Occupational disease hazards in plywood manufacturing mainly include wood dust, formaldehyde, phenol, ammonia, noise, terpene, microorganisms, etc. The exposure is complex with multiple factors accompanied or coexisted. In the production process, these factors are exceeded, and mass occupational disease hazard events occurred among workers. Exposure to wood dust, formaldehyde, terpene, etc., put workers at increased risk of cancer. This article provides a review of this issue in order to provide a scientific basis for the prevention and control of occupational disease hazards in plywood manufacturing.
Humans ; Wood/chemistry* ; Occupational Diseases/chemically induced* ; Formaldehyde/adverse effects* ; Terpenes ; Dust ; Occupational Exposure/adverse effects*

Recent studies have shown that the chemokine receptor CXCR3 and its ligand CXCL10 in the dorsal root ganglion mediate itch in experimental allergic contact dermatitis (ACD). CXCR3 in the spinal cord also contributes to the maintenance of neuropathic pain. However, whether spinal CXCR3 is involved in acute or chronic itch remains unclear. Here, we report that Cxcr3 mice showed normal scratching in acute itch models but reduced scratching in chronic itch models of dry skin and ACD. In contrast, both formalin-induced acute pain and complete Freund's adjuvant-induced chronic inflammatory pain were reduced in Cxcr3 mice. In addition, the expression of CXCR3 and CXCL10 was increased in the spinal cord in the dry skin model induced by acetone and diethyl ether followed by water (AEW). Intrathecal injection of a CXCR3 antagonist alleviated AEW-induced itch. Furthermore, touch-elicited itch (alloknesis) after compound 48/80 or AEW treatment was suppressed in Cxcr3 mice. Finally, AEW-induced astrocyte activation was inhibited in Cxcr3 mice. Taken together, these data suggest that spinal CXCR3 mediates chronic itch and alloknesis, and targeting CXCR3 may provide effective treatment for chronic pruritus.
Acetamides ; therapeutic use ; Animals ; Chemokine CXCL10 ; metabolism ; Chloroquine ; toxicity ; Chronic Disease ; Cyclopropanes ; adverse effects ; Dehydration ; complications ; Dinitrofluorobenzene ; adverse effects ; Disease Models, Animal ; Formaldehyde ; toxicity ; Freund's Adjuvant ; toxicity ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Motor Activity ; drug effects ; Pain ; chemically induced ; Pruritus ; chemically induced ; pathology ; Pyrimidines ; therapeutic use ; Receptors, CXCR3 ; antagonists & inhibitors ; genetics ; metabolism ; Skin ; pathology ; Spinal Cord ; drug effects ; metabolism ; pathology ; Time Factors ; p-Methoxy-N-methylphenethylamine ; toxicity

Although formaldehyde is well known to cause type 4 hypersensitivity, immunoglobulin E (IgE)-mediated hypersensitivity to formaldehyde is rare. Here, we report a case of recurrent generalized urticaria after endodontic treatment using a para-formaldehyde (PFA)-containing root canal sealant and present a review of previous studies describing cases of immediate hypersensitivity reactions to formaldehyde. A 50-year-old man visited our allergy clinic for recurrent generalized urticaria several hours after endodontic treatment. Prick tests to latex, lidocaine, and formaldehyde showed negative reactions. However, swelling and redness at the prick site continued for several days. The level of formaldehyde-specific IgE was high (class 4). Thus, the patient was deemed to have experienced an IgE-mediated hypersensitivity reaction caused by the PFA used in the root canal disinfectant. Accordingly, we suggest that physicians should pay attention to type I hypersensitivity reactions to root canal disinfectants, even if the symptoms occur several hours after exposure.
Disinfectants/*adverse effects ; Formaldehyde/*adverse effects ; Humans ; Hypersensitivity, Immediate/*chemically induced ; Immunoglobulin E/*immunology ; Male ; Middle Aged ; Recurrence ; Skin Tests ; Time Factors ; Urticaria/*chemically induced/diagnosis ; Zinc Oxide-Eugenol Cement/*chemistry

OBJECTIVETo investigate the effect of formaldehyde exposure on the expression of inflammatory cytokines in human bronchial epithelial cells (16HBE cells).

