Fatal Industrial Accident Involving a Chemical Blender Machine: A Rare Case Report

Abstract

Machinery, whether it is operating or idle, may cause various types of contact injuries, including caught-in or caught-between incidents with moving parts, avulsions, amputations, burns, crush injuries, falls, and impacts with the machine or surrounding surfaces. Despite the prevalence of industrial accidents, fatalities caused by chemical blender machines have never been reported. This case reports a rare fatal case involving a 48-year-old male who sustained musculoskeletal injuries after falling into a chemical blender mixer while manually stirring powder in an industrial setting. The victim became trapped in the machine for ∼30 s, leading to extensive lacerations and fractures, and died due to hemorrhagic shock. The autopsy revealed multiple lacerations and fractures on the lower limbs due to the machine's helical blades, alongside a deep laceration on the right shoulder. Internal injuries included rib fractures, liver lacerations, and significant blood loss, ultimately causing death. The unique design of the blender machine blades, with helical-shaped blades, played a critical role in the injury pattern. A crime scene investigation emphasized the absence of proper safety measures, such as guarding mechanisms, which allowed the victim's entrapment.

INTRODUCTION

The increasing rate of occupational fatalities and mortality rates has become a significant global concern. According to the International Labor Organization (ILO), a worker dies every 15 seconds due to a work-related accident or disease, resulting in ∼321,000 deaths annually (1). Among these, slips or trips resulting in falls are the most prevalent work-related injuries, constituting 20% to 40% of debilitating occupational injuries (2). Whether operating or idle, machinery can cause various types of contact injuries, including caught-in or caught-between incidents involving moving parts, avulsions, amputations, burns, crush injuries, falls, and impacts with the machine or surrounding surfaces (3). One such machine, a chemical blender mixer, is widely used for mixing solid–solid (powder materials) and solid–liquid (powder and fluid materials) in various industries, including chemical, pharmaceutical, and food sectors. Although there are possibilities of sustaining harm in any industrial setting involving machinery, to the best of our knowledge, there have been no reported incidents of fatal injury related to the chemical blender machine. Here, we present a unique case involving fatal musculoskeletal injuries sustained during the operation of a chemical blender mixer in an industrial setting, describing the injury mechanism due to entanglement with the rotating machinery and the associated autopsy findings.

CASE REPORT

A 48-year-old male was brought in an unresponsive state to the emergency department of a tertiary care hospital with an alleged history of injury sustained by a fall into a chemical blender machine. On arrival, the patient had a heart rate of 100 bpm, blood pressure of 100/70 mm of Hg, and oxygen saturation of 100%. However, the condition of the patient worsened, and despite the resuscitative measures, he died 4 hours following the trauma. According to the information provided by coworkers, the victim was operating a chemical powder blending machine that was in operation. Toward the end of the mixing process, the powder required manual stirring to ensure thorough mixing. While performing this task manually, standing on top of the machine, he inadvertently slipped and was trapped inside the rotating machine for approximately thirty seconds before coworkers managed to switch it off, resulting in severe injuries.

Autopsy Findings

The autopsy revealed an adult male of length 166 cm, weighing 85 kg. There were multiple lacerations and abrasions involving the body, with specific injuries noted on the right shoulder and lower limbs. On the right shoulder, a laceration measuring 10 cm × 4 cm was present anteriorly, with a depth extending to the humerus bone, crushing the adjacent muscles. Surrounding the laceration, a red-colored abrasion measuring 9 cm × 8 cm was noted ( Figure 1A ). The upper end of the humerus was fractured, accompanied by blood extravasation into the surrounding soft tissues.

Figure 1.

External findings on the shoulder and lower limbs. (A) The arrow indicates a laceration on the right shoulder. The laceration is surrounded by an abrasion and extends to the bone, with evidence of crushed underlying soft tissues. (B) Twisted appearance of the legs, with multiple lacerations at places. The injuries suggest significant force and rotation during trauma.

