Methyl Parathion Residue in Contaminated Fabrics after Laundering

12

Downloaded by EMORY UNIV on February 26, 2016 | http://pubs.acs.org Publication Date: February 25, 1985 | doi: 10.1021/bk-1985-0273.ch012

Methyl Parathion Residue in Contaminated Fabrics after Laundering JOAN LAUGHLIN, CAROL EASLEY, and ROGER E. GOLD University of Nebraska, Lincoln, NE 68583-0802 Denim fabrics of cotton and cotton-polyester were con taminated with methyl parathion (MeP) in emulsifiable concentrate, wettable powder, and encapsulated formu lations, and then laundered. After laundering at 60°C, 40°C, and 30°C, the fabrics were analyzed for residue by gas chromatography. A 1.25% concentration or 54% a.i. were used to contaminate fabrics. Phosphate, carbonate, heavy duty liquid, and AATCC Standard 124 detergents were used at 0.3 g/150 ml for powders and 0.4 ml/150 ml for liquids. Emulsifiable concentrate was most difficult to remove. Statistical homogeneity was found among the detergents. No differences were found between 60°C and 49°C water washing, but 30°C produced lower removal. The undiluted (54% concen trate) was almost impossible to remove by laundering. Limiting or reducing exposure of a g r i c u l t u r a l workers during mixing, handling and application of pesticides has increased i n importance with the recent s h i f t s i n pesticide use from organochlorines to high er t o x i c i t y organophosphates. Wolfe (JL) established that the p r i n c i p a l route of pesticide intake into the human body i s dermal ingestion rather than o r a l or respiratory ingestion. Thus, attention has focused on using protective systems or clothing to protect the skin to minimize dermal absorption. OSHA Standard 1919.267a (2) suggested that protective clothing include a "washable f a b r i c . " Matthews (3) describes minimum protective clothing as durable cotton o v e r a l l s , a long-sleeved s h i r t , and trousers. The recommendations for laundering include hot water washing with soap or detergent (3, 4). The National Institute for Occupational Safety and Health (5) recommends laundering i n a pH 10 s o l u t i o n . Hayes (6) recommends use of soap, detergent, or washing soda. No research i s cited to support these recommendations. Refurbishment i s an essential and c r i t i c a l part of continued

0097-6156/85/0273-Ό177$06.00/0 © 1985 A m e r i c a n C h e m i c a l Society

In Dermal Exposure Related to Pesticide Use; Honeycutt, Richard C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1985.


178

DERMAL EXPOSURE RELATED TO PESTICIDE USE

safety. Completeness of p e s t i c i d e removal i n laundering i s e s s e n t i a l i f the garment i s to be worn again. As the concentration of active ingredient i n the pesticide increases, the success of laundering i n reducing the pesticide residues i n the f a b r i c decreases. Multiple washings help decrease the amount of pesticide residue (7-9). The Federal Task Group on Occupational Exposure to Pesticides (2) requires that " a l l protective clothing s h a l l be thoroughly washed after each day's use the clothing s h a l l be adequately cleaned before i t i s passed on." Recent work has shown that, once contaminated, usual t e x t i l e items i n pesticide applicators' wardrobes are d i f f i c u l t to decontaminate through household laundering procedures currently i n use (10-16). These researchers found that laundering greatly reduces the amount of pesticide residues present. But Finley and co-workers found that even three launderings were not e f f e c t i v e i n removing a l l residue. Bioassay has shown that residues remaining after repeated launderings were b i o l o g i c a l l y active (17). Recommendations have been made that hot water temperature of at least 60 C be used for laundering p e s t i c i d e workers' clothing. Applehans (18) l i s t s several factors that increase the rate of organophosphate pesticide degradation: temperature of 32 C or more, a basic pH, organic compounds i n the s o i l , and a c t i v i t y of microorganisms. Laundering aids or practices that correspond with these factors can be established. The usual processes of s o i l i n g and the resultant mechanisms of s o i l removal from t e x t i l e substrates are complicated by the chemical nature of pesticides as s o i l . Generally, s o i l i n g depends upon the chemical nature of the t e x t i l e ; the c h a r a c t e r i s t i c s (geometry) of the f i b e r , yarn, and fabric; the chemical treatments of the t e x t i l e ; and the conditions of t e x t i l e use (19). S o i l can be p a r t i c u l a t e or l i q u i d and of an o i l base or a water base. The mechanisms of enhanced s o i l i n g , and therefore d i f f i c u l t y i n s o i l removal, include penetration of the s o i l (dependent upon surface tension of s o i l and f i b e r , v i s c o s i t y of the s o i l , and distance between f i b e r s and i n t e r s t i c e s between yarns), entrapment i n the structure of the f i b e r and(or) i n spaces of fibers fractured by the mechanical wear of laundering during use. Raheel (20) photomicrographed the entrapment of p a r t i c u l a t e s o i l i n fiber fractures. Obendorf and Klemash (21) established, through scanning electron micrographs and x-ray d i f f r a c tion analysis, the presence of o i l y s o i l i n the lumen of cotton and the folds of cotton's convolutions, and i n the c a p i l l a r y spaces between polyester f i b e r s . Although several studies have examined the pesticide residue i n garment fabric a f t e r laundering (7-16, 22-24) few studies have explored the relationship of s o i l i n g mechanisms and t e x t i l e geometry to this p a r t i c u l a r problem (9, 23). Problem The purpose of the study was to determine e f f e c t i v e laundering procedures for decontaminating work-weight f a b r i c s . The effect of f i b e r composition, pesticide formulation, detergent type, wash temperature, wash cycle procedures, laundry additives, and pesticide concentration on pesticide residue remaining a f t e r laundering were examined.


