P R E C AU T I O N S I N T H E U S E A N D H A N D L I N G
O F P E S T I C I D E S A N D C H E M I C A L R E AG E N T S
3
J o h n R . C ox 1
Natural Resources Institute, University of Greenwich at Medway, Central Avenue,
Chatham Maritime, Kent ME4 4TB, UK
I N T RO D U C T I O N
Chapters in this handbook deal with techniques for the assessment of the impact of pesticides on wildlife and
other biological components of the environment and mention the use of various chemicals for the cleaning of
sampling equipment or for the preservation of collected samples. It should be remembered that most pesticides
and many of these chemicals are hazardous materials and should be treated as such.This chapter provides basic
advice on the properties of the listed chemicals (Table 3.1) and on procedures for their safe use, as well as for
Ta bl e 3 . 1
N o n - p e s t i c i d e c h e m i c a l s s u g ge s t e d f o r u s e i n t h i s h a n d b o o k
S o l ve n t s
Acids
G e n e r a l re a g e n t s
Ethanol
Acetone
Xylene
Methanol
Nitric
Acetic
Picric
Mercuric chloride
Formalin (formaldehyde solution)
Lactophenol
Glycerol
Silica gel
Gilson’s fluid
handling pesticides or pesticide-contaminated materials.
Some of these reagents are used singly or as mixtures to prepare named reagents, e.g. Gilson’s fluid. When
handling these chemicals (or any others), always wear a laboratory coat, overalls or other protective clothing
and d o n o t e a t , d r i n k o r s m o ke .
S O LV E N T S
•
Ethanol, methanol, acetone and xylene are all flammable materials and should be kept away from naked
flames or other sources of vapour ignition. D o n o t s m o ke w h e n h a n d l i n g t h e s e m a t e r i a l s .
•
The vapour from these solvents can be harmful and should not be inhaled. Operations using solvent should
be undertaken in well-ventilated areas or outdoors. Note, that particular care should be taken when using
x y l e n e, which is a potential carcinogen.
•
Spillage on to the skin should be avoided; wear solvent-resistant (nitrile rubber) gloves when handling
solvents. Xylene is particularly harmful when absorbed through the skin and any affected areas should be
immediately and thoroughly washed with soap and water.
•
If solvent vapour affects the eyes, or if the eyes are splashed with solvent, irrigate well with water. Seek
medical attention in cases of splashing.
Contact address: 42 Boughton Lane, Maidstone, Kent ME15 9QP, UK. [email protected]
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WA R N I N G
Ethanol and methanol have well known properties of intoxication and in their concentrated form can be
particularly harmful. Keep ethanol and methanol locked away to prevent misuse.
AC I D S
•
Acetic and nitric acids are liquids: glacial acetic acid is normally greater than 99% pure; concentrated nitric
acid is normally 68–72%.
•
They are both corrosive and can cause burns to the skin; always use acid-resistant gloves (nitrile rubber)
when handling these materials.The eyes are particularly susceptible to damage if splashed; protective glasses
should be worn wherever possible.
•
P i c r i c a c i d i s a s o l i d w h i c h mu s t b e ke p t m o i s t a t a l l t i m e s ; i t c a n b e ex p l o s i ve i f d r y.
•
Picric acid solution is also corrosive, harmful to the eyes and is absorbed through the skin. Always wear
nitrile gloves when handling this substance and wear protective glasses/goggles.
•
With all acids, any affected skin should be immediately and thoroughly washed with water. Affected clothing
should be removed and soaked in water.
•
The vapour from acetic and nitric acids is an irritant and exposure can damage the respiratory system; only
use in a well-ventilated area or outdoors.
•
If any acid is inadvertantly swallowed, large quantities of water should be drunk and medical attention sought
immediately.
•
Acid spillages on work surfaces should be carefully treated with large quantities of water; mixing with
soil/sand can also help containment. Large spills of acid can be neutralized by the addition of solid, powdered
sodium carbonate.
•
When preparing dilute acid solutions, a lw ay s add acid to water, n ev e r water to acid.
G E N E R A L R E AG E N T S
F o r m a l d e hy d e s o l u t i o n
•
Formaldehyde solution (formalin) usually contains 37–41% formaldehyde and 11–14% methanol.The solution
is flammable and the vapour is an irritant to the eyes and to the respiratory system. Spillage on to the skin
should be treated with running water; if the eyes are affected by vapour, they should be irrigated with water.
Formaldehyde solution should only be used in a well-ventilated area. Be careful n o t to directly inhale the
vapour. It is also a human carcinogen and thus great care should be taken when using it.
•
If any formaldehyde solution is swallowed, large quantities of water should be drunk and medical attention
sought.
•
The solution can irritate the skin on which it has a hardening effect. Solvent-resistant gloves (nitrile rubber)
should be worn when handling the solution.
