Stay away from water with pyrethroids as they pose a high risk to fish and frogs.
Paraquat is a highly toxic bipyridilium compound that is
used as a desiccant to kill weeds. Its advantage is that it
only kills the vegetative parts of weed that are above
the soil surface and leaves the root systems unaffected.
This means paraquat is the perfect remedy for making
firebreaks as the plants are desiccated, can be burned
to create the firebreak but their roots stay intact thus
preventing soil erosion. Obviously, paraquat is highly
toxic as a concentrated liquid and ingestion of it is totally fatal as there is no antidote available. However, if
one wears protective clothing and a splash proof apron
when mixing the paraquat spray mixture there is virtually no risk to the person. If the person applying the
spray mixture wears protective clothing as recommended then the risk is absolutely negligible. Once the paraquat spray mixture has dried off on the target there is
virtually no risk for people entering such areas. Paraquat will also only affect actively growing plants with
green foliage and twigs and when mature bark is exposed to it, it is not taken up and does not affect the
plant. In all terms paraquat is a highly hazardous or
highly toxic substance but when used according to
safety precautions the risk to people and to non-target
plants is virtually zero.
Question arises why there is such a global hype about
paraquat? Simply because of misuse and suicide. In
South Africa about twenty to thirty suicide attempts
with paraquat are recorded annually. In South America
farm workers who refuse to wear protective clothing
suffer from undue paraquat exposure with serious
health effects. Does this render paraquat as a high risk
pesticide? Most definitely not. Malpractices with paraquat are the high risk and it could be with any pesticide
for that matter. Paraquat has a very low risk for people
and ever lower risk for the environment when applied
correctly.
Take another example of a herbicide: bromacil. It is a
blue band product meaning it should be used with caution. Its toxicity to mammals (read here human beings),
birds, fish and invertebrate is nothing to be concerned
about BUT it is lethal to most woody plants and very
few trees survive a beating by bromacil. It also leaches
and migrates in soil killing trees very far from the point
of application and stays active in soil for years. Bromacil
is a prime example of a low hazard, high risk pesticide.
There are places in South Africa where bromacil killed
crops fifteen years after it was applied.