12.

LAUGHLIN ET AL.

MeP

Residue

in Contaminated

Fabrics

179

Transfer of the pesticide from contaminated f a b r i c to clean cotton fabric through contamination of the washing equipment to subsequent laundry was also determined. Methods and Materials Fabrics. Two denim fabrics of 100% cotton and 50/50 cotton-polyester were used. A catalogue survey showed these f i b e r contents to be common i n men's work clothing. Both fabrics were a 2/1 left-hand t w i l l weave. The cotton and cotton-polyester fabrics had a thread count of 60 χ 42 and 65 χ 47, respectively. Average weight of both fabrics was 321.4 g/m . Downloaded by EMORY UNIV on February 26, 2016 | http://pubs.acs.org Publication Date: February 25, 1985 | doi: 10.1021/bk-1985-0273.ch012

2

Chemicals. Three formulations of methyl parathion [θ,Ο-dimethyl 0-£-nitrophenyl phosphorothioate (MeP)] were used to contaminate the f a b r i c s : 1) emulsifiable concentrate (EC); 2) encapsulated (ENC); 3) wettable powder (WP). The active ingredient (a.i.) present i n the three formulations was analyzed to insure that actual percent a . i . agreed with l a b e l s p e c i f i c a t i o n s . Analyses of the a . i . i n each f o r mulations were 95% to 120% of the labeled amounts (25). Based on these analyses a 1.25% concentration solution of MeP, a common con centration for a g r i c u l t u r a l application, was prepared from each formulation by adding d i s t i l l e d water. For the work done with f u l l strength pesticide, an emulsifiable concentrate formulation of methyl parathion, 54.0% a . i . , was used to contaminate the f a b r i c s . Contamination of Fabric. Denim f a b r i c swatches were contaminated by pipetting one ml of MeP solution onto the f a b r i c . During the con tamination process, a magnetic s t i r r e r provided uniform agitation of the solution. Swatches were supported horizontally during contamina t i o n and drying. Laundry Process. Fabric swatches were i n d i v i d u a l l y laundered i n stainless s t e e l canisters of an Atlas Launder-Ometer (model B5), using a modified AATCC test method 61-1980 (26). Constant tempera ture of the Launder-Ometer water bath was maintained. At the end of each cycle, water was decanted from the canisters. Additional water of the specified temperature was then added for the subsequent cycle. Following completion of the laundry process, the f a b r i c swatches were a i r - d r i e d and then retained i n glass for extraction. Extraction Procedures. To extract the MeP, 150 ml g l a s s - d i s t i l l e d acetone was added to each j a r containing a laundered swatch. The j a r was shaken for one hour at 170 revolutions per minute, and the acetone extract was decanted and replaced by an additional 150 ml acetone for a second hour of shaking. The f a b r i c swatch was removed at the end of the two-hour period, and the two extracts were combined. Gas Chromatographic Procedures. Extracts were analyzed by means of a Hewlett-Packard gas chromatograph, model 5850A, with a nitrogenphosphorus I.D. packed with 3% 0V-25 on 100-120 mesh chromosorb W HP. The column temperature was 213°C,that of the i n l e t was 217 C, and the



