NZ Dirty Dozen

Which foods in New Zealand are more likely to have pesticide residues?

Grapes, celery, a wide range of fruit, leafy greens, spring onions, cucumber and bread are all ranked in the top dozen of foods available in New Zealand which are more likely to contain pesticide residues. Close contenders behind this ‘dirty dozen’ are apples, spinach, olive oil, muesli, and tomatoes. Compared to previous dirty dozen editions, there are a number of foods which have not been analysed before and a number excluded simply because we rely on data produced by the Ministry of Primary Industries (MPI). Lemons, olive oil, pak choi, spring onion, tamarillos and walnuts are among foods that have not been analysed before. Plums, mandarins, raspberries and lettuce were in the previous dirty dozen, but because they have not been analysed since before 2009, we just don't know what the residues are like now. Surveys from later years continue to show multiple residues in grapes, celery, tomatoes, strawberries, and others such as kale (with a whopping 39 pesticides!), silverbeet, sweet peppers, pears, stone fruit such as cherries, nectarines and various berries. Of special mention is non-organic baby food, 32% had a total of 21 pesticides! (1) Generally we can say that fruit is more likely to contain pesticide residues along with salad vegetables, leafy greens and bread or indeed anything containing wheat, such as sausage rolls, cereal, pasta, biscuits etc.

What’s wrong with pesticide residues in food?

Should we be concerned about pesticide residues in food? Every mouthful of non-organic food we eat is also a cocktail of pesticides. Many of these pesticides have not been adequately tested to see what effects they may produce, particularly long term ones. The little testing that is carried out does not reflect actual human exposure to a multitude of chemicals, nor does it usually test the most vulnerable – the foetus and young child. We do not know enough about the effects of these chemicals in our food. However, there are various serious long term effects associated with particular pesticides that are found in our food, including endocrine or hormonal disruption, cancer, immune system suppression, nervous system damage, genetic damage and birth defects. We also know that various pesticides used to grow food have damaging effects on wildlife, polluting water, soil, air and the ecosystem.

How can pesticide residues in food be reduced?

If you buy organic at least the foods listed here, then you will be significantly reducing the pesticide load on your body. This is particularly so for infants and children, as they take in more food in proportion to their body weight than adults do, and they also tend to eat more of the types of food that are more heavily sprayed, such as fruit. Usually, washing, peeling and cooking can reduce the amount of pesticide residues, however some persist, going right through the food. Some studies also report that soaking in vinegar or a baking soda solution for 15-20 minutes and then rinsing can also reduce some pesticides.

The Dirty Dozen

Rank	Food	% with residues	No. of pesticides	Sample Size
1	Grapes	98.2	35	56
2	Celery	100	19	51
3	Bok/pak choi	95.7	21	47
4	Nectarines	100	15	36
5	Oranges	98.2	16	56
6	Strawberries	100	14	8
7	Spring onion	97.9	15	48
8	Lemons	92	20	50
9	Wheat: bread/all products	87.3	23	150
10	Cucumber	82.1	27	56
11	Pears	100	9	8
12	Broccoli	92.9	10	57

2014 analysis of government data from MPI: TDS 2009, FRSP 2009-2012 (1)

What about later results?

The last Total Diet Study (TDS) published in 2018, and the Food Residues Surveillance Programme (FRSP), published about every two years, seem to give similar results to those listed above. Unfortunately government reports written up in 2019 and later do not give complete details, with the effect that we are told only of residues above the Maximum Residue Limit (MRL), so we do not know how many of the samples had residues detected and how many pesticides were detected in which samples. Even before then, looking for the percentage of samples containing residues is very time-consuming. Results are always presented in the best possible way to reassure everyone that they can have confidence in our food supply and that they are doing their job well.

Children at special risk from pesticide residues

Dietary intake represents the major source of pesticide exposure for infants and children, concludes the authoritative National Research Council 1993 report Pesticides in the Diets of Infants and Children (2 ). This is backed up by a number of intervention studies around the world that have measured children’s urine, commonly for organophosphate metabolites, before and after eating organic food over a period of time, and usually the results have been dramatic and immediate (3). A very short video, “The Effect of Organic Food” usefully summarises one of these intervention studies with a Swedish family (4).

