Pesticides are biologically active materials and potentially hazardous to human health and the environment. Complete decontamination and effective disposal are often very difficult to achieve. One of the most important objectives of good store management is therefore to minimize the occurrence of leaks, spills and outdated stock.
There will occasionally be spills, even in the
best run stores, especially where concentrates are repacked and
transferred into other containers. Spills must be cleaned up
immediately. Always have two people working when handling severe
spills.
Untreated spills may corrode other containers,
become trodden in and contaminate store personnel and may produce
toxic or inflammable fumes. If not removed quickly, the spilled
chemicals may be absorbed by the floor. Floors therefore need to be
made of impermeable (sealed) concrete or other non-absorbent material
- removing the contaminated part and replacing it may be the only way
to decontaminate absorbent brick, earth or wooden floors.
The spill should not be hosed down as this
merely disperses the pesticide over a wider area.
A supply of absorbent sawdust, sand or dry soil
should be kept in a container in the store.
Nitrile rubber protective gloves and face-mask
should be worn.
Sawdust, sand or dry soil should be scattered over
the area of the spill and left for a few minutes to soak up the
chemical.
The sawdust, sand or dry soil containing absorbed
spilled chemical should be swept or shovelled up and placed in a
marked container for disposal (Figure 21).
FIGURE 21 - Spill soaked up by sand or sawdust being
carefully swept up by the storekeeper and placed
in a container to be collected and taken for central disposal by the
national authority
After sweeping, more than once if necessary, a scrubbing brush at the end of a stick should be used to scrub down the area of the spill with water and strong soap or detergent. Excess soapy water should be removed with a rough floor cloth and not hosed down.
Dusts, wettable powders or granules can create
dust when swept up without the use of an absorbent material. A supply
of absorbent sawdust, sand or dry soil should be kept in a container
in the store where they can easily be reached for use in an emergency
.
Nitrile rubber protective gloves and face-mask
should be worn.
The sawdust, sand or dry soil should be dampened
and applied with a shovel over the area of the spill.
The damp sawdust, sand or soil containing spillage
material should be swept or shovelled up carefully and placed in a
marked container for disposal (Figure 21).
After sweeping, more than once if necessary, a
scrubbing brush at the end of a stick should be used to scrub down
the area of the spill with water and strong soap or detergent. Excess
soapy water should be removed with a rough floor cloth and not hosed
down.
Leakage from containers is a major problem in the storage and transport of pesticides (Figure 22). The main cause is rough handling which dents drums, weakens or splits seams and weakens closures (lids, caps and stoppers). Other causes of mechanical damage are puncturing or abrasion during transport when packages and containers rub against one another or against the sides of the truck travelling over uneven surfaces and rough roads.
FIGURE 22 - Storekeeper inspecting a leak from a
pesticide container
Leaks also result from corrosion of the
container, which may be accelerated by mechanical damage (dents may
rupture drum linings, for example). Corrosion may start internally,
the pesticide itself or its breakdown products being the primary
cause. Alternatively, corrosion may begin externally, as a result of
rusting in damp storage conditions or contamination from pesticide
leaking from nearby containers. Many emulsifiable concentrate (ec)
formulations are very corrosive. Some, including monocrotophos,
dicrotophos, dichlorvos and phosphamidon are incompatible with steel,
so they should be packed in plastic or aluminium containers or in
steel containers lined with inner coatings. Some pesticides are
dissolved in organic solvents that cannot always be packed in plastic
drums.
Containers may leak for other reasons; for example,
strong sunlight can degrade some plastic containers, including
bottles and plastic sacks. Rodents may damage paper, board or fibre
containers. Termites may attack paper and card.
Stores should be inspected regularly, at least
every two months. Old, rotting and leaking containers are extremely
difficult to move safely, so any leaking containers should be dealt
with immediately.
Usually, the only way to deal with a leak is to
repack the material in a sound container. New containers are
preferable, if available, but old containers of various types and
sizes may be used for this purpose (old containers are also useful
for temporarily storing the products of spills). They must have been
thoroughly decontaminated (see next section) and their old labels
completely removed.
