Tuesday, May 12, 2015

12/05/2015: SAFETY on aquaculture farms

by Robert M Durborow, Professor and Aquaculture Specialist, Kentucky State University, and Melvin L. Myers, Associate Professor and Safety Engineer, Emory University Rollins School of Public Health, Atlanta
First published in International Aquafeed, March-April 2015

Aquaculture has many hazards that are expected when agriculture in an aquatic environment is performed. Avoiding injury maintains aquaculturists’ health and quality of life as well as their economic security. Injury can be costly due to lost work hours, medical expenses and possible lawsuits, so maintaining safe working conditions on fish farms has multiple benefits.

Occupational safety survey research performed in the US (Melvin Myers, Robert Durborow, Henry Cole, Tiffany Ogunsanya, et al. from 1997 to 2012 – see below) and the U.K. (Durborow and Gomelsky, unpublished, presented at the U.S. Trout Farmers Association annual meeting, Denver, Colorado in September 2012) identified twelve potential hazard categories present on aquaculture farms: muscle strains, falls, entanglement, drowning, electrocutions, working in confined spaces, equipment overturns, chemical exposures, impalement, self-injections, dark working conditions and lack of emergency communication.

In safety studies, the old adage of “being careful” is considered the least advanced of injury prevention intervention, avoiding the hazardous behavior is a bit more advanced while engineering the work environment to eliminate the hazard is considered the most advanced intervention.

Muscle strains
A common muscle strain occurs in the lower back region, often caused by lifting and carrying heavy loads. Leg muscles rather than back muscles should be used primarily to lift heavy weights and twisting (turning the upper body independent of the lower body) while holding a heavy load should be avoided.

A fish production facility in the US found that if workers carry smaller, more manageable loads of fish in nets, they avoid muscle strains, increase the speed of transferring fish between tanks, and avoid inadvertently dropping fish out of overloaded nets onto the floor (which not only stresses the fish but slows down the fish-moving process).

In the effort to increase fish farm safety, one could “be careful” while carrying feed bags around a farm or, better yet, one could use a truck or utility vehicle to transport the bags, but the best option for avoiding muscle strain during feeding is to fill a bin on a feeding truck and mechanically blow the feed from the bin through a pipe to dispense it into the ponds or raceways (an engineering intervention; Figure 1).

A large trout farm in the US eliminates the truck and simply augers the feed from a stationary feed storage bin through a pipe that has discharge ports over each raceway receiving a pre-determined amount of feed programmed by computer (Figure 2). Other interventions designed to reduce muscle strains include keeping the fish tank loading dock at the same level as the fish hauling truck bed to avoid having to step up and down while carrying heavy loads; constructing fish hauling tanks to be waist-high so heavy loads of fish in a dip net do not have to be hoisted chest-high; using metal chutes at the hauling tank discharge ports to allow for quick and easy stocking of fish; using dip nets attached to pulleys for easy lifting and a track for sliding (done manually in Figure 3 and mechanically in Figure 4); and using cranes and forklifts for all general lifting activities on the farm (Figure 5). Water pumps (Figure 6) and fish pumps (Figure 7) save time and prevent muscle strain.
Fall prevention

Settings with water, and possibly ice, have the inherent hazard of potential slips, trips, and falls (which includes the obvious risk of drowning after a fall). Walking on trout raceway crosswalks or on the narrow raceway walls themselves involves risks especially if the crosswalks are broken, rusty or splayed and the raceway walls are crumbling or simply very narrow. Metal crosswalks in good condition with traction/grip (‘grip-strut’) and widened raceway walls (wide concrete in Figure 8 and wide metal ‘grip-strut’ attachments in Figure 9) reduce falling risk.