In 2007, over 200 scientists from around the world urged caution with toxic chemicals to protect foetuses and children from potential long-term health risks (5). Current policies often assume chemicals are safe until proven harmful, which benefits manufacturers over vulnerable children. Exposure to chemicals can lead to health issues like diabetes, ADHD, cancer, fertility problems, and obesity. Even tiny amounts of endocrine disruptors at key times can harm organ development. Reducing foetal exposure to organophosphate pesticides, specifically, could lower the risk of ADHD.

A brain-damaging pesticide - chlorpyrifos

A 2022 study found NZ children had high levels of chlorpyrifos, a brain-damaging organophosphate banned in 39 countries (6). It is found in a wide range of food in NZ including baby food, grapes, berries, peanut butter, anything containing wheat, tomatoes, avocados, pears, mandarins and various green vegetables (7).

Chlorpyrifos in food is unsafe for ALL POPULATIONS, concludes a US EPA reassessment of the insecticide in 2016 (8). This is especially so for children aged 1–2 years old, with exposure levels 14,000% above the safety threshold for food. In spite of all this, our petition to ban chlorpyrifos, presented to parliament in February 2023, is not being given priority by our Environmental Protection Agency.

If you think organic food is too expensive, remember that non-organic food does not include the cost of biodiversity loss and other environmental degradation. With organic food you pay the real cost for real food, and you give the grower a fairer return. By having organic food you support a system which better protects our children and the environment, and this system helps reduce climate change!

Updated October 2024

1. NZ government surveys: 2009 New Zealand Total Diet Study, NZ Food Residue Surveillance Programmes 2009-2012, all available at www.nzfsa.govt.nz. Results from several years were combined to produce sample sizes that were more robust for analysis. Note that wheat samples included bread, biscuits, bran flake cereal, cake, noodles, fish fingers, battered fish, meat pies, muffins, pasta, pizza, sausages, cereal wheat biscuits.

FRSP infants 2016: Survey of agricultural compound residues in commercial foods for infants and young children https://www.mpi.govt.nz/food-business/food-monitoring-surveillance/food-residues-survey-programme/documents-for-food-residues-survey-programme/

2. NRC 1993: National Research Council (1993) Pesticides in the Diets of Infants and Children, National Academy Press.

3. Hyland 2019: Hyland, C., Bradman, A., Gerona, R., Patton, S., Zakharevich, I., Gunier, R. B., & Klein, K. (2019). Organic diet intervention significantly reduces urinary pesticide levels in US children and adults. Environmental research, 171, 568-575. https://www.sciencedirect.com/science/article/pii/S0013935119300246

There are several other intervention studies from around the world. See, for example, the pdf https://www.safefood.org.nz/article/chlorpyrifos-petition-summary

4. https://www.safefood.org.nz/why-organic

5. Grandjean P et al (2007): The Faroes Statement: Human Health Effects of Developmental Exposure to Chemicals in Our Environment, Basic & Clinical Pharmacology & Toxicology, 102, 73–75.

6. Li 2022: Li, Y., Wang, X., McKenzie, J. F., Mannetje, A. T., Cheng, S., He, C., ... & Douwes, J. (2022). Pesticide exposure in New Zealand school-aged children: Urinary concentrations of biomarkers and assessment of determinants. Environment International, 163, 107206.

https://www.sciencedirect.com/science/article/pii/S0160412022001325

7. TDS 2016: Pearson, A., Gibbs, M., Lau, K., Edmonds, J., Alexander, D., & Nicolas, J. (2018). 2016 New Zealand total diet study. Ministry for Primary Industries (New Zealand);

FRSPs 2015-2019: FRSP infants: Food Residue Survey Programmes, Ministry for Primary Industries NZ.

https://www.mpi.govt.nz/food-business/food-monitoring-surveillance/food-residues-surveyprogramme/documents-for-food-residues-survey-programme/

8. USEPA 2016: Britton et al (2016) Chlorpyrifos: Revised Human Health Risk Assessment for Registration Review. EPA https://www.regulations.gov/document/EPA-HQ-OPP-2015-0653-0454

More references concerning chlorpyrifos are available in the pdf:

https://www.safefood.org.nz/article/chlorpyrifos-petition-summary