Hi Arno, thanks! That’s a really good question. I’ll say upfront that I’ll be following-up with Open Phil over the coming weeks, and may have a better idea of what next steps look like then. Here’s my initial stab.
I think there’s three complementary approaches: 1) indirect public data/literature, 2) indirect government data, and 3) direct measurements.
I had a brief look at Google Scholar and there’s some interesting pieces of indirect evidence suggesting OP exposure might be a problem in Tanzania (I may be able to look into this in greater depth in the next few weeks): - Calista et al. (2022) appears to be an excellent and very recent source on the health effects of pesticide exposure in Tanzania, and identifies organophosphates as a concern. - Boedecker et al.’s (2020) systematic review of acute unintentional pesticide poisonings suggest severely high incidence in Tanzania with 76.35% of farmers experiencing it (among the highest results in all countries considered). Thailand, which was my reference for direct measurements of OP metabolites in the urine of pregnant women, had an incidence of 36%
- Mwevura et al. (2021) find organophosphate residues exceeding safety guidelines in soil, water, and sediment in the Rufiji River Delta in Tanzania - Bardner & Mcharo (2008) find that a moth species called L. meyricki, which is a pest for coffee crops, has developed general resistance to organophosphates in northern Tanzania. It appears a lot of other papers have been written about this, especially with respect to mosquito resistance as OPs have been used as vector control, e.g. mosquitoes, bedbugs. I think this is a tricky area. It might be hard to disentangle analysis of OPs used for farming vs. for vector control, and the use-practices, exposures, and cost-benefit analyses will differ. I didn’t look at vector control in depth in my article, partly because the benefits seem stronger and justifying regulation seems more difficult. - Ngowi (2002; dissertation) finds that most pestcides used in Tanzania are organophosphates. This dissertation is long but appears thorough and very relevant, although it is quite old. - Lekei et al. (2020) find that acute pesticide poisoning is common among women in Tanzania, and that organophosphates are the most important and most common type used. - Lekei et al. (2014) find that organophosphates are the second most common class of pesticide used in Tanzania - Lekei et al. (2014b) assessed farmer’s knowledge, practices, and experiences of exposure and found concerns, including widespread storage of pesticides in the home. This is also found by Manyilizu et al (2017). - Kapeleka (2020; thesis) found vegetables were highly contaminated with organophosphates in Tanzania. - Wylie et al. (2017) looked at urinary OP metabolites in 17 pregnant women in rural Ghana, which has a lower incidence of acute unintentional pesticide poisoning according to Boedecker et al. They found widespread exposure for specific OP metabolites with higher levels than non-pregnant U.S. cohort—but strangely, quite low levels for non-specific metabolites (they put this down to field conditions?)
FAO-STAT data is pretty coarse, but broadly suggests Tanzania is importing less hazardous pesticides over time (note however that many OP pesticides are not classified as highly hazardous). If you were collaborating with the government I would imagine that they may have much better data on import quantities and potentially usage of organophosphates specifically.
Much of the above is quite indirect. Ideally we would have good, large-sample, representative data showing levels of exposure in pregnant women in Tanzania. So far I haven’t seen such a study, although I think there were some of pesticide workers in the 1990s/early 2000s. This might suggest a natural next step—fund/organise a pilot study of urinary DAPs (or other measures) in Tanzanian pregnant women from several representative communities. As well as providing direct information to guide current action, it could also serve as the beginning of a longitudinal study to investigate the existence of a DNT effect in this context. Elikana Lekei is a Tanzanian academic whose name keeps coming up who might know a lot about this .
I hope that helps! As I said, I’ll have a better idea in coming weeks of how Open Phil might want to proceed, if indeed they do. My impression of briefly looking at the literature suggests the indirect evidence for OPs being a problem in Tanzania is strong, but there’s a lot more work to consider agricultural impact, regulatory environment, pesticide alternatives, etc, as well as considering the value of getting direct evidence. I also don’t know when and how approaches to government should be made, if indeed they should—but I hope others’ input will clarify things in the coming months.
I agree, that before trying to get them kaiboshed completely it would be very good to understand what that looks like for the ag space and what the alternatives are and how cost effective are they? From my knowledge of pesticide usage in Tz and SSA, there are definitely alternatives that exist in the market which are being used already to reasonable effect which indicates the alternatives are comparable on a price to efficacy level (smallholders wouldn’t spend money on these things if they don’t see some results).
Let me know how you’re moving forward on this, would be happy to chip in/help where possible as I think there’s some low hanging fruit that can be gotten based on my experience of the regulatory environment. Can get me on whatsapp +255763998637
Hi Arno, thanks! That’s a really good question. I’ll say upfront that I’ll be following-up with Open Phil over the coming weeks, and may have a better idea of what next steps look like then. Here’s my initial stab.
