Tag: clean

  • Operator Safety: How to Avoid Pesticide Hazards

    Operator Safety: How to Avoid Pesticide Hazards

    A Veteran Applicator’s Questions about Pesticide Handling

    Time and again, after years of working with dozens of different chemicals, I would wonder to myself “How dangerous is this chemical?”, “Is glyphosate as safe as they say it is?”, “How do I find out what type of safety gear I need while handling this chemical?”

    Beyond the agrichemical dealer, ag. consultants, and university or government ag. extension specialists, a quick internet search reveals many sources of pesticide information. Collectively they identify the active ingredient(s) in formulated products, they detail which pests are best controlled by the pesticide, and they provide instruction for application. But it’s more difficult to find consistent, practical information about safe pesticide handling. Sometimes it’s excessive to the point of being impractical (try finding actual “chemical proof” gloves), and sometimes it’s minimal and vague – it depends where you look. No matter the level of precaution, pesticide safety is time consuming and involves some fussing, but it is the hallmark of responsible pesticide use. Just as we ensure that we are applying “safe rates” when spraying chemicals, we must also ensure we are respecting our own well-being while handling chemicals.

    In Canada, the Pest Management Regulatory Agency (PMRA) is charged with protecting human health and safety by monitoring pesticides that are sold in this country. According to the Federal Pest Control Products Act all pesticides sold in Canada must be registered with the PMRA. There’s a very nice overview of how that process works here. It is during this registration process that pesticide handling precautions are identified for the label. Further classification may take place under provincial acts.

    All pesticides are designed to disrupt, repel, control or kill living organisms, but when it comes to safe handling, insecticides receive the most attention. This is because herbicides and fungicides target biochemical pathways that only exist in plants or fungi. However, most pesticides can be hazardous if they are not handled correctly. The handling precautions that appear on the label are based on five factors.

    Five factors that affect handling precautions:

    1. Pesticide Family

    This factor is the broadest way to categorize potential risk to the handler. Generally, herbicides and fungicides are considered safer than insecticides, but there are notable exceptions. Do not rely solely on the pesticide family when making decisions on pesticide handling.

    2. Pesticide Mode of Action

    The mode of action gives further detail into how a pesticide should be handled. Modes of action that inhibit biochemical pathways that exist in the target pest, but not in mammals (people, in particular), have lower acute toxicities. Examples include herbicides that inhibit enzymes involved in amino acid synthesis or in photosynthesis – these enzymes do not exist in mammals. However, once again, there are always exceptions. Do not rely solely on mode of action when making decisions on pesticide handling.

    3. Pesticide Formulation & Route of Entry

    Pesticide formulation affects how a product can potentially be absorbed into the body. Emulsifiable Concentrates (ECs), for example, have higher rates of absorption than solutions or dry products. When it comes to the route of entry, dermal contact is considered safer than inhalation or ingestion. However, not all parts of your skin are created equal, and the point of dermal contact on the body matters a great deal.

    4. Pesticide Toxicity

    Taken collectively, the first three factors form the overall toxicity of the pesticide. The level of toxicity cannot be predicted – it has to be tested. The LD50 (defined below) values that are reported for a pesticide come from standardized experiments such as animal feeding. Although the chosen species (usually white rats for mammalian endpoints) are known to be similar to humans in their response, there is still the possibility of error. Nevertheless, toxicity forms an important basis for establishing handling precautions.

    5. Operator Exposure

    People handle toxic substances every day. Household bleach, for example is surprisingly toxic, and yet it can be readily found on kitchen shelves in many homes. The risk of being harmed by a toxic product can only be determined by the likelihood of exposure. While it is possible someone might accidentally consume a hazardous dose of bleach, it’s improbable. Exposure does not just refer to a single exposure to a substance – repeated exposures to small doses of a toxic substance can have a cumulative effect. The goal when handling any pesticide is to minimize exposure, but it becomes even more critical when that pesticide is highly toxic. Together, exposure and toxicity form the basis for risk.

    Risk = Hazard x Exposure

    Studies have shown that exposure is greatest for handlers of agricultural pesticides during the mixing and loading phase of spraying. During this phase, the risk to the handler may be increased due to:

    • physical stress
    • the denial of risk
    • a negative opinion of personal protective equipment (PPE)

    The main method of pesticide exposure is dermal, and many of the surfaces on a piece of equipment are already contaminated.

