Germinomas and teratoid siphon anomalies in softshell clams, Mya arenaria, environmentally exposed to herbicides.

Abstract

Seminomas and dysgerminomas are epizootic in softshell clams, Mya arenaria, from three Maine estuaries contaminated with herbicides. The first epizootic was discovered in 22% of clams collected as Searsport near Long Cove Brook and three culverts that conveyed heating oil and jet fuel spilled from a tank farm in 1971. Data from subsequent epizootiological studies and a series of long-term experimental exposures of softshell clams to no. 2 fuel oil, JP-4, and JP-5 jet fuel at the U.S. EPA, Environmental Research Laboratory in Narragansett, Rhode Island, and in the field did not support an etiology by these petroleum products. In the two recent epizootics reported here, the germinomas have been observed in 3% of the softshell clams collected from Roque Bluffs near Machiasport and from 35% of softshell clams collected from Dennysville. Mya collected at Dennysville had pericardial mesotheliomas and teratoid siphon anomalies in addition to gonadal neoplasms. Estuaries at Dennysville had been contaminated by herbicides in a 1979 accidental spray overdrift during aerial application of Tordon 101 to adjacent forests. Further investigation determined widespread use of the herbicides Tordon 101, 2,4-D,2,4,5-T, and other agrochemicals in an extensive forestry and blueberry industry in both the Roque Bluffs and the Dennysville areas. Herbicide applications at Searsport were confirmed for railroad property bordering Long Cove estuary and for Long Cove Brook adjacent to the estuary where a highway department reportedly cleans its spray equipment. Herbicide contamination is the only common denominator identified at all three sites where Mya have been found with gonadal neoplasms.(ABSTRACT TRUNCATED AT 250 WORDS)

The sublethal effects of (2,4-Dichlorophenoxy) acetic acid (2,4-D) on narrow-clawed crayfish (Astacus leptodactylus Eschscholtz, 1823)

“…In a previous study, Benli et al (2) estimated the 96 h LC 50 for freshwater crayfish to be 32.6 mg L -1 . In addition, 2,4-D exposure has been linked with gonadal tumours in shellfish (1,(13)(14)(15)(16). Limited information about the effects of this widely used herbicide 2,4-D on the aquatic invertebrate histology and biochemical biomarkers are available in the open literature.…”

Comparative histopathology of gonadal neoplasms in marine bivalve mollusks

“…However, subsequent electron microscopy of tumor tissue at the RTLA by Dr S. C. Chang did not confirm the presence of a virus. Gardner et al (1991b) reported 2 more populations of M. arenaria with germinomas in Maine. The only factor that these sites had in common with the earlier Searsport sites was a high level of exposure to herbicides (Tordon 101; 2,4-D; 2,4,5-T) used in blueberry agriculture, from forestry industries spraying coastal railroad rights-of-way, and from the Maine Highway Department's spraying of its rights-of-way and cleaning of its spray tanks in Searsport.…”

“…These herbicides have also been linked to tumors of the reproductive tract in the military working dogs that served in Vietnam (Hayes et al 1990). Based on this epidemiological evidence, Gardner et al (1991b) proposed an herbicide etiology for the softshell germinomas; herbicides may also prove to be a factor in the Mercenaria germinomas (Van Beneden et al 1993). Relevant laboratory experiments are under way to test this theory in M. arenaria.…”

Molecular analysis of bivalve tumors: models for environmental/genetic interactions.

“…Recent ERL/N (U.S. EPA Environmental Research Laboratory, Narragansett) field surveys identified epizootic germinomas in three geographically distinct populations of softshell clams (Mya arenaria) in eastern Maine (1). Investigation into the etiology of these tumors revealed that all three locations had been subjected to herbicide exposure.…”