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Can you provide us with more information on the toxicity of fipronil?
Case ID : 00002

A pest control agency has been applying fipronil at our office once per month
for termites. This substance is also used by our landlords at our house. Our
neighbors are asking because they have 4 children under the age of 6, including
a small baby. The landlord says that if the tenants refuse to allow the
treatment, the tenants will have to pay for the termite damage.

Q1: Is fipronil the safest choice for regular (1-2 times monthly) treatment of
our office (and home)?

Q2: Does it matter that the treatment is done on a Saturday, all windows are
left shut, and we are not informed when we come in Monday that the treatment was
done (and continue to leave the windows shut).

Q3: Are there safer options to combat termites?

From : Chem HelpDesk Coordinator,
Last viewed : 16 June 2024 00:33
Viewed : 7467 (times)

Answer from expert #1
Fipronil is a very effective agent against termites. Fipronil has a moderate
acute toxicity to people and mammals. It is slightly to moderately toxic when
absorbed through the skin.

The EPA has fipronil classified as a possible human carcinogen (NPIC): it should
be emphasised that this a precautionary classification. The inhalation of fairly
large amounts of fipronil may cause convulsions and tremor (NIOSH) and small
amounts may have some adverse effect. Exposing the eyes can cause irritation
(PANNA). Long term effects of continuing exposures are unknown.

Like most pesticides, it is safe if applied with care to prevent exposure of
people or nontarget animals and, with this proviso, it is a safe and effective
choice. However, It should only be used in the home with good ventilation and
with a minimum exposure to adults and none to children, especially babies. They
should not be present when spraying is carried out although I should expect the
sprayed area to be safe after about an hour with good ventilation.

With regard to the office, I think that spraying or other application on a
Saturday when the office is empty and left empty until Monday, even without
ventilation over this period is safe provided the windows are opened for an hour
or so before or when workers arrive on Monday. I doubt if there are safer
effective options to combat termites. The key to personal safety with any
pesticide is always to minimise human exposure and particularly inhalation, skin
contact or contamination of food and drink.

Answer from expert #2
A fact sheet prepared by staff at the UK Natural Resources Institute was
prepared for Pesticide Action Network UK (PAN UK) and is available at:

This concludes that: "Fipronil ... can generally be applied at low to very
low dose rates to achieve effective pest control. Questions have been raised
about suitability [of fipronil] for use in IPM and studies suggest that this
must be evaluated on a case by case basis.

In certain situations it may disrupt natural enemy populations, depending on the
groups and species involved and the timing of application. Its acute toxicity
varies widely even in animals within the same groups. This means that the
toxicological findings from results on standard test animals are not necessarily
applicable to animals in the wild.

Testing on local species seems particularly important in determining suitability
of fipronil based products for registration in different countries or habitats
and the likely risk to non-target wildlife. Fipronil use requires careful
consideration where contamination of the aquatic environment is likely, due to
its high toxicity to some fish and aquatic invertebrates. ... in developing
countries where illiteracy, lack of protective clothing and use of insecticide
drums increase the risk of human contact with the product at above recommended
dose rates, a precautionary approach may be warranted.

In general, it would appear unwise to use fipronil-based insecticide without
environmental monitoring to accompany its use, in situations, regions or
countries where it has not been used before and where its use may lead to its
introduction into the wider environment or bring it into contact with

A detailed (30-page) briefing on fipronil, prepared by ecotoxicology experts, is
available from PAN UK at