    Health effects of pesticides: Acute and Chronic

    Acute: short term

    High exposure, resulting in immediate reaction due to a high dosage of pesticide exposure. The severity depends on the toxicity of the molecule and entry into the body (dermal, oral, eyes, etc.). The most common acute reaction is skin irritation, although in certain cases respiratory, digestive, and neurological systems may be affected. Organophosphate (e.g. Lorsban, Malathion) and carbamate (e.g. Sevin, Lannate) insecticides inhibit the cholinesterase enzyme, which is found in humans and affects nerve function. Frequent users of these insecticides undergo regular blood tests to ensure their levels are normal.

    Chronic: long term

    Chronic affects are more prolonged as they are usually due to lower doses of pesticide exposure over a longer period of time. Although some rare cancers and disruption of the reproductive system have shown to be related to this type of exposure, when the general population and farming population have been compared in studies, the farming population has shown an under-representation in the majority of cancers. In the cases were reproductive malfunctions were observed, a different cause of the malfunction, such as genetic offset, was most often observed in these situations. However, cancer types such as skin cancer and brain cancer were overrepresented in the farming community. A study in France has shown that the onset of neurological disorders in Agriculture communities shows a strong connection between Parkinson’s disease and exposure to pesticides.

    Label Information

    The majority of information needed to safely handle pesticides is found on the label. Pesticide labels are legal documents, meaning they can be enforced by the federal government. The problem is that most sprayer operators rarely look at the label as they are not very reader friendly and easy to skim through. Most pesticide boxes even have the recommended rate, or acres/case on the side of the box now, so there is even less reason to look at the label.

    LD50– the dose of pesticide in mg per kg of the test animals body weight that is lethal to 50 percent of the group of test animals.  For example, if the pesticide has an acute oral LD50 value of 1000 mg/kg, and the test animals each weigh 1 kg, then 50 percent of the animals would die if they each ate 1000 mg of pesticide at once.  A 100 kg animal would need to ingest 100,000 mg (100 g) of the pesticide for the same effect.  LD50 is often expressed by the route of entry – dermal, inhalation, acute oral (ingestion) are the main examples.

    Degree of Risk and Hazard Symbols
    Degree of Risk and Hazard Symbols

    The appropriate PPE for a job is determined by two factors

    1. The Hazard Rating (above) incorporates the minimum protection generally required for a substance with the rating.
    2. The Label Recommendations will usually give the additional specific protective clothing and equipment needs for an applicator.

    Degree of Exposure

    This increases as the length of each pesticide application increases. As the number of pesticide applications increases, the time between exposures decreases. If an operator becomes exposed to spray, dust or fumes the degree of exposure increases. Essentially, more protective wear is needed as the degree of exposure becomes greater.

    Knowledge

    This encompasses all of the above information. In order for a pesticide applicator to avoid injury or the chances of adverse effects on the body, a pesticide applicator must be knowledgeable about pesticides. It can be overwhelming for an applicator to sort through all of the information on the label or on-line regarding pesticides. So much so, that most often applicators avoid the information altogether. Ongoing training and learning will ensure that they are effective in their work. Many aspects of pest control change continuously, as new studies are conducted on the effects of pesticide exposure.

    The Material Safety Data Sheet (MSDS) is available for all pesticides registered, and these are usually linked on manufacturers’ websites. It can be eye-opening what types of toxicity tests are done, and what the results are.

    Denial that pesticides can potentially cause harm is also a major flaw in the behaviour of applicators. Maintaining a safe work environment and practicing personal safety will reduce the chances of an applicator experiencing serious injury throughout their farming career.

    Unknowns

    There is very little certainty in toxicology. For one, most testing is done using acute oral and dermal dosing. Basically, toxicologists expose test animals to the neat active ingredient and watch what happens. There is a lot of missing information – what about formulant like solvents, and surfactants? What about synergies in tank mixes? Some, but not all of these, undergo testing. We also have much less information on chronic (long-term) effects, and can only simulate these in quasi long-range tests. In addition, toxicological methodologies and statistical approaches can vary, and we should not be surprised that some reports disagree, and that there are outright conflicts between toxicologists and epidemiologists (scientists that study patterns of health in populations). Regulators are aware of these shortcomings and often use safety factors to account for them. But those of us that use these products regularly, the message is simple: be cautious, and protect yourself.

