NIOSH Evaluation of Health Hazards in a Crime Lab
Written by Kenneth Fent, PhD and Maureen T. Niemeier, BBA   

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A QUICK INTRODUCTION: The National Institute for Occupational Safety and Health (NIOSH)—part of the Centers for Disease


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Control and Prevention (CDC)—conducts research and makes recommendations for the prevention of work-related injury and illness. The NIOSH Health Hazard Evaluation (HHE) program is available to employees, employers, or union representatives who ask our comprehensive team of experts for an investigation of their health and safety concerns. Our team contacts the requestor of the HHE and discusses the problems and how to solve them. This may result in sending the requestor information, referring them to a more appropriate agency, or making a site visit (that may include environmental sampling and medical testing). If we make a site visit, the result is a report of our investigation that includes recommendations on how to improve work conditions and minimize any health hazards. (Note: For more information on the NIOSH HHE program, see “Resources and Links” at the end of this article.)

Police Department Crime Lab HHE

We received a request for an HHE from managers of a police department crime lab to address concerns about cancer among current and former employees; five crime-lab employees had cancer.

Managers were also concerned about indoor environmental quality (IEQ), adequacy of the ventilation systems, chemical exposures encountered during criminal-investigation procedures, and effectiveness of the engineering controls at minimizing chemical exposures in the crime lab.

The police department consisted of 101 employees at the time of our investigation; 16 worked in the crime lab (14 criminalists who processed evidence and two supervisory investigators). A total of 47 officers have worked in the crime lab since its inception.

We reviewed and verified medical and work-history information for employees reported to have cancer. We evaluated the performance of the local exhaust ventilation (LEV) systems in the crime lab and the heating, ventilating, and air-conditioning (HVAC) system throughout the building. The LEV systems we evaluated included a fingerprint powder downdraft table (Figure 1), two superglue fuming chambers (including the small chamber in Figure 2), a chemical fume hood, and two overhead exhaust hoods. Our investigation also included area air sampling in the locations adjacent to the crime lab and photo-processing lab to evaluate how chemicals used in these locations move throughout the building. We collected air samples for ethyl acetate during ninhydrin spraying, ethyl cyanoacrylate during superglue fuming, carbon black during fingerprint-powder application (Figure 3), ammonia and sulfur dioxide during photo-processing, and hydrogen peroxide during luminol spraying. Finally, we interviewed employees about their symptoms and work-related health concerns. Eight of the 13 employees we interviewed had respiratory, neurological, or mucous membrane symptoms they believed were work-related.

Carbon black in fingerprint powder was used regularly by the crime-lab employees. Breathing in this chemical (and other insoluble particles) can irritate the respiratory system. It is listed by the International Agency for Research on Cancer (IARC) as a possible human carcinogen (cause of cancer), but NIOSH considers it carcinogenic only if it contains more than 0.1% polyaromatic hydrocarbons (PAHs). The carbon black used in the fingerprint powders did not contain measurable PAHs, and personal exposures to carbon black and all other chemicals we evaluated were below applicable occupational exposure limits (OELs).

The different types of cancers among the five crime-lab employees reported to have cancer did not appear unusual (lung adenocarcinoma, bile-duct cholangiocarcinoma, multiple myeloma, melanoma, and non-Hodgkin lymphoma). Furthermore, the different types of cancer did not suggest a common workplace exposure, and we did not identify any exposures to known carcinogens other than tobacco smoke (four of the five employees reported to have cancer were smokers). Therefore, we did not recommend any further investigation of cancer among crime-lab employees. We advised management to encourage employees to learn about known cancer risk factors, measures to reduce their risk for preventable cancers, and cancer-screening programs.

Although personal air sampling did not identify any chemicals used in the crime lab that were over OELs, we identified areas where changes could be made to improve the overall work conditions and IEQ. First, the air pressure between different locations in the building must be properly controlled to eliminate movement of nuisance odors and contaminants. This means controlling how much air is supplied to an area compared to how much air is removed from the area. If more air is supplied to an area than is exhausted, the area is under “positive pressure.” We determined that the crime lab, photo-processing lab, and bathrooms on the fourth and fifth floors were under positive pressure, which could potentially cause contaminants and nuisance odors generated in these areas to move to other areas of the building. For example, area air-sampling results showed that ethyl acetate was migrating from the crime lab to other areas of the building.

