Gradient partnered with Boston-area community organizations and local universities to evaluate potential health risks associated with recreational boating in an urban, legacy industrial waterbody.
The Malden River emerges from a culvert south of Malden center, flows to the southern border of Malden, then forms the border between Medford and Everett as it flows toward its confluence with the Mystic River just a few miles north of Boston. During the mid-1800s to early 1900s, the Malden River was the site of expanding industrial operations that relied on the river for transportation, water supply, and waste disposal (Figure). Following World War II, the majority of these heavy industrial operations moved to other locations, but this industrial history left a legacy of hazardous materials in the Malden River sediments (USACE, 2008). The lower portion of the Malden River watershed remains heavily urbanized, and much of the land along the banks is still zoned for industrial activity.
An inaugural public boating event…was held at the Malden Rowing Center site on September 28, 2019.”
In recent years, interest in developing the Malden River corridor as an urban amenity, including for recreational boating, has increased. The Mystic River Watershed Association (MyRWA) has been working for several years to coordinate development of a recreational and non-motorized transportation corridor along the Malden River, and the Friends of the Malden River (FOMR) organized for the purpose of bringing the Malden River back to vibrant, civic life. MyRWA and FOMR have been supported in their efforts by local universities, including the Tufts University Water Systems, Science & Society program, and the Massachusetts Institute of Technology (MIT) Center for Environmental Health Sciences (CEHS). These efforts have yielded some success. River’s Edge, a 215-acre public/private mixed-use development along the Malden River, includes a boat launch dock for that development, and MyRWA was successful in getting pedestrian and bicycle access lanes along the river banks under the redeveloped Rt. 16 Bridge. Despite these successes, and the efforts and interest of many parties, development of on-water recreation stalled due to concerns about the legacy impacts from the former heavy industry and the bacterial loads from the urbanized watershed. In 2014, in an eort to begin addressing these concerns, MyRWA provided in-kind research support for MIT students working under the direction of Gradient Principal Dr. David Langseth, then also a Senior Lecturer at MIT, and Prof. Harry Hemond. Some of this research produced preliminary evaluations of potential health risks from boating on the Malden River.
In 2016, MyRWA engaged Gradient to perform a human health risk assessment for recreational boating on the Malden River that would be consistent with current regulatory protocols. MIT was also a cooperator with this program, supporting community engagement and some of the data gathering.
MyRWA specified nine sites for Gradient to evaluate in this study: two sites that were currently used by school crew teams and seven sites under consideration for public recreational boating access. After review of the available sediment trace chemical data, Gradient recommended a data collection program that would provide greater consistency of data for each site under consideration. MyRWA staff collected the samples, using protocols reviewed and approved by Gradient, and had the samples analyzed at Alpha Analytical Laboratories.
Gradient evaluated cancer and non-cancer potential human health risks using standard protocols from state and federal risk assessment guidance combined with site-specific assessment of activities and exposures expected for four different classes of recreational boaters: 1) occasional boaters; 2) frequent adult boaters; 3) competitive youth boaters; and 4) competitive collegiate boaters. We also evaluated boat launch employees. the assessment focused on three classes of compounds commonly found in sediments of rivers subjected to industrial discharges: 1) metals; 2) polychlorinated biphenyls (PCBs); and 3) polycyclic aromatic hydrocarbons (PAHs).
Gradient’s risk assessment showed that incremental cancer risks were within or below the US Environmental Protection Agency (US EPA) target risk range and at or below the Massachusetts Department of Environmental Protection (MADEP) target risk limit, and all incremental non- cancer risks were below the US EPA and MADEP target hazard index of 1. These results paved the way for initiation of public boating access to the Malden River. An inaugural public boating event, in which Gradient Principal Dr. Langseth participated, was held at the Malden Rowing Center site on September 28, 2019 (Figure; photo credit: Khalil Kaba), and efforts are currently underway to site a public boat rental location on the Malden River.
US Army Corps of Engineers (USACE). 2008. “Malden River Ecosystem Restoration Detailed Project Report & Environmental Assessment.” New England District. 114p., June. Accessed at https://www.nae.usace.army.mil/Portals/74/docs/Topics/MaldenRiver/DPR_Final.pdf.