Research Laboratory Safety

Daniel Reid Kuespert

• Éditeur: De Gruyter
• Année: 2016
• ISBN:
  9783110437058
• Édition: 1
• Sujet: Technology & Engineering
• Sous-sujet: Chemical & Biochemical Engineering

Research Laboratory Safety explains the most important prerequisite when working in a laboratory: Knowing the potential hazards of equipment and the chemical materials to be employed. Students learn how to assess and control risks in a research laboratory and to identify a possible danger. An approach on the hazard classes such as physical, chemical, biological and radiation hazards is given and exercises to each class prepare for exams.

Part I:Introductory Material

1Introduction

Science and engineering research concerns new knowledge, new technology. The scientific method depends on a hypothesis, a question with an unknown answer. The research environment, therefore, necessarily involves operations and materials whose behavior and properties are not fully understood. Lack of understanding increases the risk of working in a research laboratory or field location, and practicing scientists and engineering researchers must often take steps to control that risk and reduce it to a tolerable level.

1.1Accidents in the research laboratory

Accidents in research laboratories are common; they may involve injury, illness, damage to equipment, or simple failure of the experiment. Firm data on the incidence of laboratory accidents is not available, partially because health authorities typically do not identify incidents as lab accidents per se, and partially because employers sometimes keep incidents confidential (to avoid reputational losses or lawsuits). Nevertheless, the most serious incidents, those which require the involvement of civil authorities such as firefighters or occupational safety investigators, become widely known. Six notorious examples are summarized below, four in chemistry, one in physics, and one which involved machine shop equipment. Each example includes both an obvious lesson to be learned and a more subtle one. In all but one case, the investigator died.

1.1.1Vladimir Likhonos: eating explosives

In early December 2009, Vladimir Likhonos, a chemistry student at the Kiev Polytechnic Institute in Ukraine, was working at home on his computer. Mr Likhonos enjoyed chewing gum while working, and he often dipped his gum in a small dish of citric acid that he kept on his desk (to give it a tangy flavor).

Apparently, at some point in the recent past, he had brought a small container of an explosive chemical home from the laboratory for an unknown reason. It is theorized that while concentrating on his work, he absent-mindedly dipped his gum in the explosive instead of in the citric acid. When he bit into the explosive-laced chewing gum, the resulting explosion blew off his jaw and severely injured his face; he consequently bled to death [2].

The simple lesson to be drawn from this incident is that food and drink should never be stored or consumed near hazardous chemicals. A more general lesson might be that laboratory operations and products should always be kept strictly separate from day-to-day activities: do not remove lab coats from the laboratory, nor wear gloves outside the lab, for example.

1.1.2Karen Wetterhahn: a deadly droplet

On 14 August 1996, Dr Karen Wetterhahn, professor of chemistry at Dartmouth College (Hanover NH, US), was conducting 199Hg nuclear magnetic resonance (NMR) experiments [3]. Wetterhahn, 48, was an expert on heavy-metal toxicity—she was well-known for elucidating the mechanism of carcinogenicity for Cr6+ [4]. NMR spectroscopy requires use of a reference compound, as the spectrum of the sample under analysis is expressed relative to the reference peak. At the time, the standard 199Hg NMR reference material was dimethylmercury [5]. This compound is known to be extremely hazardous (all known exposures have been fatal [3]), and Wetterhahn handled it only in a chemical fume hood while wearing disposable latex gloves [6].

While transferring dimethylmercury to a NMR sample vial, Wetterhahn spilled one or two drops of the compound on her latex-gloved hands. Dimethylmercury can penetrate disposable latex gloves in under 15 seconds [7]. Since she was not aware of this fact, Wetterhahn tidied up the spill and removed the gloves at the end of the operation.

In January 1997, Wetterhahn was admitted to the hospital with a diagnosis of severe mercury poisoning, and despite aggressive chelation therapy and other treatments, she died 8 June 1997.