G i l s o n ’s F l u i d
Gilson’s fluid is made with 100 ml 80% ethanol, 880 ml distilled water, 15 ml 80% nitric acid, 18 ml glacial acetic
acid and 20 g mercuric chloride.Take care in the preparation of this reagent as it is corrosive, toxic and an irritant;
the properties of the individual chemicals used in its preparation are considered elsewhere in this chapter.
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M e rc u r i c c h l o r i d e
•
M e rc u r i c s a l t s a re p o i s o n o u s and should be treated with great care. Skin and eye contamination should
be avoided and affected areas immediately washed with running water. Care should be taken to avoid
breathing any fine dust from the dry material.
•
If any mercuric salt solution is swallowed, large quantities of water should be drunk and medical attention
sought urgently.
•
Disposal of solid waste material in the field, e.g. by burial, should be avoided wherever possible; mercury and
salts of mercury should always be disposed of through recognized contractors.
S i l i c a ge l
•
Silica gel is relatively safe to handle but do not do so with wet hands; inhalation of any dust should also be
avoided.The wearing of a face mask is recommended.
G l y c e ro l
•
Glycerol is a relatively harmless compound but as with all chemicals, care should be taken to avoid skin
contact or ingestion of this substance.
Lactophenol
•
Lactophenol is a toxic compound and should be handled with extreme care. Use in a well-ventilated area
and wear disposable gloves when handling the material.
P ROT E C T I V E C L OT H I N G
General
In the introduction to this section, it was stressed that when handling the listed chemicals, a laboratory coat,
overalls or other protective clothing should be worn. Solvent and acid-resistant gloves (nitrile rubber gloves can
be used for both types of material) are also recommended when handling these materials F a c e m a s k s a re
s o m e t i m e s u s e d b u t i t m u s t b e re m e m b e re d t h a t m o s t m a s k s a re o n l y d u s t o r p a r t i c l e m a s k s
(Figure 3.1);; t h ey h av e l i t t l e e f fe c t i n p re v e n t i n g i n h a l a t i o n o f s o l ve n t o r a c i d v ap o u r. To give protection
against solvents or pesticide fumes, special filtered masks or respirators must be worn (Figure 3.2); different
F i g u re 3 . 1 : F a c e m a s k
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F i g u re 3 . 2 : R e s p i r a t o r
companies have different specifications/mask model numbers so it is difficult to give specific recommendations.
Most suppliers have detailed catalogues listing specific masks for specific uses, which will provide the necessary
information. Where the catalogues are not available, the companies will normally provide the necessary
information by telephone/fax.
Pesticides
During ecotoxicological monitoring exercises, it may be necessary for sampling to be carried out in freshly
sprayed areas or even where spraying is in progress; in this case the re-entry period should be established.This
is the time interval that should elapse between application and entering a treated area and is the interval during
which the bulk of pesticide deposits on the crop are absorbed or otherwise removed from plant surfaces. T h e
r e - e n t r y p e r i o d s h o u l d n o t b e c o n f u s e d w i t h t h e h a r v e s t i n g i n t e r v a l , w h i c h i s t h e p e r i o d b e t we e n
p e s t i c i d e ap p l i c a t i o n a n d w h e n t h e c ro p i s s a fe t o h a n d l e a n d e a t . R e - e n t r y p e r i o d s m ay b e
s p e c i f i e d by t h e p ro d u c t m a nu f a c t u re r b u t i n m o s t c a s e s v a r y f ro m 1 t o 3 d ay s .
In practice, the length of the re-entry period is subject to many variables such as the nature and toxicity of the
product, its application rate, weather conditions and the nature of the crop treated. If entry is required to a
sprayed area before the time limit specified by the re-entry period has elapsed, then appropriate protective
clothing should be worn.The type of protective clothing required will depend on the toxicity and mode of action
of the pesticide applied. In some cases an overall and gloves may be all that is needed, in other cases additional
head, face and respiratory protection may be essential. Label information supplied with the pesticide will
generally specify the level of protection required. In tropical countries, wearing protective clothing can be
unpleasant because of heat fatigue. The use of cotton suits made to the GIFAP (now CropLife International)
design is recommended except where the protective clothing is going to get particularly wet (in which case
pesticide will soak through on to the skin) and where Tyvek®-type suits should be worn (Figure 3.3). W h e n
w e a r i n g p ro t e c t i ve c l o t h i n g r u bb e r b o o t s s h o u l d a lw ay s b e wo r n w i t h t h e t ro u s e r l e g s wo r n ov e r
t h e r u b b e r b o o t , a n d n o t t u c ke d i n a s s o m e t i m e s o b s e r v e d .
N o t e : W h e n i n d o u b t , a n d p ro fe s s i o n a l a d v i c e i s n o t re a d i ly av a i l a bl e , t h e i n d i v i d u a l s h o u l d a lw ay s
e r r o n t h e s i d e o f c a u t i o n a n d w e a r m o r e p ro t e c t i v e c l o t h i n g r a t h e r t h a n l e s s .