METHODS16HBE cells were treated with formaldehyde with a concentration of 0, 0.04, 0.08, 0.16, 0.32, or 0.64 mmol/L for 24 hours, and MTT assay was applied to measure proliferative activity and calculate median lethal dose; 16HBE cells were exposed to formaldehyde with a concentration of 0, 0.04, 0.16, 0.64, or 1.20 mmol/L for 4 hours, MTT assay was applied to measure proliferative activity, and enzyme-linked immunosorbent assay was applied to measure the levels of Th1, Th2, and Th17 cytokines and tumor necrosis factor α(TNF-α) in cell supernatant.

RESULTSCompared with the control group, the 0.32-and 0.64-mmol/L exposure groups had significant decreases in cell viability (P<0.05); all exposure groups had reductions in interleukin(IL)-2 and IL-12, but no significant changes in interferon-γ and IL-10. In the 1.20-mmol/L exposure group, there was an increase in IL-4, with the increasing exposure dose, IL-5 and IL-6 tended to increase first and then decrease, and there was no significant change in IL-13; with the increasing exposure dose, IL-8 tended to increase first and then decrease, and there was no significant change in IL-17. In all the exposure groups, TNF-α increased and tended to increase significantly with the increasing exposure dose(P<0.05).

CONCLUSIONFormaldehyde exposure can cause imbalance between Th1 and Th2 cytokines secreted by 16HBE cells, as well as increased expression of IL-8 and TNF-α.

Cells, Cultured ; Cytokines ; metabolism ; Epithelial Cells ; drug effects ; metabolism ; Formaldehyde ; adverse effects ; Humans ; Interferon-gamma ; metabolism ; Interleukins ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVE: To observe the effect of formaldehyde inhalation on the allergic rhinitis mice model. METHOD: Forty-eight male BALB/C mice in six experimental group were exposure to (A) saline control; (B) Der p1; (C) formaldehyde (3.0 mg/m3); (D) Derp1 + formaldehyde (1.5 mg/m3); (E) Der p1 + formaldehyde (3.0 mg/M3); (F) Der p1+ formaldehyde (6.0 mg/m3). The concentrations of IL-4, IL-10 and IFN-γ in the peripheral serum were measured by enzyme-linked immunosorbent assay(ELISA). Nasal mucosal inflammation was evaluated by HE staining. Result: Formaldehyde exposure could increase the number of allergic rhinitis mice with sneezing and rubbing nose. The levels of IL-4 and IL-10 in group B, D, E and F were higher than that ingroup A (P < 0.05). Compared with the group C, the group D, E and F could effectively increase serum IL-4 and IL-10. The concentration of IL-4 in group E and F was higher than that of group B, while the group C was lower (P < 0.05). The concentration of IL-10 in group D, E and F was higher than that in group B (P < 0.05). The expression of IFN-γ in group B, D, E and F was lower than that in group A. While, the IFN-γ expression in group B was lower than that of group C and higher than that in group F (P < 0.05). Moreover, the concentration of IFN-γ in group D, E and F was lower compared with group C (P < 0.05). The nasal mucosa HE staining showed that the density of EOS increased simultaneously in formaldehyde exposure allergic rhinitis groups. CONCLUSION The study showed that formaldehyde exposure can promote Th2 cytokines and eosinophil infiltration and then aggravate the allergic rhinitis symptoms.
Animals ; Antigens, Dermatophagoides ; Arthropod Proteins ; Cysteine Endopeptidases ; Disease Models, Animal ; Enzyme-Linked Immunosorbent Assay ; Formaldehyde ; adverse effects ; Inflammation ; Inhalation Exposure ; adverse effects ; Interferon-gamma ; blood ; Interleukin-10 ; blood ; Interleukin-4 ; blood ; Male ; Mice ; Mice, Inbred BALB C ; Nasal Mucosa ; Rhinitis, Allergic ; chemically induced