    Avoid Cross-Contamination

    Disposable nitrile gloves are the product of choice for handling pesticides. But one of the most common problems with the use of gloves is cross-contamination. You’re handling product with your gloves on, touching containers, hoses, valves, and couplers. When you’re done, you climb back into the cab where you take off your gloves. Later, someone climbs up into the cab to talk to you, using the railing and operating the door handle without gloves. Guess what’s on their hands? Even later, you put away the hose without gloves and return to the sprayer. Now it’s on the steering wheel and all the levers. There are a few solutions:

    • Double-glove so you can take the dirty outside glove off and still be protected.
    • Wipe down surfaces that you might touch with gloved or bare hands daily.
    • If using non-disposable gloves, avoid lined gloves and rinse the insides out daily.

    Learn More

    If you would like to learn more about pesticide safety, or to obtain pesticide application training, the Pesticide Applicator Licence can be obtained from the Ministry of Agriculture. This course offers in depth, valuable safety information for applicators, as well as general knowledge for pesticide applicators. The Pest Management Regulatory Agency provides workers, employers, and the general public with a wide range of pesticide information. The PMRA can be contacted from anywhere in Canada toll free at: 1-800-267-6315

    Download this Quick Reference Guide for commonly used herbicides. Print, laminate and post it at the fill station or pesticide storage area for easy reference.

    Sources

  • 7 Steps to Total Sprayer Cleanout – Tips with Tom #6

    7 Steps to Total Sprayer Cleanout – Tips with Tom #6

    The first question during the spray season is likely, “what kills this weed spectrum? The second might just be, “How do I clean our my sprayer properly without risking crop injury next go-round?”

    Tom Wolf, spray application specialist and @Nozzle_Guy, answers not just that question, but also a few more —

    • “Can you neutralize chemical?”
    • “Is there a tried and true mixing order?”
    • “What does ammonia actually do in the cleanout process?”

    From the importance of being thorough, to top tips on minimizing issues with specific Group 2 problems, to a handy method for getting a much more effective tank rinse, Wolf will walk you through his top 7 tips for effective sprayer cleanout.

  • Tank Rinse Dilution

    Tank Rinse Dilution

    If you have a limited amount of clean water to rinse your sprayer, this can help you decide how to make the best use of it.  Simple enter two values – the amount of pesticide remaining in your tank sump (including the suction line to the pump and the return line to the tank), and the amount of clean water you want to add.  The units (gal, L) are not important as long as they are the same for both entries.

    The app allows you to calculate the dilution power of up to 5 sequential rinses.

  • An Easier Way to Clean Your Sprayer

    An Easier Way to Clean Your Sprayer

    Farming can be divided into pleasant and unpleasant tasks.  Seeding is pleasant.  Hauling oats or barley not so much.  Sprayer cleaning is…not.  And yet it’s the unpleasant tasks that are often the most important.  How can we make them better?

    We all know the need for a properly cleaned sprayer.  Herbicide residue can harm a sprayed crop, and the damage might not show up for over a week.  When it does, it usually takes a while to identify the symptoms and damage patterns to be sure.  And then we wait for the inevitable yield loss.

    It wasn’t long after the introduction of the Group 2 Mode of Action that producers started noticing how even small residues of these products in sprayer tanks could damage crop yields, most noticeably canola, but also other broadleaf species.

    Thirty years later, the problems persist.  Let’s look at ways of preventing them.

    Cleaning a sprayer is a lot like doing the dishes.  Using the right detergent, soaking the hard stuff, being thorough, and rinsing properly – they all matter.

    It all starts, though, with preventing the problem.

    The main culprits that cause sprayer contamination have the following properties:

    • They are typically dry formulations,
    • they typically have poor water-solubility, and
    • they are potent in low doses.

    Many products in herbicide Group 2 MOA fit that bill.  The ones that rise to the top of the list have an additional characteristic:

    As a subgroup within the Group 2 MOA, the sulfonyl ureas are a top concern, with products like Refine, Express, and Ally on the most-wanted list. Another problem subgroup is the triazolopyrimidines, containing products like Frontline and Simplicity, which, like the SUs, have very pH-dependent solubilities (better solubility at higher pH). Other Group 2s have fewer issues. Everest and Varro have good overall water solubility, for example.  The solubility of imidazolinones like Odyssey, Pursuit, Raptor increases with low pH. We tend to see fewer problems with these products.

