Intentional Adulteration of Foods with Chemicals: Snapshot for 2009–2022

Abstract

Global occurrences of the intentional adulteration of food with a chemical toxicant culled from the literature and news reports from 2009 to 2022 were analyzed in terms of their ability to cause mass public health harm. A total of 76 intentional adulteration events that involved over 27 chemicals and 16 foods were identified. The chemicals used included pesticides, rat poisons, illicit drugs, and commercial chemicals. A total of 253 deaths and 4,887 illnesses were attributed to intentional adulteration events; there were deaths in 20% and illnesses in 50% of the events. Intentional adulteration during manufacturing, which accounted for 21 events (28%), resulted in 205 deaths (81%) and 3,572 illnesses (73%). Intentional adulteration at the food preparation node, which accounted for 17 events (22%), resulted in 39 deaths (15%) and 387 illnesses (8%). On-farm intentional adulteration, eight events (10%) resulted in 843 illnesses (17%) and no deaths. The perpetrators who were identified generally had legitimate access to the food, although in 63% of the cases studied, the perpetrator was not identified. Economically motivated adulteration and revenge resulted in over 80% of the deaths and illnesses.

The adulteration of the food supply by terrorists has been threatened, as reported in the news media and online communications (Moore, 2017). Thus, the United States Department of Homeland Security (US DHS) Science and Technology Directorate (S&T) has, for over a decade, executed studies on the viability of such attacks (DHS S&T PANTHR, 2022). The Chemical Security Analysis Center (CSAC), which is one of the DHS S&T national laboratories, has conducted studies on the feasibility and impact of the use of both commercial chemicals and chemical warfare agents to cause terror and mass public health harm to the US population. DHS work includes consideration of the toxicity of chemicals (Cox et al., 2021) and if they will survive the manufacturing processes (Jabbour et al., 2021). This document contains a snapshot of intentional attacks on the food supply with chemicals that have been reported in the press from 2009 until 2022, using articles written in a variety of languages. Major factors analyzed were the type of chemical used, the food contaminated, node of the food supply chain at which the chemical was added, identity of the perpetrator, motivation of perpetrator, number of deaths, number of illnesses, and number of arrests.

Materials and methods

Scope and limitations.

Events that involved the intentional adulteration of food with chemicals in 2008 and prior have been discussed by other authors (Dalziel, 2009; Gossner et al., 2009; Li et al., 2014) and were therefore excluded from this analysis. Also, excluded were home brewing activities and methanol in bottled beverages from commercial establishments, since these events have been covered by other publications, (Manning & Kowalska, 2021) and are often caused by poor manufacturing practices. The use of pesticides for suicide, family murders, and assassinations was also excluded since this topic has been widely covered (Bonvoisin et al., 2020).

The intentional adulteration of milk with detergents, formaldehyde, formalin, soaps, salt, neutralizers, maltodextrin, starch, sugars, hydrogen peroxide, and many other contaminants has been well-documented (Azad & Ahmed, 2016; Salih & Yang, 2017), to the extent that methods of detection for the common adulterants have been developed (Patari et al., 2022; Silva et al., 2021; Luther et al., 2017). The contamination is widespread in some countries; state-enforcement raids and prosecutions of sellers have been reported (WebIndia123, 2018; Mugo, 2016; Muthoni, 2018; Moneycontrol News 2019).

The forced ripening of fruits with calcium carbide, a source of ethylene, which is the fruit-ripening species, often contains arsenic contaminants. This practice has been explicitly banned in some countries, but regulations vary from country to country (Islam et al., 2016; Koros, 2014). There are reports of state enforcement raids on markets to remove fruit that was ripened with calcium carbide, (WebIndia123, 2018; India Today, 2011; Gupta, 2017; Parases, 2020) with prosecutions of the perpetrators. Since this widespread type of fresh fruit adulteration has been documented, it is excluded from this analysis.

Pesticide residues on food are routinely monitored (Pesticides ∣ FDA), and thus, events that involved pesticides on food were excluded. Also excluded were accidental instances of glass, metal, and plastic in food due to accidents during manufacturing, which are primarily food safety events (US FDA). Biological and toxin contamination were excluded. In addition, if intentional adulteration during manufacturing is noticed by producers and the food does not enter commerce, but is destroyed, the event may not be reported in the press, unless someone is arrested. A list of the excluded events and a comparison to included events is shown in Table 1.