PURPOSE: The aim of this study was to investigate the effect of epidural dexamethasone on analgesia and cytosolic phospholipase A2 (cPLA2) expression in the spinal cord in a rat formalin test. MATERIALS AND METHODS: Epidural dexamethasone injection was performed to Sprague-Dawley rats with a 25 gauge needle under fluoroscopy. Following the epidural injection, a formalin induced pain behavior test was performed. Next, the spinal cords corresponding to L4 dorsal root ganglion was extracted to observe the cPLA2 expression. RESULTS: There were no differences in pain response during phase I among the groups. The phase II pain response in 300 microg of epidural dexamethasone group decreased as compared to control, 30 microg of epidural dexamethasone, 100 microg of epidural dexamethasone, and 300 microg of systemic dexamethasone groups. The expression of cPLA2 decreased in Rexed laminae I-II in 300 microg of the epidural dexamethasone group compared with the ones in the control group. CONCLUSION: Taken together, these results suggest that 300 microg of epidural dexamethasone has an attenuating effect on the peripheral inflammatory tissue injury induced hyperalgesia and this effect is mediated through the inhibition of intraspinal cPLA2 expression and the primary site of action is the laminae I-II of the spinal cord.
Animals ; Anti-Inflammatory Agents/*pharmacology ; Dexamethasone/*pharmacology ; Formaldehyde/*adverse effects ; Group IV Phospholipases A2/*metabolism ; Hyperalgesia/*drug therapy ; Injections, Epidural ; Male ; Pain/chemically induced/*metabolism ; Pain Measurement ; Rats ; Rats, Sprague-Dawley ; Spinal Cord/*metabolism

OBJECTIVETo investigate the role of heme oxygenase and carbon monoxide (HO/CO) in the development of spontaneous pain and hyperalgesia of rats induced by formalin injection.

METHODSZinc protoporphyrin Znpp (the inhibitor of HO) was intrathecally injected to the rats with formalin inflammatory pain. Hemin (the agonist of HO) was intrathecally injected to the normal rats. The weighted pain scores were used to evaluate the degree of pain response. Thermal withdrawal latency and mechanical withdrawal threshold were observed to assess the degree of thermal hyperalgesia and mechanical allodynia.

RESULTSAfter the intrathecal injection of Znpp, the weighted pain score obviously reduced in a dose-dependent manner compared with the rats with formalin inflammatory pain. Intrathecal injection of Znpp had no obvious effect on thermal withdrawal latency and mechanical withdrawal threshold in injected feet compared with formalin group. But there was a prolongation in a dose-dependent manner in non injected feet. Intrathecal injection of Hemin to normal rats could shorten the thermal withdrawal latency and reduce the mechanical withdrawal threshold on both sides of hindpaws.

CONCLUSIONIntrathecal injection of the HO inhibitor produced prominent inhibition to pain related behavior and thermal and mechanical hyperalgesia induced by formalin injection. Intrathecal injection of HO inductor could induce thermal and mechanical hyperalgesia in normal rats. The results indicated that HO/CO took part in the processes of spinal cord nociceptive information transmission and the development of thermal and mechanical hyperalgesia.

Animals ; Carbon Monoxide ; Formaldehyde ; adverse effects ; Heme Oxygenase (Decyclizing) ; antagonists & inhibitors ; Hemin ; Hyperalgesia ; chemically induced ; Male ; Nociception ; Nociceptors ; drug effects ; physiology ; Pain ; chemically induced ; Protoporphyrins ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate whether formalin inflammatory pain can induce the change in heme oxygenase-1 (HO-1) expression in the spinal cord of rats or not and the time course character.

METHODS42 SD rats were divided into 7 groups (n = 6): control formalin 6 h, formalin 12 h, formalin 1 d, formalin 2 d, formalin 3 d and formalin 7 d groups. Rats were subcutaneously injected with 0.2 ml 0.5% formalin into the ventral surface of right hind paw to induce periphery inflammatory pain. The immunohistochemistry was used to observe the expression of HO-1 protein in laminae I - II of the spinal cord dorsal horn and the area around canalis centralis of the I5 spinal segment of rats.

RESULTSThere are rare HO-1 immunoreactive cells in the laminae I - II of the dorsal horn and the area around canalis centralis of the I5 spinal segment of rats of control group and HO-1 immunoreactive cells were light in staining degree. Comparing with control group, the numbers of HO-1 immunoreactive cells in the I - II laminae of dorsal horn and area around canalis centralis were increased in the rats at 6 h after formalin injection. The number and staining degree of HO-1 immunoreactive cells were further increased at 12 h and peaked at 1 d after formalin injection. They didn't return to normal level at the 7th day. There were no difference in right and left dorsal horn in the number and staining degree of HO-1 immunoreactive cells at the same time after formalin injection.