I think there’s three complementary approaches: 1) indirect public data/literature, 2) indirect government data, and 3) direct measurements.
I had a brief look at Google Scholar and there’s some interesting pieces of indirect evidence suggesting OP exposure might be a problem in Tanzania (I may be able to look into this in greater depth in the next few weeks):
- Calista et al. (2022) appears to be an excellent and very recent source on the health effects of pesticide exposure in Tanzania, and identifies organophosphates as a concern.
- Boedecker et al.’s (2020) systematic review of acute unintentional pesticide poisonings suggest severely high incidence in Tanzania with 76.35% of farmers experiencing it (among the highest results in all countries considered). Thailand, which was my reference for direct measurements of OP metabolites in the urine of pregnant women, had an incidence of 36%
- Mwevura et al. (2021) find organophosphate residues exceeding safety guidelines in soil, water, and sediment in the Rufiji River Delta in Tanzania
- Bardner & Mcharo (2008) find that a moth species called L. meyricki, which is a pest for coffee crops, has developed general resistance to organophosphates in northern Tanzania. It appears a lot of other papers have been written about this, especially with respect to mosquito resistance as OPs have been used as vector control, e.g. mosquitoes, bedbugs. I think this is a tricky area. It might be hard to disentangle analysis of OPs used for farming vs. for vector control, and the use-practices, exposures, and cost-benefit analyses will differ. I didn’t look at vector control in depth in my article, partly because the benefits seem stronger and justifying regulation seems more difficult.
- Ngowi (2002; dissertation) finds that most pestcides used in Tanzania are organophosphates. This dissertation is long but appears thorough and very relevant, although it is quite old.
- Lekei et al. (2020) find that acute pesticide poisoning is common among women in Tanzania, and that organophosphates are the most important and most common type used.
- Lekei et al. (2014) find that organophosphates are the second most common class of pesticide used in Tanzania
- Lekei et al. (2014b) assessed farmer’s knowledge, practices, and experiences of exposure and found concerns, including widespread storage of pesticides in the home. This is also found by Manyilizu et al (2017).
- Kapeleka (2020; thesis) found vegetables were highly contaminated with organophosphates in Tanzania.
- Wylie et al. (2017) looked at urinary OP metabolites in 17 pregnant women in rural Ghana, which has a lower incidence of acute unintentional pesticide poisoning according to Boedecker et al. They found widespread exposure for specific OP metabolites with higher levels than non-pregnant U.S. cohort—but strangely, quite low levels for non-specific metabolites (they put this down to field conditions?)
FAO-STAT data is pretty coarse, but broadly suggests Tanzania is importing less hazardous pesticides over time (note however that many OP pesticides are not classified as highly hazardous). If you were collaborating with the government I would imagine that they may have much better data on import quantities and potentially usage of organophosphates specifically.
Much of the above is quite indirect. Ideally we would have good, large-sample, representative data showing levels of exposure in pregnant women in Tanzania. So far I haven’t seen such a study, although I think there were some of pesticide workers in the 1990s/early 2000s. This might suggest a natural next step—fund/organise a pilot study of urinary DAPs (or other measures) in Tanzanian pregnant women from several representative communities. As well as providing direct information to guide current action, it could also serve as the beginning of a longitudinal study to investigate the existence of a DNT effect in this context. Elikana Lekei is a Tanzanian academic whose name keeps coming up who might know a lot about this .
I hope that helps! As I said, I’ll have a better idea in coming weeks of how Open Phil might want to proceed, if indeed they do. My impression of briefly looking at the literature suggests the indirect evidence for OPs being a problem in Tanzania is strong, but there’s a lot more work to consider agricultural impact, regulatory environment, pesticide alternatives, etc, as well as considering the value of getting direct evidence. I also don’t know when and how approaches to government should be made, if indeed they should—but I hope others’ input will clarify things in the coming months.
Thanks for your interest and great question!
Nice one, thanks Ben! Will dig into these a bit!
I agree, that before trying to get them kaiboshed completely it would be very good to understand what that looks like for the ag space and what the alternatives are and how cost effective are they? From my knowledge of pesticide usage in Tz and SSA, there are definitely alternatives that exist in the market which are being used already to reasonable effect which indicates the alternatives are comparable on a price to efficacy level (smallholders wouldn’t spend money on these things if they don’t see some results).
Let me know how you’re moving forward on this, would be happy to chip in/help where possible as I think there’s some low hanging fruit that can be gotten based on my experience of the regulatory environment. Can get me on whatsapp +255763998637
Cheers!