Homemade Chemical Bomb Incidents Increasing and Prevalent in Summer

Homemade chemical bombs (HCBs) are explosives made from readily available chemicals, and instructions for making them are accessible on the Internet. The volume of news reports of HCB explosions suggests they are not uncommon. To determine the number of events involving HCBs in the United States and describe the factors associated with them, the Agency for Toxic Substances and Disease Registry (ATSDR) analyzed data from its surveillance system that tracks spills and leaks of hazardous substances.


During 2003 to 2011, a total of 134 events involving HCBs were reported from 15 states. Among those events, 21 (16%) resulted in adverse health effects (i.e., respiratory symptoms, burns, and skin irritation) for 53 persons. The majority (35 [66%]) of these persons were youths. HCBs are hazardous and especially dangerous if detonated in public areas. Increasing awareness of HCBs and their dangers (particularly during summer months) among first-responders, parents, school staff members and others who work with youths might help reduce injuries associated with HCBs.


Typically, HCB ingredients are combined in a container, such as a soft drink bottle, which is then sealed and shaken. HCBs explode when the pressure from gases produced by the chemical reaction ruptures the container. The resulting explosion can be unpredictable in both timing and magnitude. Potential hazards include exposure to the blast, shrapnel, and hazardous substances. This report uses data from the ATSDR Hazardous Substances Emergency Events Surveillance (HSEES) system and the National Toxic Substance Incidents Program (NTSIP), which replaced HSEES in 2010, and updates a previous report. ATSDR has maintained a state-based surveillance program since 1990. The purpose of these surveillance systems is to track the public health consequences (e.g., morbidity and mortality) from acute toxic substance releases.


Incident records from states that participated in the surveillance program for at least 3 years during 2003 to 2011 were searched for the keywords "bottle," "bomb," or "homemade" in database fields that contain a synopsis of the event and health department comments. The resulting records were then reviewed, and those containing the keywords but not involving an HCB were excluded. Exclusions included events involving pesticide "bug bombs" or chemical bottles inadvertently broken during shipping. Events involving commercial or other, improvised explosives (e.g., pipe bombs) also were excluded.


For the period January 1996 to March 2003, ATSDR reported 29 events involving HCBs. Standardized by state-surveillance year, the rate of HCB events in that report was 0.21 (29 events per 137 state-years). In the present report, that rate was 1.26 (134 events per 106 state-years), suggesting an increase in HCB events. This increase might be the result of greater availability of materials and Internet instructions for making HCBs, the ease with which they are made, and copycatting inspired by other incidents. However, improved HSEES/NTSIP event ascertainment also might have contributed to this increase.


These data indicate that the majority of HCB-injured persons were youths or young adults. Consequently, it is important for parents, school staff members, and law enforcement to be aware of the potential hazards of HCBs and how to respond if an HCB is found. If a suspected or actual HCB is discovered, the surrounding area should be isolated until the situation is assessed by authorities. Only trained bomb squad personnel should approach, handle, or attempt to neutralize these devices. Persons whose clothing is contaminated with the contents of a bomb, whether as a result of the container bursting or from leakage, should remove contaminated clothing immediately. If the contents of a bomb come in contact with skin, the affected area should be rinsed with large amounts of water for 3 to 5 minutes. If severe adverse health effects (e.g., trauma, chemical burns, or respiratory irritation) occur, medical attention should be sought immediately.


The following are three illustrative case reports on HCB incidents with injuries.

  • A high school janitor found students mixing calcium hypochlorite and other chemicals in a bottle. The janitor seized the bottle, which exploded, releasing chlorine gas. The janitor became ill and vomited, and 12 students and three school workers were treated for respiratory problems. Approximately 1,640 persons were evacuated for 5 hours while a hazardous materials team cleaned and ventilated the school.
  • Two adults were preparing an HCB from hydrochloric acid and aluminum when it prematurely exploded. First responders found one adult unconscious, and both adults sustained physical trauma, respiratory symptoms, and chemical burns. They were treated at a local hospital.
  • An adult picked up an HCB he found outside his home. Without warning, the HCB exploded in his hand. The man sustained trauma and chemical burns to his hand and chest.


The proportion of HCB events resulting in adverse health effects was 45% greater than that of all other HSEES/NTSIP events during the same period (16% versus 11%). The majority of injured persons were male (29 [55%]); eight (15%) were female, and sex was unknown for 16 (30%). Thirty-five injured persons (66%) were youths; 17 (32%) were adults, and age was unknown for one. Twenty-one injured persons (40%) were students at school; 20 (38%) were members of the public; seven (13%) were employees at the site of the incident, and five (9%) were police officers.


Several injured persons reported more than one adverse health effect; the total number of reported adverse health effects was 62. Respiratory symptoms were most common (26 [42%]), followed by burns (14 [23%]), skin irritation (13 [21%]), and physical trauma (six [10%]). A total of 29 injured persons (55%) were treated on the scene. Fifteen (28%) were treated at the hospital and released; five (9%) were treated at the hospital and admitted; three (6%) had untreated injuries; and treatment data were missing for one. Among all 53 injured persons, 21 (40%) required decontamination at the scene or at a medical facility. No fatalities occurred in any of these events. In two events, first responders who were not injured (eight and four, respectively) were decontaminated at the scene.


The most common chemicals in these events were acids or bases mixed with a metal. Commercial household products, such as toilet bowl cleaners containing sulfuric or hydrochloric acid or drain openers containing sodium hydroxide or potassium hydroxide, were the most common sources of acids and bases. Aluminum was the most common metal. One event involved carbon dioxide (i.e., dry ice) as the main bomb ingredient.


Most HCB explosions were reported in schools, mail boxes, and residential backyards. Facility evacuations ordered by an official occurred in 17 (13%) of the 134 events. Some evacuations resulted in significant disruptions; four events, all in schools, involved evacuations of 600 or more persons for up to 8 hours.


A total of 48 events (36%) occurred within a quarter mile of a school. Summer was the season with the greatest number of events 49 [37%]), followed by fall (34 [25%]), spring (28 [21%]), and winter (23 [17%]).


The findings in this report are subject to at least three limitations. First, searching the HSEES/NTSIP databases might not capture all events involving HCBs. Second, variability in the number of HCB incidents by state might be explained by differences in state surveillance sources or by copycatting inspired by other incidents. Finally, the number of participating states is limited, and their data might not be representative of the entire United States.


See the CDC Report