Dips

Dips. Six old trials (1962-1974, 3 on sheep, 3 on cattle) and two more recent trials on sheep (1986, 1989) were available. The results are given in Table 10.

Table 10. Residues of diazinon in the milk, tissues and fat of sheep and cattle following dipping in EC formulations.

Country, ref.	Rate, mg ai/l	No. of dips	Sample	Residues, mg/kg, range and (mean)										Slaughter interval (days)				Comments
SHEEP
Australia,	200	1 for	Meat	<0.1										1				3 animals per group for
Hastie &		20 sec	Kidney fat	<0.1-1.4 (0.1)										1				fat. Dip period
Cavey, 1962a			Kidney fat	1.1-1.4 (1.2)										7				reportedly twice
			Kidney fat	0.5-1.4 (0.8)										14				recommended. Rate is
			Controls,															GAP according to
			meat & fat	<0.1														current label.
Switzerland,	200	1 plunge	Whole milk	Residues at day
Formica,	(0.8 X GAP)	dip		6h		1		2	3			4			7	15			30
1973b			Trial 1	0.09		0.06		0.02	0.02			0.02			0.02	<0.01			<0.01
			Trial 2	0.09		0.03		0.01	0.01			0.01			0.01	<0.01			<0.01
			Controls	<0.01
	400	1 plunge		Residues at day
		dip		6h		1		2	3			4			7	15			30
			Trial 3	0.18		0.10		0.04	0.03			0.02			0.03	0.01			<0.01
			Trial 4	0.16		0.07		0.04	0.02			0.02			0.03	<0.01			<0.01
			Controls	<0.01
				Method REM 29/73, reported limit of detection 0.01 mg/kg, 92% recovery at 0.03 mg/kg
Switzerland	7501	1	Muscle	0.21-0.37 (0.28)										10				Applic. rate 3X
Formica,			Liver	0.02														reported GAP
1974c			Omental fat	2.2-2.6 (2.3)														Residues of
																		hydroxydiazinon,
																		diazoxon and
																		pyrimidinol below
																		LOD.
																		Method REM 4/74,
																		reported limit of
																		detection 0.02 mg/kg
																		parent; recovery 88%
																		at 0.5 mg/kg
Australia	250	1		Residues at day
Strong et al.,		plunge		1			3			7			14				21
1986a		dip	muscle	0.15			0.08			0.05			0.03				0.01
				0.13			0.05			0.04			0.01				0.02
			liver	0.01			0.02			<0.01			<0.01				0.01
				<0.01			<0.01			<0.01			0.01				0.01
			kidney	0.04			0.03			0.02			0.02				0.01
				0.03			0.03			0.01			0.01				0.01
			kidney fat	2.6			2.2			1.6			0.67				0.29
				1.2			2.1			1.0			0.63				0.24
				Two sheep/interval. Method 114A, LOD 0.01 mg/kg;
				recovery >87% at 0.1 mg/kg
UK	400	1 minute		Residues at day
Roberts and		plunge		7			141			212			28				35
MacDonald,	(1.6 X UK		Omental fat	1.4			1.1			0.8			0.6				0.2
1989	GAP,			2.3			1.1			0.7			0.5				0.6
	1 X Ireland &			2.8 1			1.1			0.7			0.7.				0.4
	N. Zealand			1.7			1.3			0.7			0.5				0.4
	GAP)						1.1			1.2			0.5				0.3
							0.7,			0.8			0.6				0.5
			Mean	(2.1)			(1.1)			(0.8)			(0.6)				(0.4)
			Subcut. fat	-			1.3			1.4			0.9				0.5
							1.4			1.0			0.5				0.7
							4.3			1.2			1.2				0.7
			Mean				(2.3)			(1.2)			(0.8)				(0.6)
				Controls <0.005 mg/kg; 6 animals/interval (4 at 7 days)
					1 Irish GAP PHI
					2 New Zealand GAP PHI
CATTLE
Australia,	500	3	Kidney fat	3.2-3.9 (3.6)							18 h		4 animals.
Hastie, 1962													Swiss GAP is 600 mg
													ai/l and 21-day S.I.
													Same in Egypt & near
													countries, but 14 day
													S.I.
	EC1	2-3	Kidney fat	0.0-2.1 (1.5)							90 h		1 animal 3 dips
													3 animals 2 dips
		2	Kidney fat	0.6-0.8 (0.7)							7		4 animals
			Control	0.1
Australia	500	1	Kidney fat	0.4-1.5 (1)							1		4 animals in each
Hastie 1963c			Subcut. fat	0.2-0.3 (0.25)							1		group
			Kidney fat	0.4-0.6 (0.5)							4
			Subcut. fat	0.15-0.2 (0.2)							4
			Kidney fat	0.3-0.6 (0.5)							7
			Subcut. fat	0.4-0.7 (0.5)							7
			Controls:
			Kidney fat	(0.2)
			Subcut. fat	<0.1
Australia	500	3 at 3 day	Kidney fat	1.7-4 (2.7)							1		2 steers + 1 cow per
Hastie 1963b		interval	Subcut. fat	0.8-1.5 (1.2)							1		group
			Kidney fat	0.6-1.2 (0.8)							4
			Subcut. fat	0.2-1.2 (0.7)							4
			Kidney fat	0.2-0.8 (0.5)							7
			Subcut. fat	0.4							7