180


detector was 300°C. Nitrogen c a r r i e r gas flow was 21.5 cc/minute, a i r flow was 50 cc/minute, and hydrogen was 3 cc/minute. Replicated injections of 1.06 U l were made from each sample solution for calibration. Bioassays. B i o l o g i c a l assays with B l a t t e l l a germanica (L) (German cockroaches) biotype: Orlando normal were performed to assess biol o g i c a l a c t i v i t y . T r i a l s were conducted i n environmental chambers at 30°C and 10-20% R. H. Ten adult males were placed on each of the treated f a b r i c s , dorsum up. The cockroach mortality was recorded after 24 and 48 hours. 2 S t a t i s t i c a l Analysis. Differences i n the amounts of MeP (ng/cm ) between the control and laundered swatches were expressed i n percentages of i n s e c t i c i d e residue remaining. S t a t i s t i c a l differences were tested with F a c t o r i a l Experimental ANOVA, Least S i g n i f i c a n t Means, and Duncan's Multiple Range Test. Experimental The purpose of t h i s study was to determine the e f f e c t s of f i b e r composition, MeP formulations, and selected laundry procedures on removing MeP residues from contaminated fabrics and to determine whether residues are transferred i n laundry. Laundry Procedures. Four laundry procedures were examined for MeP residue remaining after one laundering. 1.

Pre-rinse: Each contaminated swatch was pre-rinsed for two minutes i n warm water at 49°C, then laundered i n a 12-minute hot water (60°C) phosphate detergent wash, and two warm water rinses (49°C), three minutes and f i v e minutes, respectively. The phosphate detergent selected was AATCC Standard Detergent 124, a 12% phosphate detergent used i n t e x t i l e research. 2. Phosphate detergent wash (Det.): Same as described for the prerinse, with the omission of the pre-rinse cycle. 3. Phosphate detergent wash plus ammonia laundry additive (Det. + NH3): Same as the phosphate detergent wash with the addition of ammonia laundry additive (3.5%-4% ammonia concentration) i n the wash cycle. 4. Phosphate detergent wash plus bleach laundry additive (Det. + NaOCl): Same as described for the phosphate detergent wash with the addition of l i q u i d chlorine bleach (5.25% sodium hypochlori t e ) laundry additive i n the wash cycle. Contaminated swatches that were pre-rinsed were placed i n d i v i d u a l l y i n 500-ml glass j a r s with d i s t i l l e d water and agitated on an Eberbach mechanical shaker to simulate the pre-rinsing cycle of an automatic washing machine. Contamination of the Fabric Before and After Laundry. Estimating the extent to which fabrics had been i n i t i a l l y contaminated was necessary for comparison with post-laundry residue levels (Table 1). Contaminated (control) f a b r i c swatches for each f a b r i c and formula-


12.

LAUGHLIN ET AL.

MeP

Residue

in Contaminated

Fabrics

181


tion were used as an indicator of i n i t i a l contamination and as a baseline (100%) for percentage residue after laundering calculations. Transfer of Contamination i n Laundry. Sustained transfer occurred when a clean fabric was laundered i n equipment that had been used to wash contaminated f a b r i c . The transfer fabric was an a l l cotton b a t i s t e of p l a i n weave construction. These f a b r i c swatches ( 8 x 8 cm) were subjected to one complete laundering cycle immediatel y after the contaminated fabrics had been through one wash and two rinse cycles. That i s , following completion of the laundering process, the contaminated denim fabric swatch was removed, the rinse water decanted, and a clean cotton transfer f a b r i c added to each canister along with 150 ml of phosphate detergent solution. Warm water (49°C) was used for the wash and two rinse cycles. After laundering, the transfer f a b r i c was a i r - d r i e d and retained i n glass for solvent extraction. B i o l o g i c a l Assays of Fabric. B l a t t e l l a ftermanica (L.) (German cockroaches) biotype: Orlando normal were used to determine i f i n s e c t i c i d e residues present i n the laundered contaminated fabrics and the laundered transfer fabrics were b i o l o g i c a l l y active. A l l t r i a l s were conducted i n environmental chambers at 30 C and 10-20% R. H. Cockroaches were anesthetized with CO2, a f t e r which ten adult males were placed on each of the f a b r i c s , dorsum up. Cockroaches recovered within f i v e min and a c t i v e l y sought the confines of the p e t r i dish b a r r i e r . The cockroaches were held on the swatches for 24 h and m o r t a l i t i e s were recorded. Detergents and Wash Temperatures. The purpose of t h i s phase of the study was to determine whether commercially available detergents were as e f f e c t i v e i n pesticide residue removal when used i n washing procedures at "hot," "warm," and "cold" water temperatures. The important and unique contribution of this study was the close d u p l i cation of in-home laundry procedures, with commerically available detergents and common laundering temperatures. Contaminated swatches were laboratory-laundered i n a 60°C (hot) wash/49°C (warm) rinse; 49°C (warm) wash/49°C (warm) rinse; or 30°C (cold) wash/30°C (cold) rinse water temperature using one of four laundry detergents. Three commercially available detergents were selected to represent p r i n c i pal detergent categories: phosphate, carbonate, heavy duty l i q u i d , and a high (12%) phosphate detergent (AATCC 124). The powdered detergents were used at 0.3 g/150 ml, and the heavy duty l i q u i d at 0.4 ml/150 ml. Pesticide Concentration Levels. The purpose of this experiment was to determine completeness of residue removal during laundering when a range of concentration l e v e l s had been used to contaminate denim f a b r i c . Five concentrations of MeP EC were prepared as contaminants: 0.25%, 0.5%, 1%, 2% and 54% (undiluted). Fabric swatches were laundered through one cycle: a 60°C wash and two 49 C rinses. A l l procedures were as previously described. Multiple Launderings.