Table 1.

Types of events that were excluded from the analysis

Excluded Events	Included Events
Murder, suicide, and assassinations–targeting of specific individuals by a relative, neighbor, or acquaintance	Intentional contamination of food given to several coworkers, poisoning a common coffee pot
Methanol in bottled beverages*	Intentional contamination of beverages with pesticides
Economically motivated adulteration of milk*	Intentional contamination of milk with pesticides
Pesticide residues on food*	Toxic quantities of pesticides intentionally put into a food, not associated with farming practices
Glass and metal shard from manufacturing*	Glass and needles that are intentionally put into food (often via tampering at the retail level)
Forced ripening of fruit with calcium carbide, a form of EMA*

^*Food safety concern, regulated and monitored in many countries.

Intentional poisonings using pesticides in a manner that was outside of traditional food safety considerations, and poisonings in nonfamilial situations, such as in the workplace, restaurants, and schools, were included. Instances of illicit drugs being packaged in food, beverage, and candy packaging were also included.

An additional goal of this document is to find accidents, scenarios, and events that could be used as models for intentional adulteration with the intent to cause public health harm. The intention of economically motivated adulteration (EMA) is for the perpetrator to benefit economically by selling a substandard product at a higher price than it is worth in a manner that is not intended to cause harm. Events in which illness or death was caused by EMA, but not those that involved only economic harm, are included in this study. The intentional addition of melamine to milk was an egregious example of EMA that had very serious human health effects (Gossner et al., 2009); this large event occurred before the date range of this report, but it is worth noting as an example. Cross-contamination events that had negative human health consequences were included, since these show potential vulnerabilities and scenarios by which the food supply could be attacked. These events showed how a third party could contaminate an ingredient or nonfood part of the supply chain (such as sanitizers) and thereby cause harm. The intentional adulteration of food with particulate materials was included, although processing-related accidental contamination with particulate materials was excluded.

Data collection.

Food adulteration and other chemical-related news events have been collected by the DHS S&T CSAC since 2016 using a Google search methodology, and select events are disseminated in the CSAC Chemical Daily News Report (CSAC, 2022). In addition, relevant events from the daily electronic publication Food Safety News (Food Safety News, 2021) were recorded. There were fewer reports from New Zealand, Australia, the Middle East, and Africa than from the other regions – this may be partially due to the number of newspapers and journal articles that have sufficient details from these locations. The search method used does translate articles from a variety of languages. The data were thus biased by the ability to collect reports, and by the fact that the process of collection at CSAC was improved in 2016 and was not retroactively applied.

The circumstances of the event, the chemical used, and the number of people affected were recorded; events that did not report this information were not used. Intent was inferred from the article whenever possible; in many cases, the intent of the perpetrator was unknown, but in some cases, arrests were made. The scope of this list of events contrasts with the U. S. Food and Drug Administration (FDA) records (US FDA, 2022a,b,c) which show that most recalls, incidents, or reports were for bacterial contamination or foreign matter (plastic, metal, wood); pesticides (above the limit or banned in the US) were occasionally found, as were heavy metals, such as lead and cadmium. The list includes 12 of the events in the Bashura and Lieb (2022) article.

Results and discussion

Seventy-six intentional food adulteration events that met the criteria were analyzed in terms of the category of food contaminated, chemical used, chemical motivation of perpetrator, node of contamination, node of consumption, identity of perpetrator, and country/continent.

Variety of foods that were intentionally adulterated.

The adulterated foods were categorized into 16 groups; nondairy beverages were the most adulterated item (20 events, 26%), followed by meals (14 events, 16%), meats (9 events, 11%), milk, and dry foods (5 events each, 7%) Table 2).

Table 2.