¹ Formulation not stated but presumably EC

Hastie (1963a) reviewed several reports of studies on the dipping and spraying of sheep and cattle (Hastie, 1962, 1963b,c; Hastie and Cavey, 1962a,b, 1963). The reports were essentially brief summaries with little information on sample storage and handling, analytical methods or other details.

The other trials were on sheep dipping. Those by Formica (1973b, 1974c) are fairly well documented in terms of method, sample storage etc. The report by Strong et al. (1986) is reasonably detailed (e.g. sample storage at -15°C), although the periods from sampling to analysis are not provided. The trial by Roberts and MacDonald (1989) is the best documented and reported to be in accordance with recognized GLP. Details are given of all aspects of the trial, including sample storage and analysis of dip solutions.

Spraying. Reports of eighteen new or previously reviewed trials were provided: 13 on cattle, 2 on sheep, 2 on goats and 1 on pigs. The results are shown in Tables 11 (cattle) and 12 (sheep, goats and pigs).

Table 11. Residues of diazinon in the milk, fat and tissues of cattle after spraying.

Country, ref.	Formulation. Application rate, ai	No. of sprays	Sample		Residues, mg/kg, at withdrawal interval
Australia Hastie and Cavey, 1962a	Emulsifiable	1			1					7			14 days
	1500 mg/l (3 X high		meat		<0.1					-			-
	vol. GAP)		kidney fat		1.1					1.2			0.4
					0.9					1.2			0.4
	9.5 l/animal				3.2					1.3			0.3
	(2 X high vol. GAP)				Residues in fat from 3 animals.
					Residue in meat from single animal.
					GAP S.I. (pre-slaughter interval) = 3 days
Australia Hastie and Cavey, 1962b	Emulsifiable	1			1							3 (GAP) days
	1000 mg/l		kidney fat		1.8, 1.2							1.0, 0.8
	(1 X low vol. or 2		(6 animals)		0.9, 1.1							0.7, 0.9
	X high vol. GAP)				1.5, 1.1							0.9 -
	3.8 l/animal		subcut. fat		0.2, 0.1							0.3, 0.4
	(High vol. GAP is		(6 animals)		<0.1, 0.2							0.2, 0.7
	4.5 1)				0.3,<0.1							0.5, -
Australia Hastie and Cavey, 1963	Emulsifiable	1			1							2				3 days
	1000 mg/l		milk		0.07							0.01				Nil
	(2 X high vol. GAP)		(3 cows)		0.05							<0.01				Nil
	7.6 l/animal				0.04							0.01				Nil
	(High vol. GAP)
	Emulsifiable	1	milk		0.03							0.01				Nil
	500 mg/l		(3 cows)		0.04							0.01				Nil
	(High vol. GAP)				0.04							0.01				Nil
	7.6 l/animal
	(High vol. GAP)
USA Clabom, et al., 1963	WP	16 at	omental fat		1			6				7				14 days
	500 mg/l	weekly	Spray no.: 1					<0.05,
	(1/2 max. low vol.	intervals						0.06
	GAP for Australia)		2					<0.05,
	1-1.5 l/animal							0.09
			6					0.2,
								0.4
			10					0.2,
								0.2
			11		0.5
					0.9
			16		0.8							0.2				<0.08
					0.7							0.4				<0.05
	WP	16 at	1					0.7
	1000 mg/l	weekly						0.5
	(max. low vol. GAP	intervals	2					0.6
	for Australia)							0.5
			6					0.5
								0.8
			10					0.8
								0.8
			16		2.3							0.7				<0.05
USA Matthysse and Lisk, 1963	EC	2	Milk		0.5			1				2			3	4					7 days
	600 mg/l	10-day	1st spray		0.3			0.09				0.03									0.02
	11.4 l/cow	interval	2nd spray					0.3							0.1	0.04
	(high vol.)				Residue at 4 days is mean of 2 cows.
					All others are means of 3 cows.
UK Chilwell et al., 1967	Oil emulsion		Milk		2				5			9				24 hours
	200 mg/l		Cow 1		0.01				0.06			0.07				0,02
	10 l/cow		Cow 2		0.02				0.06			0.08				0.02
	(high vol.)		Cow 3		0.02				0.05			0.09				0.02
			Mean		0.02				0.06			0.08				0.02
					Each residue is mean of two analyses by
					GLC/thermionic. Recoveries 79% at 0.1 mg/kg.
Switzerland Blass, 1971	Formulation not	4 (weekly	Milk		0					3		4 (GAP)					6 days
	stated	intervals)	Spray
	500 mg/l		no.
	(600 mg/l is GAP)	(Max. 3 is	1	Range		0.2-0.4					<0.02-0.02	<0.02					<0.02
	10 l/cow	Swiss		Mean		(0.3)					(0.02)	(<0.02)					(<0.02)
	4 cows	GAP)	2	Range		0.1-0.2					<0.02-0.04	<0.02-0.02					<0.02