Fabric swatches were contaminated with


1.25%

182


a . i . ( f i e l d strength) or 54% a . i . (undiluted) MeP EC. Contaminated swatches were i n d i v i d u a l l y laundered one through ten complete laundry cycles. A 49 C wash and rinse water temperature were used as t h i s combination was most frequently selected by consumers (27). Other procedures were as e a r l i e r described.


Results and Discussion Analysis of variance (ANOVA) comparing the degree of contamination between fabrics and formulations showed no s i g n i f i c a n t difference (F=1.601, d.f.=5,12), indicating that both f a b r i c s i n i t i a l l y r e tained l i k e amounts of MeP. Comparisons of fabric contamination after laundry were calculated to ascertain the amounts of MeP r e maining after the laundry process. Residue Remaining After Laundering. The laundry process removed a mean of 80% to 99% MeP (Table I ) . Residues were lower f o r encapsu lated (ENC) and wettable powder (WP) formulations, with ranges of 1% to 7% MeP residue. Emulsifiable concentrate (EC) MeP residues were higher, ranging from 12% to 20%, indicating that EC formulation apparently was more d i f f i c u l t to remove. Table

I.

Pre-rinse Treatment EC-C EC-C/P ENC-C ENC-C/P WP-C WP-C/P

% 12.2 11.8 2.6 2.1 0.9 0.1

MeP R e s i d u e s a f t e r

Det.

% 16.5 15.4 1.9 3.2 6.7 4.3

Laundering

Det. + NH

% 19.4 16.3 2.1 2.5 6.4 3.7

3

Det. + NaOCl

% 11.2 13.7 2.2 2.1 6.2 3.7

Pre-rinsing proved to be e f f e c t i v e when fabric and formulation were considered, that i s , percentages of MeP residue were generally lower than f o r the other laundry procedures. MeP residue was s i g n i f i c a n t l y lower (Ρ ^ 0.05) when the wash cycle was the f i r s t aqueous solution, than when the pre-rinse cycle was the i n i t i a l aqueous solution. This s i g n i f i c a n t finding could have resulted from a s s i s tance of detergent or detergent plus additive. MeP residue removal during the washing cycle may be p a r t i a l l y attributed to the a l k a l i n i t y (pH 9.7) of the phosphate detergent, since MeP i s hydrolyzed to 4-nitrophenol i n an alkaline medium (10). Differences Attributable to Fabric and Formulation. Although i t was observed that the EC formulation was more d i f f i c u l t to remove from both fabrics than the ENC or WP formulations, f i b e r content of fabrics made no difference i n the completeness of MeP residue removal (Table I I ) . I t was i n i t i a l l y suspected that since EC formu lations are oil-based, there might be an a f f i n i t y f o r o l e o p h i l i c polyester f i b e r s , although no s i g n i f i c a n t difference between f i b e r content was shown based on gas chromatographic analysis. S i g n i f i c a n t differences (P

Methyl Parathion Residue in Contaminated Fabrics after Laundering

Recommend Documents