Chemical food safety quarterly report: April to June 2022
Updated 29 July 2022
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Potential food safety incidents April to June 2022
| Food safety incidents (FSI) number | Date | APHA VIC or contracted postmortem provider (ppp) | Species | Toxin (reported toxic agent) | Likely source |
|---|---|---|---|---|---|
| 2022-007 | 27 May 2022 | Shrewsbury, Wales | Sheep | Copper | Plane of nutrition |
| 2022-008 | 27 May 2022 | Carmarthen, Wales | Cattle | Lead | Battery in field |
| 2022-009 | 07 June 2022 | Starcross | Cattle | Lead | Battery, bonfire |
| 2022-010 | 14 June 2022 | Shrewsbury | Cattle | (Botulism) | Not confirmed. Metabolic disease |
| 2022-011 | 14 June 2022 | Bury St Edmunds | Cattle | Lead | Battery in field |
Highlights
| Year (second quarter) | Total FSIs (England and Wales) | Total FSIs Wales | Lead (England and Wales) | Total lead Wales | Botulism (England and Wales) | Total botulism Wales |
|---|---|---|---|---|---|---|
| 2022 | 5 | 2 | 3 | 1 | 1 | 0 |
| 2021 | 18 | 8 | 16 | 7 | 1 | 0 |
| 2020 | 15 | 7 | 11 | 5 | 2 | 1 |
| 2019 | 21 | 4 | 9 | 1 | 6 | 1 |
| 2017 | 15 | 3 | 9 | 1 | 4 | 2 |
Significantly reduced incidents have been recorded this quarter which is of concern as there is a possibility that this reflects a decrease of reporting rather than a real-time decrease of livestock exposures to potential hazards. This trend needs to be explored further to understand the reasons behind it. It has been noted that scanning surveillance submissions for postmortem examination have also dropped which might reflect sector market forces and increasing costs. Within this area of work the main reduction reflects decreased lead poisoning incidents.
Lead incidents
An incident is recorded where the kidney or liver lead concentrations exceed 0.5 parts per million (ppm) wet matter (WM), muscle lead concentration exceeds 0.1ppm WM, bulk milk lead concentration exceeds 0.02ppm or blood lead concentration exceeds 0.48µmol/l (ppm equates to mg/kg).
Most incidents arise from cases that are submitted to APHA following animal disease outbreaks. APHA receives clinical samples or carcases for investigation enabling confirmation of lead poisoning. However, occasionally as a result of laboratory testing, we come across high blood or tissue lead levels that, although not high enough to cause clinical signs of poisoning, are still important in terms of food residues and food safety.
Risk management measures for lead incidents involve:
- Removal of animals from the source of lead.
- The implementation of a 16-week voluntary withdrawal from slaughter. Should emergency slaughter of any of the clinically unaffected cattle in the exposed group be required during the restriction period then the animal should be accompanied by food chain information stating that offal should be discarded.
- Further blood sampling for blood lead analysis. This is used as a biomarker of internal (carcase) lead residues. Should the animals be close to or at finishing weight or producing milk for dairy products, the following risk management guidance parameters should be considered.
- Bulk tank milk requires monitoring if there is evidence of exposure of milking cows to lead. The lead concentration of bulk tank milk must remain below 20 parts per billion. If there is initially uncertainty at the start of an incident then bulk tank milk must be held to allow for testing or milk discarded.
- Blood lead concentrations of < 0.15 µmol/l: no restrictions required.
- Blood lead concentrations of 0.15 µmol/l to 0.48 µmol/l: provide food chain information (FCI) to the abattoir and ensure offal is discarded. Bulk tank milk is likely to remain compliant.
- Blood lead concentrations of > 0.48 µmol/l: provide food chain information to the abattoir, ensure offal is discarded and make an additional risk assessment as to whether carcase meat requires testing prior to carcase release into the food chain.
- Blood lead concentrations of >1.21 µmol/l: clinical toxicity is likely. Ideally a further withdrawal period should be observed. If slaughter is essential, then provide FCI to the abattoir ensuring offal is discarded and that carcase meat is tested for lead residues prior to carcase release into the food chain.
Lead incidents in cattle
FSI 2022-008
Lead poisoning was confirmed to be the cause of neurological signs and death of a few cattle in a spring calving organic dairy herd consisting of 180 milkers (the heifer followers and younger stock were on a different farm and not exposed). All 180 milking cows were paddock grazed and had access to a point source of lead via a battery for 2 days. The first two cows were clinically affected on day 2, 2 more a day later, and one other 4 days after exposure. Only one of these was found dead with the rest showing neurological signs originally suspected to be staggers, but later described as typical lead poisoning by the private veterinary surgeon. The milk purchasers were immediately informed so that milk could be held and a risk assessment undertaken. All the cattle contributing to the bulk tank milk were blood sampled to establish the extent of lead exposure. Fortunately the blood results confirmed that exposure was limited to a few cattle in the milking herd and because of this it seemed unlikely that the bulk tank milk would have, at any time, failed to meet the regulatory limit for lead of 0.02mg/kg. The results confirmed that the clinically unaffected cows could continue to be milked with food safety restrictions applied to exposed individual cattle for meat and offal only in accordance with usual risk advice.