				Mean		(0.13)					(0.03)	(0.02)					(<0.02)
			3	Range		0.06-0.13					<0.02-0.03	<0.02-0.03					<0.02
				Mean		(0.09)					(0.02)	(0.02)					(<0.02)
			4	Range		0.05-0.14					0.02-0.05	<0.02-0.04					<0.02
				Mean		(0.08)					(0.03)	(0.03)					(<0.02)
	1000 mg/l		1	Range		0.2-0.6					<0.02-0.08	<0.02-0.05					<0.02
	(1.7 XGAP)			Mean		(0.3).					(0.04)	(0.04)					<(0.02)
	10 l/cow		2	Range		0.1-0.2					0.04-0.1	0.02-0.07					<0.02-0.04
	4 cows			Mean		(0.2)					(0.07)	(0.04)					(0.02)
			3	Range		0.09-0.1					<0.02-0.08	<0.02-0.05					<0.02-0.02
				Mean		(0.1)					(0.05)	(0.03)					(0.02)
			4	Range		0.05-0.2					0.03-0.04	<0.02-0.05					<0.02
				Mean		(0.14)					(0.04)	(0.03)					(<0.02)
Australia Bull and Dougall, 1974	EC?	1	Milk & milk		Residues from 5 individual cows
			products		Whole milk
					Range					Mean		Skim milk1					Butter1
			Pre-treatment							0.03		0.02					0.08
			Milking Day
			1st 1		0.2-0.3					0.2		0.03					5.2
			2nd 1		0.03-0.14					0.06		0.02					1,7
			3rd 2		0.04-0.08					0.06		-					0.8
			4th 2		0.02-0.05					0.03		-					0.3
			10th 5		0.01-0.05					0.02		-					0.05
							1 Composites
					Method 132, 0.01 mg/kg limit of detection
					reported. Recovery >97% from milk at 0.13 mg/kg
Bull and Dougall, 1974	500 mg/l		Milk & milk		Residues from herd bulk storage
	(High vol. GAP)		products
	10 l/animal (high				Milk					Skim milk		Cream					Butter
	vol.)		Pre-treatment		0.03					0.02		0.09					0.08
			Milkings
			1st		0.25					0.04		2.4					4.5
			1st & 2nd		0.15					0.03		2.1					2.6
			3rd		0.06					0.02		0.57					0.60
			3rd & 4th		0.04					0.02		0.26					0.30
					Herd size: 60. Method REM 20/71, autoanalyser.
					Recovery 76% at 0.05 mg/kg
Australia Bull et al., 1986a	EC	1	Whole milk
	600 mg/l	10l/cow			# Range							Mean (5 cows)
	(1.2 X GAP)		Pre-treatment		<0.01							<0.01
			Milking	Hours	0.08-0.4							0.2
			1	7	0.05-0.1							0.08
			2	21	0.04-0.07							0.06
			3	31	0.01-0.03							0.02
			4	45	0.01-0.03							0.02
			5	55	<0.01-0.01							<0.01
			6	(GAB)	<0.01							<0.01
			7	80
					GLC thermionic detection. Reported LOD 0.01
					mg/kg, recovery 91% at 0.1 mg/kg. No
					corrections made to results.
Australia Strong et al., 1986b	EC	1
	600 mg/l	10l/steer			1				7			14						21 days
			Muscle		0.06,				0.01.			<0.01,						NA1
					0.06				0.01			<0.01						NA
			Liver		<0.01,				<0.01.			<0.01,						NA
					0.02				<0.01			<0.01						NA
			Kidney		0.07,				0.01.			<0.01,						NA
					0.06				0.01			<0.01						NA
			Kidney fat		2.9,				0.4,			0.06,						<0.01,
					1.3				0.7			0.06						0.01
			Omental fat		2.5,				-			0.2,						<0.01,
					1.4				-			0.12						0.05
					GAP withdrawal interval is 3 days.
							1Not analysed.
					Two steer calves sampled at each time.
					-15°C storage. Uncorrected for recovery.
					Method 135. 0.01 mg/kg reported LOD.
					Recovery >88% at 0.1 mg/kg except omental fat 73%.
Egypt Kholif et al., 1994	EC	1?	Milk
	600 mg/l	(Report
	(GAP)	not	Hours		Cows									Buffaloes
		specific,	2		0.05									0.11
		but 1	4		0.2									0.2
		application	6		0.2									0.3
		presumed)	8		0.1									0.2
			16		0.05									0.02
		2l/cow	24		0.03									0.01
			36		ND1									0.005
			48		ND									ND
					GAP milk withdrawal interval is 3 days
							1 Not detected.
					Method AOAC 1990, GLC/ECD.
					Total of 20 cows and buffaloes.
Australia, Rose, 1995; Queensland and New South Wales, 1996	EC	1			Days:
	800 mg/l nominal	Back spray			2			4				7		10					14	16
	553 mg/l actual	0.5 l/cow	Loin Fat		<0.05			<0.05				<0.05		<0.05					<0.05	<0.05
		(GAP)						0.08
	(800 is GAP)		Renal fat					<0.05				<0.05
					Controls all 0.05 mg/kg
					3 cows sampled at 2, 14, and 16 days; 6 cows at
					4, 7 and 10 days. All samples except one 4-day
					loin fat contained 0.05 mg/kg.
					AOAC method, reported 0.02 mg/kg "limit of detection"