The lower limbs showed more extensive and severe injuries. Both legs had a twisted appearance ( Figure 1B ). On the right thigh, multiple lacerations ranging from 1 cm × 1 cm × 1 cm to 6 cm × 1 cm × 5 cm were observed, surrounded by an abraded contusion over an area of 20 cm × 10 cm. There was an associated fracture of the lower third of the femur, with extravasation of blood into the soft tissues ( Figure 2A ). An abrasion measuring 18 cm × 16 cm covered the outer lower third of the right thigh and the upper right leg. The right foot displayed multiple lacerations on its dorsal aspect, ranging from 0.5 cm × 0.5 cm×soft tissue deep to 1 cm × 1 cm × soft tissue deep, with irregular and contused margins.

Figure 2.

Depicts the fracture of the femur. (A) Depicts the fracture of the right femur. The adjacent muscles are crushed, with visible extravasation of blood. (B) The lower end of the left femur protrudes through a defect in the posterior aspect of the knee joint.

On the left lower limb, a 16 cm × 5 cm abraded contusion was present over the lower thigh anteriorly. Another laceration, measuring 16 cm × 7 cm × bone deep, was located on the back of the left knee, with irregular and contused margins. The lower end of the femur, along with the medial and lateral condyles, protruded through the defect with crushing of the adjacent muscles ( Figure 2B ). The left knee prominence also bore a 2 cm × 1 cm red-colored abrasion.

On internal examination, a sub-scalp contusion was observed, corresponding to the injuries on the scalp, along with the contusion of the right temporalis muscle. The thoracic cavity contained ∼500 mL of blood. There was a fracture of the fifth and sixth ribs on the right and the third to fifth ribs on the left side along the mid-clavicular line with extravasation of blood into the surrounding intercostal muscles. The peri-hepatic pouch contained ∼500 mL of blood. Two lacerations, each measuring 1 cm × 0.5 cm × parenchymal deep, were present on the diaphragmatic surface of the right lobe of the liver, surrounded by a contusion over an area of 4 cm × 2.5 cm. All the organs were pale in appearance. The toxicological analysis ruled out the presence of alcohol or any other intoxicating agents. The patient died after 4 h and 50 min of sustaining the injury, and the cause of death was attributed to hemorrhagic shock resulting from multiple musculoskeletal injuries.

A crime scene visit was conducted to assess how the injuries were sustained. The machine involved in the present case was a semi-automatic machine. The blender machine is made up of stainless steel apparatus engineered for the effective and uniform blending of powdered or granular substances in industrial settings. The machine was 1975 mm × 1059 mm × 1120 mm and weighed ∼1000 kg, with a U-shaped mixing drum, a horizontal center shaft, helical-shaped blades, and drive components ( Figure 3A ). The machine operates at 75 kW power and a volume of 300 L. The helical blade of the machine features a unique design, with the inner blade curving outward and the outer blade curving inward, both of which have blunt edges. This unique design allows the inner blades to transport material outward, and the outer blade conveys materials inward, facilitating the adequate mixing of the powder ( Figure 3B ). This circular motion guarantees comprehensive blending and allows the mixer to attain elevated mixing efficiency quickly. The machine operated at 40 r/min, facilitating regulated and exact mixing, with an inlet port for material loading and a discharge valve for product disposal.

Figure 3.

Describe the blender machine. (A) External appearance of the blender machine. The arrow indicates the U-shaped mixing drum that the victim had fallen into. (B) Inner aspect of the mixing drum. The straight arrow highlights fragments of the victim's clothing trapped inside the drum, while the dotted arrow points to the helical blades.

DISCUSSION

Occupational safety is a challenge for all companies globally. It safeguards the most vital asset of companies, their workforce, and enhances production and efficiency (4). In the present case, according to co-workers, the victim inadvertently fell into the central part of the machine and became entangled between the blades. The ribbon blade of the machine has a unique design, with the inner blade curving outward and the outer blade curving inward, featuring blunt edges. Considering the machine's speed of 40 r/min and an entrapment duration of 30 seconds, the victim underwent 20 complete cycles of rotation inside the machine during the incident. The outward-curving inner blade pulled the victim further into the machine, while the inward-curving outer blade pushed them back outward, creating a continuous and forceful cycle. This motion trapped the victim effectively, preventing any chance of escape. The combination of circular motion and the spiral configuration of the blades caused crushed lacerations in the lower extremities.