FSI 2022-009
Lead poisoning was diagnosed following postmortem examination of a 15-month-old dairy heifer. The animal initially presented with neurological signs but later died. None of the rest of the original group of 10 appeared affected. There was no obvious gross postmortem pathology evident except that there were swollen cerebral hemispheres. Analysis of kidney tissue gave a lead concentration of 24mg/kg wet weight. The source of lead was confirmed as a lead acid battery. The battery was in site where the farmer’s neighbour had bonfires. The cattle were moved away from the source. The remaining 9 cattle were blood tested for lead and exposure to lead at a low level was confirmed in 3 others. There was no immediate food safety risk as the cattle were intended for milking following calving. The farmer agreed to a 16-week restriction of the 3 exposed cattle following which further blood samples will be taken to establish whether longer term risk management measures are required.
FSI 2022-011
Lead poisoning was diagnosed as the cause of death of a 6-month old bullock. The bullock showed clinical nervous signs prior to death. In a group of 60, 6 animals died within a week of moving onto this pasture. The blood lead concentration of one affected animal was 4.75µmol/l, confirming lead poisoning. The group of cattle were removed from this pasture and no further cases occurred. An on farm postmortem was carried out. No notable gross pathology was observed but pieces of plastic were found in rumen. There were no pieces of battery plate. Battery parts/plates were subsequently found in field by the farmer. The pasture was last used by another batch of cattle over 6 months ago without mishap. However, since then, the pasture has been ‘cultivated’ involving breaking up the surface with a type of shallow plough which is believed to have broken the battery. The field is roughly 40 acres and the battery parts found in an area of 1 or 2 acres, close to the end of a lane. The farmer believes the batteries along with other plastic items were fly tipped there. The farmer is attempting to clear pasture with metal detectors before considering re-stocking, and/or will fence off the area where the battery parts found. The farmer agreed to a 16-week restriction of the group following which further blood samples will be taken from a cohort of the group to assess whether there is evidence of subclinical exposure. The results of bloods will establish if longer term risk management measures are required.
Botulism
An incident is usually recorded when more than one animal is affected with clinical signs deemed typical of botulism and with no other explanatory diagnosis following veterinary investigation.
Most incidents arise from cases that are submitted to APHA and postmortem providers for postmortem examination following animal disease outbreaks. Some botulism cases are notified verbally especially when there is an obvious association with the use of broiler litter.
Risk management measures to protect the food chain during botulism incidents is as follows:
Clinically affected animals should not be presented for slaughter into the food chain, and neither should produce from clinically affected animals be used - recovered clinical cases should not be presented into the food chain for 17 days following recovery.
Botulism incidents
FSI 2022-010
APHA are investigating a recumbency issue in cattle where botulism initially could not be ruled out.
Two bullocks were submitted for postmortem examination following the loss of 5 animals showing nervous signs. The first animal died following a period of recumbency. It was not pyrexic and was thought to have had hindleg paralysis. Four other cattle were affected similarly over a few days. The cattle were fed on silage and grass and bakery waste (as dough). Limited minerals were fed. There is no history of poultry litter being used. Metabolic disease was considered to be a more likely differential diagnosis rather than botulism, with hypocalcaemia alongside hypomagnesaemia being high on the list of differentials. It was also thought that acidosis may have had a role in some of the presentations. Other considerations were ruminal dysbiosis due to the fat component of the dough. Saponification can occur and excess dietary fat can also lead to the formation of insoluble calcium salts. Blood testing of others in the herd was recommended and results supported hypomagnesaemia. As a precaution APHA initiated testing for botulinum toxin and also mycotoxins. Lead toxicity was ruled out.
Copper
Copper incidents
FSA/APHA incident trigger is when the liver copper concentration exceeds 500 mg/kg WM.
Especially in sheep, chronic copper poisoning can also occur when liver concentrations of copper are well below this incident trigger value. The same food safety advice is still provided. The APHA normal reference range for liver copper concentrations in cattle and sheep is approximately 300 to 8000 µmol/kg dry matter (DM), equivalent to approximately 5 to 125 mg/kg WM. Advice given is that copper supplementation is withdrawn from sheep where possible, additional forage fed and that a two-week withdrawal period is observed.
FSI 2022-007
A very high liver copper concentration consistent with copper toxicity was confirmed in a shearling ram. The ram was one of 4 that died over a month from an original group of 10.
A postmortem of the ram identified a yellow liver raising the possibility of copper toxicity. Liver was sent for analysis and the copper concentration analysed to be 39,900µmol/kg DM (approx. 638.4 mg/kg WM). There was no specific source of copper identified but the ram was on a high plane of nutrition with concentrates fed in order to prepare it for showing and sales. APHA provided advice on animal health and welfare and food safety, stating that a 2-week restriction should ideally be applied following the withdrawal or reduction of the concentrate feed and an increase in forage fed. Since the rams were intended for breeding there was no immediate risk to food safety.
Plant-related incidents
None reported.
In general, except for ragwort and bracken fern, plant toxicity incidents are not considered to pose a significant risk to the food chain.
Contact
Send any enquiries about this publication to:
- Alan Murphy: alan.murphy@apha.gov.uk
- Aidan Dryden: aidan.dryden@apha.gov.uk
- Lizzie Dunnett: elizabeth.dunnett@apha.gov.uk