The 13 spray trials on cattle were from 1962 through 1996. One was not reviewed as it was available only in Russian (Leschchev et al., 1972). Hastie (1963a) reviewed three of the trials (Hastie and Cavey, 1962a,b, 1963). The first trial (Hastie and Cavey, 1962a) was not according to GAP. The second (Hastie and Cavey, 1962b), which might be interpreted to represent GAP, showed maximum residues of 1 mg/kg and 0.7 mg/kg in kidney fat and subcutaneous fat respectively. Hastie and Cavey (1963) reported residues of <0.01 mg/kg in milk from a GAP application rate after 3 days, the withholding period for milk in several countries. All of the trials were with single sprays whereas GAP allows multiple sprays in most countries.

Another old publication (Mathysse and Lisk, 1963) reports residues in milk up to 0.04 mg/kg with a mean of 0.03 mg/kg 3 days (the Australian withdrawal period) after a spray at 600 mg/l, slightly above the GAP rate for high-volume application, and up to 0.1 mg/kg with a mean of 0.04 mg/kg 4 days after a second spraying. Analysis was based on spectrophotometry.

Another dated publication (Claborn et al., 1963) reported the residues of diazinon in omental fat resulting from 16 spray applications at weekly intervals. Residues 6 days after treatment at half the maximum GAP application rate increased with repeated applications from 0.06 mg/kg after the first application to 0.4 mg/kg after the 6th: they had decreased to <0.08 mg/kg 14 days after the last application. Residues 6 or 7 days after each application at the maximum GAP rate remained between 0.5 and 0.8 mg/kg. They had decreased to <0.05 mg/kg by 14 days after the 16th treatment. Analyses were again by spectrophotometry.

