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SUMMARY OF FINDINGS

The findings and conclusions of this report are briefly. sum-
marized in answer to the questions listed below. The chart on the
following page graphically illustrates the results of research to date
on the four herbicides being considered for use in Lake Washington,

i. What are the potential risks to human health from aquatic use of
these herbicides?

Potential risks include both acute and long-term toxic effects.
Acute effects are those likely to be experienced by people applying
‘the chemical without adequate precautions, for example by inhaling it
Or spilling it on skin or eyes. Long-term effects, which dra the main
subject of this report, may result from repeated exposure to: small
amounts of the substances, for example by swimming in treated water,
ingesting contaminated food or water, or walking in sprayed areas.
These include developmental effects on fetuses and growing children
(malformations, malfunctions, growth retardation or death); reproduc-
tive effects on the rate of pregnancy and the number of embryos; gene~
tic effects (mutations, damage to DNA molecules or the process of cell
division); and carcinogenic effects.

It is important to note that in the United States, people ara
widely exposed to a variety of untested, potentially cancer-causing
substances along with a lesser number of proven carcinogens, which
tead to an accumulation of pre-cancerous cells in the body. Americans
now face’ a 25% chance of developing cancer at some time Guring their
lives. Under such conditions, the presence in the environment of
additional chemicals which can stimulate these pre~cancerous celis to
grow into tumors must be considered a significant hazard.

2. Which of these risks is associated with each of the herbicides
under consideration?

The risks for each herbicide are displayed in Columns 5 and 6 of
the accompanying chart, and summarized below:

For 2,4-D, laboratory tests have shown developmental toxicity of
all four varieties listed above, and have been positive for genetic
and carcinogenic effects; there is no indication of effect on repro-

\_duction. Acute effects of 2,4-D observed in humans include headaches,

dizziness, impaired senses of taste and smell, nausea, sore throat,
muscular spasms and nerve damage.

Toxicological testing of dichlobenil has been extremely limited.
Carcinogenic tests have been inadequate and there has been no testing
cf developmental or genetic effects in animals. One Study indicates
shat dichlobenil inhibits the growth of young rats and decreases fer~
tility. -Some of its breakdown products are known to be highly toxic