CONCLUSIONFormalin inflammatory pain induced increased expression of HO-1 in the spinal cord dorsal horn and the area around canalis centralis of rats. At 1 d after injection of formalin, the increased expression of HO-1 was the most obviously.

Animals ; Formaldehyde ; adverse effects ; Heme Oxygenase (Decyclizing) ; metabolism ; Male ; Pain ; metabolism ; Pain Measurement ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; metabolism

OBJECTIVETo evaluate the anti-inflammatory and analgesic activities of leaf extract of Melanthera scandens (M. scandens).

METHODSThe crude leaf extract (39-111 mg/kg) of M. scandens was investigated for anti-inflammatory and analgesic activities using various experimental models. The anti-inflammatory activity was investigated using carragenin, egg-albumin induced oedema models, while acetic acid, formalin-induced paw licking and thermal-induced pain models were used to evaluate the antinociceptive property.

RESULTSThe extract caused a significant (P<0.05 - 0.001) dose-dependent reduction of inflammation and pains induced by different agents used.

CONCLUSIONSThe leaf extract possesses anti-inflammatory and analgesic effects which may be mediated through the phytochemical constituents of the plant.

Acetic Acid ; toxicity ; Albumins ; adverse effects ; Analgesics ; therapeutic use ; Animals ; Anti-Inflammatory Agents ; therapeutic use ; Asteraceae ; metabolism ; Carrageenan ; toxicity ; Edema ; drug therapy ; Formaldehyde ; toxicity ; Inflammation ; chemically induced ; drug therapy ; Mice ; Pain ; chemically induced ; drug therapy ; Phytochemicals ; therapeutic use ; Phytotherapy ; Plant Extracts ; therapeutic use ; Plant Leaves ; metabolism

OBJECTIVETo investigate the effects of occupational exposure to formaldehyde on the micronuclei frequencies in peripheral blood lymphocytes of workers.

METHODSTwo hundred thirty six plywood workers were divided into 3 exposure groups (low, middle and high) according to internal exposure biomarker (formaldehyde human serum albumin conjugate, FA-HSA), which was detected by ELISA. The concentrations of formaldehyde (FA) in air of two workshops were measure using the high performance liquid chromatography. Cytokinesis-block micronucleus (CBMN) test was used to detect the micronuclei frequencies of peripheral blood lymphocyte in 236 workers.

RESULTSThe average concentrations of FA in the low and high exposure workshops were 0.58 +/- 0.20 and 1.48 +/- 0.61 mg/m3, respectively, there was significant difference (P < 0.01). The average concentrations of serum FA-HAS of workers in two workshops were 69.22 +/- 15.37 and 136.29 +/- 89.49 pg/ml, respectively, there was significant difference (P < 0.01). The results of CBMN test showed that the micronucleus frequencies in low, middle and high exposure groups were 1.94 +/- 1.72, 2.10 +/- 1.92 and 2.10 +/- 1.70 per thousand, respectively, there were no significant differences between groups. However, the micronucleus frequencies in accumulative low, middle and high exposure groups were 1.36 +/- 1.36, 2.31 +/- 1.81 and 2.49 +/- 1.92 per thousand, respectively, there were significant differences between different accumulative exposure groups (P < 0.01). The results of correlation analysis indicated that there was a positive correlation between accumulative exposure levels and micronucleus frequencies (r(s) = 0.321, P < 0.01). The accumulative exposure doses may be a risk factor for high micronucleus frequencies in workers exposed to FA (P(trend) = 0.002).

CONCLUSIONFA-HSA levels can serve as an internal exposure biomarker for assessing the exposure level of workers exposed to FA. Accumulative formaldehyde exposure resulted in an increase of micronuclei frequencies of peripheral blood lymphocyte in plywood workers.

Adult ; Asian Continental Ancestry Group ; Biomarkers ; blood ; Formaldehyde ; adverse effects ; blood ; Humans ; Lymphocytes ; cytology ; drug effects ; Micronucleus Tests ; Occupational Exposure ; analysis ; Respiratory Hypersensitivity ; blood