Categories of adulterated foods

Type of Adulterated Foods	Number of Events
Nondairy beverage	20
Meal	14
Meats	9
Milk	5
Dry food (e.g., chips, cereal)	5
Raw fruit and vegetables	4
Cans (e.g., peas, beer)	4
Cake or bread	3
Candy	3
Fake seasonings	2
Dog food	2
Baby food	1
Cheese	1
Dietary pills	1
Fish	1
Vinegar	1
TOTAL	76

Identity of chemical adulterants.

A total of 27 chemicals were named in the reports; however, the specific chemical identities of pesticides, rat poisons, and cleaners were often not given. The chemicals that were readily commercially available were the most often used for intentional adulteration, accounting for 22 events, 29% of the total, in comparison to the CFATS-regulated chemicals, which were used in only two events, 2.6% of the total (Table 3). Illicit drugs were used in 18 events (24%), 12 of which involved the use of deceptive packaging, e.g., counterfeit candy wrappers used for fentanyl (Table 3). Pesticides accounted for 11 events (14%, Table 3). The chemicals used were relatively easy for people to procure; other readily available adulterants used were rat poison, prescription drugs, sand, dirt, and urine. Chemical warfare agents were not identified in any cases.

Table 3.

Chemicals used in intentional adulteration events

Type of Chemical	Specific Chemical	Number of Events
Commercial	cleaner, nitrite, nitrate, paint, antifreeze, bleach, thallium, lead acetate, hydroxylamine sulfate, calcium carbide, furniture polish, oleoresin capsicum, 2,4-dinitrophenol,	22
Illicit drug	MDMA, THC, marijuana, cannabinoid, opium, fentanyl, cocaine, methamphetamine	18
Pesticide	ethylene oxide, monocrotophos, methomyl, unspecified	11
Rat poison	1,080, brodifacoum, tetramine, unspecified	9
Rx drug	ractopamine, clenbuterol, Viagra®, phenobarbital	7
CFATS	formaldehyde, hydrogen peroxide, cyanide	2
Particulate	soil, sand, dirt, needles	3
Urine	Urine	2
Unidentified	Unidentified	1
Herbicide	Paraquat	1

The oral human LD₅₀ toxicity estimate for the chemicals used ranged from fentanyl (~0.03 mg/kg, US DEA) to strychnine (1.5–2 mg/kg, CDC) to methomyl (~25 mg/kg, Pope, 2005) to ethylene glycol (1,560 mg/kg, Fisher). Illnesses and deaths occurred for chemicals that spanned the full range of toxicity, since the total dose depends on the quantity of the chemical consumed, and when the chemical is tasteless, lethal quantities may easily be consumed.

The chemicals in the reports were binned into six groups: pesticides & herbicides; rat poisons; illicit drugs; prescription drugs; commercial & CFATS chemicals, including cleaners; urine, particulate, and unknown. Many foods were adulterated with a variety of chemicals (Fig. 1). In addition to the foods shown in Figure 1, there were two instances of dog food that was adulterated with phenobarbital, one instance of baby food jars adulterated with the commercial compound ethylene glycol, one instance of vinegar adulterated with pesticides, and four instances of canned food that contained illicit drugs.

Figure 1.

Heatmap of chemical adulterants found in various foods.

Node of consumption.

The node of consumption was binned into five categories – “Food prep”, “Grocery, store, immediate”, “Not eaten”, “Home meal”, and “School/Work common area (SWCA)” (Table 4). “Food prep” is the name given to situations in which food was prepared by a chef or cook at a restaurant, school, prison, or other catered event. Intentional adulterations in “Food prep” situations accounted for 23 events (30%). “Grocery, store, immediate” is the category for situations in which a person purchases a prepackaged food and consumes it immediately; candy and beverages fall into this category, which accounted for 23 events (30%). SWCA is the scenario in which workers or students store their lunches in a common fridge, or eat food brought in by one worker. In some cases, a person who has access to the fridge will intentionally adulterate the food brought in by colleagues. There were six SWCA events (8%). In 18 events (24%) labeled “Not eaten” there was something about the food that made the potential consumer suspicious, or, in the case of concealed drugs, the item was intercepted by law enforcement. There were six events (8%) in which consumption occurred at a home-cooked meal eaten by the family. Thus, the adulterated food was consumed in 76% of the events.

Table 4.

