Insecticidal aerosols are used to repel or kill insects such as mosquitoes, flies, cockroaches, and other common household pests. Their main ingredients usually include insecticides (pyrethroids), adjuvants (stabilizers, preservatives), solvents (unscented gasoline, alcohol or water), propellants, and scents. The common routes of insecticidal spray poisoning are through the respiratory tract, digestive tract, or skin. Under normal condition, only minimally active drugs are distributed systemically and metabolized, and the toxicity is very low.^[1] We reported a case of parasuicide by intravenous self-injection of insecticide spray, which was mainly composed of Es-bioallethrin, dextro-phenyl ether, pyrethrin, odourless kerosene, and propyl butane as a dispersion medium. The active ingredient content was only 0.41%, while the dispersion medium accounted for 99.59%.

Suicide by intravenous injection of pesticide is rare. The clinical manifestations are different from those associated with common poisoning. This study aims to report a case of survival after insecticide spray injection in a teenager with depression, with a good outcome after supportive treatment and corticosteroid therapy.

A 14-year-old boy was admitted to the local hospital due to chest pain, chest tightness, and shortness of breath approximately six hours after intravenous self-injection of insecticide spray. He had a history of depression for half a year without systematic diagnosis or treatment, and had a history of suicide attempts with oral medications for gastric disorders. During infusion treatment due to anxiety, the patient added approximately 5 mL of Gunner brand insecticide in the liquid state, which he purchased by himself, into a syringe that contained 100 mL of 0.9% sodium chloride (the drug composition was unknown) that was released at the infusion rate limit. He recalled that he experienced dizziness, visual disturbance, chest pain (back of sternum, inspiratory pain), chest tightness, shortness of breath, and sweating in the initial 2-3 minutes after injection, but no fever, no cough, or no sputum. After approximately ten minutes, the symptoms of dizziness and visual disturbance were alleviated, but the symptoms of chest pain, chest tightness, and shortness of breath remained. Then, he stopped the infusion himself with approximately two-thirds of the liquid remaining in the infusion bag.

In the emergency room, the patient was conscious, and vital signs revealed blood pressure 132/73 mmHg (1 mmHg=0.133 kPa), body temperature 36.3 °C, and respiratory rate 21 breaths/minute. He had pupils of equal roundness and size and a positive light reflex in both eyes. Neurological and abdominal examinations were normal. Chest computed tomography (CT) scan and electrocardiogram (ECG) findings were normal. Initial and serial laboratory tests revealed normal liver and kidney functions, without electrolyte disorder. Plasma cholinesterase was normal. An arterial blood gas test indicated that oxygen partial pressure was normal. He received oxygen supplementation through a face mask and empirical antibiotics (ceftriaxone) and intravenous fluid at admission. After treatment, the symptoms of chest pain and chest tightness were not alleviated. On day 5, the symptoms of chest tightness and shortness of breath were aggravated, accompanied by irritating dry cough and fever. The highest body temperature was 39.0 °C. After he was treated with antipyretic drugs, the body temperature returned to normal but rose again for less than eight hours. On day 6, laboured breathing sounds existed in both lungs.

On day 8, he was transferred from the local hospital to the emergency department of the Second Hospital of Hebei Medical University, Hebei Province, China. The results of the examinations were: white blood cells (WBCs) 23.6×10⁹/L and neutrophils (NEs) 95.7%. The biochemical results were: high-sensitivity C-reactive protein (hs-CRP) 140.6 mg/L, albumin (ALB) 33.9 g/L, alanine aminotransferase (ALT) 294.0 U/L, aspartate aminotransferase (AST) 96.6 U/L, creatinine (CREA) 57 μmol/L, and procalcitonin (PCT) 9.97 ng/mL. The other results were all normal. The arterial blood gas analysis revealed pH 7.436, partial pressure of carbon dioxide 29.6 mmHg, partial pressure of arterial oxygen 87.4 mmHg, and fraction of inspired O₂ (FiO₂) 49%. ECG findings and serum electrolytes were normal. A chest CT scan revealed thickened interlobular septa, high-density shadows of diffuse patchy infiltration and grids throughout both lungs compatible with noncardiogenic pulmonary edema or chemical pneumonitis progressing to atelectasis and interstitial pneumonia with bilateral pleural thickening. The patient's symptoms of fever, chest tightness, and shortness of breath deteriorated, and the patient was admitted to our intensive care unit (ICU). An anti-infective therapeutic regimen of meropenem replaced the previous cefoperazone-sulbactam. In addition, glucocorticoid (120 mg/d methylprednisolone) was administered intravenously, and budesonide aerosol inhalation therapy and antipyretic drugs were administered when necessary. Twelve days after admission, the patient's pulmonary function was improved but with slightly restrictive syndrome. The symptoms of cough and chest tightness were also improved. The corticosteroid treatment dose was halved. Chest CT showed that interstitial pneumonia and bilateral pleural hypertrophy decreased.