The clear lesson to be learned from Wetterhahn’s death is that when handling compounds known or suspected to be highly toxic, it is essential to fully understand the properties of the material and to take additional precautions, such as using multiple layers of different gloves to slow penetration and changing gloves at the first sign of exposure. In this case, the “supertoxicity” of dimethylmercury had been known since its first synthesis in 1863, within months of which both lab technicians who had performed the procedure died horribly [8].

Another lesson is more subtle: the manner in which Wetterhahn conducted her operation created a situation where her gloves were the only line of protection between her skin and the compound. Personal protective equipment (universally known as PPE) is notoriously unreliable. Never rely on PPE as the only line of defense against an incident unless absolutely necessary, and if it appears to be absolutely necessary to do so, obtain professional advice on selection and use of the equipment.

1.1.3Michele Dufault: hair is a hazard

A particularly sad incident occurred on 12 April 2011, at Yale University. Physics and astronomy student Michele Dufault was working late at night in a machine shop. She was working on her senior thesis: a device employing liquid helium for detection of dark matter in the universe [9].

Ms. Dufault was using a lathe, a machine tool used for producing axially-symmetric pieces of materials such as wood or metal. The workpiece is clamped with a pair of chucks to hold it steady, and it is spun at great speed. Sharp tools placed against the workpiece quickly cut any shape desired, provided that it has a circular cross-section.

Figure 1.1:Machinist Richard Middlestadt uses a lathe to shape a part.

Her hair was suddenly caught in the lathe, which would have quickly wound it in like thread on a spool. This is an example of a wrap point (see section 6.1.5 below). The shop was unmanned outside business hours, and she died of asphyxia before she was discovered by other students working in the building.

A medical examiner ruled her death an accident caused by neck compression [9]. Michele Dufault was a trained and qualified individual, by the standards of her institution. Machine shop rules and training materials specifically warned of putting hair up in shop to prevent injury: “...if your hair is caught in spinning machinery, it will be pulled out if you are lucky.” Dufault was not lucky in this instance.

A simple lesson that can be drawn from Michele Dufault’s death is that one should never work alone when performing work posing significant risk. It was well-known that lathes can catch hair and cause serious injury [10]. The presence of a “buddy” in the shop during hazardous operations would have provided someone to shut down the machine, render first aid, possibly extract Ms. Dufault from the lathe, and call for help.

A more subtle lesson is that oftentimes in the rush to complete a research project, it is very easy to fall prey to a very simple hazard, even if one has been trained and warned of its presence. Training and warning signs are examples of administrative controls (see section 4.2.2 below), and one reason other, more engineering-based controls (such as guards) are preferred over administrative controls is that they are more reliable. (Note that it is not possible to place a guard over the spinning workpiece in a standard lathe, though, so Yale and Michele Dufault were forced to fall back on administrative controls.)

1.1.4Louis Slotin: A slipped screwdriver

On 30 May 1946, Dr. Louis Slotin, a physicist at what is now the US Los Alamos National Laboratory, which designed and prototyped the first atomic bombs, conducted an experiment to determine criticality thresholds in a plutonium core assembly. The experiment involved holding two Pu spheres slightly apart with a screwdriver and measuring neutron emission as they were brought closer and closer [11]. Slotin had performed this procedure several times; he was demonstrating it to a new researcher who was to take over the experiment, but he was in somewhat of a hurry to conduct the demonstration ([12]; as duplicated in [13]).

The screwdriver slipped, and the plutonium spheres were brought into full contact; the safety wedges provided to prevent such contact also slipped. The presence of Slotin’s hand in a hole as he held the upper sphere inadvertently boosted the reactivity of the assembly (the high water content of flesh makes it an excellent neutron moderator, thereby slowing some of the neutron emissions already present and boosting the reactivity of the assembly). This created a supercritical assembly from which neutron emission immediately increased drastically [14]. There was a blue flash as the surrounding air was ionized by the str...