Formaldehyde-negative allergic contact dermatitis from melamine-formaldehyde resin

Sensitization to Formaldehyde in Northeastern Italy, 1996 to 2012

BACKGROUND

Formaldehyde is a widely used organic compound, used in several applications (hard thermoset resins, adhesives, disinfectants, tissue fixatives, etc), in its free form or released by formaldehyde releaser products. Its use is under control due to its toxic, carcinogenic, and allergenic properties.

OBJECTIVE

The aim of this study was to investigate the frequency of formaldehyde sensitization, time trend, and correlation to occupations.

METHODS

This study is a cross-sectional study on a population of 23,774 patients tested from 1996 to 2012 in Northeastern Italy.

RESULTS

Frequency of sensitization was 3.3%, without any significant time trend. Hands (39.8% overall) and face (25.6% females, 15.5% males) were mainly involved. We found a trend toward decrease by age in females (3.11% in first quintile [14-26 years], 2.29% in fifth quintile [59-97 years], P < 0.01). On a logistic regression analysis (control group: white-collar workers), we found associations in health care (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.04-1.81), wood (OR, 2.14; 95% CI, 1.30-3.51), and textile (OR, 1.79; 95% CI, 1.14-2.79) sectors and professional drivers (OR, 1.94; 95% CI, 1.05-3.60). We found a high rate of cosensitization to formaldehyde in patients with positive patch test reactions to quaternium-15 (OR, 18.7; 95% CI, 12.6-27.7).

CONCLUSIONS

Sensitization to formaldehyde is relevant in our population, especially in the health care sector, wood and textile industries, and professional drivers. No significant time trend was found.

Ambient Melamine Exposure and Urinary Biomarkers of Early Renal Injury

Information about environmental exposure to melamine and renal injury in adults is lacking. We investigated this relationship in 44 workers at two melamine tableware manufacturing factories in Taiwan (16 manufacturers, eight grinders, ten packers, and ten administrators) and 105 nonexposed workers (controls) at one shipbuilding company who were enrolled in August-December of 2012. For melamine workers, personal and area air samples were obtained at the worksite over 1 workweek (Monday-Friday). In the same week, pre- and post-shift one-spot urine samples were collected each workday and one first-spot urine sample was collected on each weekend morning and the following Monday morning. For each control, a one-spot urine sample was collected on Friday morning. A blood sample was also obtained from each participant at this time. Melamine levels were measured in air, urine, and serum, and early renal injury biomarkers were measured in urine. Urinary melamine concentrations in manufacturers increased sharply between pre- and post-shift measurements on Monday, remained significantly elevated throughout the workweek, and decreased over the weekend; changes in urinary melamine concentrations were substantially lower for other melamine workers. Manufacturers were exposed to the highest concentrations of ambient melamine and had significantly higher urinary and serum melamine concentrations than did the controls (P<0.001). Urinary melamine levels were positively associated with urinary N-acetyl β-d-glucosaminidase (NAG) levels but not microalbumin levels, and the detectable β2-microglobulin rate increased in the manufacturers group. In conclusion, ambient melamine exposure may increase the levels of urinary biomarkers of renal tubular injury in this occupational setting.

Derivation of a melamine oral reference dose (RfD) and drinking-water total allowable concentration

Due to its high nitrogen content, melamine has been used to adulterate food to increase apparent protein content. In 2008, thousands of Chinese infants consumed reconstituted formula derived from melamine-adulterated milk. Urinary-tract stones (comprised of melamine and uric acid) accumulated in some victims and lead to acute renal failure or death. Premature infants and children (<2 yr) have an increased susceptibility to ingested melamine. Due to incomplete reporting, the human data were inadequate to identify a no-observed-adverse-effect level (NOAEL) for melamine-induced pediatric urolithiasis. Urolithiasis, urinary bladder cystitis, and ulcerations were observed in F344 rats after subchronic or chronic ingestion of melamine at > or =72 mg/kg-d. Bladder epithelial damage was followed by epithelial hyperplasia that progressed to bladder papillomas and carcinomas in male but not female F344 rats or male or female B6C3F1 mice. Short-term assays suggest, at best, weak genotoxic activity, and kinetic data show that melamine is not metabolized. Since reliable exposure information was lacking from the clinical reports, an oral reference dose (RfD) based on urolithiasis in male rats after 13 wk of continuous melamine ingestion was calculated as a 10% benchmark dose (38 mg/kg-d). Incorporation of 10-fold interspecies and intraspecies (for the increased susceptibility of infants) uncertainty factors and a threefold database uncertainty factor (for the lack of immunological, neurological and reproduction toxicity data) yields an oral RfD of 0.13 mg/kg-d. Assuming the 70-kg adult consumes 2 L of drinking water daily, a total allowable concentration of 0.9 mg/L (900 microg/L) was calculated for melamine in drinking water.

Hand/face/neck localized pattern: sticky problems--resins

Plastic resin systems have an increasingly diverse array of applications but also induce health hazards, the most common of which are allergic and irritant contact dermatitis. Contact urticaria, pigmentary changes, and photoallergic contact dermatitis may occasionally occur. Other health effects, especially respiratory and neurologic signs and symptoms, have also been reported. These resin systems include epoxies, the most frequent synthetic resin systems to cause contact dermatitis, (meth)acrylics, polyurethanes, phenol-formaldehydes, polyesters, amino resins (melamine-formaldehydes, urea-formaldehydes), polyvinyls, polystyrenes, polyolefins, polyamides and polycarbonates. Contact dermatitis usually occurs as a result of exposure to the monomers and additives in the occupational setting, although reports from consumers, using the raw materials or end products periodically surface. Resin- and additive-induced direct contact dermatitis usually presents on the hands, fingers, and forearms, while facial, eyelid, and neck involvement may occur through indirect contact, eg, via the hands, or from airborne exposure. Patch testing with commercially available materials, and in some cases the patient's own resins, is important for diagnosis. Industrial hygiene prevention techniques are essential to reduce contact dermatitis when handling these resin systems.