Wooden surfaces can be given more traction even when wet by veneering with rough, unfinished lumber or attaching chicken wire to the surface (commonly seen in the U.K.). Newly poured cement surfaces can be given a rough texture by a coarse broom before the cement dries completely (Figure 10); this helps to avoid the extremely slippery wet smooth cement that poses an extreme falling hazard. Slips can occur when walking from a rough to smooth surface, and conversely, trips can occur when walking from a smooth to rough surface. Falls from high places like the tops of feed bins can be avoided by active safety measures such as enclosed metal guards surrounding the metal ladder on the feed bin sides.
Active safety measures require the person to play a role in their safety such as catching oneself on the metal guard in the event of falling. An engineered safety intervention of having a cable attached to the feed bin lid that can be pulled from ground level to open the lid eliminates the need to climb to the top, and an even better engineering intervention is having a pipe extend from the feed bin top to ground level where a feed tanker truck can attach to the pipe and blow feed into the top of the feed bin (Figure 11).

In cases, however, when someone needs to climb ladders, a harness attached to a cable paralleling the ladder can be worn by the worker. Usually when a worker is on a hauling truck side platform, the potential fall is only three or four feet unless the truck is parked on a ledge or steep levee; under this scenario, falls could exceed 20 feet. To safeguard against such hazards, an Idaho trout farm has engineered retractable guard rails for the side of their hauling trucks (Figure 12). 

Under icy conditions (on hauling trucks or elsewhere on the farm), salt can be applied to melt ice or prevent it from forming. To increase traction, one Kentucky operation surfaced their trucks with SlipNOT® high traction metal plating (“pepper plate”) that is also used on battleship decks.

Entanglement, drowning and electrocution

Loose and random placement of bird netting around raceways and ponds can present an entanglement hazard that can lead to drowning. Using a more rigid netting material fastened to wooden frames is effective in excluding bird predators without posing a drowning hazard; additionally, workers falling into these structures will likely have their fall broken, reducing the chance of injury (Figure 13).
Drowning can also be prevented by having anchored rope ‘lifelines’ extending into ponds, especially ponds with slippery rubberized pond liners on the levees. Aquaculturists should also be aware of a rare drowning threat present at wastewater treatment facilities; fish are sometimes produced in decommissioned (retired) concrete tanks at wastewater treatment plants. Some bodies of water at these plants are aerated so intensively that the water loses its buoyancy friction, making it impossible to swim in the “foamy” water.

Another type of entanglement that can occur on fish farms is being caught in a tractor’s power take-off (PTO) while aerating a pond or being caught and traumatized in a paddlewheel aerator. PTOs should have a protective guard to prevent workers from having their clothing caught in it and being spun and beaten to death on the ground (Figure 14). Likewise, aquaculturists working near or on a paddlewheel aerator must take precautions to assure that the main breaker box as well as individual aerator switches in the breaker box are turned off.

The Lock Out – Tag Out system of breaker box locking should be practiced (Figure 15); a worker doing electrical repairs on an aerator, for example, locks the breaker box in the off position and a second worker working on equipment coming off of the same breaker box also locks the breaker box so that the first worker does not complete his job and then return to the breaker box to turn it back on while the second worker is still working on his or her piece of equipment. This prevents both workers from being exposed to entanglement trauma as well as electrocution hazards.

Also in the realm of electrocution prevention, ground fault interruptors should be used around outlets and on breaker boxes (Figure 16). A farm in North Carolina raised their overhead electrical wires from their original 30 foot height up to 45 feet to prevent cranes from contacting the wires when moving trout between raceways. Another precaution taken by a fish farm in Arkansas is to use only gasoline-powered power washers; one of the farm owners was killed using an electric-powered washer when the plastic insulation on some internal wires eroded away allowing the metal wires to come into contact with the metal casing of the washer.

Confined spaces

Toxic gases that are heavier than air (such as hydrogen sulfide and carbon dioxide) can accumulate in deep confined spaces including in-ground manure collection tanks on trout farms (Figure 17). Calibrated multi-gas monitors should be lowered into confined spaces to test air quality before workers descend into them, and in all cases these workers should wear harnesses and be observed/assisted by a co-worker at ground level. As with other safety issues, engineering the hazard out of the procedure is the best approach; figure 18 shows a confined space at an Idaho trout farm where the controls have been moved to where workers at ground level can make adjustments without entering the space.

