PANUPS: Breast Cancer & Pesticides

                         P A N U P S
                   Pesticide Action Network 
                        North America
                       Updates Service
                   EMAIL: panna@panna.org

August 1, 1997

Breast Cancer and Pesticides in Hawaii

Rising breast cancer rates in Hawaii may be partially 
attributable to intensive pesticide use in the state, 
according to a recent study in Environmental Health 
Perspectives. Breast cancer rates have increased for all 
racial groups in Hawaii since 1970, but only 30% to 40% of 
these cancers can be explained by known risk factors. The 
study points out that an emerging body of evidence suggests 
that certain chemicals including pesticides play a role in 
causing the disease by interfering with the body's natural 
hormone balance. Over the past 40 years in Hawaii, there has 
been widespread use of endocrine disrupting pesticides, 
including DBCP, DDT, DDE, kepone, heptachlor, chlordane, 
dieldrin, mirex, lindane and toxaphene.

Exacerbating the hazards of these pesticides, Hawaii is 
characterized by volcanic soils and heavy rainfall, making it 
particularly vulnerable to groundwater contamination. Because 
groundwater provides a large portion of Hawaii's population 
with drinking water, the study argues that people living in 
Hawaii may have experienced unusually high exposures to 
probable endocrine disruptors.

Compared to other U.S. regions, breast cancer's rate of 
increase in Hawaii has been high, according to the study. For 
example, breast cancer incidence among Japanese women in 
Hawaii increased 42% between 1970 and 1985. Rates in other 
U.S. areas during the same period did not exceed 20%. In 
1985, both Caucasians and native Hawaiians had rates higher 
than 200 out of 100,000. The researchers said that breast 
cancer screening is slightly more common in Hawaii than in 
other areas of the U.S., but not enough to explain the higher 
breast cancer rates. 

The study highlighted several cases in which carcinogens and 
endocrine disruptors were intensively used in Hawaii 
resulting in groundwater contamination and human exposure. 
For instance, in Oahu, growers regularly fumigated pineapple 
fields with DBCP until it was restricted in the early 1980s. 
In 1980, drinking water samples taken from a plantation 
village in Oahu showed levels of DBCP at 0.01 parts per 
million (ppm), two orders of magnitude greater than EPA 
drinking water standards (0.0002 ppm). As a result, drinking 
water wells in the village were closed. All 738 residents of 
the village were most likely exposed to DBCP through 
ingestion and skin contact with contaminated water. Studies 
later found that this village had a significantly higher rate 
of abnormal cell growth, including breast cancer, compared to 
another village five miles away where DBCP was not found in 

The pesticides chlordane and heptachlor were also used in 
Oahu -- for agriculture and for termite control in homes. 
Although banned in the U.S. in 1988, existing stocks of the 
chemicals in Hawaii could still be used, and as recently as 
1993, heptachlor was applied to pineapple fields in Oahu by 
Del Monte. According to the study, chlordane and heptachlor 
cause cancer, harm the immune system and may be endocrine 
disruptors -- and their long half-lives ensure they remain 
biologically active for decades. 

During a 15 month period in 1981 and 1982, many of the dairy 
cattle in Oahu were accidentally fed pineapple leaves 
containing heptachlor residues. As a result, the local milk 
and dairy supply remained contaminated for years. Between 
1981 and 1984, the legal standard for heptachlor residues in 
food (0.3 ppm) was exceeded ten-fold in milk and dairy 
products supplied by local dairies in Oahu. Follow-up 
investigations found that the breast milk of women who had 
consumed local dairy products contained heptachlor at levels 
averaging 200 ppm -- some cases exceeded 400 ppm. The study 
says that other researchers compared heptachlor levels in 
human milk among U.S. regions and reported that levels in 
Hawaii were 20% higher than in southeastern states and 65% 
higher than in northeastern states. Ten years after the 
incident, in 1993, a study found that levels of heptachlor 
epoxide (heptachlor's breakdown product) were higher in 
adults and children in Oahu compared to neighboring islands.

The study points out that people in Hawaii have been exposed 
to a variety of chemicals that could contribute to increasing 
rates of breast cancer. The researchers called for detailed 
analytic studies to clarify the extent to which avoidable 
environmental factors account for this increase.

Source: Breast Cancer and Pesticides in Hawaii: The Need for 
Further Study. Environmental Health Perspectives, Volume 105, 
Supplement 3, April 1997.
Contact: PANNA

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