Is Cancer in Israeli Professional Divers Exposed to Polluted Waters an Occupational Disease?

ABSTRACT

Because there is some contamination of practically every body of water, risk analysis is important to determine diving exposure standards to pollutants, including requirements for protective equipment. In the following study we attempt to determine the increased risk of cancer in Israeli Naval divers exposed to pollutants in the Kishon River system. We calculated two risks, one using maximally recorded levels of pollutants outside the diving areas (worst-case scenario), and the other using maximally recorded levels in the actual diving areas. For both calculations we used conservative assumptions for exposure (2500 exposure hours with 50% of body covered with sediment), and a synergistic risk model. We considered all chemicals that were carcinogenic by inhalation also to be carcinogenic by oral and dermal absorption. The relative risk was 1.13 for the worst-case scenario, and 1.004 for exposures in actual diving areas. We conclude that it is unlikely that exposure to the polluted Kishon River waters can cause a detectable increase in cancer risk in Israeli Navy divers. This study has implications for professional divers exposed to polluted waters.

Key Words:

• risk analysis
• divers
• river waters
• sediment
• water pollution

Acknowledgments

Prof. Paul Froom is being paid for his professional opinion against claims that the Kishon waters and sediments caused diseases. Dr. Asher Pardo and Dr. Shlomo Almog have no conflicts of interest.

Notes

*Water standard (USEPA), work standard (American Conference of Governmental and Industrial Hygienists' threshold limit value expressed as a time-weighted average), absorption coefficients are from the USEPA (2005e)

**Not found, but assumed a value as measured upstream from the Fisherman's Cove, and a 10-fold dilution factor as was found for other substances for the Kishon and Haifa harbors

***Level of between 5–10 ppm was found in the discharge pipes of one of the factories

*TLV-TWA (American Conference of Governmental and Industrial Hygienists' threshold limit value expressed as a time-weighted average) or PEL (U.S. Occupational Safety and Health Administration's permissible exposure limit) × 10 m3/day × 10,340 days (47 years × 220 days per year) × proportion absorbed in the lungs

† over 70 years, 51,100 liters × water standard × proportion absorbed

‡ Suggested maximal concentration limit

§ outdoor concentration global average 6 μg/m3 × 50% absorbed × 20 m3 per day × 25,500 days (70 years)

*Using the greatest value recorded and estimated hours in the actual diving areas corrected for (2000 hours Haifa Harbor, 400 hours Kishon harbor, and 100 hours Fisherman's cove)

† using 40% gastro-intestinal absorption

‡ corrected for 0.31 absorption

§ A or B divided by D/100,000, and if A or B were less than D, then an increased risk of 0.00001 (1 per 100,000) is assumed

¶ Lifetime risk for cancer = 0.3 + E

**Relative risk = F/0.3