Comparison of node of contamination with node of consumption

				Node of Consumption – Number of Events
Node of contamination	Number of Deaths	Number of Illnesses	Number of Arrests	Food prep	Grocery or Store, Immediate	Not eaten	Home meal	SWCAa	TOTAL
Manufacture	205	3,572	33	2	13	5	1	0	21
Food prep	39	387	50	15	0	1	1	0	17
Deceptive pkg	2	16	6	1	4	7	0	0	12
On farm	0	843	130	3	1	1	3	0	8
Tampered	6	20	6	1	5	2	0	0	8
SWCA	1	45	2	0	0	1	0	6	7
Grocery & store	0	0	1	1	0	1	0	0	2
At home	0	4	3	0	0	0	1	0	1
Total	253	4,887	231	23	23	18	6	6	76

^aSWCA = school or work common area.

Node of contamination.

The node of contamination was binned into eight categories (Table 4). The most common node was during manufacture (21 events, 28%), followed by “Food prep” (17 events, 22%) and deceptive packaging for illicit drugs (12 events, 16%). Other nodes of contamination were on farm (8 events, 11%), and tampered, which were situations in which someone obtained packaged food, took it home, and then put it in a location where someone else would purchase and consume it (8 events, 11%), SWCA (7 events, 9%), in groceries and stores, and lastly, at home (Table 4). Deaths only occurred due to contamination at four nodes: manufacture, 205 deaths; food prep 39 deaths, deceptive packaging, 2 deaths and SWCA, 1 death (Table 4).

Human health consequences – Node of contamination and node of consumption.

A total of 39 of the 76 events (51%) had at least one death or illness; 15 of 76 (20%) of the events had at least one death, for a total of 253 deaths (Table 4). When the five nodes of consumption were compared with the eight nodes of contamination, similar events that had five or more occurrences emerged. When the food was contaminated during manufacture, in 16 of 21 events, it was eaten, resulting in a total of 205 deaths and 3,572 illnesses, the highest totals of all the nodes; in 5 of 21 events, it was not eaten at all. In cases where the node of contamination was in manufacture and the node of consumption was soon after purchase, there were 143 deaths from a single event in India (BBC News, 2011) and 11 deaths at another event in China (The Guardian, 2011). One event in Pakistan in which food was prepared at a factory and then eaten had 34 deaths (Ary News, 2016). Another event in Africa in which a low-cost, fraudulent ingredient was used during manufacture had 10 deaths (Bala et al., 2022; Afro News, 2021).

When food prepared by a cook (food prep) was contaminated, it was consumed in 15 of 17 contamination events, accounting for 39 deaths and 387 illnesses. On-farm contamination occurred in eight events; in 5 of 8, the food was eaten, accounting for 843 illnesses but no deaths. Drugs that were disguised in deceptive packaging, presumably by a drug dealer, were consumed in 5 of 12 events, and not eaten (sometimes intercepted) in seven events. Tampering with food resulted in consumption in 6 of 8 events, and adulteration of food in SWCA resulted in consumption in 6 of 7 events (Table 4).

Identity and motivation of perpetrator.

Employees were the perpetrators in 20 events (26%), and other corporate personnel, such as owners, were the perpetrators in 15 events (20%). The perpetrator was unknown in 11 events (15%) and a drug dealer (presumed) in 11 events (15%) (Table 5). The motivation of the perpetrator was unknown in 18 events (24%), EMA in 14 events (18%), drug trafficking in 12 events (16%), and revenge in 10 events (13%, Table 5). A few trends were noted: 12 of the 14 EMA events were done (or directed) by corporate owners, and drug dealers were presumed responsible for 11 of 12 cases of hiding drugs in food packaging. Employees and acquaintances accounted for 7 and 3 of the 10 revenge events, respectively. Employees also contaminated food for unknown reasons, accounting for 7 of 20 employee events and 7 of 18 unknown motivation events (Table 5).

Table 5.

