catalog and ordering information for Statehouse bookstore publications can also be accessed via Internet at www.magnet.state.ma.us/sec/spr.