The Br concentration in Rongelap lagoon water wassimilar to that of Atlantic
ocean water (62.4 ppm and 67.2 ppm, respectively). Rain catchment water on

Rongelap had no detectable Br. Intermediate Br values of 2.2, 13.8, and 17.9 ppm

were found in three Rongelap wells. The Br concentration in three samples of
Rongelap coconut water was 7.0, 6.4, and 5.3 ppm, similar to the 7.0 and 6.8 ppm

found in two Florida-grown coconuts.

The mean serum and red cell Br levels of the 20 Marshallese studied were
significantly higher than those of the 10 New Yorkers, as well as being higher than
levels reported for other populations (1—6). Cross and Smith (8) have suggested

that the tissue ratio of Br to Cl is determined physiologically and that elevated
ratios indicate excessive Br intake. The mean Br/Clratios of 1.83 for serum and
4.1 for red cells in the Marshallese were higher than the New York ratios (which
were arbitrarily set at unity), This finding suggests excessive Br intake by the
Marshallese. It is of interest to point out that Rb, which is considered to be a K
analog just as Br is considered to be Cl analog, had similar ratio Rb/K in all three
populations studied.

Tissue Br can be elevated by an increase in the dietary Br intake and also by

respiratory and cutaneous exposures (4). Leaded gasoline, which contains organic bromide, is little used on Rongelap, where Br levels were highest, and can

be ruled out as a significant Br source. There is no atmospheric pollution with
Br-containing dust or industrial fumes. Someresidual fumigant Br may be present
on imported U.S. Department of Agriculture foods on Rongelap, but these foods

are not supplied on Majuro. Therefore, a local environmental source of Br was
Ocean water has a bromine concentration of 65.0 ppm (12), consistent with the
measurements of Atlantic ocean and lagoon water sampled for the present study.
There is significant vertical exchange of lagoon and ocean water with the fresh
water lens system ofatoll islands (13), and dug wells exhibit different degrees of
salinity depending on their depth and placement about the lens. The variable
levels of Br detected in well water are consistent with earlier atoll studies of Cl
and other elements (unpublished 1972 water quality data from Bikini and Enewetakatolls kindly supplied by C. J. Huxel, U.S. Dept. of the Interior Geological

Survey, Honolulu, Hawaii). However, the most important source of drinking

water is rain catchment water, samples of which showed no Br present. Another

commonly ingested liquid is coconut water, which is used for cooking as well as
for drinking. An estimate of the weight of coconut products ingested daily, including coconut water, is 2.4 kg for a man aged 23-50 years of age (14). The Br
concentrations measured in coconut water samples would provide an average
daily consumption of 17 mg Br solely from coconuts. The acceptable daily intake
of Br set by the FAO/WHO is 1 mg/kg body weight (15). It has been suggested
that a more appropriate value would be 0.1 mg/kg body wt (16), which would
approximate one-third of a Marshallese man’s daily intake of Br from coconuts
alone. Br levels in other food supplied were not tested in the present study, but

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