Equipment overturns
Farm equipment (notoriously tractors) can roll over and crush the driver unless a proper rollover protection structure (ROPS) is used. A combination of a roll bar or enclosed cab with a seatbelt keeps the driver in a protected zone of the equipment. Using dual tires on tractors adds to their stability (Figure 19). Proper management of the farm’s roadways, especially on levees, can also help to prevent rollovers. Maintaining an adequate gravel surface and repairing areas where the road has eroded (or at least keeping grass mowed so any washed-out areas can be seen and avoided more easily) can keep a vehicle from sliding or rolling off the road and into a pond.

Additionally, the water in a pond can erode the levee causing a cavity into the levee in which the under-cut can give way from the weight of equipment on the levee. This erosion can be mitigated with aggregate at the interface between the levee and water. A safety precaution commonly practiced in the coal mining industry is to construct an earthen berm on the edge of the road to deflect the truck or tractor tires away from the drop-off (Figure 20). An additional safety intervention is to mount a metal screen on the tractor ROPS to block debris (rocks, logs, etc.) propelled toward the driver (Figure 21).

Chemical exposures, impalement, falling hauling tank lids, and self injection

In a somewhat miscellaneous listing of potential hazards in aquaculture, respiratory, eye and skin protection (Figure 22) should be worn when applying chemical treatments including fertilizers, disease therapeutants and herbicides. Protruding rebars used to enforce the strength of concrete should either be capped with plastic protectors or bent to a horizontal position to prevent impalement. Bruises and cuts can also occur from falling hauling tank lids; hands have been broken and fingers can be severed. This can be prevented by installing locking hinges (Figure 23) or even by using lightweight lids (e.g., sheet metal).

When injecting trout with vaccines, corrugated fiberglass roofing material (Figure 24) can help to stabilize the trout to prevent them from making sudden movements that could lead to self-injection by the worker. Accidental injections of fish vaccines into people can cause a strong inflammatory response or even anaphylactic shock (if the person had a previous accidental injection of the vaccine). If previously injected with a fish vaccine, a person should consult a physician about keeping an EpiPen® injection kit handy in the event of another inadvertent vaccine injection. Moreover, automatic fish vaccination machines have been produced in Norway and Denmark that eliminate manual vaccination of fish.

Dark working conditions and lack of communication
Much work on fish farms takes place at night, a time when visibility is compromised. Being visually restricted makes it more likely for farm workers to experience injury; sufficient lighting can help to reduce this risk. Aquaculture ponds often require aeration at night when respiration is at its peak and fish experience low oxygen stress.
Working in a hurried fashion in an attempt to save as many hypoxic fish as possible while not being able to see very well can result in serious injury; a catfish farm manager in Alabama had electric cables powering pond aerators get tangled under his truck in the middle of the night – his attempts to free the wires resulted in his electrocution. Similarly, on a North Carolina trout farm in the middle of the night during the winter, the water intake to the trout raceways was frozen and clogged; a farm manager died during his attempt to clear the intake and restore the water supply. In both cases lighting was inadequate. Installing bright overhead lights on utility poles and on pickup trucks can provide increased visibility to make the nighttime tasks less risky.

Having adequate communication during emergencies can help to avoid tragedy. Mobile telephone service in remote locations (typical of many fish farm settings) is often unreliable. Fish farmers in rural Alabama often rely on two-way radios to reach co-workers or family members during such emergencies.

The objective of presenting this aquaculture occupational safety information is to make aquaculturists aware of potential hazards in the fish farm workplace and provide ideas on how to avoid or eliminate them. The text should be helpful in explaining these ideas, but the photos and captions may even be more helpful by triggering the thought process involving circumstances that are similar to those on the reader’s farm. For more detailed information and references, please contact robert.durborow@kysu.edu.

Read the magazine HERE.

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