Our evaluation identified a number of problems with the design and function of the HVAC and LEV systems. Several air filters were in need of replacement (Figure 4). Also, the build-up of carbon dioxide exhaled by occupants suggested there was not enough outdoor air being delivered to the office areas during peak occupancy. We observed that the overhead exhaust hoods in the crime lab and darkroom shared the same ductwork, which could potentially pull contaminants from one room and deposit them in the other room. Since the evidence room did not have a dedicated exhaust system, the smell of marijuana stored in it was strong outside of the room. In addition, we found that employees were being exposed to ethyl cyanoacrylate vapors (a chemical in superglue) due to poor ventilation design and maintenance of superglue fuming chambers. These vapors can irritate the respiratory system and mucous membranes.

General Recommendations for Crime-Lab Management and Workers

We provided a list of recommendations to the police department to improve the overall work conditions in the crime lab and IEQ in the building. This list is summarized below and may be applicable to other crime labs and police departments.

Ventilation

  • Consult a ventilation specialist to evaluate your facility’s HVAC and LEV systems (chemical fume hood, etc.) if these systems do not appear to be working optimally. In particular, the chemical fume hood should be tested and certified annually.
  • Replace air filters in the HVAC and LEV systems routinely. Consult manufacturer specifications for guidelines. The manufacturer of the high-efficiency filter in the fingerprint downdraft table at this crime lab recommends replacement of the filter every four to six months in a busy lab. The pressure gauge can also be used to determine when the filter should be replaced.
  • Maintain rooms with potential sources of contaminants or nuisance odors under negative pressure relative to adjacent areas, and consider installing a dedicated exhaust system in such areas to control odors. A room is under negative pressure when more air is exhausted from it than is supplied to it, which causes air from adjacent areas to flow into the room. For guidance on appropriate exhaust rates, consult the 2007 (or the most recent edition) of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) Standard 62.1, and the “Laboratories” chapter of the ASHRAE Handbook: HVAC Applications.
  • Install separate ductwork for each overhead exhaust hood. If two hoods share ductwork, cap or remove one hood or operate both hoods at the same time. (Note: Overhead exhaust hoods should not be used for fingerprint powder application as the upward airflow could draw the dust into the employee’s personal breathing zone.)
  • Consider installing superglue fuming chambers with safety features such as: locks that can’t be opened during use until the chamber is fully evacuated; exhaust systems that vent to the outdoors and/or contain organic vapor filtration systems; a laboratory-determined filter change-out schedule based on the number of cycles or an end of service life indicator; and counters that display the number of cycles run since the filters were last changed.

Work Practices and Policies

  • Reduce exposures to chemicals by only handling them under a chemical fume hood. Evidence sprayed with ninhydrin solution should be allowed to dry completely before being placed into the development cabinet.
  • Operate the chemical fume hood with the sash at half-opened height to improve its performance. Consider marking the half-opened height to serve as a reminder.
  • Develop a written crime-lab health and safety plan describing workplace hazards, listing standard operating procedures, engineering controls, and PPE for each method used to process evidence. Refer to the International Association for Identification’s Safety Guidelines and the Federal Bureau of Investigation’s Handbook of Forensic Services.
  • Organize a health and safety committee consisting of management and employee representatives who meet regularly to address health and safety concerns and update the laboratory health and safety plan.

Personal Protective Equipment

  • Use appropriate personal protective equipment (PPE)—including gloves, chemical-resistant clothing, safety glasses, or goggles—for all criminal-investigation procedures, especially when working with chemicals and powders that have the potential to contact the skin or eyes. Consult a reference guide to determine the appropriate PPE for the chemicals at your facility.
  • Provide N95 filtering facepiece respirators for voluntary use when applying fingerprint powder. Inhalation of poorly soluble particles (such as carbon black in fingerprint powder) can be irritating to the respiratory system. N95 filtering facepiece respirators, when fitted and worn properly, will help reduce the amount of inhaled particles. Although a written respiratory protection program is not mandatory for voluntary respirator use, provide employees with a copy of Appendix D, “Information for Employees Using Respirators When Not Required Under the Standard,” of the OSHA Respiratory Protection Standard [29 CFR 1910.134].

Acknowledgements

The authors would like to acknowledge the contribution of Dr. Anthony Almazan in the assessment of health symptoms among the former and current crime-lab employees. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Resources and Links

NIOSH HHE program information

American Cancer Society website

National Cancer Institute website

NIOSH occupational cancer and cancer cluster investigations topic page

About the Authors

Dr. Kenneth Fent is a National Institute for Occupational Safety and Health (NIOSH) employee.

Maureen Niemeier is a freelance technical writer.

 
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