    Instances that add to the problem involve tank mixing with weak acid herbicides, including glyphosate, but especially those that are formulated as emulsifiable concentrates (oils, EC), appearing milky when mixed with water.  Most of our herbicides are weak acids.

    Two problems occur with these:

    • The weak-acid herbicide lowers the pH of the spray mix, possibly reducing the solubility of the problematic Group 2s.
    • Then, oily formulation can adhere the herbicide to plastic and rubber sprayer parts such as tanks, connectors, and hoses.

    The best advice on preventing a cleanout problem, is, therefore, to make sure the product is fully dissolved or suspended.   Proper mixing technique and time are the key components.  Some products, like Simplicity, can benefit from a pH increase (adding ammonia) prior to mixing the product.

    Once properly mixed, we can still have problems at the screens. Dry formulations require a screen mesh of 50 or coarser according to their labels.  But many sprayers contain 80 mesh screens, some even have 100 mesh.  All screens should be inspected both before, during, and after spraying these products.  Screen residues cause longer-term contamination, and their cleaning is an important part of this whole process.

    After spraying, the cleaning process relies on three main things:

    1. We need to remove as much of the problem mixture as possible.
    2. We need to dilute the remainder as much as possible and use it to clean the boom plumbing.
    3. Ensure anything that came in contact with spray mix has been cleaned.

    Removing the mixture

    The best way to remove the remainder is to spray it out in the field you’ve just treated.  You can overspray some products again, or if you have any land set aside it can be used for this purpose.  It’s never a good idea to drain the tank on any land.  Obviously, some experience and math is helpful to make sure the last tank empties nicely on the field.

    Diluting the remainder

    The next step is to dilute the remainder, using tank cleaning adjuvants like ammonia (this raises the pH and helps remove those products whose solubility benefits from this) and detergent (this removes the oily layer formed by EC formulations).  Commercial cleaners like All Clear or Cleanout combine these properties in one jug.

    Diluting is most effective when done in multiple smaller batches, as long as we can ensure the tank walls are reached.  Wash-down nozzles installed in the tank can do this for us.

    Let’s assume the sprayer has a 150 gallon clean water reservoir.  It’s tempting to empty the whole thing into the tank.  We can calculate the diluting power of this:  if we had a 10 gallon remainder in the tank and added 150 gallons water, the remainder would be diluted by a factor of 16.  After spraying this out, we’d then have to re-fill the rinse tank if we wanted to do more.

    If we rinsed in two 75 gallon batches (add 75 gallons, agitate via wash-down nozzle, spray out, repeat), we would dilute by a factor of 72.  If we did three rinses of 50 gallons each, our final dilution factor would be 216.  That’s the same dilution as adding about 2150 gallons to the first 10 gal spray tank remainder, and is about 14 times better than dumping the whole 150 gallons in at the beginning!

    An improvement in diluting power can be achieved by adding a separate clean water pump.  Introducing clean water to the tank as rinsate is sprayed out the boom reduces water use even further.

    Cleaning all spray mix contact points

    The last step is to pay attention to the things you can’t see: Screens, boom lines and boom ends. The total interior surface area of black rubber boom hoses on a 100 ft sprayer with 7 sections can be as much as several square metres, and this surface can bind residues. Seven sections, each with boom ends, can hold several gallons, as well as accumulated debris. Scrubbing screens, soaking boom lines, and flushing boom ends is the necessary detail that this job requires.

    A few final pointers:

    • Adding a surfactant or a commercial cleaner can generate a lot of foam. Have de-foamer handy, it will save a lot of frustration.
    • A bucket helps collect and clean screens and nozzles.
    • Consider upgrading to more steel components on your next sprayer – tanks and booms. Stainless steel cleans faster than plastic.
    • Install a way to flush your boom ends. Traditional ball valves do the job, but Hypro’s Express Nozzle Body End Caps do it automatically. These inexpensive units eliminate the dead space in boom ends and as a bonus, bleed air from the lines on the go.
    Hypro's Express Nozzle Body End Caps on a short length of stainless boom.
    Hypro’s Express Nozzle Body End Caps on a short length of stainless boom.

    Done well, sprayer cleaning doesn’t have to be unpleasant. And it certainly results in a better night’s sleep.