Pr e c a u t i o n s i n t h e U s e a n d H a n d l i n g o f P e s t i c i d e s a n d C h e m i c a l R e a g e n t s
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F i g u re 3 . 3 : S p r ay ap p l i c a t i o n m o n i t o r i n g a n d e c o t ox i c o l og y p e r s o n n e l we a r i n g Ty ve k ® s u i t s a n d
p re p a r i n g t o wo r k i n a re c e n t ly s p r ay e d a re a
C l e a n i n g a n d m a i n t e n a n c e o f p ro t e c t i v e c l o t h i n g
Protective clothing worn in the field requires regular washing to minimize the build-up of residues which may
cause sample cross-contamination or, in extreme cases, bodily contamination and possibly illness. In addition, the
regular inspection and maintenance of protective clothing is essential for personal protection. It is
r e c o m m e n d e d that as a routine, the items of protective clothing that can be washed without special facilities
(e.g. boots, gloves, face shields, etc.) are washed before leaving the sample site with the rinsings disposed of at
that site. O n n o a c c o u n t s h o u l d a ny o p e r a t o r c o n d u c t i n g s a m p l i n g b e a l l ow e d t o e n t e r a ve h i c l e
w i t h o u t re m ov i n g ov e r a l l s , b o o t s a n d g l ov e s . Used overalls should be placed within a polyethylene bag
after removal to prevent any contamination of the vehicle. It is further r e c o m m e n d e d that where potentially
contaminated items are being disposed of, that they be damaged/destroyed to remove the temptation for others
to take them for their own use or so that children to do not find them and play with them.
Cotton suits/overa l l s
Cotton suits should be washed in warm water containing a strong detergent and then rinsed in clean water. In
cases where the level of contamination is suspected to be high, the warm water/detergent wash should be
repeated. The person doing the washing should wear nitrile rubber gloves during the washing process. The
washing solutions produced should preferably be disposed of in a pit dug 30–40 cm deep and away from any
watercourses or wells.
Note that Tyvek® suits are meant to be disposable and should be destroyed after use. In some cases, depending
upon the degree of contamination and the nature of the pesticide, it may be possible to re-use the suit once or
twice. In field sampling, however, the suit will have been worn when entering a recently treated area and when
the residues of pesticide will have been at their highest. In view of this, there is a significant risk of sample crosscontamination and despite the cost implications, it is r e c o m m e n d e d for field sampling that a fresh suit be worn
for each day’s sampling and certainly when visiting different sample areas. Contaminated suits should be disposed
of by burning on a hot fire; stand clear of the fire and take care not to breath in any vapours produced by the
fire (wear a respirator if possible).
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Gloves
Except in the most extreme cases where high contamination levels are anticipated and where heavy duty gloves
will be worn, individuals involved in sampling within pesticide-contaminated areas will normally wear lightweight
disposable gloves (latex or nitrile).After use these should be collected in a bag and returned to the operational
base for appropriate disposal (burial or burning). To minimize the risk to any other individual, it is
r e c o m m e n d e d that disposable gloves be water/detergent-washed before removal and that the gloves then be
cut such that they cannot be re-used by any other individual. Heavy duty gloves should also be cleaned by
water/detergent-washing before leaving the sample site with the washings disposed of in a shallow pit and then
covered over.
Rubber boots
Rubber boots should be removed, washed down with water/detergent and scrubbed clean before leaving the
sampling site (this prevents the movement of pesticide from the treated area into vehicle, etc.). The washings
should be disposed of at the sample site; dig a small pit, pour in the washings and then cover over with soil.The
boots should be inspected for damage after cleaning; any tears or holes may enable contamination of the feet
and such damaged boots should be replaced.
Fa c e m a s k s
Disposable face masks (for use against dust and slight vapours, depending on design) should be viewed as single
use and not re-used.The mask should be disposed of by burning or burial after being cut in half. If face shields
are worn, these should be washed down with water/detergent before leaving the site and the washings disposed
of in a shallow pit (see above).
R e s p i ra t o r s
If respirators have been worn, the cartridges need to be removed and the mask washed with water/detergent
and then rinsed with clean water before leaving the site.The cartridges in the mask will have a specified life of
(x) hours (see the manufacturer’s literature provided with the cartridges). If this time period has been reached
then the cartridge should be disposed of and replaced with a fresh one if the respirator is required for another
site or for the next day. Opened respirator cartridges have a reduced life span and should be regularly changed
even if they have not been used.The best approach is not to open and insert a cartridge into the respirator until
immediately before it is required for use. The used cartridges should be returned to base for appropriate
disposal; where suitable facilities are not available, the used cartridges can be buried in a hole at least 50 cm deep.
F U RT H E R R E A D I N G
GIFAP/CropLife International Guidelines and Technical Monographs. Available from CropLife International,
Avenue Louise 143 – B1050 Brussels. A list of guidelines and monographs can be obtained by post, e-mail
([email protected]) or by visiting the CropLife International web page (www.gcpf.org).
Product Data Safety Sheets are provided by suppliers with all chemical materials. These should be read and
retained for further reference.