The total economic impact of construction union earnings on the Bay State amounted to $4.6 billion in 2007, according to a new study by Boston’s The Construction Institute.

Building trades unions represent approximately 73,000 members in Massachusetts, or more than 60 percent of the construction production workforce.

"This study confirms what we already knew to be true – unionization in the construction industry not only creates middle-class career opportunities in the building trades for Massachusetts residents, but results in significant economic benefits for the commonwealth and the local communities in which our members live and work," said Mary Vogel, executive director of TCI.

The increase in aggregate earnings of unionized as compared to non-union construction workers has a positive effect on the total income of Massachusetts families, the study found. As union workers enjoy higher income levels, their ability to spend in goods and services in their communities also increases, resulting in $1.74 billion of increased income for all state residents.

Union wage premium has a positive effect on state tax revenues. Sales tax revenues increased by $23.8 million and state personal income tax revenues increased by $92.3 million, according to the study.

Despite state legal requirements for employees’ health benefits coverage, the coverage provided to non-union workers is mostly inadequate or virtually non-existent, according to the study. Existing research has found that union training programs are more effective than non-union programs in terms of enrolling apprentices and producing journey-level workers. The quality of training has important implications for workers’ productivity as well as for decreasing occupational injuries. OSHA records for Massachusetts construction industry reveal that 88 percent of the violations between 2004 and 2009 were committed by non-union contractors.