Southeastern U.S. Vegetable Crop Handbook - 2023 - 132

inadvertently by another applicator who is unaware of their contaminated
condition.
Chemical cartridge respirators cannot provide protection
against extremely toxic gases such as hydrogen cyanide, methyl
bromide, or other fumigants. Masks with a self-contained air
supply are necessary for these purposes.
USE AND CARE OF RESPIRATORS
Respirators are worn as needed for protection when handling
certain pesticides. The use of respirators is now regulated
requiring a health screening prior to their use by a health
professional. This is due in part to the Fumigant re-registration
decisions by EPA. These prerequisites are outlined in the OSHA
Respiratory Protection Act. Prior to using a respirator, read and
understand the instructions on the cartridge or canister and all
supplemental information about its proper use and care. Be sure
the filter is approved for protection against the pesticide intended
to be used. Respirators labeled only for protection against particulates
must not be used for gases and vapors. Similarly, respirators
labeled only for protection against gases and vapors should
not be used for particulates. Remember, cartridges and filters do
not supply oxygen. Do not use them where oxygen may be limited.
All respirators must be inspected for wear and deterioration
of their components before and after each use. Special attention
should be given to rubber or plastic parts which can deteriorate.
The facepiece, valves, connecting tubes or hoses, fittings, and
filters must be maintained in good condition.
All valves, mechanical filters, and chemical filters (cartridges
or canisters) should be properly positioned and sealed. Fit
the respirator on the face to ensure a tight but comfortable seal.
Facial hair will prevent a tight seal and consequently OSHA regulations
prohibit the use of a respirator when the user has a beard
or facial hair. Two tests can be done to check the fit of most
chemical cartridge respirators. The first test requires that you
place your hand tightly over the outside exhaust valve. If there
is a good seal, exhalation should cause slight pressure inside the
facepiece. If air escapes between the face and facepiece, readjust
the headbands until a tight seal is obtained. Readjusting the
headbands may at times not be sufficient to obtain a good seal.
It may be necessary to reposition the facepiece to prevent air
from escaping between the face and facepiece. The second test
involves covering the inhalation valve(s) by placing a hand over
the cartridge(s). If there is a good seal, inhalation should cause
the facepiece to collapse. If air enters, adjust the headbands or
reposition the facepiece until a good seal is obtained.
Get to fresh air immediately if any of the following danger
signals are sensed:
* Contaminants are smelled or tasted
* Eyes, nose, or throat become irritated
* Breathing becomes difficult
* The air being breathed becomes uncomfortably warm
* Nauseous or dizzy sensations are experienced
Cartridges or filters may be used up or abnormal conditions may
be creating contaminant concentrations which exceed the capacity
of the respirator to remove the contamination.
After each use of the respirator, remove all mechanical and
chemical filters. Wash the facepiece with soap and warm water,
and then immerse it in a sanitizing solution such as household
bleach (two tablespoons per gallon of water) for two minutes,
followed by a thorough rinsing with clean water to remove all
traces of soap and bleach. Wipe the facepiece with a clean cloth
and allow to air dry.
Store the respirator facepiece, cartridges, canisters, and
mechani cal filters in a clean, dry place, preferably in a tightly
sealed plastic bag. Do not store respirators with pesticides or
other agricultural chemi cals.
Handle respirators with the same care given to other protective
equipment and clothing.
PROTECTING OUR GROUNDWATER
Groundwater is the water contained below the topsoil.
This water is used by 90% of the rural population in the United
States as their sole source of drinking water. Contamination of
the water supply by pesticides and other pollutants is becoming
a serious problem. One source of contamination is agricultural
practices.Protection of our groundwater by the agricultural community
is essential.
Groundwater collects under our soils in aquifers that are
comprised of layers of sand, gravel, or fractured bedrock which,
by their nature, hold water. This water comes from rainfall,
snowfall, etc., that moves down through the soil layers to the
aquifer. The depth of the aquifer below the surface depends on
many factors. Where it is shallow, we see lakes, ponds and wetlands.
In areas where it is deep, we find arid regions.
FACTORS THAT AFFECT MOVEMENT OF WATER AND
CONTAMINANTS
The depth of aquifers, in conjunction with soil types, influences
how much surface water reaches the aquifer. Their depth
also affects how quickly water and contaminants reach an aquifer.
Thus, shallow water tables tend to be more vulnerable to
contamination than deeper ones.
This tendency, however, depends on the soil type. Soils with
high clay or organic matter content may hold water longer and
retard its movement to the aquifer.Conversely, sandy soils allow
water to move downward at a fast rate. High levels of clay and/
or organic content in soils also provide a large surface area for
binding contaminants that can slow their movement into groundwater.
Soil texture also influences downward water movement.
Finer textured soils have fewer spaces between particles than
coarser ones, thus decreasing movement of water and contaminants.
CHEMISTRY
PLAYS A ROLE
The characteristics of an individual pesticide affect its ability
to reach groundwater. The most important characteristics are
solubility in water, adsorption to soils, and persistence in the environment.
132
2023
Vegetable Crop Handbook for Southeastern United States
Southeastern U.S. Vegetable Crop Handbook - 2023

Table of Contents for the Digital Edition of Southeastern U.S. Vegetable Crop Handbook - 2023