Pesticides should be repacked in containers made of
the same materials as the original containers as some chemicals are
not compatible with different materials. Ideally a drum that
contained the same product should be used. If unavailable, the
container must have been properly cleaned of previous contents to
avoid cross-contamination. New labels must be written out immediately
with all the information on the old label and fastened securely to
the new container. Write the date of repacking (and the date of the
original receipt) on the replacement container and ensure that the
repacked material is used first.
Many accidents have been caused by empty
pesticide containers being used to store water and food. An empty
pesticide container can never be cleaned completely of pesticide and
should be disposed of in a way that ensures it cannot be used for
other purposes. It is, however, wise to retain samples of various
types of container, which have been carefully cleaned, in the
pesticide store for use in repacking the contents of damaged
containers and storing cleaned up leaks and spills prior to final
disposal.
Empty containers awaiting disposal should be stored
in a special, secure area in the pesticide store to ensure that they
are not stolen and used for other purposes.
Empty containers should always be cleaned out, as
far as is practicable, before disposal to minimize both hazard and
waste of residual pesticide. Containers that have contained ec or
wettable powder (wp) formulations should be rinsed with water several
times and the rinsings added to the spray tank before it is topped up
to the required volume. Following this, containers can be washed out
with a mixture of water, detergent and caustic soda (Figure 23).
Containers of liquid formulations may be cleaned with kerosene
(paraffin) or diesel fuel and the washings (small quantities of about
5 litres) collected for sending later to a central location for
disposal by the national authority in a safe and environmentally
sound manner.
FIGURE 23 - Decontamination of a pesticide container -
the inside and outside are being cleaned with detergent and water
-
highly contaminated rinsings should be saved for disposal with other
major toxic waste
As long as they are not heavily contamined paper, cardboard and fibreboard containers should be burnt on a fire in the open (Figure 24). However, cartons that have contained phenoxy acid herbicides should not be burnt because the combustion products can damage crops at long distances. Highly contaminated cardboard, paper and jute materials should be collected and sent to the central disposal centres along with other toxic waste.
FIGURE 24 - Disposal of lightly contaminated cardboard
pesticide container on a fire,
ensuring that fumes travel away from personnel
Containers rendered unusable, the products of decontamination
procedures, leaks and spills, and container rinsings (where these
have not been added to the spray tank) should all be collected for
sending later to a central location for disposal by the national
authority.
Glass containers should be smashed and steel drums
and metal and plastic containers punctured (Figure 25) and crushed
(do not puncture aerosol containers) before being sent to a central
location for disposal by the national authority.
FIGURE 25 - Metal container being crushed son that it
cannot be reused -
it will be collected for central disposal by the national
authority
Using pesticides for their intended purposes
according to label instructions is the most satisfactory means of
disposing of them. For this reason, no more than one year's
requirement of pesticides should be ordered and stored, so that none
will remain at the end of the product's shelf-life of two years. Only
as much pesticide as can be used in a day's operations should be
withdrawn from the store and only as much as will go into the sprayer
tank should be mixed.
Occasions will arise when it will be necessary to
dispose of pesticide concentrates, either because the stock is
outdated and has been found to be unusable or because the product is
no longer registered for the original purpose. Where very large
quantities are to be disposed of, professional advice must be sought
from the suppliers and national authority.
If only a few kilograms or litres of pesticide are
involved, they should be collected for sending later to a central
location for disposal by the national authority. Larger quantities of
pesticides are best disposed of by burning in a special incinerator
(at 1 200°C) - this does not mean that it would be safe to burn
them at a lower temperature on a fire. Incineration requires special
equipment with provision for "scrubbing" the combustion products, but
this is beyond the capacity of pesticide storekeepers and should be
referred to the relevant national authority.
Other means of disposal are to return the pesticide
to the supplier or pass it on to a specialist disposal agent elected
by the national authority.
Returning the pesticide to the supplier or to the
national authority is the safest means of disposal. Disposal involves
chemical methods such as alkaline and acid hydrolysis. Oxidation,
reduction and spraying on to the ground or allowing to escape into
the atmosphere may also be employed, but require specialist skills.
The end product in most cases is still toxic. Storekeepers should not
become directly involved with pesticide disposal and should refer to
the relevant national authority.