Identity of perpetrator compared to the motivation of perpetrator

				Motivation of Perpetrator – Number of Events
Perpetrator	No. of Deaths	No. of Illnesses	No. of Arrests	Accident	Cross Contamination	Drug traffic	EMAa	Extort	Insanity	Intentional	Revenge	Unknown	Total
Employee	58	2,991	59	2	1		1	1		1	7	7	20
Corporate	164	1,504	148	1	1	1	12					0	15
Drug dealer	2	16	6	0	0	11							11
Unknown	1	68	0	1	0				1	1		8	11
Acquaintance	24	281	11	0	0					3	3	2	8
Criminal	0	11	7	0	0		1	2	2	3		1	9
Bioaccumulate	0	3	0	1	0								1
Accidental	4	13	0	1	0								1
Total	253	4,887	231	6	2	12	14	3	3	8	10	18	76

^aEMA = economically motivated adulteration.

Human health consequences – Perpetrator.

EMA events accounted for 153 deaths, and revenge accounted for 53 deaths (Table 6). The largest number of illnesses in one event, 2,800, was due to a revenge event in Asia (Table 6) that used a pesticide (Table 7). Overall, 43% of the events had an illness, for a total of 4,887. Revenge accounted for a total of 3,081 illnesses, EMA accounted for 1,384, and cross-contamination accounted for 167. The largest number of people arrested for one event was 114 in China for EMA. Overall, 35 (46%) of the events had an arrest, for a total of 231 people arrested (there were 6 events that had an arrest but no illness; 225 arrests in Table 6 are only for the events that had a human health consequence). EMA accounted for 183 arrests, and revenge accounted for 22.

Table 6.

Human health consequences by motivation of perpetrator and geographical region

			Maximum in one event			Total for all events
Motivation	Geographical Region	Number of Events	Dead	Ill	Arrested	Dead	Ill	Arrested
Accident	Latin America	1	4	13	0	4	13	0
Accident	NZ & AUS	1	0	3	0	0	3	0
Accident	USA	3	0	1	0	0	1	0
Cross Contamination	China	1	11	120	0	11	120	0
Cross Contamination	Asia	1	23	47	1	23	47	1
Drug trafficking	Europe	1	1	13	0	1	13	0
Drug trafficking	Latin America	7	1	1	3	1	1	6
Drug trafficking	USA	4	0	2	0	0	2	0
EMA	Africa	1	10	400	3	10	400	3
EMA	China	6	0	286	114	0	286	170
EMA	Latin America	2	0	500	0	0	554	0
EMA	Asia	4	143	144	10	143	144	10
Insanity	Europe	2	0	7	1	0	10	1
Intentional	Africa	1	3	7	1	3	7	1
Intentional	China	1	2	0	2	2	0	2
Intentional	Europe	1	0	32	1	0	32	1
Intentional	NZ & AUS	1	0	1	0	0	1	0
Intentional	USA	3	0	12	2	0	20	3
Revenge	China	2	3	76	1	5	112	2
Revenge	Middle East	1	0	4	3	0	4	3
Revenge	Asia	4	34	2,800	9	48	2,916	13
Revenge	USA	3	0	48	2	0	49	4
Unknown	China	1	0	23	1	0	23	1
Unknown	Europe	4	1	25	1	1	27	1
Unknown	Latin America	1	1	9	0	1	9	0
Unknown	Asia	1	0	5	0	0	5	0
Unknown	USA	10	0	45	1	0	88	3
	Total	76	–	–	–	253	4,887	225

Table 7.

Number of deaths due to food adulteration with chemicals by geographical area and year

Type of Chemical	Africa	China	Europe	Latin America	Asia	Total
Pesticide	3 (2015)				214a	217
Commercial	10 (2021)	14 (2011, 2011)	1 (2018)	4 (2020)		28
Rat poison		4 (2013, 2014)				4
Illicit drug			1 (2022)	2 (2017, 2017)		3

NOTE: There were no deaths in the Middle East, USA, New Zealand, or Australia. There were no deaths due to CFATS, herbicide, particulate, prescription drug, urine, or unidentified chemicals.

^aThe pesticide deaths in Asia were 143 in 2011; 23 in 2013; 34 in 2016, and 14 in 2018.

Human health consequences – Chemical used.