On day 17, creatinine clearance, urinalysis, and hepatic function test results were normal. However, the WBC counts remained high at 10.10×10⁹/L. The patient's chest symptoms were obviously alleviated. On day 21 after admission, the patient had no chest tightness, shortness of breath, chest pain, fever, cough, or sputum. After treatment and at discharge, routine blood, liver function, electrolyte, renal function, procalcitonin, and other indicators were normal. Methylprednisolone tablets (20 mg/d) were provided at discharge, reducing the dosage by one tablet every five days. Chest CT showed that bilateral pulmonary interstitial pneumonia decreased and bilateral pleural hypertrophy slightly reduced. We also consulted with the psychiatry department, and antidepressant drugs along with psychotherapy were provided. The patient was discharged from the hospital with a good outcome. At the three-month follow-up, he had complete recovery confirmed by lung CT examinations.

Numerous commercially available insecticidal spray is commonly used in and around homes, and related illnesses are increasing. The main components of insecticidal spray are deodorized kerosene, probutane, and pyrethroids (the active ingredient).^[2] The toxicity of pesticides may result from oral ingestion, inhalation, or absorption through the skin, which commonly leads to nervous system symptoms and rarely severe lung lesions. Suicide by poisoning with self-injected insecticide has rarely been reported.^[3]

In rare cases, chemical pneumonitis is the most important clinical manifestation, similar to the clinical manifestation of hydrocarbon poisoning by intravenous injection. Cough (70.0%), chest pain (62.5%), dyspnoea (55.0%), and fever (52.5%) were the most common symptoms in hydrocarbon poisoning pneumonitis patients.^[4] Neeld et al^[5] reported the case of a man who intravenously injected himself with 2-6 mL of hydrocarbon insecticide (comprising 0.03% pyrethroid, 99.25% gasoline, and other constituents). Severe pleuritic and abdominal pain developed almost immediately, followed by blurred vision and dry cough. Goldberg et al^[6] reported that a young man developed high fever after intravenous insecticide injection, but the fever did not necessarily indicate a superimposed infection. In our case, the patient developed dizziness, visual disturbance, chest pain, chest tightness, shortness of breath, and sweating in the initial 2-3 minutes after injection, followed by irritating dry cough and fever. These symptoms were similar to the typical symptoms of hydrocarbon poisoning, which supported the theory that the patient's symptoms were mainly caused by the dispersion medium, odourless kerosene, and propyl butane. The lower content of pyrethroids in insecticidal aerosols in our case may cause lung symptoms and lesions through hypersensitivity reactions, which might also be a toxicological mechanism. Chan et al^[7] presented a case of hypersensitivity pneumonitis induced by sustained inhalation of pyrethrin containing insecticidal spray.

The intravenous gasoline may cause lung damage, renal damage, hepatocellular damage, intracellular haemolysis, gastric ulcers, and even sudden death from abrupt cardiac arrest according to the dose.^[8] In our case, the patient had lung injury and mild liver dysfunction without renal dysfunction, which can be explained by the low dose of the spray insecticide injected.

Radiological manifestations, characterized by perihilar infiltration and opacification, may appear within hours after ingestion and commonly involve the right basal and right middle lobes.^[4,9] Hydrocarbons enter the pulmonary circulation from blood, inducing direct toxicity to type II lung pneumocyte,^[10] interfering with gas exchange, leading to interstitial pulmonary edema and severe hypoxemia, and causing chemical pneumonia.^[8]

In the reviewed study, we found that pulmonary lesions remained obvious at two months after discharge.^[4] Lung CT is important for the diagnosis and evaluation of prognosis. In this report, the patient presented with typical characteristics of hydrocarbon chemical pneumonia. There is no specific antidote for hydrocarbon poisoning. Supportive care remains the foundation of treatment. In addition to supportive care, treatments with intravenous antibiotics (92.0%), steroids (57.5%), and bronchoalveolar lavage (BAL) (32.5%) are common therapies.^[10] In the reported case, the patient received adrenal glucocorticoid treatment to inhibit excessive inflammation and promote recovery. As the main detoxification organ, the liver is often affected. Therefore, it is necessary to protect liver function.

Chemical pneumonitis is the clinical manifestation of poisoning after intravenous insecticide injection. The prognosis is good after glucocorticoid treatment.

Funding: None.

Ethical approval: Not needed.

Conflicts of interest: The authors have no conflicts of interest to report.

Contributors: YQA and TKZ contributed equally to this sudy. YQA and TKZ proposed the study and wrote the paper. All authors approved the final version.