Cancer Risks in Naval Divers with Multiple Exposures to Carcinogens. (Environmental Medicine)

Article excerpt

We investigated risks for cancer and the case for a cause--effect relationship in five successive cohorts of naval commando divers (n = 682) with prolonged underwater exposures (skin, gastrointestinal tract, and airways) to many toxic compounds in the Kishon River, Israel's most polluted waterway, from 1948 to 1995. Releases of industrial, ship, and agricultural effluents in the river increased substantially, fish yields decreased, and toxic damage to marine organisms increased. Among the divers (16,343 person-years follow-up from 18 years of age to year 2000), the observed/expected ratio for all tumors was 2.29 (p < 0.01). Risks increased in cohorts first diving after 1960 compared to risks in earlier cohorts, notably for hematolymphopoietic, central nervous system, gastrointestinal, and skin cancer; induction periods were often brief. The findings suggest that the increases in risk for cancer and short induction periods resulted from direct contact with and absorption of multiple toxic compounds. Early toxic effects in marine life predicted later risks for cancer in divers. Key words: cancer, diving, heavy metals, multiple exposures, naval divers, petroleum derivatives, solvents, water pollution.

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In 2000, we received reports of a suspect cancer cluster in Israeli naval divers who trained in the Kishon River, its estuary, and in Haifa Bay (Richter et al. 2000b). Since the late 1940s, the Kishon River and Haifa Bay served as a training site for recruits and naval commandos, an elite and highly select group in the Israeli military (Figure 1). In the past 50 years, pollution in the Kishon had progressively worsened, reaching levels close to those found in the world's most polluted rivers (e.g., Reine, Alba, Po) [Government of Israel Commission of Inquiry (GICI) 2001]. The major sources of pollution were industrial effluents, dredging of sediments, and dumping of waste from ships in the Haifa Harbor.

[FIGURE 1 OMITTED]

As early as 1953, government reports documented isolated fish kills from fertilizer runoff, odors of oil from the fish and loss of edibility, and, later, in the 1970s, repeated episodes of acidity, pollution, and fish kills (GICI 2001). Thereafter, an array of anecdotal reports, site visits, governmental reports, and research projects cited in the GICI document confirmed these observations as well as the presence of numerous toxic compounds and effects on marine life. For example, one report from the 1970s (Library, Archival Files on Kishon River, Israel Ministry of Health, Jerusalem, Israel states that

   Fertilizers began to pose a problem in 1953 ... and
   fish kills began. Before 1953, many species of fish
   lived.... [T]oday the only fish are "buri," which are
   especially resistant to pollution, and even from them
   there is a sharp smell of oil and they are inedible.

Another report stated that

   ... during the years 1971-[1972] a number of
   "disasters" occurred in the river; some of these
   caused major fish kills, for example, the death of
   the fish species Sardina pilchardus in May 1971,
   as a result of increased pollution combined with
   acidic conditions....

(Library Archival Files on Kishon River, Israel Ministry of Health, Jerusalem, Israel) (Figure 2). In 2000, veteran fishermen recalled the progressive decrease in fish yield from "abundant" in the 1950s to "reduced" in the 1960s, to "poor" in the 1970s, to "disastrous" in the 1980s, to "catastrophic" in the 1990s (Richter ED. Unpublished data).

[FIGURE 2 OMITTED]

The first two divers with cancer presented in the late 1960s, (one with brain cancer, one with bowel cancer), and nine more divers presented with diverse cancers in the 1970s. By 1989, the cumulative number had increased to 26. Between 1990 and 1999, there were 24 additional cancers. Although there have been population-based surveys of cancer risks in naval personnel (Garland et al. …