Pesticides caused 217 deaths in 5 events; 214 of these deaths were in Asia. Commercial chemicals (not CFATS) caused 28 deaths in 5 events; rat poisons caused 4 deaths in two events and illicit drugs caused 3 deaths in 3 events in two different geographical areas (Table 7). The chemicals that caused the most illnesses were pesticides, accounting for 3,166 people, with 3,107 in Asia and 48 in the US; prescription drugs, accounting for 840 people, with 286 in China and 554 in Latin America; commercial chemicals (not CFATS), accounting for 654 people in six areas, the largest were in Africa (400) and China (179); rat poisons, accounting for 141 people in 4 geographical areas, and illicit drugs, 82 accounting for people in 3 geographical areas, with 59 in the US (Table 8). The country that had the greatest number of events reported between 2009 and July 2022 was the U.S., with 25; China, Europe, and Latin America each had 11 events, and there were 12 events in Asia (Table 9). There were three or fewer reports from Africa, the Middle East, New Zealand, and Australia. The reports from Latin America began in 2017 and have been consistent since then.

Table 8.

Number of illnesses due to food adulteration: chemicals used by geographical area

Type of Chemical	Africa	China	Europe	Latin America	Middle East	New Zealand & Australia	Asia	USA	Total
Pesticide	7				4		3,107	48	3,166
Rx drug		286		554					840
Commercial	400	179	41	13			5	16	654
Rat poison		76	25			3		37	141
Illicit drug			13	10				59	82
Unidentified			3						3
Particulate						1			1

NOTE: There were no illnesses due to CFATS, herbicide, urine, or unidentified chemicals.

Table 9.

Number of events and illnesses reported by geographical area and year.

Year	Africa		China		Europe		Latin America		Middle East		NZ & Austr		Asia		USA
	Events	Ill	Events	Ill	Events	Ill	Events	Ill	Events	Ill	Events	Ill	Events	Ill	Events	Ill
2009															2	54
2011			4	442					1	4			2	149
2013			1		1	25							2	2,847
2014			1	76	2	32									1
2015	1	7													3	82
2016			1		1								1	14	2
2017	1		2		2		4	10			1	3	3		2	1
2018					1	2	1				1	1	3	102	4
2019			1	23			3								1
2020					1	3	2	67					1		2	8
2021	1	400			1	7									3	2
2022			1		2	13	1	500							5	13
Total	3	407	11	541	11	82	11	577	1	4	2	4	12	3,112	25	160

Conclusions

It was observed that more than 27 different chemicals were used in the 76 intentional adulteration events that were studied; the major factor in the choice of chemical seemed to be convenient access to the chemical. Pesticides, rodenticides, illicit drugs, prescription drugs, and commercial chemicals were all used. Pesticide usage occurred mostly in Asia, illicit drugs concealed in food were prevalent in Latin America, commercial chemicals were used in almost all locales, and the US had the widest variety of chemicals used.

The list of food defense events collected by Dalziel (2009) included biological and radiological incidents and homicides, which were excluded from this analysis. Dalziel noted that 75% of the cases involved.

“a relative, neighbour, acquaintance or co-worker attempting to harm a specific individual by contaminating food or beverages.”

Dalziel identified 85 retail and food service node cases plus 263 consumer and home cases; upon removal of the attacks by relatives, neighbors, and acquaintances, which would align the data with the CSAC criteria, mostly food service and retail node cases remain. Dalziel (2009) concluded that 98% of the intentional adulteration events occurred later in the food supply chain – nearest to the consumer, and that intentional adulteration that occurred at the food service point had the greatest impact on public health.

In this study, contamination of food that was intended to harm one or two specific individuals was excluded, since in these situations, the general public was not at risk. Therefore, the results of this study are different from Dalziel, in large part because of the choice of which type of events to include or exclude. Intentional adulteration at the manufacturing and food preparation nodes, which accounted for 50% of the events, resulted in over 95% of the deaths and over 80% of the illnesses. On-farm intentional adulteration (10% of the events) resulted in 17% of the illnesses. In this study, intentional adulteration at the food prep node did cause 15% of the deaths and 8% of the illnesses, but intentional adulteration at the manufacturing node caused 81% of all deaths and 73% of all illnesses.