In a UK study Chilwell et al. (1967) reported diazinon residues in milk within 24 hours of spray treatments at 200 mg ai/l. The mean residues were 0.02 mg/kg after 2 hours, rose to 0.08 mg/kg after 9 hours and decreased to 0.02 mg/kg after 24 hours. No information on UK GAP for cattle sprays was provided, although the application rate is below most reported GAP rates.

In an old but reasonably well-described study in Switzerland (Blass, 1971) residues of diazinon in milk were determined at various intervals after applying 4 sprays 500 or 1000 mg/l at weekly intervals. The lower rate complies with GAP. After 4 days (the GAP interval for Switzerland) the residues from the lower rate did not exceed a maximum of 0.03 mg/kg or a mean of 0.02 mg/kg after the third spray (the maximum number allowed by Swiss GAP) nor above 0.04 mg/kg maximum (0.03 mg/kg mean) after 3 days, which is the withdrawal interval in other countries. Analyses (presumably colorimetric) were by an autoanalyser.

In another old, but fairly well-described, Australian study residues of diazinon in the milk of cattle were determined after various intervals (Bull and Dougall, 1974). Samples from five individual cows and bulk samples from the whole herd were analysed after one treatment at 500 mg ai/l, the GAP rate. The cows were milked twice daily. The mean residues from the 5 cows were 0.2 mg/kg (0.3 mg/kg maximum) at the first milking, 0.06 mg/kg at the second, 0.03 at the 4th (day 2) and 0.02 mg/kg at the 10th (the 5th day after treatment). There is no specified Australian withdrawal period for milk but 3 or 4 days is common in other countries with similar GAP. Residues from the first milking were 0.03 mg/kg in skim milk and 5.2 mg/kg in butter, the residue in butter decreasing to 0.05 mg/kg after the 10th milking. Residue levels in the bulk herd samples were similar to the means of the 5 cows.

Two relatively recent studies from Australia were not especially well reported by current standards (e.g. they lacked details of the intervals from sampling to analysis and analytical confirmation of the active ingredient content of the sprayed solutions), but sample storage was at -15°C. In one of these studies diazinon residues were measured in the milk of 5 cows 7 to 80 hours after a single EC spray at 600 mg/l, 1.2 times the high-volume GAP rate (Bull, et al., 1986). The residues, ranged from a mean of 0.2 mg/kg and a maximum of 0.4 mg/kg 7 hours after application to a mean of <0.01 mg/kg after about 3 days (70 hours).

In the other fairly recent Australian study (Strong et al., 1986b) a similar application was made to calves, from which tissues were analysed for diazinon. The residues were up to 2.9 mg/kg in fat, about 0.06 mg/kg in muscle and kidney and up to 0.02 mg/kg in liver 1 day after treatment. No results were available for the Australian withdrawal interval of three days, but the residues in muscle, liver and kidneys had decreased to <0.01 mg/kg after 7 days, when kidney fat contained up to 0.7 mg/kg. Residues up to 0.2 mg/kg were found in omental fat after 14 days.

In a more recent Egyptian study (Kholif et al., 1994) a total of 20 Friesian cows and buffaloes were spray-treated once after the morning milking with an EC formulation at 600 mg/l (the Egyptian GAP rate). The animals were milked twice daily by machine. The residues in the milk of the buffaloes and cows respectively decreased from a maximum of 0.3 and 0.2 mg/kg after 6 hours to 0.005 mg/kg and not detected after 36 hours. The Egyptian withdrawal interval for milk is three days. The trial was generally well described but some desirable details were not included (e.g. sample handling and storage conditions and period of storage.

In a recent Australian trial cattle were back-sprayed once with 0.51 at 553 mg diazinon/1: the nominal rate was 800 mg/l which is the maximum GAP concentration. Loin and renal fat were analysed for residues at intervals from 2 to 16 days after treatment (Rose, 1995; Queensland and

New South Wales, 1996). Samples were taken from frozen export packs from the treated cattle. One loin fat sample of six taken four days after treatment contained 0.08 mg/kg; all other residues were below 0.05 mg/kg. Spray solutions were analysed for the active ingredient, but other important information such as sample handling and storage conditions and intervals from sampling to analysis was not reported.