The injuries primarily occurred in the lower one-third of the thighs and the upper one-third of the legs, where the blades directly contacted the limbs, leading to lacerations and fractures. The outer blade, with its inward-curving helical design, pulled the victim's limbs deeper into the machine as it rotated. This pulling action created a twisting force, or rotational torque, which caused the bones to twist along their length, resulting in fractures. At the same time, the continuous circular motion of the blades compressed and sheared the surrounding soft tissue, causing severe lacerations. The combination of these forces (pulling, twisting, and compression forces) worked together to produce the severe and complex injuries observed in the victim.

The deep laceration on the front shoulder is likely produced by direct contact with the free edge of the blade. The continuous circular motion and repeated hits at the exact location elucidate the severity of the laceration, regardless of the blunt nature of the blades. The large dimensions of the lacerations, combined with the blunt characteristics of the edges, corroborate this mechanism. Internally, the patient suffered multiple rib fractures and liver lacerations due to the impact of the blades. Additionally, the multiple abrasions and lacerations on different regions are due to its circular motion against the blunt blades.

The blade arrangement has a significant role in determining the pattern of injury produced. Zine et al reported a case of a fatal crush injury caused by falling into a paddle mixer machine. The patient had sustained multiple crush injuries, resulting in fragmentation of the body into several pieces (5). In contrast, in our case, there was no evidence of amputation of body parts. This difference can be attributed to the design of the machines. As in paddle mixers, the blades are closely arranged, whereas in the blender machine reported in our case, there was a considerable gap between the blades. Moreschi et al (6) studied injury patterns in individuals trapped in feed mixer wagon augers. The injuries ranged from dismemberment to decapitation, with hemorrhagic shock as the leading cause of death. The injury mechanism begins when the victim is grabbed and pulled rapidly by the upper augers, leading to entanglement. They are then drawn into the bottom auger, where sharp rotating and fixed blades shred tissues, organs, and body parts. Fractures and fragmentation occur due to the combined pulling force of the upper augers and the cutting action of the bottom blades, resulting in severe and often fatal injuries. Similarly, in our case, the entrapment occurred because of the unique design and motion of the blades, in which the inner blade pushes the victim outwards while the outer blades drag them inward, making self-rescue impossible.

In the present case, the blood loss was a significant factor leading to the death of the individual. The total circulating blood volume can be calculated using the Nadler equation: (0.3669 × H3) + (0.03219 × W) + 0.6041; H = height (meters) and W = weight (kg) (7). Considering a weight of 85 kg and height of 166 cm, the total blood volume was calculated in our subject as 5.02 L. Death or profound hypovolemic shock may result from a loss of over 40% of the total blood volume (8). The anticipated blood loss following a closed femur fracture ranges from 1000 to 1500 mL, and for open fractures, these figures may double (9). In this instance, the patient suffered femur fractures in both legs, one closed and the other open, along with 500 mL of blood collected in both the thoracic and peritoneal cavities, resulting in a total blood loss of ∼3000 to 3500 mL (60%-70% of the total blood volume).

The injury resulted from a lack of safety awareness and protective measures during machine operation. Occupational Safety and Health Administration (OSHA) guidelines 1910.212(a)(3)(ii) and 1910.212(a)(3)(iii) state that machine operations exposing employees to injury must be equipped with guards to prevent any part of the body from entering the danger zone during operation. Additionally, special hand tools should be used to safely handle materials without placing hands in the danger zone. These tools are meant to supplement, not replace, the required guarding (10).

CONCLUSION

This case illustrates a rare fatal case of a blender machine injury, describing its mechanism, injury pattern, and the significance of crime scene investigation. The distinctive shape and motion of the blender machine's helical blades had a vital role in producing the characteristic lacerations and fractures, ultimately leading to fatal hemorrhagic shock. The absence of sufficient guarding and safety standards contributed considerably to the victim's entrapment and inability to rescue himself. This incident highlights the critical necessity for adequate machine guarding, operator training, and compliance with safety requirements to prevent similar incidents in the future.

Authors

Deepu Mathew, MD, Department of Forensic Medicine and Toxicology Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER) Puducherry India Role: A, B, C, D, E

Vinod Ashok Chaudhari, MD, Department of Forensic Medicine and Toxicology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India Role: C, D, E, 4

Abisha Tino LN, MBBS, Department of Forensic Medicine and Toxicology Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER) Puducherry India Role: B, C, E, 6

Richard Robert S, MBBS, Department of Forensic Medicine and Toxicology Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER) Puducherry India Role: B, C, 6