Pesticides are substances or mixtures of substances intended for preventing, destroying or repelling an undesirable plant, animal or microorganism. Some of the most common pesticides include herbicides, insecticides, fungicides and rodenticides. Over the centuries, naturally-occurring elements were used as pesticides; but starting in the 1930’s, chemical synthesis advances allowed for the development of synthetic pesticides. After World War II, several synthetic pesticides, including dichlorodiphenyltrichloroethane (DDT) were introduced and used extensively in the agricultural environment. At that time, the development and  effectiveness of synthetic pesticides were so important that the chemist who developed DDT was awarded a Nobel Prize in 1948 for combating hunger. Pesticide development has progressed since those initial    discoveries; however exposure to this group of chemicals is still a significant hazard to humans. [Note: The use of DDT is now banned globally under the Stockholm Convention of 2001, because it persists in the environment and becomes concentrated in animals at the top of the food chain.]

Types of Pesticides

Pesticides may be synthetic or organic. Organic pesticides, or biopesticides, are naturally-occurring chemicals; but they may be reproduced in labs for use in organic farming. Synthetic pesticides are designed to be stable, have a good shelf life, and be easy to distribute. They are also intended to be effective at targeting pests and have low toxicity to non-target animals and the environment.

Classes of synthetic pesticides include:

• Organophosphates: Insecticides that target the nervous system. Several of them have been banned or restricted due to toxic accidental exposures.
• Carbamates: Insecticides that affect the nervous system similarly to organophosphates; but they are less toxic, as their effects wear off more quickly.
• Pyrethroids: Laboratory-produced versions of a natural pesticide that’s found in chrysanthemums – also affecting the nervous system.
• Organochlorines: Including DDT, these have been largely banned or restricted due to negative effects on the environment.
• Neonicotinoids: Insecticides used on leaves and trees. They are currently under scrutiny by the U.S. Environmental Protection Agency (EPA) for reports of unintended harm to bees.
• Glyphosate: Commonly known as a product called Roundup™, this herbicide has become important in weed control for farming genetically-modified crops. [Note: Monsanto, the manufacturer of Roundup™, is involved in litigation over health claims associated with the product. In 2018, a California jury awarded a former school groundskeeper $289 million in damages from Monsanto, after the groundskeeper developed a terminal case of non-Hodgkin’s lymphoma.]

Hazards

Pesticides can be hazardous to people if they are exposed to them through the skin or eyes, by mouth, or in the air they breathe. Pesticides pose risks of short- and long-term illness to pesticide applicators, hand laborers, employee families, and rural residents. Workers who mix, load or apply pesticides can be exposed to pesticides due to spills and splashes; defective, missing or inadequate protective equipment; direct spray; or airborne drift. Those who perform hand-labor tasks in areas that have been treated with pesticides face exposure from direct spray, drift, or contact with pesticide residues on plants, weeds or soil.

Other types of potential employee exposure include eating with contaminated hands or in a pesticide-contaminated field, or consuming contaminated fruits and vegetables. Workers may also be exposed to pesticides if they drink from, or wash their hands/bathe in, irrigation canals or holding ponds where pesticides can accumulate. Pesticides can present a hazard to family members due to contamination brought home on clothes worn by workers and to rural residents via air, ground water and food.

Unfortunately, it isn’t just the pesticide applicators that are often exposed to these chemicals. Pesticides are persistent, and are unlikely to dissipate rapidly – lasting from a few weeks to decades in the environment. They are designed for longevity in providing effective control of the organisms they are meant to prevent,   destroy or repel – resulting in potential exposure long after the initial pesticide application. In addition, their robustness allows these chemicals to be transported to areas away from the application site. This longevity and ease of transport have resulted in several secondary exposures, such as those occurring from direct  contact with pesticides in the soil and water as well as consumption of plants or animals. Bioaccumulation  occurs when organisms on the lower end of the food chain ingest pesticides, and are then ingested by organisms higher up the food chain. The concentration of pesticide increases as it works its way up the food chain, until it reaches a concentration that is harmful to its host.

Controlling Risks

Handling of commercial pesticides – including agricultural pesticides – requires the proper certificates, permits and training to use them safely, correctly, and according to the requirements of the law. The use of   commercial pesticides is regulated by the EPA through the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). FIFRA requires certification and training for applicators of restricted-use pesticides, and training for workers in pesticide-treated areas. For some pesticide use, engineering controls using closed application and mixing systems to reduce worker exposure during use, may be required. Workers are required to be trained on the proper use of this equipment, and the equipment must be properly maintained and inspected prior to each use.

In addition to engineering control methods, or when the use of these methods is not practical, personal protective equipment (PPE) may be used. PPE required for pesticide applicators varies depending on the material and the application method. The pesticide label will identify the types of PPE required for applicators or workers with potential exposure risks. Examples of PPE often used for these activities include chemical-resistant coveralls, aprons and hoods; eye protection; protective gloves and footwear; and respiratory protection.

To reduce the potential for contamination, decontamination facilities with adequate supplies of soap, water, and towels must be provided to workers using pesticides. Emergency eyewashes must be immediately   available, and emergency medical care information should also be posted at the worksite. Employees should use proper hygiene by washing hands and face and changing clothes before leaving the worksite.

Warnings must be posted at the site of pesticide use. Workers should monitor weather and other factors that may affect the application process, as well as the safety and health of humans and animals near the application site. Records of pesticide use should be maintained. Pesticide containers must be handled properly – storing them in a secure place and disposing or recycling them according to product label requirements. Pesticides should never be stored in unlabeled containers, especially those that may appear to be food containers (such as cans or bottles).

HETI…Experienced EHS Professionals

Although the use of pesticides is a significant hazard to humans and faced with the challenges described above, HETI can assist in the response to these issues. We can provide workplace exposure assessments along with appropriate and feasible solutions – including the development and implementation of written  training programs; standard operating procedures; and, most importantly, employee training.